Arctic Sea Ice : Forum

Cryosphere => Arctic sea ice => Topic started by: Wherestheice on July 12, 2018, 07:46:32 AM

Title: When will the Arctic Go Ice Free?
Post by: Wherestheice on July 12, 2018, 07:46:32 AM
This thread is kinda like the one titled "How soon could we go ice free", but I am curious on everyone's thoughts on WHEN exactly the ice will melt to 1 Mil. Km...

Votes up for 15 days, 1 vote per user.
Title: Re: When will the Arctic Go Ice Free?
Post by: mostly_lurking on July 12, 2018, 08:55:19 AM
There is an error in this poll. No option for anything above 2100. Should have at least one option After 2100/not in foreseeable future/never.
Title: Re: When will the Arctic Go Ice Free?
Post by: Sleepy on July 12, 2018, 08:57:13 AM
Since you also asked for thoughts; thinking when we get our next moderate to strong La Nina, so between 2020-2025 was my choice.
Title: Re: When will the Arctic Go Ice Free?
Post by: RikW on July 12, 2018, 10:25:42 AM
I go for 2018-2020;

I can't believe this year will be the year, although the ice is falling apart in small parts quickly, the melt season will be too short/ freezing will start soon enough, but based on the graphs/ satelite numbers etc. I think the state of the ice is changing so fast the models overestimate ice-quality and it's much worse than it appears to be.

And even then I think/fear we will reach record low numbers end of august/ in september.
Title: Re: When will the Arctic Go Ice Free?
Post by: Wherestheice on July 12, 2018, 10:41:41 AM
There is an error in this poll. No option for anything above 2100. Should have at least one option After 2100/not in foreseeable future/never.

Edit made and you can change your vote, i'm guessing you were the vote for 2080-2100, so you can change now. 8)
Title: Re: When will the Arctic Go Ice Free?
Post by: mostly_lurking on July 12, 2018, 10:44:46 AM
There is an error in this poll. No option for anything above 2100. Should have at least one option After 2100/not in foreseeable future/never.

Edit made and you can change your vote, i'm guessing you were the vote for 2080-2100, so you can change now. 8)

Thnx :)  Doesn't seem to let me change at the moment.
Title: Re: When will the Arctic Go Ice Free?
Post by: Wherestheice on July 12, 2018, 10:45:59 AM
I'd prefer a 2023-2027 option :)

5 year increments for the 20's seemed best imo, 2025-2030 would fit your thoughts best id say. ;)
Title: Re: When will the Arctic Go Ice Free?
Post by: Wherestheice on July 12, 2018, 10:47:33 AM
There is an error in this poll. No option for anything above 2100. Should have at least one option After 2100/not in foreseeable future/never.

Edit made and you can change your vote, i'm guessing you were the vote for 2080-2100, so you can change now. 8)

Thnx :)  Doesn't seem to let me change at the moment.

Oh hmm, can you not remove your vote than re-vote?
Title: Re: When will the Arctic Go Ice Free?
Post by: Neven on July 12, 2018, 10:57:26 AM
I've edited the poll.

And voted 2030-2040.
Title: Re: When will the Arctic Go Ice Free?
Post by: Wherestheice on July 12, 2018, 10:58:41 AM
I've edited the poll.

And voted 2030-2040.

Thanks Neven!
Title: Re: When will the Arctic Go Ice Free?
Post by: oren on July 12, 2018, 11:07:08 AM
2025-2030. I would be very surprised if it didn't happen by 2030. I wouldn't be surprised if it came earlier.
Title: Re: When will the Arctic Go Ice Free?
Post by: Hefaistos on July 12, 2018, 11:55:41 AM
We need to move out of the solar minimum and we need a strong El Nino, I voted 2030-40
Title: Re: When will the Arctic Go Ice Free?
Post by: Richard Rathbone on July 12, 2018, 12:54:19 PM
Never. Under BAU 2030-2040, but I don't think there's that much BAU left.
Title: Re: When will the Arctic Go Ice Free?
Post by: Stephan on July 12, 2018, 12:58:51 PM
I expect 0 km² around 2025 ± 2 years. Therefore I chose the bin 2020-2025 for the 1M km² question.
Title: Re: When will the Arctic Go Ice Free?
Post by: Pmt111500 on July 12, 2018, 01:21:13 PM
Went for 2020-2025 to keep the middle finger of the right hand up...year 2022 was a projection before 2017 dissed the statistics and partial mechanism used to concoct the value. Really if the increased cloudiness over arctic can divert some of the oceanic heat accumulated in the tropics to be moved back to Tropics and then Southern hemisphere, this might be off by some tine.
Title: Re: When will the Arctic Go Ice Free?
Post by: DavidR on July 13, 2018, 02:20:13 AM
2020 - 2025 : Without a significant reduction in the average volume loss from one year to the next there is little chance of extent surviving beyond 2025.  The average decline in minimum volume has been 440 km^3 / year over the past 20 years, up from 161 km^3 / year over the previous 20 years.  If  that rate of decline continues the minimum volume will be around 1000 km^3 by  2025.

The average minimum over this decade has been 4920 km^3.  I expect that there will be at least one year in the next 8 where the volume minimum will drop sufficiently to take extent below 1M km^3.
Title: Re: When will the Arctic Go Ice Free?
Post by: Wherestheice on July 14, 2018, 02:26:43 AM
I voted 2020-2025, but with an El Niño likely developing, and the ice already in a bad state, I wouldn’t be surprised if next year is the “year”.
Title: Re: When will the Arctic Go Ice Free?
Post by: Sterks on July 14, 2018, 07:43:23 AM
Yeah I also feel that when the next Super Niño develops we may subsequently have a bad year or bad sequence of years for Arctic ice (superimposed to the gradual decline). 1998 may have started the slide down in the 2000's. Assisted by the super warm 2005 year. 2014-2015 Niño may have triggered the warm Winters of recent...
No vote, no idea when the next Super Niño will come.
Title: Re: When will the Arctic Go Ice Free?
Post by: Ken Feldman on July 19, 2018, 09:03:24 PM
I went for 2025 - 2030, assuming a 2012 like season (lots of early melt ponds followed by a GAC at exactly the wrong time) after another decade of increased volume losses. 

I think the first ice-free September will be followed by several strong rebound years due to the negative feedbacks associated with ice freezing, so we won't see repeated ice-free Septembers until the late 2030s or 2040s.  By that time, the Laptev will be more like the Atlantic than the Arctic in salinity, allowing more warm Atlantic water to flow into the central Arctic, which will bring too much heat into the Arctic to prevent ice free falls beyond the middle of this century.
Title: Re: When will the Arctic Go Ice Free?
Post by: litesong on July 20, 2018, 02:42:49 AM
Should have at least one option After 2100/not in foreseeable future/never.
Ah.... an AGW denier who knows the solar TSI will continue...into the foreseeable future/never..... at a subnormal irradiation level, as it has for the last 12+ years (including a 3+ year period setting a 100 year record low).
Title: Re: When will the Arctic Go Ice Free?
Post by: Wherestheice on July 20, 2018, 04:22:55 AM
Should have at least one option After 2100/not in foreseeable future/never.
Ah.... an AGW denier who knows the solar TSI will continue...into the foreseeable future/never..... at a subnormal irradiation level, as it has for the last 12+ years (including a 3+ year period setting a 100 year record low).

The chances of an ice free arctic not happening till then is probably really low anyways
Title: Re: When will the Arctic Go Ice Free?
Post by: Juan C. García on July 20, 2018, 04:40:11 AM
And voted 2030-2040.

Same as Neven [2030-2040].
And the same as my vote on when will PIOMAS be less than 1,000 km3.
Title: Re: When will the Arctic Go Ice Free?
Post by: Wherestheice on July 20, 2018, 06:07:19 AM
And voted 2030-2040.

Same as Neven [2030-2040].
And the same as my vote on when will PIOMAS be less than 1,000 km3.

I'm curious to know why both of you opine that period. Thanks.

Me as well
Title: Re: When will the Arctic Go Ice Free?
Post by: Wherestheice on July 20, 2018, 06:29:09 AM
And voted 2030-2040.

Same as Neven [2030-2040].
And the same as my vote on when will PIOMAS be less than 1,000 km3.

I'm curious to know why both of you opine that period. Thanks.

Me as well

My 'guess' is increasing cloudiness and snow cover due to a change in normal past arctic climate/weather from global climate changes .... but I don't like making assumptions or guesses as to what others think or why, so I asked.

Thats also the mainstream view in science. I think its safe to say it could happen next year or 22 years from now.
Title: Re: When will the Arctic Go Ice Free?
Post by: miki on July 20, 2018, 07:24:35 AM
Unless some real winter cold kicks in, I don't see how the arctic ice can go on to survive past the summer of 2022. Voted 2020-2025. Thanks, Neven.
Title: Re: When will the Arctic Go Ice Free?
Post by: slow wing on July 20, 2018, 11:06:30 AM
These polls keep coming up, I thought I just missed voting in one that looked like this.

This is an easy vote as I don't know the answer but the bin 2020-2025 spans 6 years in the near future. That's my choice.

It doesn't look like it is going to be this year, so the 2018-2020 bin only has two potentially realistic years and so can't compete with the 6 years in the second bin. The year 2020 is in both bins so the only year the first bin really has going for it is next year, 2019.

The bins after that are disfavored because the event may well have already happened prior to the years in those bins.


Comment: it looks a little strange to have the bins overlapping by one year. For example, the year  2020 is in both of the first 2 bins. This could have been avoided (and my vote made more difficult) by reducing the second bin to the 5-year interval 2021-25. Similarly, the later bins could be changed to begin in years starting with either a '1' or a '6'.

Also, the units should be km^2, not just km.
Title: Re: When will the Arctic Go Ice Free?
Post by: Wherestheice on July 20, 2018, 12:13:21 PM
These polls keep coming up, I thought I just missed voting in one that looked like this.

This is an easy vote as I don't know the answer but the bin 2020-2025 spans 6 years in the near future. That's my choice.

It doesn't look like it is going to be this year, so the 2018-2020 bin only has two potentially realistic years and so can't compete with the 6 years in the second bin. The year 2020 is in both bins so the only year the first bin really has going for it is next year, 2019.

The bins after that are disfavored because the event may well have already happened prior to the years in those bins.


Comment: it looks a little strange to have the bins overlapping by one year. For example, the year  2020 is in both of the first 2 bins. This could have been avoided (and my vote made more difficult) by reducing the second bin to the 5-year interval 2021-25. Similarly, the later bins could be changed to begin in years starting with either a '1' or a '6'.

Also, the units should be km^2, not just km.

Done
Title: Re: When will the Arctic Go Ice Free?
Post by: Dharma Rupa on July 30, 2018, 12:07:24 AM
“It is getting interesting.”

“Interesting” - is that what you call it when you reach the top of roller coaster, head down the slope at high speed, only to see that ahead of you there is no track?! - that it has been torn down!

As current volume trends continue, we are looking at the first ice free arctic September in 2022-23 plus or minus a few years. Subtract a year for breaking through the 1 million square kilometer “ice free” level.

After that, the wheels come off and we enter free fall. The atmospheric and oceanic circulations are already changing in major ways. Soon that will be dramatic. Not long after that the conditions will be properly described as extreme. And then to use your word - things get “exciting”.

Sadly, I am going to get to live long enough to see us all the way through to a year round ice free arctic. I am not looking forward to that, or to the inevitable droughts, pandemics, deluges, wars, disease, and climate catastrophes that will come with it.

I am only thankful that I will not live long enough to see an ice free Greenland.

I fully expect to die in the foregoing disasters long before then.

Sam

in general one can look at things the way you do but until we see year-round ice-free arctic it will take centuries IMO while ice free Augusts and Septembers are most probable to happen not too far out IMO.

I think a year round ice free Arctic is only a few decades away. We need to recognize that once we get the blue ocean event there will be rapid amounts of warming from the latent heat effect as well as loss of albedo that will inhibit ice from re-freezing. The age of ice in the Arctic is coming to an end.

I don't know when, but once it happens at all it happens every year for centuries (millenia?).
Title: Re: When will the Arctic Go Ice Free?
Post by: litesong on July 30, 2018, 12:38:18 AM
Should have at least one option After 2100/not in foreseeable future/never.
Ah.... an AGW denier who knows the solar TSI will continue...into the foreseeable future/never..... at a subnormal irradiation level, as it has for the last 12+ years (including a 3+ year period setting a 100 year record low).
The chances of an ice free arctic not happening till then is probably really low anyways
If the solar TSI remains low for a while longer, the Arctic will still be ice-free by 2020-2040. But, solar nuclear physics demands solar TSI WILL rise back to normal & higher, in the future. Then, AGW effects & feedbacks will take off at a rate, Earth economics can't adjust for, because wide ranging AGW deniers' propaganda has been at work for decades.
Title: Re: When will the Arctic Go Ice Free?
Post by: Sam on July 30, 2018, 12:59:49 AM
I agree with Wherestheice.

Based on current volume trends -
1st completely ice free September Arctic Ocean 2022-2023 +/- 2
1st completely ice free year-round Arctic Ocean 2035-2050
1st I’ve free Greenland & northern hemisphere 100-250 years after that
Maybe sooner - depending on feedbacks

If we trigger a catastrophic methane clathrate break, massive tundra fires ... the entire timescale could be compressed to a few years to an ice free arctic and less than a century for an ice free Greenland & northern hemisphere

About the only thing that will slow that at this point is the eruption of one of the twenty or so supervolcaneos. And that won’t stop it. It will only delay it for decades.

Sam
Title: Re: When will the Arctic Go Ice Free?
Post by: jdallen on July 30, 2018, 01:28:35 AM
I agree with Wherestheice.

Based on current volume trends -
1st completely ice free September Arctic Ocean 2022-2023 +/- 2
1st completely ice free year-round Arctic Ocean 2035-2050
1st I’ve free Greenland & northern hemisphere 100-250 years after that
Maybe sooner - depending on feedbacks
<snippage>
I think 2022-2023 is still early.  I'm putting thinking a sub-1 million KM2 September extent won't arrive until 2030 +/- a couple.

I don't think we'll see a year round ice free Arctic for at least a couple of centuries.  As long as there's 3 million+ KM3 of ice sitting on Greenland, combined with "cold continents"  I think most of the CAB will refreeze annually.
Title: Re: When will the Arctic Go Ice Free?
Post by: DavidR on July 30, 2018, 04:50:42 AM
I agree with Wherestheice.

Based on current volume trends -
1st completely ice free September Arctic Ocean 2022-2023 +/- 2
1st completely ice free year-round Arctic Ocean 2035-2050
1st I’ve free Greenland & northern hemisphere 100-250 years after that
Maybe sooner - depending on feedbacks
<snippage>
I think 2022-2023 is still early.  I'm putting thinking a sub-1 million KM2 September extent won't arrive until 2030 +/- a couple.

I don't think we'll see a year round ice free Arctic for at least a couple of centuries.  As long as there's 3 million+ KM3 of ice sitting on Greenland, combined with "cold continents"  I think most of the CAB will refreeze annually.

Ice Free, or Ice below 1M km^2 in September needs to be defined a bit more clearly obviously.  Sam is talking about an ice free September, ie 30 days with no ice. That is quite different from the accepted view of the benchmark being met when there are a few consecutive ice free days. 

For Ice Free I suggest having the NSIDC SIE 5 day average hitting 0 would be sufficient. For less than 1 M Km^2 the definition should be 5 consecutive days below 1M km^2.
Title: Re: When will the Arctic Go Ice Free?
Post by: Wherestheice on July 30, 2018, 08:03:22 AM
I agree with Wherestheice.

Based on current volume trends -
1st completely ice free September Arctic Ocean 2022-2023 +/- 2
1st completely ice free year-round Arctic Ocean 2035-2050
1st I’ve free Greenland & northern hemisphere 100-250 years after that
Maybe sooner - depending on feedbacks
<snippage>
I think 2022-2023 is still early.  I'm putting thinking a sub-1 million KM2 September extent won't arrive until 2030 +/- a couple.

I don't think we'll see a year round ice free Arctic for at least a couple of centuries.  As long as there's 3 million+ KM3 of ice sitting on Greenland, combined with "cold continents"  I think most of the CAB will refreeze annually.

I think it would be very surprising if the Arctic wasn't ice free year round after another 2-4 decades. The amount of heat that will be in the Arctic after it goes ice free is truly scary. All that energy that melts the ice.....once there is no more ice to melt it will make things hot, really hot, and that will make it hard for the ice to refreeze. We are already seeing these warm winters. I think the Arctic going ice free year round in a couple centuries seems to be the mainstream view, but things are changing very rapidly. I can't say I agree, but at the end of the day nature will play how it wants not my or your thoughts.
Title: Re: When will the Arctic Go Ice Free?
Post by: jdallen on July 30, 2018, 09:01:11 AM
I think it would be very surprising if the Arctic wasn't ice free year round after another 2-4 decades.
The main-stream view (a couple centuries+) has a 3 million KM3+ gorilla supporting it - The Greenland Ice Cap.

That mass of ice will dominate regional temperatures until it's gone. It will also dominate local circulation which along with the winter cold pool on the continents will create regional conditions sufficiently cold to permit enough heat to be dissipated in winter to permit local refreeze at the very least, if not a full refreeze of the ocean.  The behavior of the system annually will come to resemble that currently in play in regions like Hudson Bay, the Bering, the Okhostk and Labrador seas.

Even after that local conditions will probably permit freezing in the CAA and along the continental margins for even longer after that.
Title: Re: When will the Arctic Go Ice Free?
Post by: oren on July 30, 2018, 09:15:04 AM
I think it would be very surprising if the Arctic wasn't ice free year round after another 2-4 decades. The amount of heat that will be in the Arctic after it goes ice free is truly scary. All that energy that melts the ice.....once there is no more ice to melt it will make things hot, really hot, and that will make it hard for the ice to refreeze. We are already seeing these warm winters. I think the Arctic going ice free year round in a couple centuries seems to be the mainstream view, but things are changing very rapidly. I can't say I agree, but at the end of the day nature will play how it wants not my or your thoughts.
I disagree. Even with storms, clouds, humidity, fog and whatever not - when the sun doesn't shine for 6 months, with the vagaries of weather there will come a calm clear day when temps fall below -10oC, and the surface will freeze somewhere in the central arctic basin. IMHO what could prevent such freezing is a major change of arctic ocean circulation, which could well happen at some point but not in a few decades.
Title: Re: When will the Arctic Go Ice Free?
Post by: binntho on July 30, 2018, 09:52:40 AM
We already have parts of the arctic ice-free all year round, reaching up to above 80 degrees north of Svalbard.

The ocean currents are well able to maintain an ice-free state through 6 months of darkness, but as Oren points out, this would require quite some reconfiguration of the current currents (!) for the whole Arctic to become ice-free through winter.
Title: Re: When will the Arctic Go Ice Free?
Post by: DavidR on July 30, 2018, 10:15:06 AM
I think it would be very surprising if the Arctic wasn't ice free year round after another 2-4 decades.
I disagree. Even with storms, clouds, humidity, fog and whatever not - when the sun doesn't shine for 6 months, with the vagaries of weather there will come a calm clear day when temps fall below -10oC, and the surface will freeze somewhere in the central arctic basin. IMHO what could prevent such freezing is a major change of arctic ocean circulation, which could well happen at some point but not in a few decades.
I  come down on the side of a few decades before the Arctic will be ice free year round.  If we extrapolate from the volume decline the prediction is 2023 +- 2 for the first ice free summer days and 2053 for the first ice free year.  Currently the average year to year volume decline is still increasing.   If the trends are correct by 2035 we should see the Arctic Ice free from about July  1st.  That  means three months of insolation doing nothing but warming the ocean.  The combination of the extra heat in the ocean combined with more dynamic activities would seem to  suggest a shorter time to ice free all year rather than a longer period. 

If we look at how  fast SST's are increasing in the area above 80N+ , within 50 years they should be warm enough (> -10 degC in winter) to  prevent  much  ice forming.
Title: Re: When will the Arctic Go Ice Free?
Post by: Peter Ellis on July 30, 2018, 10:28:41 AM
The amount of heat that will be in the Arctic after it goes ice free is truly scary. All that energy that melts the ice.....once there is no more ice to melt it will make things hot, really hot, and that will make it hard for the ice to refreeze.
This applies to every seasonal ice zone in the world, and yet (to give but one example) Hudson Bay refreezes every winter.
Title: Re: When will the Arctic Go Ice Free?
Post by: binntho on July 30, 2018, 10:36:53 AM
The amount of heat that will be in the Arctic after it goes ice free is truly scary. All that energy that melts the ice.....once there is no more ice to melt it will make things hot, really hot, and that will make it hard for the ice to refreeze.
This applies to every seasonal ice zone in the world, and yet (to give but one example) Hudson Bay refreezes every winter.
Well, the Hudson doesn't have a major warm ocean current flowing into it - it is well inland (which means it has a continental climate with cold winters and warm summers) and the nearest warm ocean currents are very far away.
Title: Re: When will the Arctic Go Ice Free?
Post by: wili on July 30, 2018, 03:54:04 PM
"...what could prevent such freezing is a major change of arctic ocean circulation..."

Yes, that could be a part of it. Another could be an ever-more open Arctic Sea seeing ever bigger waves that stir the very salty warm lower layers of sea water up to the surface.

Also, atmospheric circulation bringing more and more warm up from the lower latitudes up to the Arctic is another dynamic we are likely to see (and are seeing already) that will drive  things in that direction.

I'm not saying that I know for sure when we will have a year-round ice-free (or nearly so) Arctic, but the Arctic has a way of surprising us, and any one factor (even sunless six-month winters) is never the only determinant of dynamics there.
Title: Re: When will the Arctic Go Ice Free?
Post by: gerontocrat on July 30, 2018, 04:17:47 PM
If the Paris Accord is implemented on time (??) then an Arctic with a lot less ice at all times of year (and zero in summer) seems the the most logical outcome for the rest of this century.

If the Paris Accord happens but a lot more slowly then an outcome as above but with longer periods of zero ice and even less ice in winter and happening sooner?

If it is BAU (both on CO2 emissions and economic growth), as above but even earlier and worse than above, until the crash comes. Those left standing will then see the Paris Accord implemented by force majeure.

And if all that methane in the highly organic sediments under the Eastern Siberian Ice Shelf and elsewhere are released ??????????

Timing - I have, do, and will plump for a BOE before 2030. But after one? two? three? more 2012 anomalies have happened ?

For anything else I might as well consult "The Book of Revelations".

And as Forrest Gump said - "And that's all I'm going to say about that".
Title: Re: When will the Arctic Go Ice Free?
Post by: Sam on July 30, 2018, 04:56:39 PM
Gerontocrat -

If we trigger the release of the ~1,600 gigatons of carbon in the methane and carbon stores of the Arctic planes and the tundra, it is game over. The earth will go to the hot earth stable state. The Arctic will melt rapidly. The Antarctic will take substantially longer, but will also completely melt before CO2 levels can reduce.

Once that happens, the Earth reenters a climate state that we do not understand how to model - the equable climate. That isn't a bad place once we get there. The pressure is higher along with O2 percentage (30%) and temperature. Wet forests burn in the rain. Giant insects become common as O2 transport becomes easy.

The problem is in getting there. In the interim, the oceans go anoxic. O2 levels plummet to 14%. Large animals die from insufficient O2 unless they have extreme high altitude adaptations. Iron falls out of the oceans. Shelled creatures all but vanish as the oceanic pH falls. All of the biomes are disrupted and most species die off leading to an evolutionary explosion as the survivors move to fill all of the vacant evolutionary niches.

In the end it becomes a massively good thing as new life flourishes on the graves of the last failed attempt. New adaptations take over and dominate.

The problem there is that we only have about 500 million years left to leave the Earth before we begin the terminal slide to a lifeless Earth as the goldilocjs zone moves outward with an ever hotter aging sun. By 750 million years, large life cannot exist. By a billion, life is done as the thermal runaway begins.
Title: Re: When will the Arctic Go Ice Free?
Post by: Sam on July 30, 2018, 05:23:40 PM
Btw-

The point here is that messing with high CO2 and CH4 levels is extremely dangerous. In gaming terms (and no thus isn't a game, that is the name used from studies that were developed during the Cold War), this is a "non zero sum game". And isn't the nice version where most or everyone wins. It is the nastiest version where nearly everyone loses.

Should we be so foolish as to push the Earth hard enough to trigger methane and tundra releases, the "game" is over. The Earth flips in a highly non-linear response to a wholly different environmental state - the hot Earth state. And in the long history of life on Earth, the greatest amount of time has been in either the hot Earth or cold Earth states. It has been relatively rare for the Earth to sit in a quasi stable condition between those two extremes.

The shift from one state to the another seems to always be catastrophic for life as it exists, but ultimately beneficial for life and evolution. Our existence as complex intelligent life may well be the direct result of these episodic catastrophes.

But that doesn't mean either that mankind will or would survive such a transition. Ignoring those risks and pumping immense stores of carbon into the atmosphere seems to be the major cause for transition to the hot Earth state, whether by asteroid impact, or supervolcanic flood basalt eruptions. 
Title: Re: When will the Arctic Go Ice Free?
Post by: magnamentis on July 30, 2018, 05:58:47 PM
I think it would be very surprising if the Arctic wasn't ice free year round after another 2-4 decades.
The main-stream view (a couple centuries+) has a 3 million KM3+ gorilla supporting it - The Greenland Ice Cap.

That mass of ice will dominate regional temperatures until it's gone. It will also dominate local circulation which along with the winter cold pool on the continents will create regional conditions sufficiently cold to permit enough heat to be dissipated in winter to permit local refreeze at the very least, if not a full refreeze of the ocean.  The behavior of the system annually will come to resemble that currently in play in regions like Hudson Bay, the Bering, the Okhostk and Labrador seas.

Even after that local conditions will probably permit freezing in the CAA and along the continental margins for even longer after that.

thank you for putting this so well and nicely, i just don't have the nerves for it ;)

IMO year round ice free in the dark season is a kind of sensationalism which is not helping the cause to make a majority aware of the seriousness of global warming of which arctic ice loss is only one of many consequences.
Title: Re: When will the Arctic Go Ice Free?
Post by: magnamentis on July 30, 2018, 06:02:38 PM
We already have parts of the arctic ice-free all year round, reaching up to above 80 degrees north of Svalbard.

The ocean currents are well able to maintain an ice-free state through 6 months of darkness, but as Oren points out, this would require quite some reconfiguration of the current currents (!) for the whole Arctic to become ice-free through winter.

each warm current has it's counterpart which is why svalbard can be ice-free and st. lawrence can be frozen.

same as above, seeking sensation IMO and it will never happen as long as the rest of the NH doesn't have temps above 30C in winter and that's a far way to go if possible at all.

after all everything is sun-powered and the sun is and will remain a low angles above 35 latitude.

we better stay realistic and find solutions that are feasible for what's probable or possible then drifting off into phantsylands.

to make it clear, i talk about year-round-icefree, not about ice-free in summer which is the topic of theis thread, there i'm in full agreement that it will happen more sooner than later while i don't like all the "interpretations"  for me ice-free is zero (no significant amounts) of ice left, evertyhing else sounds a bit like who is right instead of what is right.
Title: Re: When will the Arctic Go Ice Free?
Post by: sinocentric on July 30, 2018, 06:04:25 PM
I went with 2020-2025. I'm nowhere near an expert, and I do feel it's a bit aggressive, but that's my purely subjective opinion.

Here's a couple of thoughts I have on why:

1. From the American Geophysical Union (2013)https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/grl.50316 (https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/grl.50316):

Quote
observations and citations support the conclusion that most global climate model results in the CMIP5 archive are too conservative in their sea ice projections. Recent data and expert opinion should be considered in addition to model results to advance the very likely timing for future sea ice loss to the first half of the 21st century, with a possibility of major loss within a decade or two.

It seems to me that any date past 2050 is not supported by the current science. Obviously, things could change, but that's what it is for now. In addition, the projections now have a track record of being conservative on projections of melt.

Someone also mentioned the possibility that a destruction of "BAU", which I take to mean a major societal disruption, could stop the melt. That may be possible, but I'm skeptical of that. Even if that does occur, I remember this quote from the 2017 CSSR (https://science2017.globalchange.gov/chapter/executive-summary/):

Quote
over the next few decades (2021–2050), annual average temperatures are expected to rise by about 2.5°F for the United States, relative to the recent past (average from 1976–2005), under all plausible future climate scenarios

I also recently watched the NASA sea ice video, showing the loss of the older and thicker ice...this is subjective but the region just appears so fragile now. Seems like it wouldn't take too much of a negative development to get a day under 1 million. There's gonna be probably a couple record hot years between now and 2025, and I think one of them will get it done. 



Title: Re: When will the Arctic Go Ice Free?
Post by: GoSouthYoungins on July 30, 2018, 06:21:47 PM
The arctic going ice couldn't possibly have less to do with the Paris deal.  The warming we are feeling now is mostly from GHG emissions from decades ago. GHGs are like a lid on a pot; as the lid gets thicker the stuff in the pot gets warmer, but it takes some time...in this case probably 20-30 years. The warming we have seen so far is primarily from emissions up to 1990, so about 350 ppm.

There is also a serious lag due to ice melting. Stable climate conditions that would lead to zero ice wouldn't result in the change occurring in a single year. It would likely take at minimum a decade.  Our current GHG levels are plenty high for an ice free arctic (ocean), but we are in the lag phase.

Of course, we haven't stabilized GHG levels, and plans like the Paris deal only scratch the surface of the necessary solutions.  Unfortunately even people who do pay attention to the climate situation are somehow soothed into believing that if only we adopt Paris and then maybe a little more, we will avoid the worst. 

It is madness. Worse than pure denial of the entire situation. I'm less bothered by those who think it is all an elite globalist ploy to enslave the masses, than I am by those who engage with the data on a daily basis but come to the conclusion that mild solutions will be sufficient to save civilization.  OR for that matter those who think that it is no big deal to change the climate drastically and kill off humanity cuz the earth will bounce back.  Are we really going to successfully prevent nuclear war as everything falls apart? Are we really going to successfully decommission the hundreds of nuclear power plants around the world? Even if you aren't bothered by the collapse of civilization and the horrible deaths of billions of people, the possibility of turning the earth into a planet like venus or mars should give you some pause.

The only genuine solution would be for the entire world to embark on creating a global carbon-negative permaculture landscape. Global knowledge sharing could continue but global trade would be reduced to maybe 1% its current volume.  Ironically, everyone would be happier and healthier, but this is not an option...lets just adopt Paris, pat ourselves on the back, and when it all starts to burn blame somebody else.
Title: Re: When will the Arctic Go Ice Free?
Post by: magnamentis on July 30, 2018, 06:28:09 PM
The arctic going ice couldn't possibly have less to do with the Paris deal.  The warming we are feeling now is mostly from GHG emissions from decades ago. GHGs are like a lid on a pot; as the lid gets thicker the stuff in the pot gets warmer, but it takes some time...in this case probably 20-30 years. The warming we have seen so far is primarily from emissions up to 1990, so about 350 ppm.

There is also a serious lag due to ice melting. Stable climate conditions that would lead to zero ice wouldn't result in the change occurring in a single year. It would likely take at minimum a decade.  Our current GHG levels are plenty high for an ice free arctic (ocean), but we are in the lag phase.

Of course, we haven't stabilized GHG levels, and plans like the Paris deal only scratch the surface of the necessary solutions.  Unfortunately even people who do pay attention to the climate situation are somehow soothed into believing that if only we adopt Paris and then maybe a little more, we will avoid the worst. 

It is madness. Worse than pure denial of the entire situation. I'm less bothered by those who think it is all an elite globalist ploy to enslave the masses, than I am by those who engage with the data on a daily basis but come to the conclusion that mild solutions will be sufficient to save civilization.  OR for that matter those who think that it is no big deal to change the climate drastically and kill off humanity cuz the earth will bounce back.  Are we really going to successfully prevent nuclear war as everything falls apart? Are we really going to successfully decommission the hundreds of nuclear power plants around the world? Even if you aren't bothered by the collapse of civilization and the horrible deaths of billions of people, the possibility of turning the earth into a planet like venus or mars should give you some pause.

The only genuine solution would be for the entire world to embark on creating a global carbon-negative permaculture landscape. Global knowledge sharing could continue but global trade would be reduced to maybe 1% its current volume.  Ironically, everyone would be happier and healthier, but this is not an option...lets just adopt Paris, pat ourselves on the back, and when it all starts to burn blame somebody else.

of course you're right, the paris agreement has nothing to do with it because that train has left the station and there is no red signal, i mean ice-less summers in the arctic will happen.

further the paris agreement IMO is better than nothing because it means that slowly (too slowly) those in charge move into the right direction but the agreement as such as it is today is a toothless tiger and will have zero real-live effect while zero is not none, just smaller than 1 ;)

the fact that this agreement is mentioned so often makes it even counter productive because it's abused as an excuse and to sooth public opinion.

the agreement as such is useless because there are no means of enforcement, no penalties, no consequences if targets won't be reached and they are already not possible to reach by now.

IMO we should start talking "tacheless" and speak out that fact and ask for more, else they're getting away with it, nothing else than eyewash and keeping people in hope that's in vain, at least in it's current implementation.

now, just to remind the reader, i said above that it's better than nothing and that it's a move into the right direction, hence i'm not AGAINST it but it's not sufficient by far and should not be hyped.

all those acclamation were ok the first few months but now we have to take things a few steps further.

BTW, we've not reached the 2C and ice will be gone for good in summer soon and that will boost temps for sure and it will be abrupt, we gonna witness it most probably.
Title: Re: When will the Arctic Go Ice Free?
Post by: binntho on July 30, 2018, 06:28:50 PM
We already have parts of the arctic ice-free all year round, reaching up to above 80 degrees north of Svalbard.

The ocean currents are well able to maintain an ice-free state through 6 months of darkness, but as Oren points out, this would require quite some reconfiguration of the current currents (!) for the whole Arctic to become ice-free through winter.

each warm current has it's counterpart which is why svalbard can be ice-free and st. lawrence can be frozen.

Really? Is that a natural law? The often toted oceanic conveyor belt moves warm water along the surface, and cold water along the bottom. That's the "counterpart" - there is no reason why there should be cold surface "counterparts" to warm surface currents.

Besides, St. Lawrence is a very bad example, it hardly ever sees any ice, and when it does, it's usually stuff that drifts in from the north.
Title: Re: When will the Arctic Go Ice Free?
Post by: Dharma Rupa on July 30, 2018, 07:35:53 PM
Gerontocrat -

If we trigger the release of the ~1,600 gigatons of carbon in the methane and carbon stores of the Arctic planes and the tundra, it is game over. The earth will go to the hot earth stable state. The Arctic will melt rapidly. The Antarctic will take substantially longer, but will also completely melt before CO2 levels can reduce.

Once that happens, the Earth reenters a climate state that we do not understand how to model - the equable climate. That isn't a bad place once we get there. The pressure is higher along with O2 percentage (30%) and temperature. Wet forests burn in the rain. Giant insects become common as O2 transport becomes easy.

The problem is in getting there. In the interim, the oceans go anoxic. O2 levels plummet to 14%. Large animals die from insufficient O2 unless they have extreme high altitude adaptations. Iron falls out of the oceans. Shelled creatures all but vanish as the oceanic pH falls. All of the biomes are disrupted and most species die off leading to an evolutionary explosion as the survivors move to fill all of the vacant evolutionary niches.

In the end it becomes a massively good thing as new life flourishes on the graves of the last failed attempt. New adaptations take over and dominate.

The problem there is that we only have about 500 million years left to leave the Earth before we begin the terminal slide to a lifeless Earth as the goldilocjs zone moves outward with an ever hotter aging sun. By 750 million years, large life cannot exist. By a billion, life is done as the thermal runaway begins.

The problem with your argument is that if civilization isn't to collapse then the computers will have to take over and basically coat the Earth with a skin of Silicon, and they won't really care about Carbon-based life.

For a bunch of reasons, the only two choices are complete collapse and robotic ascendance.
Title: Re: When will the Arctic Go Ice Free?
Post by: gerontocrat on July 30, 2018, 07:59:19 PM

Someone also mentioned the possibility that a destruction of "BAU", which I take to mean a major societal disruption, could stop the melt. That may be possible, but I'm skeptical of that. Even if that does occur, I remember this quote from the 2017 CSSR (https://science2017.globalchange.gov/chapter/executive-summary/):

Quote
over the next few decades (2021–2050), annual average temperatures are expected to rise by about 2.5°F for the United States, relative to the recent past (average from 19762005), under all plausible future climate scenarios


"all plausible future climate scenarios". Now that needs thinking about. The world's future according to the decision-makers is built on a world economic growth assumption of 3 to 4 percent per annum growth. Future climate scenarios have this built in specifically (IPCC system) or even subconsciously by climate and other scientists in general. It is impossible to even suggest the possibility that this is hogwash without being labelled a doomsday nut. But this assumption is only a post WWII phenomenon as regards the world. China only got on the track in the early 1980's, India and many other Asian countries even later.

Look at the threads on forests, soil degradation, world ocean desertification (fish stocks), insect and other wildlife decline, water resources problems. I believe that severe economic disruption is a real possibility sometime not so far in the future. CO2 emissions did decline a bit in the financial crash of 2008 and its aftermath, and might decline much more in an era of world economic contraction.

My view is that there is a plausible future climate scenario where there is a significant change in humans impact on climate - we are in the anthropocene age, after all.

But that is likely to be after the first few instances of a BOE.

This time I really, really mean it - as Forrest Gump said - "And that's all I'm going to say about that".
Title: Re: When will the Arctic Go Ice Free?
Post by: bluesky on July 30, 2018, 08:02:55 PM
The arctic going ice couldn't possibly have less to do with the Paris deal.  The warming we are feeling now is mostly from GHG emissions from decades ago. GHGs are like a lid on a pot; as the lid gets thicker the stuff in the pot gets warmer, but it takes some time...in this case probably 20-30 years. The warming we have seen so far is primarily from emissions up to 1990, so about 350 ppm.

There is also a serious lag due to ice melting. Stable climate conditions that would lead to zero ice wouldn't result in the change occurring in a single year. It would likely take at minimum a decade.  Our current GHG levels are plenty high for an ice free arctic (ocean), but we are in the lag phase.

Of course, we haven't stabilized GHG levels, and plans like the Paris deal only scratch the surface of the necessary solutions.  Unfortunately even people who do pay attention to the climate situation are somehow soothed into believing that if only we adopt Paris and then maybe a little more, we will avoid the worst. 

It is madness. Worse than pure denial of the entire situation. I'm less bothered by those who think it is all an elite globalist ploy to enslave the masses, than I am by those who engage with the data on a daily basis but come to the conclusion that mild solutions will be sufficient to save civilization.  OR for that matter those who think that it is no big deal to change the climate drastically and kill off humanity cuz the earth will bounce back.  Are we really going to successfully prevent nuclear war as everything falls apart? Are we really going to successfully decommission the hundreds of nuclear power plants around the world? Even if you aren't bothered by the collapse of civilization and the horrible deaths of billions of people, the possibility of turning the earth into a planet like venus or mars should give you some pause.

The only genuine solution would be for the entire world to embark on creating a global carbon-negative permaculture landscape. Global knowledge sharing could continue but global trade would be reduced to maybe 1% its current volume.  Ironically, everyone would be happier and healthier, but this is not an option...lets just adopt Paris, pat ourselves on the back, and when it all starts to burn blame somebody else.

Agree with the fact that there is long hysteresis in global warming, i.e. we are still experiencing the consequence of 300 to 350 ppm of CO2, and agree with most of the remaining.
There have been a few research paper confirming that even if we would stop any greenhouse gas emission from today the Arctic sea ice would still continue to melt; The well publicised 2012 paper on El’gygytgyn lake temperature in North East Siberia, testimony that in the early Pleistocene the CO2 level was close to today 's level (so we need to go back almost 3 million years ago to find a similarly very high level of CO2) and the temperature in the Artic was approximately 8°C warmer than today, although the orbital (Milankovitch) cycle forcings were likely different. Also the most recent paper "Palaeoclimate constraints on the impact of 2° C anthropogenic warming and beyond" H Fischer et al, they state that the impact of a 1 to 2°C warming, so were we are in the moment including the hysteresis impact in the pipeline, lead to several centuries of substantial melting of Greenland and Antarctic ice sheet:

Abstract:
"Over the past 3.5 million years, there have been several intervals when climate conditions were warmer than during the preindustrial Holocene. Although past intervals of warming were forced differently than future anthropogenic change, such periods can provide insights into potential future climate impacts and ecosystem feedbacks, especially over centennial-to-millennial timescales that are often not covered by climate model simulations. Our observation-based synthesis of the understanding of past intervals with temperatures within the range of projected future warming suggests that there is a low risk of runaway greenhouse gas feedbacks for global warming of no more than 2 °C. However, substantial regional environmental impacts can
occur. A global average warming of 1–2 °C with strong polar amplification has, in the past, been accompanied by significant shifts in climate zones and the spatial distribution of land and ocean ecosystems. Sustained warming at this level has also led to substantial reductions of the Greenland and Antarctic ice sheets, with sea-level increases of at least several metres on millennial timescales. Comparison of palaeo observations with climate model results suggests that, due to the lack of certain feedback processes, model-based climate projections may underestimate long-term warming in response to future radiative forcing by as much as a factor of two, and thus may also underestimate centennial-to-millennial-scale sea-level rise."
http://eprints.esc.cam.ac.uk/4301/2/41561_2018_146_MOESM1_ESM.pdf



Title: Re: When will the Arctic Go Ice Free?
Post by: Ned W on July 30, 2018, 08:36:03 PM
There certainly is a lot of doom and gloom around here, as usual.  I'll dissent from that, with some predictions that don't involve the near-future collapse of civilization:

1. The first year with a sub-1 million km ice extent day will probably occur in the late 2020s or 2030s. 

2. Insofar as the past 40 years' reduction in September ice extent has induced some fairly subtle changes in northern hemisphere climate during the fall months, those changes will continue and get bigger as the ice extent at minimum shrinks, but there won't be any sudden game-changing effect from crossing the purely arbitrary 1,000,000 km2 threshold.

3. Subsequent years will bounce back (as 2013 did after the 2012 low) but extreme low-ice (under 1,000,000 km2) years will become more and more common until they are the rule, rather than the exception, probably by 2040 or so. 

4. The duration of that annual very-low-ice-extent period will expand during the second half of the century to produce first ice-free Septembers, then ice-free summers.  There won't be an ice-free year in this century, and probably not in the next, either.

5. There won't be any 50-GT "methane bomb".   There was none in the early Holocene when the Arctic Ocean was ice-free during summers.  There was none during the previous interglacial (MIS 5e), when the Arctic was quite warm.  There was none during interglacial MIS-11, when the Arctic was so warm for so long that virtually all the land ice in Greenland melted. 

6. An ice-free Arctic Ocean won't lead to the collapse of civilization. The Arctic is already halfway ice-free in September now, and the effects of that are not particularly civilization-imperiling.

Title: Re: When will the Arctic Go Ice Free?
Post by: bluesky on July 30, 2018, 08:40:19 PM
too late for the poll but would have hesitated between 2020-25 and 2026-30, even if it is later than the less optimistic, the situation is extremely dire as in the meantime Asia and Africa would have substantially increase its greenhouse gases emission leading to further hysteresis in the climate warming; while Europe, Japan and US would  have barely decreased theirs unless electrical cars replace combustion engine very quickly and everybody decide to equip his house/comdo  estate roof with solar panels, but I doubt it will happen seriously before 2030 - 2040, and not sure some lobbying energy conglomerate will allow massive equipment of solar panel (it will be their demise), besides, battery production might still be non environmental friendly…the issue of low cost air travel will still be around, electric lorries will take time to take off, together with freight boats, while permafrost could start to melt seriously after summer blue arctic event leading to uncontrollable warming (together with other numerous tipping point) … it could be that the hinderance from energy companies may lead to a carbone emitting production of electrical energy… We need a grassroot change, each of us should try to convince a couple of friends around us who do not know anything about climate change, and that they in turn convince a couple of friends. If 25% of the world population decide to change their way of life within the next couple of years, that could be the beginning of a  positive social awareness, a positive citizen tipping point… then it could spread massively
Title: Re: When will the Arctic Go Ice Free?
Post by: Steven on July 30, 2018, 08:56:48 PM
This applies to every seasonal ice zone in the world, and yet (to give but one example) Hudson Bay refreezes every winter.
Well, the Hudson doesn't have a major warm ocean current flowing into it - it is well inland (which means it has a continental climate with cold winters and warm summers) and the nearest warm ocean currents are very far away.

Laptev Sea is another example.  It is seasonally ice free, but it refreezes completely every year in October, even after strong melt seasons.  An interesting feature about Laptev Sea is that the ice edge in October usually expands from two directions: from the north (Central Arctic) as well as from the south (Siberian coast):


(https://i.imgur.com/ziQyk2V.png)


The freeze-up date in Laptev Sea has a long term trend of about 5 days per decade (see table below from Stroeve et al 2014 (https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2013GL058951)).  Clearly it's still a long way from perennially ice-free.



(https://i.imgur.com/SP1ks0i.png)
Title: Re: When will the Arctic Go Ice Free?
Post by: bluesky on July 30, 2018, 09:04:11 PM
There certainly is a lot of doom and gloom around here, as usual.  I'll dissent from that, with some predictions that don't involve the near-future collapse of civilization:

1. The first year with a sub-1 million km ice extent day will probably occur in the late 2020s or 2030s. 

2. Insofar as the past 40 years' reduction in September ice extent has induced some fairly subtle changes in northern hemisphere climate during the fall months, those changes will continue and get bigger as the ice extent at minimum shrinks, but there won't be any sudden game-changing effect from crossing the purely arbitrary 1,000,000 km2 threshold.

3. Subsequent years will bounce back (as 2013 did after the 2012 low) but extreme low-ice (under 1,000,000 km2) years will become more and more common until they are the rule, rather than the exception, probably by 2040 or so. 

4. The duration of that annual very-low-ice-extent period will expand during the second half of the century to produce first ice-free Septembers, then ice-free summers.  There won't be an ice-free year in this century, and probably not in the next, either.

5. There won't be any 50-GT "methane bomb".   There was none in the early Holocene when the Arctic Ocean was ice-free during summers.  There was none during the previous interglacial (MIS 5e), when the Arctic was quite warm.  There was none during interglacial MIS-11, when the Arctic was so warm for so long that virtually all the land ice in Greenland melted. 

6. An ice-free Arctic Ocean won't lead to the collapse of civilization. The Arctic is already halfway ice-free in September now, and the effects of that are not particularly civilization-imperiling.

1 Human kind is pushing the process in a way that the world has never experienced before. There is no scientific paper showing any time in paleoclimate when the greenhouse gases have increased so quickly. As James Hansen often say, we are doing a unique experiment at an extremely high speed

"Global mean atmospheric carbon dioxide (CO2) concentration has now passed 400 ppm, a level that last occurred about 3 million years ago, when global average temperature and sea level were significantly higher than today (high confidence). Continued growth in CO2 emissions over this century and beyond would lead to an atmospheric concentration not experienced in tens of millions of years (medium confidence). The present-day emissions rate of nearly 10 GtC per year suggests that there is no climate analog for this century any time in at least the last 50 million years (medium confidence)."
https://science2017.globalchange.gov/chapter/4/


And I think we are now in the process of tipping 410 ppm

2 therefore modelling the tipping points and when and how they are going to happen is dangerously uncertain

3 climate change is coming on top of other major environmental impacts very well described by Elizabeth Kolbert in the 6th extinction published in 2015

4 the tipping points are numerous (see below, and the Postdam Institut website) , and some are "modelled" (with high uncertainty) to be triggered at 2.5°c (e.g. the end of carbone sink role from the rain forest in the amazon... ocean acidification...) this could almost already be in the pipeline due to climate change hysteresis and the evident BAU path that we are continuing

5 There is a risk of multiple or sequential/cascading  tipping points could happen  in close sequences, this was pinpointed in the US climate assessment (chapter 15) to the US congress at the end of last year

6 As an exemple, the synchronicity of blue ocean Arctic sea triggering a much faster Greenland ice sheet melting and rapid permafrost melting increasing further greenhouse gases, with a potential rapid collapse of West Antartic ice sheet, is not to excluded post 2050. While simultaneous collapse of Amazon rain forest and ocean carbon sink is not to be excluded...

Tipping points:

https://www.youtube.com/watch?v=G25dGJ3yUYk
(even if I don't necessarily agree with all the interpretation from Paul Beckwith particularly SRM solar radiation management -probably not feasable-, this somewhat  tie with the great uncertainty pinpoint the US climate report)


https://www.pik-potsdam.de/services/infodesk/tipping-elements


Title: Re: When will the Arctic Go Ice Free?
Post by: sinocentric on July 30, 2018, 09:24:04 PM

Look at the threads on forests, soil degradation, world ocean desertification (fish stocks), insect and other wildlife decline, water resources problems. I believe that severe economic disruption is a real possibility sometime not so far in the future. CO2 emissions did decline a bit in the financial crash of 2008 and its aftermath, and might decline much more in an era of world economic contraction.

Just to be clear, I agree this is a possibility. I don't think the future is looking very bright for the world economy. However, from the CSSR again (https://science2017.globalchange.gov/chapter/4/ (https://science2017.globalchange.gov/chapter/4/)):

Quote
Even if existing concentrations could be immediately stabilized, temperature would continue to increase by an estimated 1.1°F (0.6°C) over this century, relative to 1980–1999.

Correct me if I'm wrong, but that seems to indicate that temperatures will continue to increase throughout the century even if we stop emissions. And we're already over 400 ppm. My guess is that we have enough C02 in the atmosphere to get an ice free day in the arctic, even if civilization collapsed totally tomorrow.
Title: Re: When will the Arctic Go Ice Free?
Post by: gerontocrat on July 30, 2018, 09:38:14 PM

Quote
Even if existing concentrations could be immediately stabilized, temperature would continue to increase by an estimated 1.1°F (0.6°C) over this century, relative to 1980–1999.

Correct me if I'm wrong, but that seems to indicate that temperatures will continue to increase throughout the century even if we stop emissions. And we're already over 400 ppm. My guess is that we have enough C02 in the atmosphere to get an ice free day in the arctic, even if civilization collapsed totally tomorrow.

Yes.
Title: Re: When will the Arctic Go Ice Free?
Post by: magnamentis on July 30, 2018, 09:53:09 PM
There certainly is a lot of doom and gloom around here, as usual.  I'll dissent from that, with some predictions that don't involve the near-future collapse of civilization:

1. The first year with a sub-1 million km ice extent day will probably occur in the late 2020s or 2030s. 

2. Insofar as the past 40 years' reduction in September ice extent has induced some fairly subtle changes in northern hemisphere climate during the fall months, those changes will continue and get bigger as the ice extent at minimum shrinks, but there won't be any sudden game-changing effect from crossing the purely arbitrary 1,000,000 km2 threshold.

3. Subsequent years will bounce back (as 2013 did after the 2012 low) but extreme low-ice (under 1,000,000 km2) years will become more and more common until they are the rule, rather than the exception, probably by 2040 or so. 

4. The duration of that annual very-low-ice-extent period will expand during the second half of the century to produce first ice-free Septembers, then ice-free summers.  There won't be an ice-free year in this century, and probably not in the next, either.

5. There won't be any 50-GT "methane bomb".   There was none in the early Holocene when the Arctic Ocean was ice-free during summers.  There was none during the previous interglacial (MIS 5e), when the Arctic was quite warm.  There was none during interglacial MIS-11, when the Arctic was so warm for so long that virtually all the land ice in Greenland melted. 

6. An ice-free Arctic Ocean won't lead to the collapse of civilization. The Arctic is already halfway ice-free in September now, and the effects of that are not particularly civilization-imperiling.

i'm generally with you but here we go with the arbitrary and man-made threshold of 1M km2

it's exactly as big of a problem as i always thought and future will prove.

you say there will be no sudden game change once reaching less than 1M km2 extent, you're right, which is why i say only close or quasi zero extent will cause that game change.

once there will be no ice left in mid-summer and exactly that year, once of a sudden, temps in the arctic will be driven up from the current 0C +/- a few to something like 10, 15 and perhaps even peaking at 20C and THAT my dear friends WILL BE a sudden change and have a huge impact on the following winters and the entire NH and later global.

all this is totally logical and the entire discussion about effects, scale as well as speed, could be almost entirely saved or at least reduced to the important parts once we would stop inventing arbitrary thresholds just to satisfy our lust for sensation (headlines)

the year the news will call it an ice-free arctic while we shall see 999999km2 of ice by naked eyes from above i'll lough out loudly.

IMO this 1M km2 thingy is ridiculous at best and very damaging most probably. that threshold will pass without major impact and after doomsday news abate people will say, you see, nothing happens and again we shall have to fight for awareness for something that WILL happen but
our impatience and the eagerness to call it as early as possible will spoil the effect and once
the day will come mankind will not be ready AGAIN and unfortunately it will be those who
do not have much capabilites left (timewise, moneywise, educationwise etc.) to make a change
and those who had it preferred to discuss in who is right and superlatives way.
Title: Re: When will the Arctic Go Ice Free?
Post by: miki on July 30, 2018, 10:14:48 PM
There certainly is a lot of doom and gloom around here, as usual.  I'll dissent from that, with some predictions that don't involve the near-future collapse of civilization:

1. The first year with a sub-1 million km ice extent day will probably occur in the late 2020s or 2030s. 

2. Insofar as the past 40 years' reduction in September ice extent has induced some fairly subtle changes in northern hemisphere climate during the fall months, those changes will continue and get bigger as the ice extent at minimum shrinks, but there won't be any sudden game-changing effect from crossing the purely arbitrary 1,000,000 km2 threshold.

3. Subsequent years will bounce back (as 2013 did after the 2012 low) but extreme low-ice (under 1,000,000 km2) years will become more and more common until they are the rule, rather than the exception, probably by 2040 or so. 

4. The duration of that annual very-low-ice-extent period will expand during the second half of the century to produce first ice-free Septembers, then ice-free summers.  There won't be an ice-free year in this century, and probably not in the next, either.

5. There won't be any 50-GT "methane bomb".   There was none in the early Holocene when the Arctic Ocean was ice-free during summers.  There was none during the previous interglacial (MIS 5e), when the Arctic was quite warm.  There was none during interglacial MIS-11, when the Arctic was so warm for so long that virtually all the land ice in Greenland melted. 

6. An ice-free Arctic Ocean won't lead to the collapse of civilization. The Arctic is already halfway ice-free in September now, and the effects of that are not particularly civilization-imperiling.

I'm basically ok with the above, but only if the global temperature anomalies stay as they are, and, possibly, if the rate of arctic and global warming "miraculously" inverts drastically its current course.

Otherwise, I do not see how the ice, on sea and on land, would make it past the end of the next century.
Title: Re: When will the Arctic Go Ice Free?
Post by: gerontocrat on July 30, 2018, 10:17:11 PM
There certainly is a lot of doom and gloom around here, as usual.  I'll dissent from that, with some predictions that don't involve the near-future collapse of civilization:

1. The first year with a sub-1 million km ice extent day will probably occur in the late 2020s or 2030s. 

5. There won't be any 50-GT "methane bomb".   There was none in the early Holocene when the Arctic Ocean was ice-free during summers.  There was none during the previous interglacial (MIS 5e), when the Arctic was quite warm.  There was none during interglacial MIS-11, when the Arctic was so warm for so long that virtually all the land ice in Greenland melted. 

6. An ice-free Arctic Ocean won't lead to the collapse of civilization. The Arctic is already halfway ice-free in September now, and the effects of that are not particularly civilization-imperiling.

1. I am going for mid 2020's based on PIOMAS volume trend plus a bit of a crash when the ice just gets too thin.

5. Methane Bombs ? probably not. Accelerated methane release ? A real possibility. Lots of posts on the methane thread in permafrost board from a few months ago - some real science there from Russian scientists based on field research.

6. An ice-free Arctic Ocean won't lead to the collapse of civilization. Who said it did ? (Not guilty, quoth I). I agree, but there is lots of other stuff going on where climate change is just making bad things being done by humans worse.
Title: Re: When will the Arctic Go Ice Free?
Post by: Stephan on July 30, 2018, 10:17:21 PM
When I understood Prof Beckwith correctly, the BOE does not stand for zero but for "less than a million" km² of sea ice. I do not know how scientists came to that number.
The problem is the coastal zone of Greenland. If you follow Espen's wonderful threads on individual glaciers you can see a lot of bays and fjords on almost all the eastern, northern and NW coast into which many glaciers flow. Many of these glaciers end up in these bays and fjords which seem to be almost all-year-round covered by fast ice. This is probably thicker and much more resilient towards melt than "usual" sea ice and its movement is blocked by islands, ice rises or other obstacles. Therefore they can not flow away as "usual" sea ice is able to. And the glaciers are permamently calving, adding new ice into these places.
The second point is the northern shore of Ellesmere island. Currents push ice towards this coast and even if most of the sea ice is gone remains will keep stuck there.
I have no idea how many km² of these bays and fjords will be still ice-covered even if the "usual" sea ice is gone (apart from the Ellesmere island). But it will be much more than only some thousand km². Climate deniers will - of course - point their fingers into this direction and blame us to publish another fake news.

The problem is - if BOE once happens it WILL change the weather, the currents and have an impact on the next freezing season. And it WILL then be too late for humanity to change their behaviour, their consumption, their energy needs etc. Probably it is already too late...
Title: Re: When will the Arctic Go Ice Free?
Post by: gerontocrat on July 30, 2018, 10:33:19 PM

The problem is the coastal zone of Greenland. If you follow Espen's wonderful threads on individual glaciers you can see a lot of bays and fjords on almost all the eastern, northern and NW coast into which many glaciers flow. Many of these glaciers end up in these bays and fjords which seem to be almost all-year-round covered by fast ice. This is probably thicker and much more resilient towards melt than "usual" sea ice and its movement is blocked by islands, ice rises or other obstacles. Therefore they can not flow away as "usual" sea ice is able to. And the glaciers are permanently calving, adding new ice into these places.


Greenland is surrounded by the Baffin, Greenland and Canadian Archipelago seas. The 2010's average total minimum extent for these 3 seas is under 0.6 million km2.  The fjords and bays on the Greenland coast are a small fraction of that, and sea ice data excludes the glaciers (not being sea ice).

The 1 million km2 figure is, I suspect designed to stop deniers looking to remaining odd bits of ice to deny a BOE. By then I think even the Koch brothers will have stopped financing climate denier organisations (they don't like wasting money).
Title: Re: When will the Arctic Go Ice Free?
Post by: Wherestheice on July 30, 2018, 10:39:13 PM
When the ice is where it’s At now or even in 2012, there is still enough ice to absorb most of the solar radiation, when that’s all gone where does the radiation go?? Into the twilight zone maybe?? No it goes into the ocean. Once that happens everything won’t be ok. What happens in the arctic doesn’t stay in the arctic. Our civilization is really close to collapsing. We’ve lost so much of the natural world, and yet we continue. The whole world is in debt, things are getting worse( if you can’t see that, than open your eyes). When that ice goes away enough for the solar radiation to be focused on the ocean, I think that’s gonna do it. I will admit that I could be wrong (and hope to be wrong btw), earth is a very unpredictable system. You just can’t keep shitting on your nest and not expect bad stuff to happen. Idk when the collapse of civilization will happen, but it looks to be sooner than later. Humans are an animal and yes it’s possible for us to go extinct, idk why people think we’re so special. We have smart brains, and 5 fingers, but we aren’t invincible. There is obviously a clear divide in opinion on this forum. I respect everyone’s views and thoughts because I believe that’s how science is truly learned.
Title: Re: When will the Arctic Go Ice Free?
Post by: GoSouthYoungins on July 30, 2018, 10:43:28 PM
There certainly is a lot of doom and gloom around here, as usual.  I'll dissent from that, with some predictions that don't involve the near-future collapse of civilization:

1. The first year with a sub-1 million km ice extent day will probably occur in the late 2020s or 2030s. 

2. Insofar as the past 40 years' reduction in September ice extent has induced some fairly subtle changes in northern hemisphere climate during the fall months, those changes will continue and get bigger as the ice extent at minimum shrinks, but there won't be any sudden game-changing effect from crossing the purely arbitrary 1,000,000 km2 threshold.

3. Subsequent years will bounce back (as 2013 did after the 2012 low) but extreme low-ice (under 1,000,000 km2) years will become more and more common until they are the rule, rather than the exception, probably by 2040 or so. 

4. The duration of that annual very-low-ice-extent period will expand during the second half of the century to produce first ice-free Septembers, then ice-free summers.  There won't be an ice-free year in this century, and probably not in the next, either.

5. There won't be any 50-GT "methane bomb".   There was none in the early Holocene when the Arctic Ocean was ice-free during summers.  There was none during the previous interglacial (MIS 5e), when the Arctic was quite warm.  There was none during interglacial MIS-11, when the Arctic was so warm for so long that virtually all the land ice in Greenland melted. 

6. An ice-free Arctic Ocean won't lead to the collapse of civilization. The Arctic is already halfway ice-free in September now, and the effects of that are not particularly civilization-imperiling.

It is not GLOOM and DOOM. It is only that way if people can't wrap their minds around the reality of the situation.

1. Rather optimistic. Ice could easily go sub 1 million in the next 5 years based on current trends in volume, Pacification related retreat, Atlantification related retreat, salinity encroachment, increased ocean temperature, increased atmospheric temperature, etc. The next serious El Nino will probably do the trick...just look at what is happening this year during neutral conditions.

2. Exponential function. The past 40 years of ice reduction in September are a result of GHG levels 20-40 years prior to that period. Which were hardly a deviation from historical trends. Since then we are 10 times further outside the semi-recent historical bounds. Obviously some random extent number threshold doesn't hold any real significance but that is totally moot in the larger context.

3. Ya, there will be some level variability. Again, so what? Totally moot. However, large scale melt and ocean mixing will be difficult to reverse.

4. WOW; 200 more years before the arctic could go ice free for the whole year. Yes, greenland may create a local effect which allows for some ice formation to its north for longer than the rest of the arctic but in general this idea is delusionally conservative. A simple extrapolation of current volume trends puts that timeline off by at least 150 years...without any lag and without any continued emission.

5. I agree. I think the giant methane burp idea is a little fanciful. I do think there will be a significant amount of methane released from permafrost that will cause short term and local effects which shouldn't be ignored.

6. An ice free arctic probably WILL lead to the collapse of civilization. As long as there is widespread ice in the arctic, the temperature stabilizer is in place. Once the arctic is a more typical ocean, this stabilizing dampener is gone, and the heat will kick into another year. Take a pistol with a trigger pull weight of 5 pounds. Pull it 3 pounds. Nothing happens. Are you comfortable putting the barrel in your mouth and doubling the pull force? Hyperbolic, yes. But reality is somewhere in between this and your extrapolation.  The north hemisphere will undergone almost unimaginable climate change once the ice mostly gone from the arctic. The northern ice cap will be drastically reduced and re-centered over greenland.  No computer can begin to accurately model the effects of a hemispheric cold center 15 degrees south of the pole. Russia will be the most severely and immediately effected, but the entire hemisphere where almost everyone happens to live will go into extreme climate chaos.
Title: Re: When will the Arctic Go Ice Free?
Post by: josh-j on July 30, 2018, 11:29:49 PM
4. WOW; 200 more years before the arctic could go ice free for the whole year. Yes, greenland may create a local effect which allows for some ice formation to its north for longer than the rest of the arctic but in general this idea is delusionally conservative. A simple extrapolation of current volume trends puts that timeline off by at least 150 years...without any lag and without any continued emission.
(My bold)

I'm not sure that a simple extrapolation of the trend is necessarily correct when talking about a complex system. Various posters here have highlighted the "slow decline" theory in which the decline slows because more open ocean in summer means more space for ice to grow in winter.
Title: Re: When will the Arctic Go Ice Free?
Post by: Dharma Rupa on July 30, 2018, 11:32:11 PM
once there will be no ice left in mid-summer and exactly that year, once of a sudden, temps in the arctic will be driven up from the current 0C +/- a few to something like 10, 15 and perhaps even peaking at 20C and THAT my dear friends WILL BE a sudden change and have a huge impact on the following winters and the entire NH and later global.

When there is no longer enough ice to Keep DMI 80N pinned to near 0 in Summer everything will have changed, and all the this or that KM are meaningless.

My point is that we don't have any reason to believe the flip will happen in Summer.  At least one possibility is that the formation of ice in the Fall will suck up the last of the "fresh" water and release the warm water below.

Title: Re: When will the Arctic Go Ice Free?
Post by: GoSouthYoungins on July 30, 2018, 11:50:39 PM
4. WOW; 200 more years before the arctic could go ice free for the whole year. Yes, greenland may create a local effect which allows for some ice formation to its north for longer than the rest of the arctic but in general this idea is delusionally conservative. A simple extrapolation of current volume trends puts that timeline off by at least 150 years...without any lag and without any continued emission.
(My bold)

I'm not sure that a simple extrapolation of the trend is necessarily correct when talking about a complex system. Various posters here have highlighted the "slow decline" theory in which the decline slows because more open ocean in summer means more space for ice to grow in winter.

I agree, a simple extrapolation is way too basic. My point is that claiming something far outside the current trend requires strong supporting evidence. The slow decline theory has some serious merit but there are plenty of factors that work in the other direction: continued increased GHG forcing from lag and from continued emissions being the largest or at least most certain.
Title: Re: When will the Arctic Go Ice Free?
Post by: magnamentis on July 31, 2018, 03:14:37 AM
once there will be no ice left in mid-summer and exactly that year, once of a sudden, temps in the arctic will be driven up from the current 0C +/- a few to something like 10, 15 and perhaps even peaking at 20C and THAT my dear friends WILL BE a sudden change and have a huge impact on the following winters and the entire NH and later global.

When there is no longer enough ice to Keep DMI 80N pinned to near 0 in Summer everything will have changed, and all the this or that KM are meaningless.

My point is that we don't have any reason to believe the flip will happen in Summer.  At least one possibility is that the formation of ice in the Fall will suck up the last of the "fresh" water and release the warm water below.

i understood that we have different views about what's possible but then just to point it out once, i very much appreciate your input because it would be foolish to not at least consider the apparently impossible. just wanted you to know that.

i disagree but with respect to your different views while we shall most probably hear (read) from each other, may it help to find the truth.

 ;)
Title: Re: When will the Arctic Go Ice Free?
Post by: binntho on July 31, 2018, 07:39:25 AM
This applies to every seasonal ice zone in the world, and yet (to give but one example) Hudson Bay refreezes every winter.
Well, the Hudson doesn't have a major warm ocean current flowing into it - it is well inland (which means it has a continental climate with cold winters and warm summers) and the nearest warm ocean currents are very far away.

Laptev Sea is another example.  It is seasonally ice free, but it refreezes completely every year in October, even after strong melt seasons.  An interesting feature about Laptev Sea is that the ice edge in October usually expands from two directions: from the north (Central Arctic) as well as from the south (Siberian coast):

Again it's the difference that a warm ocean current, or absence of same, can make. The Laptev Sea is on similar latitudes to Svalbard and the surrounding ocean. One freezes solid each year, the other has had an almost totally ice-free winter. Both receive the same amount of insolation, but vastly different heat inputs from the oceans.

There have been some signs (more based on guesswork and satellite observations than direct measurements) that the warm tongue of the North Atlantic Current part of the Gulf Stream is creeping ever farther north, and perhaps to the east along the continental margin.

A scenario of year-round ice-free Arctic can only be reached (IMO) by further a northward reach of the warm ocean currents. Whether this is something that will happen, I've no idea. The Arctic has frozen every winter for the last 47 million years (according to a paper I read yesterday), and I guess it will take quite a lot to make it stop!
Title: Re: When will the Arctic Go Ice Free?
Post by: wili on July 31, 2018, 08:16:36 AM
And don't forget: https://en.wikipedia.org/wiki/Polar_stratospheric_cloud
Title: Re: When will the Arctic Go Ice Free?
Post by: liefde on August 01, 2018, 12:09:54 AM
warming we are feeling now is mostly from GHG emissions from decades ago. GHGs are like a lid on a pot; as the lid gets thicker the stuff in the pot gets warmer, but it takes some time...in this case probably 20-30 years. The warming we have seen so far is primarily from emissions up to 1990, so about 350 ppm.
Actually, no, that's not true; http://iopscience.iop.org/article/10.1088/1748-9326/9/12/124002;jsessionid=BC6F9B408139804AB3587C183EE22AAC.c1.iopscience.cld.iop.org

Maximum warming occurs a median of 10.1 years after the CO2 emission event and has a median value of 2.2 mK GtC−1.
Title: Re: When will the Arctic Go Ice Free?
Post by: Dharma Rupa on August 01, 2018, 12:17:53 AM
warming we are feeling now is mostly from GHG emissions from decades ago. GHGs are like a lid on a pot; as the lid gets thicker the stuff in the pot gets warmer, but it takes some time...in this case probably 20-30 years. The warming we have seen so far is primarily from emissions up to 1990, so about 350 ppm.
Actually, no, that's not true; http://iopscience.iop.org/article/10.1088/1748-9326/9/12/124002;jsessionid=BC6F9B408139804AB3587C183EE22AAC.c1.iopscience.cld.iop.org

Maximum warming occurs a median of 10.1 years after the CO2 emission event and has a median value of 2.2 mK GtC−1.
A quick glance says that is a model study.  Care to demonstrate any skill at all in the models?
Title: Re: When will the Arctic Go Ice Free?
Post by: liefde on August 01, 2018, 12:32:40 AM
A scenario of year-round ice-free Arctic can only be reached (IMO) by further a northward reach of the warm ocean currents.
I keep reading this dreamy misconception everywhere. People seem to be forgetting about the fact that the quantity of heat energy required to melt 1kg of ice (of just below freezing) to 1kg of water (of just above freezing) would raise the temperature of that same 1 kg of water to 80 degrees Celsius. This means that as soon as ice is gone, and there is heat energy (i.e. Sunlight), the oceans will be very hot at the surface (provided that surface T will also keep on rising as it does) all around the Arctic circle. It already is super anomalously warm, by the way. So when the sun is gone at the polar caps, all it needs is a little flow from warmer lower ocean currents to keep it from freezing up, and/or surface winds blowing the warmer (sun-heated) waters Northwards. Considering all the additional feedbacks, I'd say year round ice free poles could be a reality around 2035 at the very latest.
Title: Re: When will the Arctic Go Ice Free?
Post by: Dharma Rupa on August 01, 2018, 12:37:33 AM
A scenario of year-round ice-free Arctic can only be reached (IMO) by further a northward reach of the warm ocean currents.
I keep reading this dreamy misconception everywhere. People seem to be forgetting about the fact that the quantity of heat energy required to melt 1kg of ice (of just below freezing) to 1kg of water (of just above freezing) would raise the temperature of that same 1 kg of water to 80 degrees Celsius. This means that as soon as ice is gone, and there is heat energy (i.e. Sunlight), the oceans will be very hot at the surface (provided that surface T will also keep on rising as it does) all around the Arctic circle. It already is super anomalously warm, by the way. So when the sun is gone at the polar caps, all it needs is a little flow from warmer lower ocean currents to keep it from freezing up, and/or surface winds blowing the warmer (sun-heated) waters Northwards. Considering all the additional feedbacks, I'd say year round ice free poles could be a reality around 2035 at the very latest.

Don't know when, though I suspect soon, but with the first Summer the DMI 80N isn't pinned to nearly 0c the ice will not return for at least millennia.
Title: Re: When will the Arctic Go Ice Free?
Post by: liefde on August 01, 2018, 12:41:00 AM
A quick glance says that is a model study.  Care to demonstrate any skill at all in the models?
Assuming you can read; Care to read it again?
https://www.youtube.com/watch?v=JBe60pVAePY
Title: Re: When will the Arctic Go Ice Free?
Post by: Dharma Rupa on August 01, 2018, 02:07:24 AM
A quick glance says that is a model study.  Care to demonstrate any skill at all in the models?
Assuming you can read; Care to read it again?


No.  I only pay attention to studies which have a demonstrated skill; which includes zero Global modeling studies.
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on August 01, 2018, 02:51:31 AM

Actually, no, that's not true; http://iopscience.iop.org/article/10.1088/1748-9326/9/12/124002;jsessionid=BC6F9B408139804AB3587C183EE22AAC.c1.iopscience.cld.iop.org

Maximum warming occurs a median of 10.1 years after the CO2 emission event and has a median value of 2.2 mK GtC−1.

Seems to use lots of different models, so I doubt that is much of a problem.

I could easily be misunderstanding, but my impression is that the oceans take hundreds of years to warm up. So how is this study arriving at maximum warming after 10.1 years?

I am not sure, but suspect this study is putting 100GtC into atmosphere. Half of that gets absorbed by oceans fairly quickly; practically too quickly for heating effect to be noticed before it is gone but then land, weathering, other sinks and new ocean water coming to the surface take up more of the carbon over various timescales. So the carbon level reaches its peak very quickly and then declines.

So I believe there is lots more heating to come as the oceans warm up but in the study there is probably fairly steady declining CO2 levels as time goes on. The ocean warming is most rapid to start with but slows down over time. Consequently after 10.1 years the declining CO2 level becomes more important than the ocean heating so there is a slow net cooling.

If I am understanding correctly:

The pulse injection followed by declining CO2 levels in this study may be interesting, but that is not what has happened and if you want to know what happens if we stabilise GG levels, then there is decades if not hundreds of years of warming to come, at declining rates, assuming other things also stay constant.

Emissions for next 1 or 10 years have some effect but compared to effects of past 50+years all still working to warm the oceans, current emissions are small and don't have much effect for some time. Rework the numbers with 20 years of rapid emission changes and then you start to see noticeable effect.

I don't think the study is wrong, but you are being mislead by it.
Title: Re: When will the Arctic Go Ice Free?
Post by: oren on August 01, 2018, 03:48:22 AM
A scenario of year-round ice-free Arctic can only be reached (IMO) by further a northward reach of the warm ocean currents.
I keep reading this dreamy misconception everywhere. People seem to be forgetting about the fact that the quantity of heat energy required to melt 1kg of ice (of just below freezing) to 1kg of water (of just above freezing) would raise the temperature of that same 1 kg of water to 80 degrees Celsius. This means that as soon as ice is gone, and there is heat energy (i.e. Sunlight), the oceans will be very hot at the surface (provided that surface T will also keep on rising as it does) all around the Arctic circle. It already is super anomalously warm, by the way. So when the sun is gone at the polar caps, all it needs is a little flow from warmer lower ocean currents to keep it from freezing up, and/or surface winds blowing the warmer (sun-heated) waters Northwards. Considering all the additional feedbacks, I'd say year round ice free poles could be a reality around 2035 at the very latest.

Don't know when, though I suspect soon, but with the first Summer the DMI 80N isn't pinned to nearly 0c the ice will not return for at least millennia.
liefde and DR your arguments sound right, but then again all the seasonally ice-free seas undergo the same summer heating only to freeze up again during winter. Such behavior is not going to go away the first year the arctic ocean gets above the DMI chart.
Title: Re: When will the Arctic Go Ice Free?
Post by: GoSouthYoungins on August 01, 2018, 05:04:36 AM

Actually, no, that's not true; http://iopscience.iop.org/article/10.1088/1748-9326/9/12/124002;jsessionid=BC6F9B408139804AB3587C183EE22AAC.c1.iopscience.cld.iop.org

Maximum warming occurs a median of 10.1 years after the CO2 emission event and has a median value of 2.2 mK GtC−1.

Ya, despite the Carnegie Institution for Science seeming very sciency and legit, this article doesn't make a lick of sense. It is all based on models and doesn't correspond to the history of how earth works. Not that that ever seems to bother the modelers, or those who reference their work.

The purported purpose of the study is to determine how long the lag in warming is for our real world, but then the scenario they choose to model is insanely unlike the situation we are actually. But let's just cut to the chase and look at why the conclusion is malarkey...

If we are currently experiencing the effects of warming from CO2 emissions up to 2008 (to slightly simply things), then 380 ppm should correspond to about 1C temperature rise. SO SO SO SO SO WRONG. Last time concentrations were that high was a few million years ago and the temperature was significantly higher, sea level was significantly higher, and there wasn't any significant ice in the northern hemisphere. More recently, the co2 to temperature correlation would suggest at least 5C of warming from a 280 to 380 increase.

Title: Re: When will the Arctic Go Ice Free?
Post by: Wherestheice on August 01, 2018, 07:00:30 AM

Actually, no, that's not true; http://iopscience.iop.org/article/10.1088/1748-9326/9/12/124002;jsessionid=BC6F9B408139804AB3587C183EE22AAC.c1.iopscience.cld.iop.org

Maximum warming occurs a median of 10.1 years after the CO2 emission event and has a median value of 2.2 mK GtC−1.

Ya, despite the Carnegie Institution for Science seeming very sciency and legit, this article doesn't make a lick of sense. It is all based on models and doesn't correspond to the history of how earth works. Not that that ever seems to bother the modelers, or those who reference their work.

The purported purpose of the study is to determine how long the lag in warming is for our real world, but then the scenario they choose to model is insanely unlike the situation we are actually. But let's just cut to the chase and look at why the conclusion is malarkey...

If we are currently experiencing the effects of warming from CO2 emissions up to 2008 (to slightly simply things), then 380 ppm should correspond to about 1C temperature rise. SO SO SO SO SO WRONG. Last time concentrations were that high was a few million years ago and the temperature was significantly higher, sea level was significantly higher, and there wasn't any significant ice in the northern hemisphere. More recently, the co2 to temperature correlation would suggest at least 5C of warming from a 280 to 380 increase.

Well we haven’t gotten to 5c yet??
Title: Re: When will the Arctic Go Ice Free?
Post by: jdallen on August 01, 2018, 08:50:16 AM
That "yet" word again 😉
Title: Re: When will the Arctic Go Ice Free?
Post by: Wherestheice on August 01, 2018, 09:01:36 AM
That "yet" word again 😉

haha. Climate science is a field of "Yet's". We can all project and predict, until the "yet's" start happening.
Title: Re: When will the Arctic Go Ice Free?
Post by: Wherestheice on August 01, 2018, 09:05:17 AM
That "yet" word again 😉

At the end of the day, nothing is under our control. Maybe nature decides to kill off humans, or maybe not. Only one way to find out, lol.
Title: Re: When will the Arctic Go Ice Free?
Post by: Wherestheice on August 01, 2018, 09:14:34 AM

Actually, no, that's not true; http://iopscience.iop.org/article/10.1088/1748-9326/9/12/124002;jsessionid=BC6F9B408139804AB3587C183EE22AAC.c1.iopscience.cld.iop.org

Maximum warming occurs a median of 10.1 years after the CO2 emission event and has a median value of 2.2 mK GtC−1.

Ya, despite the Carnegie Institution for Science seeming very sciency and legit, this article doesn't make a lick of sense. It is all based on models and doesn't correspond to the history of how earth works. Not that that ever seems to bother the modelers, or those who reference their work.

The purported purpose of the study is to determine how long the lag in warming is for our real world, but then the scenario they choose to model is insanely unlike the situation we are actually. But let's just cut to the chase and look at why the conclusion is malarkey...

If we are currently experiencing the effects of warming from CO2 emissions up to 2008 (to slightly simply things), then 380 ppm should correspond to about 1C temperature rise. SO SO SO SO SO WRONG. Last time concentrations were that high was a few million years ago and the temperature was significantly higher, sea level was significantly higher, and there wasn't any significant ice in the northern hemisphere. More recently, the co2 to temperature correlation would suggest at least 5C of warming from a 280 to 380 increase.

I will add that it is true that the last time co2 was this high, the world was much warmer and sea levels much higher. http://www.climatecentral.org/news/the-last-time-co2-was-this-high-humans-didnt-exist-15938

I will also add that the co2 levels have been rising much faster than any previous warming periods, https://mashable.com/2016/03/21/co2-fastest-66-million-years/

So its a bit interesting considering we have warmed only about 1.2-1.5 c with that rapid amount of change, things seem to be picking up though....

The more I think about it, things point to a rapid rise in temp. Only questions is how much and when....
Title: Re: When will the Arctic Go Ice Free?
Post by: misfratz on August 01, 2018, 11:01:47 AM
Even if existing concentrations could be immediately stabilized, temperature would continue to increase by an estimated 1.1°F (0.6°C) over this century, relative to 1980–1999.
Correct me if I'm wrong, but that seems to indicate that temperatures will continue to increase throughout the century even if we stop emissions. And we're already over 400 ppm. My guess is that we have enough C02 in the atmosphere to get an ice free day in the arctic, even if civilization collapsed totally tomorrow.
No, you are confusing two different things: emissions and concentrations - which is really easy to do.

If present-day concentrations of GHG could be stabilised then there would be warming still in the pipeline to come.

If emissions of GHG are stopped entirely then GHG concentrations will decline somewhat, and this will roughly cancel out the temperature increase lag effect, so that you would expect global temperatures to stabilise at about the same level they are at now. Since it takes some while for ice to melt in response to elevated temperatures you would expect to see some continued decline in Arctic sea-ice levels - probably to an ice-free state (as an aside the likely sensitivity of Arctic sea-ice to present-day conditions is probably one reason why coupled GCMs are on the conservative side when it comes to Arctic sea-ice predictions, due to the way in which those models are developed).

It's actually pretty hard to stabilise GHG concentrations at their current elevated level. Either they continue increasing, or they start to decline (this decline happens at different speeds due to different processes). The stabilisation scenario is simply an interesting "what-if?" scenario that is easy to set up with a GCM. I tend to think that if we suddenly became really serious about tackling GHG, in a Apollo project or World War fighting sort of way, that we could do better than a stabilisation scenario. I just don't see the political route to that seriousness.
Title: Re: When will the Arctic Go Ice Free?
Post by: Richard Rathbone on August 01, 2018, 12:30:17 PM
As far as FYI goes, its very sensitive to current conditions as each year is a new one. This same sensitivity means that whenever temperature stabilises, so does the trend in sea ice extent.
Title: Re: When will the Arctic Go Ice Free?
Post by: Lou on August 01, 2018, 06:39:02 PM
It is madness. Worse than pure denial of the entire situation. I'm less bothered by those who think it is all an elite globalist ploy to enslave the masses, than I am by those who engage with the data on a daily basis but come to the conclusion that mild solutions will be sufficient to save civilization.  OR for that matter those who think that it is no big deal to change the climate drastically and kill off humanity cuz the earth will bounce back.  Are we really going to successfully prevent nuclear war as everything falls apart? Are we really going to successfully decommission the hundreds of nuclear power plants around the world? Even if you aren't bothered by the collapse of civilization and the horrible deaths of billions of people, the possibility of turning the earth into a planet like venus or mars should give you some pause.

While I agree with your whole post, the quoted graf really resonated with me.  I find it astonishing how many people, many of them real, honest-to-Pete scientists, see the data and the (often conservative yet terrifying) projections, and aren't standing on tables screaming about this mess we've created.  Just as bad are the environmental activists who will argue that you can't tell mainstreamers the full truth about CC or "you'll scare them away".  (I've had that argument numerous times with local enviros.)

Barring some nearly miraculous ramping up of carbon removal and sequestration, there is no way we'll avoid something between horrific consequences and a full-blown, worldwide catastrophe.

As for the topic of this thread, while I missed the voting window, I would definitely have voted for the 2020-2025 period.  Trends plus variability means we won't need some wildly improbable set of events in a given summer to hit <1M km^2.  I would also predict it gets no more than 60 seconds of, "Golly, look at that!" coverage on TV news, with the usual suspects talking about the economic benefits of newly-opened shipping routes every summer.
Title: Re: When will the Arctic Go Ice Free?
Post by: josh-j on August 01, 2018, 07:02:31 PM
A scenario of year-round ice-free Arctic can only be reached (IMO) by further a northward reach of the warm ocean currents.
I keep reading this dreamy misconception everywhere. People seem to be forgetting about the fact that the quantity of heat energy required to melt 1kg of ice (of just below freezing) to 1kg of water (of just above freezing) would raise the temperature of that same 1 kg of water to 80 degrees Celsius. This means that as soon as ice is gone, and there is heat energy (i.e. Sunlight), the oceans will be very hot at the surface (provided that surface T will also keep on rising as it does) all around the Arctic circle. It already is super anomalously warm, by the way. So when the sun is gone at the polar caps, all it needs is a little flow from warmer lower ocean currents to keep it from freezing up, and/or surface winds blowing the warmer (sun-heated) waters Northwards. Considering all the additional feedbacks, I'd say year round ice free poles could be a reality around 2035 at the very latest.

But water is not just stagnant in the Arctic and waiting to warm. While its true that a lot more heat can go into the water once there's no ice to melt, its also the case that the worlds oceans are very large, very deep, and circulating. I find it hard to believe that mainstream science is so wrong on the timescales for a year-round BOE. I'm not saying the current mainstream predictions are gospel and won't change, but 2035 is so at odds with the mainstream view that I find it hard to accept. No ice in winter also means more can escape, does it not? (No really, correct me if I'm wrong - I'm no expert!)
Title: Re: When will the Arctic Go Ice Free?
Post by: GoSouthYoungins on August 01, 2018, 07:50:27 PM
I find it hard to believe that mainstream science is so wrong on the timescales for a year-round BOE. I'm not saying the current mainstream predictions are gospel and won't change, but 2035 is so at odds with the mainstream view that I find it hard to accept.

The mainstream science said 2005, 2007, 2012, 2016 will occur a couple decades from now. Mainstream science is funded by those in power. Those in power don't want to drastically change everything.  The science they fund reliable says that the serious effects will occur just outside the lifespans of the voting public. Contrary opinions & evidence get shunned.

The most telling example is the IPCCs most recent report which estimated that under a worst case scenario, arctic ice extent would retreat to a minimum 3.5 million sq kilometers in the 2030s. This was based on their video games...I mean models. In reality, extent had already had a minimum below this amount PRIOR TO THE PUBLICATION OF THE IPCC'S REPORT!!!

When reality points towards needing drastic and immediate change, it is safe to assume that mainstream science will be outrageously inaccurate.
Title: Re: When will the Arctic Go Ice Free?
Post by: Steven on August 01, 2018, 09:21:53 PM
The most telling example is the IPCCs most recent report which estimated that under a worst case scenario, arctic ice extent would retreat to a minimum 3.5 million sq kilometers in the 2030s. This was based on their video games...I mean models. In reality, extent had already had a minimum below this amount PRIOR TO THE PUBLICATION OF THE IPCC'S REPORT!!!

No, it hasn't.  The IPCC uses a 5-year running average of the September sea ice extent.  The lowest value for this metric so far is 4.6 million km2, which is the average September extent for the 5 years 2012-2016.

Below is one of the relevant figures of the latest IPCC report.  The thick colored lines are the ones they used for their main assessment.


(https://i.imgur.com/AWypBVq.png)
Title: Re: When will the Arctic Go Ice Free?
Post by: gerontocrat on August 01, 2018, 09:44:18 PM
The most telling example is the IPCCs most recent report which estimated that under a worst case scenario, arctic ice extent would retreat to a minimum 3.5 million sq kilometers in the 2030s. In reality, extent had already had a minimum below this amount PRIOR TO THE PUBLICATION OF THE IPCC'S REPORT!!!

No, it hasn't.  The IPCC uses a 5-year running average of the September sea ice extent.  The lowest value for this metric so far is 4.6 million km2, which is the average September extent for the 5 years 2012-2016.

Below is one of the relevant figures of the latest IPCC report.  The thick colored lines are the ones they used for their main assessment.

And that 5-year average has gone up as 2012 left the average.

Table of 5 year averages - that year and previous 4 years
NSIDC Sept Av
                JAXA daily min
2009    5.20     4.88
2010    5.07     4.77
2011    4.80     4.50
2012    4.66     4.32
2013    4.79     4.39
2014    4.77     4.35
2015    4.72     4.28
2016    4.73     4.23
2017    4.97     4.49

Title: Re: When will the Arctic Go Ice Free?
Post by: Dharma Rupa on August 02, 2018, 12:42:37 AM
The most telling example is the IPCCs most recent report which estimated that under a worst case scenario, arctic ice extent would retreat to a minimum 3.5 million sq kilometers in the 2030s. This was based on their video games...I mean models. In reality, extent had already had a minimum below this amount PRIOR TO THE PUBLICATION OF THE IPCC'S REPORT!!!

No, it hasn't.  The IPCC uses a 5-year running average of the September sea ice extent.  The lowest value for this metric so far is 4.6 million km2, which is the average September extent for the 5 years 2012-2016.

Below is one of the relevant figures of the latest IPCC report.  The thick colored lines are the ones they used for their main assessment.


(https://i.imgur.com/AWypBVq.png)

I must admit to being a bit confused about your response, though I haven't checked out the actual numbers.  GoSouthYoungins didn't say that IPCC contradicted their own numbers.  Cir said that the IPCC's numbers contradicted generally accepted data.
Title: Re: When will the Arctic Go Ice Free?
Post by: Michael Hauber on August 02, 2018, 01:02:39 AM

If we are currently experiencing the effects of warming from CO2 emissions up to 2008 (to slightly simply things), then 380 ppm should correspond to about 1C temperature rise. SO SO SO SO SO WRONG. Last time concentrations were that high was a few million years ago and the temperature was significantly higher, sea level was significantly higher, and there wasn't any significant ice in the northern hemisphere. More recently, the co2 to temperature correlation would suggest at least 5C of warming from a 280 to 380 increase.

The graph you supplied is for temperature at Vostok (Antarctica) not global temps.  Also note that the primary temperature driver over this period was orbital changes - and then the temp changes drove CO2, and Co2 provided an additional feedback to warming.  So 5C in Antarctica is reduced by about half to get a global value, and then further reduced by however much of the warming was caused by orbital changes.
Title: Re: When will the Arctic Go Ice Free?
Post by: Dharma Rupa on August 02, 2018, 02:46:57 AM

If we are currently experiencing the effects of warming from CO2 emissions up to 2008 (to slightly simply things), then 380 ppm should correspond to about 1C temperature rise. SO SO SO SO SO WRONG. Last time concentrations were that high was a few million years ago and the temperature was significantly higher, sea level was significantly higher, and there wasn't any significant ice in the northern hemisphere. More recently, the co2 to temperature correlation would suggest at least 5C of warming from a 280 to 380 increase.

The graph you supplied is for temperature at Vostok (Antarctica) not global temps.  Also note that the primary temperature driver over this period was orbital changes - and then the temp changes drove CO2, and Co2 provided an additional feedback to warming.  So 5C in Antarctica is reduced by about half to get a global value, and then further reduced by however much of the warming was caused by orbital changes.

Let's start with stating that the theory of orbital changes as a primary driver as if it were a demonstrated fact, and then move on to wondering where you came up with cutting the Antarctic value in half, and then in half again.

I will agree that the orbital variation seems to have a part to play, but I will not agree that its role has been demonstrated, but even assuming that, where do you come up with the rest of your statement????
Title: Re: When will the Arctic Go Ice Free?
Post by: GoSouthYoungins on August 02, 2018, 02:48:19 AM
so does anyone disagree with the spirit of what i am saying, or is it simply that 5C increase in Antarctic temps is no big deal ( which is used cuz its the best record available, due to its long term stability, hence GO SOUTH YOUNGINS ) ? Does anyone actually believe there is only a 10.1 year lag? It just doesn't pass the smell test. It flies in the face of everything that I would like to think that everyone who follows ARCTIC ICE understands about the climate system. I would be thrilled if somebody can explain to me how the effects of a 10.1 year lag makes sense. Ill pop the champagne I have in the fridge (even though I don't drink) and just shoot it all over my house. I understand that IPCC takes care to make sure that they can't be pinned down and discredited in the short term on a hard a fast data point, but that doesn't make the message they are conveying dangerously misleading.

I understand why the article reaches the conclusion that they do. They model an enormous instant increase in CO2, and then let their video game play out. So there is an extreme amount of dispersion into the ocean and the land biosphere which reduces the atmospheric concentrations very rapidly. Too bad that has NO CORRELATION to the actual situation, which is what they claim to be trying to provide information for.

Our sinks are starting to fill up. The ocean is getting full. And there is no short or medium term path towards reduction in emissions. The land we are paving at a rate which will soon overcome what the unpaved can make up for. Soon the unprecedented rise in atmospheric GHGs will cause ecology to start burning globally which will be a stick of TNT in the sink. The idea expressed by the Carnegie folks is dangerous, and it makes me sad that ppl ( even FUCKING HERE ) are lulled to pseudo-complacency by it.
Title: Re: When will the Arctic Go Ice Free?
Post by: bluesky on August 02, 2018, 08:03:14 AM
warming we are feeling now is mostly from GHG emissions from decades ago. GHGs are like a lid on a pot; as the lid gets thicker the stuff in the pot gets warmer, but it takes some time...in this case probably 20-30 years. The warming we have seen so far is primarily from emissions up to 1990, so about 350 ppm.
Actually, no, that's not true; http://iopscience.iop.org/article/10.1088/1748-9326/9/12/124002;jsessionid=BC6F9B408139804AB3587C183EE22AAC.c1.iopscience.cld.iop.org

Maximum warming occurs a median of 10.1 years after the CO2 emission event and has a median value of 2.2 mK GtC−1.

We now can reasonably deny the validity to apply this research paper to polar amplification without a shade of doubt:

Palaeoclimate constraints on the impact of 2° C anthropogenic warming and beyond (P. Bakker et al ), Nature Geoscience June 2018

free version:
http://eprints.esc.cam.ac.uk/4301/2/41561_2018_146_MOESM1_ESM.pdf

The paper is very well articulated and documented, probably the most updated paper on past reconstruction of warming events due to orbital forcing and GHG, the main purpose of the paper is to back test the validity of the models -used for our current man made GW-  to these paleoclimatic events.

on page 4 of the article, we can read the following:

"The MPWP (mid-Pliocene warm period 3.3–3.0 million years ago)
  was subject to intermittently elevated CO2 (potentially up to 450 ppm)
compared to the HTM (Holocene Thermal Maximum)  and the LIG9 (last Interglacial).
The CO2 concentration at that time was most similar to the RCP2.6
scenario, and a factor of three-to-four less than concentrations
expected by ad 2100 for the RCP8.5 scenario. Climate models
simulate an increase in tropical temperatures by 1.0–3.1 °C (for
RCP2.6 CO2 forcing of 405 ppmv (ref. 2)), generally in line with
MPWP proxy reconstructions at low latitudes127. Strong polar
amplification is observed for the MPWP. For example, proxy data
from the North Atlantic and northeastern Russian Arctic indicate a
rise of surface air temperatures by 8 °C (ref. 128) during the MPWP
and even higher in the early Pliocene129. These regional temperature
changes are similar to projected warming at ad 2100 for the RCP8.5
scenario, in spite of the much lower CO2 rise during the MPWP,
and suggest that current models may underestimate the warming
response in the Arctic130 to increased CO2 concentrations."




Title: Re: When will the Arctic Go Ice Free?
Post by: binntho on August 02, 2018, 08:09:03 AM

Let's start with stating that the theory of orbital changes as a primary driver as if it were a demonstrated fact, and then move on to wondering where you came up with cutting the Antarctic value in half, and then in half again.

I will agree that the orbital variation seems to have a part to play, but I will not agree that its role has been demonstrated, but even assuming that, where do you come up with the rest of your statement????

How many factors can influence the climate? The clear cyclical glaciation - intermediate - glaciation signal over the last 2 million years or so match the Milankovich cycles to such a degree that I think it is safe to say that orbital variation is the accepted explanation for the warming during intermediaries and cooling during glaciations.

The Vostock core shows that in the Antarctic, the four last intermediary temperature maxima reached some 5 degrees C above present  (which is usually centered on 1970 in palaeoclimate terms), with our Holocene climate maximum being slightly lower, at some 3-4 degrees C above present. (Note that the Vostock core was drilled in 1995, but meaningful data can only really be extracted from ice that is quite old, on a scale of centuries if not millennia).

Global temperature during the Holocene show that the Holocene climate maximum was less than 1 degree C warmer than present time (i.e. 1970) - which seems to indicate that the maximum at Antarctica was some 4 times higher than the global maximum.

Research in the northern hemisphere (mainly Europe) seems to indicate that the Holocene maximum was much stronger the closer to the (North) pole one goes. So the Holocene maximum (and other intermediary maxima) may well have been exaggerated towards the poles.

Previous rapid warming events over the last 2 million years, when going from glaciation to intermediary, were caused by orbital change with added feedback from CO2 and methane. The current rapid warming goes against the effects of orbital change (the climate should be cooling rapidly) and is mainly caused by a large increase in CO2, so it is reasonable to expect the pattern of warming being different this time.
Title: Re: When will the Arctic Go Ice Free?
Post by: Wherestheice on August 02, 2018, 08:54:56 AM

Let's start with stating that the theory of orbital changes as a primary driver as if it were a demonstrated fact, and then move on to wondering where you came up with cutting the Antarctic value in half, and then in half again.

I will agree that the orbital variation seems to have a part to play, but I will not agree that its role has been demonstrated, but even assuming that, where do you come up with the rest of your statement????

How many factors can influence the climate? The clear cyclical glaciation - intermediate - glaciation signal over the last 2 million years or so match the Milankovich cycles to such a degree that I think it is safe to say that orbital variation is the accepted explanation for the warming during intermediaries and cooling during glaciations.

The Vostock core shows that in the Antarctic, the four last intermediary temperature maxima reached some 5 degrees C above present  (which is usually centered on 1970 in palaeoclimate terms), with our Holocene climate maximum being slightly lower, at some 3-4 degrees C above present. (Note that the Vostock core was drilled in 1995, but meaningful data can only really be extracted from ice that is quite old, on a scale of centuries if not millennia).

Global temperature during the Holocene show that the Holocene climate maximum was less than 1 degree C warmer than present time (i.e. 1970) - which seems to indicate that the maximum at Antarctica was some 4 times higher than the global maximum.

Research in the northern hemisphere (mainly Europe) seems to indicate that the Holocene maximum was much stronger the closer to the (North) pole one goes. So the Holocene maximum (and other intermediary maxima) may well have been exaggerated towards the poles.

Previous rapid warming events over the last 2 million years, when going from glaciation to intermediary, were caused by orbital change with added feedback from CO2 and methane. The current rapid warming goes against the effects of orbital change (the climate should be cooling rapidly) and is mainly caused by a large increase in CO2, so it is reasonable to expect the pattern of warming being different this time.

That’s interesting. Things are definitely much different than anything ever before. I would say what’s happening now is unprecedented in earths history. The question that looms is, how much will things be different, quite substantially different imo.
Title: Re: When will the Arctic Go Ice Free?
Post by: Pmt111500 on August 02, 2018, 09:08:47 AM
Have humans altered ocean currents enough to produce an interglacial simulate of Dansgaard-Oeschger events (+3,5-4 over deep glacial climate)? Maybe we need a new term for this? Anthropogenic End-of-glacial Extreme Hyperthermal, A-EEH!?!? Off to pick some berries. 
Title: Re: When will the Arctic Go Ice Free?
Post by: bluesky on August 02, 2018, 10:27:04 AM

Let's start with stating that the theory of orbital changes as a primary driver as if it were a demonstrated fact, and then move on to wondering where you came up with cutting the Antarctic value in half, and then in half again.

I will agree that the orbital variation seems to have a part to play, but I will not agree that its role has been demonstrated, but even assuming that, where do you come up with the rest of your statement????

How many factors can influence the climate? The clear cyclical glaciation - intermediate - glaciation signal over the last 2 million years or so match the Milankovich cycles to such a degree that I think it is safe to say that orbital variation is the accepted explanation for the warming during intermediaries and cooling during glaciations.

The Vostock core shows that in the Antarctic, the four last intermediary temperature maxima reached some 5 degrees C above present  (which is usually centered on 1970 in palaeoclimate terms), with our Holocene climate maximum being slightly lower, at some 3-4 degrees C above present. (Note that the Vostock core was drilled in 1995, but meaningful data can only really be extracted from ice that is quite old, on a scale of centuries if not millennia).

Global temperature during the Holocene show that the Holocene climate maximum was less than 1 degree C warmer than present time (i.e. 1970) - which seems to indicate that the maximum at Antarctica was some 4 times higher than the global maximum.

Research in the northern hemisphere (mainly Europe) seems to indicate that the Holocene maximum was much stronger the closer to the (North) pole one goes. So the Holocene maximum (and other intermediary maxima) may well have been exaggerated towards the poles.

Previous rapid warming events over the last 2 million years, when going from glaciation to intermediary, were caused by orbital change with added feedback from CO2 and methane. The current rapid warming goes against the effects of orbital change (the climate should be cooling rapidly) and is mainly caused by a large increase in CO2, so it is reasonable to expect the pattern of warming being different this time.

completely agree, maybe we could add that CO2 is currently rising faster than at any time in the past 66 million years and faster than at the PETM extinction 56 million years ago , leading to an even more hazardous  warming pathway, on a BAU path we are in a completely uncharted territory ...
https://www.skepticalscience.com/co2-rising-ten-times-faster-than-petm-extinction.html
https://www.nature.com/articles/ngeo2681

"more rapid or extensive warming in scenarios such as
RCP8.5 would be outside the experience provided by past interglacial
periods reviewed here. Such a pathway into conditions without
well-studied precedent would be inherently risky for human society
and sustainable development."

http://eprints.esc.cam.ac.uk/4301/2/41561_2018_146_MOESM1_ESM.pdf



Title: Re: When will the Arctic Go Ice Free?
Post by: Tor Bejnar on August 02, 2018, 04:40:32 PM
...
Previous rapid warming events over the last 2 million years, when going from glaciation to intermediary, were caused by orbital change with added feedback from CO2 and methane. The current rapid warming goes against the effects of orbital change (the climate should be cooling rapidly) and is mainly caused by a large increase in CO2, so it is reasonable to expect the pattern of warming being different this time.
I will quibble only with the parenthetical "the climate should be cooling rapidly" due to Milankovich forcing.  Without AGW, I understand Earth's climate would be cooling slowly during my lifetime (that is, on a human scale), although I'll accept "rapidly" in the geological scheme of things.
Title: Re: When will the Arctic Go Ice Free?
Post by: Pmt111500 on August 02, 2018, 05:20:27 PM
...
Previous rapid warming events over the last 2 million years, when going from glaciation to intermediary, were caused by orbital change with added feedback from CO2 and methane. The current rapid warming goes against the effects of orbital change (the climate should be cooling rapidly) and is mainly caused by a large increase in CO2, so it is reasonable to expect the pattern of warming being different this time.
I will quibble only with the parenthetical "the climate should be cooling rapidly" due to Milankovich forcing.  Without AGW, I understand Earth's climate would be cooling slowly during my lifetime (that is, on a human scale), although I'll accept "rapidly" in the geological scheme of things.
Yeah well that partly depends on how you look on the early anthropocene hypothesis, Holocene was exeptionally long for an interglacial so it could be a thousand year plunge to the next glacial would be on already. Agree that a thousand years is still quite slow for a human timescale, f.e. I don't even know any of my ancestors that far back  :o 8) :P ::)  . But some people know, so maybe this is rapid.
Title: Re: When will the Arctic Go Ice Free?
Post by: Wherestheice on August 02, 2018, 11:08:05 PM
Let’s try to stay on topic
Title: Re: When will the Arctic Go Ice Free?
Post by: magnamentis on August 02, 2018, 11:48:19 PM
Let’s try to stay on topic

this is on topic IMO, or don't you think that looking into the past will help to understand mechanisms as well as the relevance of positive and negative feedbacks as well as seeing repeating patterns that help to come to better conclusions?

if we have an opinion about when the arctic will become ice-free it's good practice to underline our opinion with know facts from the past and weigh them in the process, else we can play the lottery.
Title: Re: When will the Arctic Go Ice Free?
Post by: Wherestheice on August 02, 2018, 11:49:54 PM
Let’s try to stay on topic

this is on topic IMO, or don't you think that looking into the past will help to understand mechanisms as well as the relevance of positive and negative feedbacks as well as seeing repeating patterns that help to come to better conclusions?

if we have an opinion about when the arctic will become ice-free it's good practice to underline our opinion with know facts from the past and weigh them in the process, else we can play the lottery.

You right, you right
Title: Re: When will the Arctic Go Ice Free?
Post by: Shared Humanity on August 03, 2018, 02:43:58 PM
Given the recent rapid melt in the Arctic despite having a season not overly conducive to melt, I think a summer BOE event could be just one disastrous melt season away. If we were to get 2007 conditions next year, we could see our first BOE event IMHO.

A BOE in the summer does not, however, guarantee another BOE in the following summer. As we saw in both 2007 and 2012, the melt season minimums bounced back the following seasons, although at a new lower level. I would expect the melt seasons after the 1st BOE to exhibit similar behaviors, bouncing back to another new, lower level.
Title: Re: When will the Arctic Go Ice Free?
Post by: oren on August 03, 2018, 03:24:27 PM
Well said SH.
Title: Re: When will the Arctic Go Ice Free?
Post by: magnamentis on August 03, 2018, 04:04:57 PM
Given the recent rapid melt in the Arctic despite having a season not overly conducive to melt, I think a summer BOE event could be just one disastrous melt season away. If we were to get 2007 conditions next year, we could see our first BOE event IMHO.

A BOE in the summer does not, however, guarantee another BOE in the following summer. As we saw in both 2007 and 2012, the melt season minimums bounced back the following seasons, although at a new lower level. I would expect the melt seasons after the 1st BOE to exhibit similar behaviors, bouncing back to another new, lower level.

you "if then" assumption is of course entirely correct.

what remains to assess is how big the possibility for i.e. a 2007 melting season currently is, given the vast increaso of humidity that will most probably most of the coming summers lead to extensive cloud cover which makes it much more probably that the last 2 summers will be kind of a new normal.

this of course does by no means exclude the possibility for exceptions and outliers, hence, as mentioned you "if then" the way you wrote it is perfectly true, just wanted to add probability of such and "if then" scenario to the discussion.
Title: Re: When will the Arctic Go Ice Free?
Post by: misfratz on August 03, 2018, 04:33:53 PM
The decrease in NSIDC minimum extent between 2007 and 2012 was 0.76 (million square km) from 4.15 to 3.39.

I would suggest, therefore, that we might be more than one super-melt summer away from a summer below 1 million square km.

As to the clouds and humidity, the dominant factor here is atmospheric pressure. Under a stable high pressure system you have descent of the air, which warms as it descends (due to the increase in pressure, it warms a lot), and so this will tend to keep the clouds away.

Humidity in the boundary layer can create fog temporarily in these conditions, but the 24-hour nature of the summer Arctic sun will tend to militate against that too.
Title: Re: When will the Arctic Go Ice Free?
Post by: Shared Humanity on August 03, 2018, 04:36:13 PM
The decrease in NSIDC minimum extent between 2007 and 2012 was 0.76 (million square km) from 4.15 to 3.39.

I would suggest, therefore, that we might be more than one super-melt summer away from a summer below 1 million square km.

Perhaps. But in 2012 and especially in 2007, there was a large amount of very thick MYI that had to melt. Now. Not so much.

The step function we see in this SIE chart which occurred in 2007 is a direct result of the massive destruction of thick MYI. 2007 essentially set a new floor for minimums by causing the Arctic to enter into a new regime where MYI made up a much smaller portion of the Arctic. This has set the stage for a catastrophic drop whenever we have another season conducive to melt.

We see the exact same impact on volume. We simply have far less volume to melt and a disastrous melting season will have a much more damaging impact.
Title: Re: When will the Arctic Go Ice Free?
Post by: Lou on August 03, 2018, 07:12:14 PM
Given the recent rapid melt in the Arctic despite having a season not overly conducive to melt, I think a summer BOE event could be just one disastrous melt season away. If we were to get 2007 conditions next year, we could see our first BOE event IMHO.

A BOE in the summer does not, however, guarantee another BOE in the following summer. As we saw in both 2007 and 2012, the melt season minimums bounced back the following seasons, although at a new lower level. I would expect the melt seasons after the 1st BOE to exhibit similar behaviors, bouncing back to another new, lower level.

Strongly agree.  As I often say when talking to newcomers about this topic: There's a very well established trend/signal that's combined with a lot of noise in the form of yearly weather variations.  We're about to enter a period where a BOE (or lack thereof) in any given year is a result of how much noise and in which direction we see.

I wouldn't be surprised to see a BOE in the next year or two, only to not see another for five years, then get them two years running, etc.
Title: Re: When will the Arctic Go Ice Free?
Post by: Dharma Rupa on August 03, 2018, 07:31:26 PM
I wouldn't be surprised to see a BOE in the next year or two, only to not see another for five years, then get them two years running, etc.

I'll pay attention to DMI 80N rather than extent, but once there is not enough ice to pin the temperature close to 0 in the Summer there won't be enough cold to keep the ocean from overturning and losing its protective fresh halocline layer.  When there isn't enough ice to keep it cold in Summer it won't really get cold in Winter.
Title: Re: When will the Arctic Go Ice Free?
Post by: GoSouthYoungins on August 03, 2018, 10:06:36 PM
Shouldn't we be looking at the Hudson bay to go blue ocean year-long, long before the CAB does?!! 
Actually, counter intuitively, the greater probability is that it will continue to freeze after the CAB becomes "ice free" - less than 1 million KM2 of ice in winter.
And I am pretty sure, that the Hudson Bay as well as the North Pole will always* freeze in winter. On the North Pole you have 180 days of no sunlight, that will always be much below zero, no matter what. Average temperature in Winter is around -30°C at the North Pole and -20°C over most of Hudson Bay. So even if temperaturs would raise globally by 15°C, it would still be well below freezing in many areas there and therefore ice would form.

I agree.

Even after a summer BOE, ice will still form in the Arctic during the dark, polar winter for many decades. This cover of FYI will look and behave differently, likely thinner due to warmer winters, more mobile even in the dead of winter and more susceptible to melt the following melt season. This is no different than what we are observing in the peripheral seas in the basin. The Beaufort and Chukchi froze late and the resulting ice was far thinner and, as can be seen this year, will melt out despite conditions not conducive to melt.

I'm quoting here from the Melt Season thread cuz it makes more sense to discuss here:

I idea that the north pole will freeze for over for at least the next new thousand years because it is dark for half the year doesn't hold up to scrutiny because there are already areas north of 80N that have gone the past year without any ice. Not only no ice, but very warm SSTs. The ocean will continue to warm. The atmosphere will continue to warm. The Atlantic will encroach and the ice will retreat.

Also, it is kinda a "humpty dumpty situation".  Once the ice melts in the summer, there will be mixing. The salinity of the water nearest to the surface will increase and refreeze will be more difficult. The salinity around the entirety of greenland and west into the CAA has already started to show significant increase. Once the summer ice melts, its much more difficult for it to be put back together again.

This process will take several years, but there are so many forcing to hurt ice, and very few to help. A big one that is rarely discussed in the likely drastic increase of soot from increased wildfires north of 60N. Layer greenland and the remaining arctic ice with black particles and all the models and predictions go out the window. Thousands of years becomes decades.

If global temperature rise 15 degrees C, there WILL NOT be any sea ice in the northern hemisphere. And there WILL NOT be any humans in the northern hemisphere to pay attention.

EDIT: while i was posting this A Team posted something along the same lines in the Melt Thread, just 1000x more classy and science-like.
Title: Re: When will the Arctic Go Ice Free?
Post by: magnamentis on August 03, 2018, 11:25:23 PM
Shouldn't we be looking at the Hudson bay to go blue ocean year-long, long before the CAB does?!! 
Actually, counter intuitively, the greater probability is that it will continue to freeze after the CAB becomes "ice free" - less than 1 million KM2 of ice in winter.
And I am pretty sure, that the Hudson Bay as well as the North Pole will always* freeze in winter. On the North Pole you have 180 days of no sunlight, that will always be much below zero, no matter what. Average temperature in Winter is around -30°C at the North Pole and -20°C over most of Hudson Bay. So even if temperaturs would raise globally by 15°C, it would still be well below freezing in many areas there and therefore ice would form.

I agree.

Even after a summer BOE, ice will still form in the Arctic during the dark, polar winter for many decades. This cover of FYI will look and behave differently, likely thinner due to warmer winters, more mobile even in the dead of winter and more susceptible to melt the following melt season. This is no different than what we are observing in the peripheral seas in the basin. The Beaufort and Chukchi froze late and the resulting ice was far thinner and, as can be seen this year, will melt out despite conditions not conducive to melt.

I'm quoting here from the Melt Season thread cuz it makes more sense to discuss here:

I idea that the north pole will freeze for over for at least the next new thousand years because it is dark for half the year doesn't hold up to scrutiny because there are already areas north of 80N that have gone the past year without any ice. Not only no ice, but very warm SSTs. The ocean will continue to warm. The atmosphere will continue to warm. The Atlantic will encroach and the ice will retreat.

Also, it is kinda a "humpty dumpty situation".  Once the ice melts in the summer, there will be mixing. The salinity of the water nearest to the surface will increase and refreeze will be more difficult. The salinity around the entirety of greenland and west into the CAA has already started to show significant increase. Once the summer ice melts, its much more difficult for it to be put back together again.

This process will take several years, but there are so many forcing to hurt ice, and very few to help. A big one that is rarely discussed in the likely drastic increase of soot from increased wildfires north of 60N. Layer greenland and the remaining arctic ice with black particles and all the models and predictions go out the window. Thousands of years becomes decades.

If global temperature rise 15 degrees C, there WILL NOT be any sea ice in the northern hemisphere. And there WILL NOT be any humans in the northern hemisphere to pay attention.

EDIT: while i was posting this A Team posted something along the same lines in the Melt Thread, just 1000x more classy and science-like.

this is about the arctic, not about the north pole or any point above 80N

if we talk about the arctic being ice free i say that each warm current has it's cold counterpart and that in one part of the arctic (one side if you prefer) there will always be a lot of ice.

since we don't know how currents will change and develop under new conditons no-one can say which part but it probably won't be be pole itself but one of the  seas attached to large continentals land masses.

before siberia for example will come up to -10C average from curretnly -40C (dunno exact numbers) it will take quite a while and those winds will blow over the ice exactly like the warm winds from another side.

hence even if the north pole will be ice-free all year, the arctic as a whole will not.

this topic is more about how big a picture someone is able or willing to think. most of the reasoning used here is cherry picked petty reasoning mostly forgetting an entire big chunk of the cake (story) simply to fit into whichful (sensational) thinking.

if the chucki and svalbard are ice free it is because there are opeings on both sides into huge oceans with huge amounts of heat stored while on the canadia and russian side this won't be the case.

since i opt for zero (close to zero) ice cover to name the arctic ice-free the arctic will hold ice in winter for a long long time.

those opting for the 1 million km2 as a threshold, which is arbitrary and counterintuitive to get an earlier headline, will see THEIR event earlier but even the million will be reach for a long time to come. don't forget we are over 10 million during winter now and don't tell me that we go from above 10 to below 1 million in a few years if ever.

EDIT:

we don't even know whether the so often mentioned warm currents that currently keep the so often mentioned svalbard ice-free most of the times will still exist in that are when the time has come.

after all it's well possible the the so called "gulf stream" will start to drop to the sea-flor much more south once the salinity of the arctic will be more impated by greenland melt and less saline water freezes much earlier, hence we don't even know whether freshwater supplies and lack of warm water supply could even increase ice cover during winter.

i don't really believe that but it's still possible, we simply don't know.
Title: Re: When will the Arctic Go Ice Free?
Post by: binntho on August 04, 2018, 08:16:23 AM

if we talk about the arctic being ice free i say that each warm current has it's cold counterpart and that in one part of the arctic (one side if you prefer) there will always be a lot of ice.

You've said it before, and I asked: Is that some sort of natural law? That each warm current has it's cold counterpart? How and why?

To me this indicates a lack of understanding of how the big warm surface currents and the big cold bottom currents are tied together: The real counterpart of any warm surface current is a cold bottom current.

The image shows warm and cold currents in the North-Atlantic, both surface and deep. The warm currents are all on the surface, while the cold currents (with the exception of the narrow one running down the east coast of Greenland) are deep currents.
Title: Re: When will the Arctic Go Ice Free?
Post by: magnamentis on August 04, 2018, 06:33:33 PM

if we talk about the arctic being ice free i say that each warm current has it's cold counterpart and that in one part of the arctic (one side if you prefer) there will always be a lot of ice.

You've said it before, and I asked: Is that some sort of natural law? That each warm current has it's cold counterpart? How and why?

To me this indicates a lack of understanding of how the big warm surface currents and the big cold bottom currents are tied together: The real counterpart of any warm surface current is a cold bottom current.

The image shows warm and cold currents in the North-Atlantic, both surface and deep. The warm currents are all on the surface, while the cold currents (with the exception of the narrow one running down the east coast of Greenland) are deep currents.

now i'd have to post a book to counter your statements, we'd have to go into density, salinity, when warm currents start to drop to the sea-floor to return south etc. but there are cold currents on the surface for sure, humbolt and many others, so the "all" is not correct and more time i'm not willing to spend on this topic. we can agree that we disagree and see what happens.

i tell you that none of us shall see an ice-free arctic in winter (arctic not north pole) and
you have another opinion which to proof false would take years work of studies and combine them into an excerpt. this is just too much and won't change the future anyways, hence i propose to leave it at that for the moment, it simply doesn't matter who is right and the future will tell what is right/wil happen.

enjoy further
Title: Re: When will the Arctic Go Ice Free?
Post by: Dharma Rupa on August 04, 2018, 08:32:03 PM
i tell you that none of us shall see an ice-free arctic in winter (arctic not north pole) and
you have another opinion which to proof false would take years work of studies and combine them into an excerpt. this is just too much and won't change the future anyways, hence i propose to leave it at that for the moment, it simply doesn't matter who is right and the future will tell what is right/wil happen.

enjoy further

If I were to exclude certain areas, most notably the Hudson, would you still make that claim?

Suppose I posit that everywhere that is not very close to a cold continent will melt out soon (5 years) and stay melted out in the winter?  What would you say about that?

Title: Re: When will the Arctic Go Ice Free?
Post by: magnamentis on August 04, 2018, 09:19:51 PM
i tell you that none of us shall see an ice-free arctic in winter (arctic not north pole) and
you have another opinion which to proof false would take years work of studies and combine them into an excerpt. this is just too much and won't change the future anyways, hence i propose to leave it at that for the moment, it simply doesn't matter who is right and the future will tell what is right/wil happen.

enjoy further


If I were to exclude certain areas, most notably the Hudson, would you still make that claim?

Suppose I posit that everywhere that is not very close to a cold continent will melt out soon (5 years) and stay melted out in the winter?  What would you say about that?

i see what you mean.

consequently if you exclude certain areas we shall certainly see certain areas going ice-free year round, i.e. i suspect that the pole will be much earler ice free in winter than hudson bay, just to take on your example, but then:

if we exclude areas we don't talk "arcitic" anymore and certainly the discussion is originally meant the for the arctic basin.

i know that we distinguis between arcitc basin, central arctic basin, arctic as to above tropic of cancer and arctic ocean as to the waters that freeze over.

IMO hudson bay except that it's freezing and connected to the big oceans does not even belong to the arctic. no matter what humans find as criteria, it's below the tropic of cancer almost entirely.

i know that my definitions don't count but i propose that if we talk about an ice-free arctic that we don not exclude regions arbitrarily so that the result meets our hypothesis.

perhaps i have to add that i'm open to discuss everything, i simply react to what i read and think that it's not absolutely correct or target leading. i do NOT claim to know better but i take the freedom to bring up a certain logic for others to consider while i can live well with other opinions as long as there is at least a kind of reason.

thing is that i agree with all those who predict a dramatical game change once most or big parts of the arctic ocean will be ice free in summer. this includes the probability that perhaps twice as much or more area that is currently freezing each winter will remain ice-free not that far out.

what i refuse to accept is that the arctic as per "entire arctic" which without further definition is meant IMO, will remain ice-free any time soon year-round.

if we start to exclude the areas that don't fit into our "idea" for a year-round-ice-free arcitc we are kind of cherry-picking or bending the facts so they fit in our claims and that is just not the way i think things should be approached, provided we are doing it to achieve something positive, be it to acquire most accurate knowledge and/or to tackle a problem and turn it into something better.

this is called an illusion IMO and illusions and wishful thinking are part of the reasons that brought us that far (down)

finally this is nothing personal of course, but i can only talk in reply to users that said something while my take on things is neither flawless nor personal.
Title: Re: When will the Arctic Go Ice Free?
Post by: magnamentis on August 04, 2018, 09:22:37 PM
we can try with the exclusion of i.e. the CAA, that's definitely in the arctic but then i'm interested to read why that region or any other should be excluded. (genuinely open to input)
Title: Re: When will the Arctic Go Ice Free?
Post by: Wherestheice on August 04, 2018, 09:56:43 PM
I agree that the Arctic won’t be completely ice free year round anytime soon, but it will eventually happen, we are taking the climate out of ice age to hothouse
Title: Re: When will the Arctic Go Ice Free?
Post by: magnamentis on August 04, 2018, 11:23:04 PM
I agree that the Arctic won’t be completely ice free year round anytime soon, but it will eventually happen, we are taking the climate out of ice age to hothouse

i agree on that one. i think the main differences are that some believe it will happen soon while i think it will take a lot of time still.

considering that some scientists FWIW predict sub 1 million km for the second half of this century in summer and then considering how much it will take form 1M km2 in summer to about no ice in winter i just didn't hear any convincing reasoning how this should be possible.

can be that reasoning lacks because there is no valid reason to believe that and could be that someone will sooner or later come up with good arguments.

further i sometimes think that those who "fight" so much for sensational shocking events forget to keep in mind that it would be much better for spaceship earth if it would take millenia rather than decades. i for my part will be happy if there will still be ice in winter the year a start my next journey to oblivion, mean pass away. as interesting as times are, there should be now wish to witness the consequences and the general global conditions once there will be zero ice year-round.

wish everyone a nice and cool weekend ;)
Title: Re: When will the Arctic Go Ice Free?
Post by: oren on August 04, 2018, 11:41:07 PM
The central arctic basin will not be ice-free in winter for at least some centuries, IMHO.
Take a look at the behavior of peripheral seas like the Chukchi and Bering, over time their ice-free season grows longer, but it's a very slow process and they still freeze over in winter. The Bering sea is very stormy, adjacent to the warm pacific, lies at only around 60 deg N, and still partially freezes over. So don't expect the north pole to stay ice-free year-round in your lifetime.
Title: Re: When will the Arctic Go Ice Free?
Post by: magnamentis on August 05, 2018, 12:01:36 AM
The central arctic basin will not be ice-free in winter for at least some centuries, IMHO.
Take a look at the behavior of peripheral seas like the Chukchi and Bering, over time their ice-free season grows longer, but it's a very slow process and they still freeze over in winter. The Bering sea is very stormy, adjacent to the warm pacific, lies at only around 60 deg N, and still partially freezes over. So don't expect the north pole to stay ice-free year-round in your lifetime.

i thinks it's obvious that i share your opinion while which exact additonal part of the central arctic will first go ice free during winter is dependent on how exactly ocean (and wind) currents will develop over time when there will be generally less and less ice.

there is a certain possibility that a warm current will eventually take a path into the CAB and cause earlier than expected ice free winter than even in more southerly and peripheral regions adjacent to cold continents.

i'm by no means saying this will be the case but i think we cannot totally exclude the possibility, no matter how little probable it may appear and i think those who opt for a quick development into such direction here mean exactly that, only that this would still not make an ice-free arctic in winter.

as usual you brought it to the point with few words, thanks.
Title: Re: When will the Arctic Go Ice Free?
Post by: binntho on August 05, 2018, 09:40:09 AM

if we talk about the arctic being ice free i say that each warm current has it's cold counterpart and that in one part of the arctic (one side if you prefer) there will always be a lot of ice.

You've said it before, and I asked: Is that some sort of natural law? That each warm current has it's cold counterpart? How and why?

To me this indicates a lack of understanding of how the big warm surface currents and the big cold bottom currents are tied together: The real counterpart of any warm surface current is a cold bottom current.

The image shows warm and cold currents in the North-Atlantic, both surface and deep. The warm currents are all on the surface, while the cold currents (with the exception of the narrow one running down the east coast of Greenland) are deep currents.

now i'd have to post a book to counter your statements, we'd have to go into density, salinity, when warm currents start to drop to the sea-floor to return south etc. but there are cold currents on the surface for sure, humbolt and many others, so the "all" is not correct and more time i'm not willing to spend on this topic. we can agree that we disagree and see what happens.

i tell you that none of us shall see an ice-free arctic in winter (arctic not north pole) and
you have another opinion which to proof false would take years work of studies and combine them into an excerpt. this is just too much and won't change the future anyways, hence i propose to leave it at that for the moment, it simply doesn't matter who is right and the future will tell what is right/wil happen.

enjoy further

Well a simple explanation of what you meant by the twice-repeated statement that "each warm current has it's cold counterpart" would be fine. Did you mean that they run in tandem, i.e. for each warm current that flows into the Arctic, another cold current also flows into the Arctic? Easy question which you should be able to answer!

Perhaps we could pair them up: What is the cold surface current counterpart of the Gulf Stream in the North Atlantic? (Hint: there isn't one). I've helpfully provided a map of the ocean currents (again!), I for one am unable to see the "cold counterpart" surface current of the "Norwegian Atlantic Current" as named on the map. Note that on this map, the deep currents are helpfully shown with broken lines.

Another thing: I find it amazing that you seem to know what my opinion is! I've no idea whether we will see an effectively ice-free Arctic in my lifetime (or, to set the bar a bit lower, even open sea lanes through the arctic all year round for normal shipping). But I do think that if it does happen within the next several thousand years it could only happen because of increased inflows of warm ocean currents, and I do believe that this is a real possibility and that we are seeing it happen these last few years. Whether the warm currents will continue to creep further into the Arctic or not is the big question.

And this is where your spurious statement came from: You seem to be claiming that this could not happen  because of some strange current symmetry where each warm current has a "cold counterpart".

So please make an effort at explaining what it is you are trying to claim!
Title: Re: When will the Arctic Go Ice Free?
Post by: gerontocrat on August 05, 2018, 10:06:51 AM
90+ percent of additional heat trapped by increasing CO2 concentrations in the atmosphere is going into long-term storage in the oceans.

Does this not suggest that over time warm currents get warmer and cold currents less cold?

And that in turn is not good news for winter sea ice ?
Title: Re: When will the Arctic Go Ice Free?
Post by: mostly_lurking on August 05, 2018, 10:43:10 AM
I agree that the Arctic won’t be completely ice free year round anytime soon, but it will eventually happen, we are taking the climate out of ice age to hothouse

What is eventually? If its 200 years why is everyone fear-mongering on the subject ? The failed predictions of the past is one of the main reasons people are still debating AGW.  Saying the arctic will be ice free in 50,30,20,10 years, sea level rise will disappear islands and roads on the coast will be under water and so many other predictions have failed.I agree that most are made by Politicians, celebrities and media (and some scientists looking for fame). Besides climate you can add in failed predictions on world famine,peak oil,population bomb and so many more. 200 years is a long time. Who knows what humanity can achieve in that time frame.
Title: Re: When will the Arctic Go Ice Free?
Post by: Wherestheice on August 05, 2018, 11:09:55 AM
I agree that the Arctic won’t be completely ice free year round anytime soon, but it will eventually happen, we are taking the climate out of ice age to hothouse

What is eventually? If its 200 years why is everyone fear-mongering on the subject ? The failed predictions of the past is one of the main reasons people are still debating AGW.  Saying the arctic will be ice free in 50,30,20,10 years, sea level rise will disappear islands and roads on the coast will be under water and so many other predictions have failed.I agree that most are made by Politicians, celebrities and media (and some scientists looking for fame). Besides climate you can add in failed predictions on world famine,peak oil,population bomb and so many more. 200 years is a long time. Who knows what humanity can achieve in that time frame.

Eventually is following trends.
Title: Re: When will the Arctic Go Ice Free?
Post by: mostly_lurking on August 05, 2018, 11:35:29 AM
snip..

What is eventually? I..snip

Eventually is following trends.

Too cryptic.
Everyone here follows trends- and are giving different answers to the poll.
Title: Re: When will the Arctic Go Ice Free?
Post by: magnamentis on August 05, 2018, 03:55:02 PM
90+ percent of additional heat trapped by increasing CO2 concentrations in the atmosphere is going into long-term storage in the oceans.

Does this not suggest that over time warm currents get warmer and cold currents less cold?

And that in turn is not good news for winter sea ice ?

put this way it's absolutely correct, question is if this "warmer" and "less cold" will suffice to compensate airtemps between -20C and -50C anytime soon.

since there's not much dispute about that sooner or later it can happen that the arctic will be ice-free year round (can, not will, we dont' know) this discussion is about WHEN and some say soon and i and others say in a few 100 years if at all.

now we only have to calculate how much energy has to be stored in the ocean to compensate for those extremely low winter temps, fed by land winds that can be down to -60C even.

so even if the entire system gets 20C warmer (air wise) we still have to see whether -30C or -20C
over a period of weeks will not be able to freeze at least parts of the oceans each winter.

as to currents (cold and warm) if the tone of that guy (not the quoted) get's slightly more condescending without reason i'll opt out, don't need to deal with things like that, one meeting in person would take care of  that but it won't happen.

back on topic, there is and will be a warm in-flow and cooler out-flow. the cooler outflow will reach temps that are cold now and will be cold in the future while still being in "arctic waters" hence we shall for a long time to come have cold currents in the arctic that won't withstand winter temps to avoid ice-building for quite some time to come which is my entire point.

i never said it can't be, i only say two things:

a) it won't happen any time soon (soon like in decades)

b) we can't know whether it will ever happen but currently i'd say yes it sooner or later will happen
.   if things continue the way they do now which as well is not a given.

those are the points, the rest is noise based on righteousness and antipathy, both well known
and speaking for themselves.

EDIT:

the number of times i have to repeat basic statements to filter the distracting noise around it depends on feedbacks. if one looks at the quoted post and my direct answer to it there is no repetition. it's a normal exchange/discourse.

that changes only if someone, who is not, thinks he can play extra smart just because this place is in his mother tongue and not in another language which many of those intolerant players don't even speak. now one can ask how do i know about the "he is not" that's very simple, a wise or at least fair person would never ever attack that way in a discussion that is case oriented, just because the reasoning and/or opinion does not fit his own and without being totally off.

why should there be a thread with a question in the title if the answer would be clear and self-evident? that only would be the case if someone ask questions not to get answers but to get confirmation, a very widely spread evil indeed and then whoever dares to try to find an answer
will be discredited.

who ever does not agree with my reasoning and/or opinion or (language skills) and does that in a reasonable useful manner will receive either new reasons and/or a genuine thanks for the new knowledge he/she provided to me, many times been proven to be so MR. B
Title: Re: When will the Arctic Go Ice Free?
Post by: binntho on August 05, 2018, 04:58:59 PM
as to currents (cold and warm) if the tone of that guy (not the quoted) get's slightly more condescending without reason i'll opt out, don't need to deal with things like that, one meeting in person would take care of  that but it won't happen.

So it's the personal attack now, along with a threat of bodily harm? How can you expect to make claims and not having to defend them, and instead start attacking and threatening people?

hat changes only if someone, who is not, thinks he can play extra smart just because this place is in his mother tongue and not in another language which many of those intolerant players don't even speak. now one can ask how do i know about the "he is not" that's very simple, a wise or at least fair person would never ever attack that way in a discussion that is case oriented, just because the reasoning and/or opinion does not fit his own and without being totally off.

And more of the same, personal attacks are symptomatic of a failed argument. And besides I'm not a native English speaker - I thought I made that clear?

And the point about spelling was that both you and gerantocrat had made stupid spelling mistakes because neither of you seemed to have read through what you had written before posting. But there is a big difference in that what gerantocrat writes actually makes sense.

But your original claim, that every warm ocean current has it's cold counterpart, can be deemed to be just something that you thought sounded good at the time? You did put it forward to dispute my point about possible changes in warm ocean currents as part of a normal debate, and then repeated it at a later point. Since you don't seem to be able to stand by your claim, I assume that you have acknowledged that my point has some merit.

To reiterate: The sea surface does not necessarily freeze even when temperatures are in the -20s or -30s centigrade, if there is a warm current keeping the surface above freezing (and remember that the surface of the sea needs to reach a temperature of abut -11 degrees centigrade to actually freeze over).

And we are seeing the northern extrusion of the Gulf Stream inching ever further north, it would seem by a hundred kilometers from year to year, and even moving in over deeper waters as A-Team pointed out yesterday, north of Svalbard. Earlier this summer it also seemed as if there was a creeping tongue of warm water moving along the Siberian seaboard.

But I can see from your musings that you have essentially accepted this point.
Title: Re: When will the Arctic Go Ice Free?
Post by: magnamentis on August 05, 2018, 06:53:32 PM

So it's the personal attack now, along with a threat of bodily harm? How can you expect to make claims and not having to defend them, and instead start attacking and threatening people?
an see from your musings that you have essentially accepted this point.

people always understand what they want or what is along their own way of thinking.

it's almost painful how many word are abused and/or misinterpreted to meat your goals.

wich bodily harm?

if you refer to the personal meeting ? where did i mention any physical exchange of energies ?

i meant and always mean talking, nothing else and nothing i ever wrote would hint at that i
support physical force, on the contrary, if i still really get into verbal fights with people, even people i love, like my dad,  it's if they support war, weapons and any other means of physical harm to get what they want or in support of their favourites.

which personal attack:

i simply replied and referred to your low input as well as your trying to discredit me which with this post you do for the 3rd time in a row by accusing me of threatening you physically only because i believe that a personal meeting would make many things clear and while in each other sentence i offered a case oriented discussion.

however it's not me who started being personal if i may remind you about you mocking my language skills and i think i excessively tried to show and explain how a discussion of this kind can go without issues.

you disagree with my claims that some data are flawed, then state it and proof if you can, i shall gladly learn and listen.

if you have no proof, (you cannot proof something is right by taking that same something as a proof of itself) then just state your opinion and let's agree that we disagree, easy as that no problem for me, never was.

i had this discussions several times and there were such and such replies, some were reasonable and i reacted reasonably and all was good, some were trying to put me into a specific corner and then, even with a certain amount of ego-control, it's still there and at times i'd certainly like to post a bunch of a few thousands of pages i wrote in philosophy and astro physics just to make some stubborn haters aware who is on the other end but that's exactly not good which i try to keep things civil until giving up which i certainly do with this post. it's my last one on this topic, no matter what you call me, i'll not react anymore, i idid my best to bring this to fruition because beginnings can be difficult at times even between good guys. but i admit that i failed in this case.

So Long!
have a happy life, no bad feeling will remain and if we ever meet i shall only say hello and talk nicely, hope it's clear enough
Title: Re: When will the Arctic Go Ice Free?
Post by: Wherestheice on August 05, 2018, 07:10:56 PM
snip..

What is eventually? I..snip

Eventually is following trends.

Too cryptic.
Everyone here follows trends- and are giving different answers to the poll.

You can believe what you want. I have no power over that. I’ll post a graph later.
Title: Re: When will the Arctic Go Ice Free?
Post by: Sam on August 05, 2018, 07:12:40 PM
In regard to the idea of needing to overcome -50 to -20 degree C conditions to get sea water to freeze... One important thing to remember is that the current conditions are just that, the current conditions.

There is an all too easy bias that the way things are and the way things work now is the way they always have been and always have worked. This is clearly untrue.

We know from past geologic periods that the conditions supporting year round ocean temperatures of 20 C and atmospheric temperatures of 25 C. We do not have even good theories about how the earth’s systems worked to allow, let alone support, this.

We may very well be within decades of gaining first hand experience about how that works.

And if that isn’t terrifying for its global implications, I do not know what is.

Sam
Title: Re: When will the Arctic Go Ice Free?
Post by: binntho on August 05, 2018, 07:24:43 PM

So it's the personal attack now, along with a threat of bodily harm? How can you expect to make claims and not having to defend them, and instead start attacking and threatening people?
an see from your musings that you have essentially accepted this point.

wich bodily harm?

if you refer to the personal meeting ? where did i mention any physical exchange of energies ?

Well, I might have misunderstood you. Normally, when people say something along the lines of what you said, they do actually mean having a physical fight! So perhaps better not say those kind of things.

But all in all, no harm done.
Title: Re: When will the Arctic Go Ice Free?
Post by: kassy on August 06, 2018, 12:54:49 AM
quoting from 132 above:
"now we only have to calculate how much energy has to be stored in the ocean to compensate for those extremely low winter temps, fed by land winds that can be down to -60C even."

But only a part of the heat gets there and calculating this is rather complicated.

And the heat is there already but it can't get up without help.

I sort of think of the Arctic as a bastion. The edges are contested first. The Barentz is lost and both oceans are intruding further into the Arctic. With the ice being thin as it is now that should show up as a pattern the next couple of years? (see animation 2 in #2555 in 2018 Melting Season).

These areas will then warm up early creating water areas which can destroy more ice with wave action and warmer water (and if it warms up enough it should connect with warmer water below?).

In the old days most of the old ice was at some side so that side was stronger and the other weaker. But the Arctic was sort of covered.

Now at some point the CAB ice will more or less float freely and with the wrong direction that will destroy a lot of ice (and that is where most of the remaining extent is hiding now) . It might take multiple years.

A bit surprised at how many voted 2018-2019. I think i would go for the 2020-2040 bin and yes that is cheating. 
Title: Re: When will the Arctic Go Ice Free?
Post by: Shared Humanity on August 06, 2018, 03:14:29 PM
I agree that the Arctic won’t be completely ice free year round anytime soon, but it will eventually happen, we are taking the climate out of ice age to hothouse

What is eventually? If its 200 years why is everyone fear-mongering on the subject ?

Because the Arctic Ocean need not be ice free to have a dramatic impact on the climate. We are already seeing the effect with blocking highs and persistent ridges causing extreme weather events all over the northern hemisphere.
Title: Re: When will the Arctic Go Ice Free?
Post by: Comradez on August 06, 2018, 03:51:19 PM
The Bering Sea is almost perennially ice-free now, and I predict will be within 5 years, so that would be a bad example to pick to show that ice will continue to form in the CAB for a long time. 

Look at the ocean around Svalbard.  It routinely stays ice-free past 80-north.  It is because it has a huge reservoir of heat constantly flowing in.  Right now that reservoir is balanced out by the cold of the CAB, but when it is augmented by summer sun, we are going to see Svalbard-like conditions take over all of the deep, non-coastal parts of the Arctic. 

The cold from land is no match for heat built up in water.  Those -60C winds will quickly warm to around freezing if the heat is there in the water to support it.  You simply won't see -30C in the CAB anymore if the water has a chance to soak up enough heat during the summer.  It's not like the Hudson Bay, which is shallow, and can't build up much heat, and which will probably have ice in the winter until maybe after 2100.  The ESS is shallow too, so I wouldn't be surprised to continue to see fast ice form there for many many decades in the winter.  But I wouldn't expect this ice to go much farther than the continental shelf once the CAB gets a few ice-free summers from May onwards, and gets to warm up to 15C by each September.  Heck, I wouldn't be surprised if it became possible to comfortably swim in the Arctic Ocean in some places in a few decades!
Title: Re: When will the Arctic Go Ice Free?
Post by: Sam on August 06, 2018, 04:31:53 PM
This story is an excellent summary of precisely where an ice free arctic takes us.

https://www.theatlantic.com/science/archive/2018/08/earths-scorching-hot-history/566762/
Title: Re: When will the Arctic Go Ice Free?
Post by: Dharma Rupa on August 06, 2018, 06:45:38 PM
The cold from land is no match for heat built up in water.  Those -60C winds will quickly warm to around freezing if the heat is there in the water to support it.  You simply won't see -30C in the CAB anymore if the water has a chance to soak up enough heat during the summer.  It's not like the Hudson Bay, which is shallow, and can't build up much heat, and which will probably have ice in the winter until maybe after 2100.  The ESS is shallow too, so I wouldn't be surprised to continue to see fast ice form there for many many decades in the winter.  But I wouldn't expect this ice to go much farther than the continental shelf once the CAB gets a few ice-free summers from May onwards, and gets to warm up to 15C by each September.  Heck, I wouldn't be surprised if it became possible to comfortably swim in the Arctic Ocean in some places in a few decades!

There is already plenty of heat in the Arctic, about 30 meters below the surface.
Title: Re: When will the Arctic Go Ice Free?
Post by: Pmt111500 on August 06, 2018, 07:05:51 PM

Heck, I wouldn't be surprised if it became possible to comfortably swim in the Arctic Ocean in some places in a few decades!
Too bad Barentz is nowadays counted as Atlantic also in the north so my legs haven't again been soaked in the Arctic ocean.
Title: Re: When will the Arctic Go Ice Free?
Post by: Niall Dollard on August 07, 2018, 10:45:03 AM
I took this image from Nat Geographic edition Jan this year.

Ive seen many projections like this showing the likely last areas to retain summer ice. But given the recent lift off from Cape Morris-Jessup, the lack of ice off Eastern Greenland and northern advancement of warm salty Atlantic water, I wonder have the models got it all wrong and the last preserve of ice will be a lot further west than northern Greenland.
Title: Re: When will the Arctic Go Ice Free?
Post by: binntho on August 07, 2018, 11:09:52 AM
I took this image from Nat Geographic edition Jan this year.

Ive seen many projections like this showing the likely last areas to retain summer ice. But given the recent lift off from Cape Morris-Jessup, the lack of ice off Eastern Greenland and northern advancement of warm salty Atlantic water, I wonder have the models got it all wrong and the last preserve of ice will be a lot further west than northern Greenland.

We've talked about this a few times. I don't think, once ice goes below a certain threshold, that it will be close to land like on the National Geographic image (and other similar images). It would more likely just float around, and in reality just melt.

So below a certain threshold, we'd probably see the open Arctic ocean totally ice free.
Title: Re: When will the Arctic Go Ice Free?
Post by: RikW on August 07, 2018, 11:19:36 AM
I guess in winter we will still see ice near the coast, but it will get smaller and smaller and float away a lot of times - of course depending on wind conditions etc
Title: Re: When will the Arctic Go Ice Free?
Post by: kynde on August 07, 2018, 11:44:49 AM
I guess in winter we will still see ice near the coast, but it will get smaller and smaller and float away a lot of times - of course depending on wind conditions etc

I think the point was that once it gets small enough to move as a whole the random(ish) distribution of winds will take it out and it will not return. That's how random walk works and that's what we see in other shorelines as well. (This obviously holds true only for the larger chunk leaning against northern Greenland and CAB, not the ice soup inside the CAB)

While it's large enough to not really move as a whole, like now, the ice can retreat away by compression and it can and will get back over and over by decompression and refreezing.


Where's the threshold for that? I have no idea and that's one of the interesting things I'm waiting to see.
Title: Re: When will the Arctic Go Ice Free?
Post by: opensheart on August 14, 2018, 11:29:55 PM
I have been Looking at that large area of remaining ice in the Beaufort Sea.   This is not the first time we have seen such a separation or near separation of an area of ice from the main pack.
I think we will see more and more of these separate ice patches in the future.

I am no longer envisioning the ice would retain a large central pack with clear fronts on all sides.   Where long term the fronts would advance and the central pack would shrink,  until the remaining ice is piled up along Greenland and Canada.

Instead I would propose that over years, we will see this central pack slowly dissolve into an increasing number of separate areas or concentrations of ice.    Sort of like the breakup of a super continent into smaller, separate continents. 

Eventually we will be tracking individual patches, for their own extent, area and concentration.   Tracking the ups and downs of each, as we watch the sub-packs fade on their own schedules.

Thus the Blue Ocean Event will come when the few remaining scatterings of ice melt below the combined threashold.   On that day there could be 3 or so separate areas of remaining ice in an otherwise blue ocean.   And those remaining areas of ice could be anywhere in the Arctic Ocean.
Title: Re: When will the Arctic Go Ice Free?
Post by: Stephan on September 07, 2018, 05:30:02 PM
It is time for the monthly update of my extrapolation when the extent [Extent], volume [Volumen] and thickness [Dicke] will reach zero. The extrapolation occured linearly and by a logarithmic function; the latter one constantly resulting in earlier times. See attached table.
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on September 07, 2018, 05:40:45 PM
It is time for the monthly update of my extrapolation when the extent [Extent], volume [Volumen] and thickness [Dicke] will reach zero. The extrapolation occured linearly and by a logarithmic function; the latter one constantly resulting in earlier times. See attached table.

Log function arrives at later date than linear for extent but earlier for volume and thickness. Why? Perhaps an example fit and extrapolation would help?

Also why a log function?

Curve seems more like gompertz to me and the models also seem to show gompertz shape. So why use a function that arrives at an earlier date than linear, particularly for volume?
Title: Re: When will the Arctic Go Ice Free?
Post by: Stephan on September 07, 2018, 07:46:07 PM
My answers to your questions and remarks:
1. Volume (and, in part, thickness) reduces faster than extent, therefore the non-linearity of the volume data is more expressed than the extent. This leads to extrapolation results with bigger differences between log and lin evaluation. For the winter and spring season the extent differences from year to year were slower in the 80s and 90s and have increased in the 00s but reduced in the 10s. This leads to the effect that the linear evaluation reaches zero a few years earlier than the log fit.
2. I used the log function in addition to the linear because the deviation is slightly smaller in the log function. A quadratic extrapolation delivers almost the same results than the log evaluation.
3. I have no expertise in Gompertz fits therefore I leave this to those who know how to deal with them correctly. But I confess that "Gompertz type fitted curves" look more closer to the volume data than linear, log or quadratic fits.

Generally: Extrapolations into the far future are scientifically nonsense. No-one knows which effect the first BOE in early autumn will have on the extent of the following months and years. With increasing GHG concentrations and changing ocean currents new mechanisms (at least new rates) in melting and re-freezing will be put into place.
I did this evaluation for myself just to know whether - on the basis of a continuation of the trend of the last 40 years - it will take decades, centuries or millenia to reach zero and I decided to share this information with you.
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on September 07, 2018, 08:49:22 PM
My answers to your questions and remarks:
1. Volume (and, in part, thickness) reduces faster than extent, therefore the non-linearity of the volume data is more expressed than the extent. This leads to extrapolation results with bigger differences between log and lin evaluation. For the winter and spring season the extent differences from year to year were slower in the 80s and 90s and have increased in the 00s but reduced in the 10s. This leads to the effect that the linear evaluation reaches zero a few years earlier than the log fit.
2. I used the log function in addition to the linear because the deviation is slightly smaller in the log function. A quadratic extrapolation delivers almost the same results than the log evaluation.
3. I have no expertise in Gompertz fits therefore I leave this to those who know how to deal with them correctly. But I confess that "Gompertz type fitted curves" look more closer to the volume data than linear, log or quadratic fits.

Generally: Extrapolations into the far future are scientifically nonsense. No-one knows which effect the first BOE in early autumn will have on the extent of the following months and years. With increasing GHG concentrations and changing ocean currents new mechanisms (at least new rates) in melting and re-freezing will be put into place.
I did this evaluation for myself just to know whether - on the basis of a continuation of the trend of the last 40 years - it will take decades, centuries or millenia to reach zero and I decided to share this information with you.

Thanks for the answers.  :)

Not sure I have much expertise with gompertz functions other than the forumla looks like:
=parameter1*EXP(-EXP(Parameter 2*(year-Parameter3))) [+parameter4 if using 4 parameters)]

It is fairly easy to set up a spreadsheet to calculate 'sum of the errors squared' (or squareroot thereof) then optimise the parameters to minimise that total using a solver function/add-in.

I expect all your 'answers' will all be closer than my 4 parameter fits ;)
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on September 08, 2018, 02:27:19 PM
I believe (and correct me if I am wrong) that this exercise is just curve fitting to the best possible line.  What we lack (me included) is an explanation as to why any particular fit should be chosen.  Oftentimes, a linear fit can approximate a particular data curve over a specified range.  As the data approaches zero, I would expect this to fail, although in which direction is debatable.  In an unknown situation, oftentimes a moving average can best define the trend, as it incorporates recent data, without bias.  Not that it is any more accurate, but it tends to smooth out the data, removing variations which may mislead the eye.  Lastly, extrapolated beyond known parameters is always highly speculative, as we do not know how that affects the environment.  In short, it is a guess.  But we strive to make it the most educated best possible, and your guess may be different than mine, depending on which parameters we each feel might predominate in a future scenario.
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on September 08, 2018, 04:00:12 PM
I believe (and correct me if I am wrong) that this exercise is just curve fitting to the best possible line.  What we lack (me included) is an explanation as to why any particular fit should be chosen.  Oftentimes, a linear fit can approximate a particular data curve over a specified range.  As the data approaches zero, I would expect this to fail, although in which direction is debatable.  In an unknown situation, oftentimes a moving average can best define the trend, as it incorporates recent data, without bias.  Not that it is any more accurate, but it tends to smooth out the data, removing variations which may mislead the eye.  Lastly, extrapolated beyond known parameters is always highly speculative, as we do not know how that affects the environment.  In short, it is a guess.  But we strive to make it the most educated best possible, and your guess may be different than mine, depending on which parameters we each feel might predominate in a future scenario.

Yes it is highly speculative.

>What we lack (me included) is an explanation as to why any particular fit should be chosen.

I try to refer to the models and if they almost all show a Gompertz like shape, then why would you use a different shaped curve to fit the data? A better fit might be one reason but if this gompertz shape does pretty well at reducing the RMSE that seems additional reason to go with it.

Use too many parameters and you can get a better fit and send the extrapolation off in any direction you choose. Hence it is necessary to try to minimise the number of parameters used. This can be considered to be a form of Occam's razor - if you don't need extra complexity to explain the data then that extra complexity is likely just wrong and should be omitted.

These considerations (particularly considering the physics which is what the models do) tends to act to place some limits on where the extrapolation goes.

Yes, it is highly speculative and the more so the further you go away from the known data. But at least it is based on something. If the alternative is making stuff up off the top of your head, and the people doing that sort of thing tend to be concerned about the issue and therefore likely to give a biased view towards catastrophic effects in order to motivate action,.... guess which I think should be preferred?
Title: Re: When will the Arctic Go Ice Free?
Post by: Stephan on October 04, 2018, 09:11:24 PM
It is time for the monthly update of my extrapolation when the extent [Extent], volume [Volumen] and thickness [Dicke] will reach zero. The extrapolation occured linearly and by a logarithmic function; the latter one almost constantly resulting in earlier times. September value now includes 2018, and BOE seems to appear later than extrapolated last year, mostly due to a slight increase in volume 2018 compared to 2017.
See attached table.
Title: Re: When will the Arctic Go Ice Free?
Post by: kassy on October 05, 2018, 01:49:27 PM
Are any of these three measures ´better´ then the other two?

We measure extent directly (and then express it in a SIE way) while thickness and volume are further model extrapolations?

Just curious about this since the extrapolated dates diverge. The first to hit zero in the real world would mean that the others are then zero too.
Title: Re: When will the Arctic Go Ice Free?
Post by: Stephan on October 05, 2018, 03:15:16 PM
The real value to look at is the volume. If you imagine a block of ice 1km*1km wide and 1 m thick, melting on its edges, say 1m/year, will almost not change its area and you need 500 years until it is gone. But if you melt 10 cm/year (only 10% of the edges' value) from below at the same time, it only needs 10 years to be completely gone. This is the "secret" behind the diverge of the data.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on October 05, 2018, 05:03:10 PM
The real value to look at is the volume. If you imagine a block of ice 1km*1km wide and 1 m thick, melting on its edges, say 1m/year, will almost not change its area and you need 500 years until it is gone. But if you melt 10 cm/year (only 10% of the edges' value) from below at the same time, it only needs 10 years to be completely gone. This is the "secret" behind the diverge of the data.

Not sure I agree with this logic.  Melting is really only occurring in two dimensions; above from sunlight and below from sea water.  Hence, extent seems to better reflect real world conditions. 
Title: Re: When will the Arctic Go Ice Free?
Post by: Pmt111500 on October 05, 2018, 05:28:13 PM
The real value to look at is the volume. If you imagine a block of ice 1km*1km wide and 1 m thick, melting on its edges, say 1m/year, will almost not change its area and you need 500 years until it is gone. But if you melt 10 cm/year (only 10% of the edges' value) from below at the same time, it only needs 10 years to be completely gone. This is the "secret" behind the diverge of the data.

Not sure I agree with this logic.  Melting is really only occurring in two dimensions; above from sunlight and below from sea water.  Hence, extent seems to better reflect real world conditions.
Well, ice conducts heat like any solids.
Title: Re: When will the Arctic Go Ice Free?
Post by: Stephan on October 05, 2018, 07:10:06 PM
My explanation was not to describe exactly what happens when an ice floe on sea water is melting but to illustrate the much more important volume decrease in comparison to an extent (or area) decrease, when it comes to define which one of the three measures (area/extent, volume or thickness) plays the major role in the time until the first BOE occurs.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on October 05, 2018, 08:20:05 PM
My explanation was not to describe exactly what happens when an ice floe on sea water is melting but to illustrate the much more important volume decrease in comparison to an extent (or area) decrease, when it comes to define which one of the three measures (area/extent, volume or thickness) plays the major role in the time until the first BOE occurs.

Yes, but if you examine the charts, the first dimension to fail is thickness, which reaches a BOE in 2053.  The combined length and width does not occur until 2073.  How could volume decline to zero, before any of the dimensions?  Mathematically, volume will always decrease faster than any one- or two-dimensional measurement, and then slow as less volume is present.  Hence, I question the use of volume to make predictions.
Title: Re: When will the Arctic Go Ice Free?
Post by: oren on October 05, 2018, 08:44:26 PM
Extent is deceptive. If the arctic has a typical thickness of 2.5m at max, and each year's melt is 2m, what does extent tell you? That all is well. When typical thickness drops to 2.3m at max, and annual melt increases to 2.1m, extent still looks almost fine. But when thickness at max drops to 2.2m and annual melt to 2.3m, you get a BOE all of a sudden.
Extent is showing a trend because at the edges the ice is thinner and annual melt larger than at the heart of the pack. But volume trend is much more indicative.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on October 06, 2018, 02:16:26 PM
Extent is deceptive. If the arctic has a typical thickness of 2.5m at max, and each year's melt is 2m, what does extent tell you? That all is well. When typical thickness drops to 2.3m at max, and annual melt increases to 2.1m, extent still looks almost fine. But when thickness at max drops to 2.2m and annual melt to 2.3m, you get a BOE all of a sudden.
Extent is showing a trend because at the edges the ice is thinner and annual melt larger than at the heart of the pack. But volume trend is much more indicative.

I thick you are misrepresenting the situation.  The thickness varies across the Arctic, and does not melt uniformly.  What you are describing is a small inland lake, which will freeze overnight in the winter, and then slowly melt in the spring, until one day it all disappears. 
Title: Re: When will the Arctic Go Ice Free?
Post by: Stephan on October 06, 2018, 06:37:08 PM
Extent is deceptive. If the arctic has a typical thickness of 2.5m at max, and each year's melt is 2m, what does extent tell you? That all is well. When typical thickness drops to 2.3m at max, and annual melt increases to 2.1m, extent still looks almost fine. But when thickness at max drops to 2.2m and annual melt to 2.3m, you get a BOE all of a sudden.
Extent is showing a trend because at the edges the ice is thinner and annual melt larger than at the heart of the pack. But volume trend is much more indicative.

I thick you are misrepresenting the situation.  The thickness varies across the Arctic, and does not melt uniformly.  What you are describing is a small inland lake, which will freeze overnight in the winter, and then slowly melt in the spring, until one day it all disappears.
oren has just explained the possibility of a "surprising" BOE. His figures are completely valid, independent how thick the ice is and independent how high the melting rate is. It is just an example.
I am very convinced that volume is the measure that has to be looked at if you want to extrapolate to the first BOE. oren's example shows that the extrapolation of area or extent gives much too high values, because if the ice gets very thin, then the floes' area will reduce with an accelerating rate. This rate will once meet the volume reduction rate in the graph close before the BOE will take place.
Title: Re: When will the Arctic Go Ice Free?
Post by: El Cid on October 06, 2018, 08:57:14 PM
As far as I understand, volume figures are just estimates, and very rough ones at that. We do however have measurements of temperatures which indirectly tell us how thick the ice is. Wintertime temperatures should be higher as the ice gets thinner and more fragmented, since ice is an insulator between air and sea. Thinner ice = higher temperatures.

Indeed, that is happening, and quite rapidly in the past few years. Attached is a chart of 70-90N temps with some notable outliers (winter of 2006/7, and 2011/12). The past 3 years have seen higher than ever temps up North. This probably means that the ice is in a bad shape, actually worse than ever (since we have measurements I mean).
Title: Re: When will the Arctic Go Ice Free?
Post by: Stephan on October 06, 2018, 10:00:49 PM
What once was declared as outliers (2006/07 and 2011/12) is now below of what we saw the last three winters...
Title: Re: When will the Arctic Go Ice Free?
Post by: GoSouthYoungins on October 06, 2018, 11:19:27 PM
2019 or 2020
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on October 08, 2018, 03:49:00 AM
Extent is deceptive. If the arctic has a typical thickness of 2.5m at max, and each year's melt is 2m, what does extent tell you? That all is well. When typical thickness drops to 2.3m at max, and annual melt increases to 2.1m, extent still looks almost fine. But when thickness at max drops to 2.2m and annual melt to 2.3m, you get a BOE all of a sudden.
Extent is showing a trend because at the edges the ice is thinner and annual melt larger than at the heart of the pack. But volume trend is much more indicative.

I thick you are misrepresenting the situation.  The thickness varies across the Arctic, and does not melt uniformly.  What you are describing is a small inland lake, which will freeze overnight in the winter, and then slowly melt in the spring, until one day it all disappears.
oren has just explained the possibility of a "surprising" BOE. His figures are completely valid, independent how thick the ice is and independent how high the melting rate is. It is just an example.
I am very convinced that volume is the measure that has to be looked at if you want to extrapolate to the first BOE. oren's example shows that the extrapolation of area or extent gives much too high values, because if the ice gets very thin, then the floes' area will reduce with an accelerating rate. This rate will once meet the volume reduction rate in the graph close before the BOE will take place.

If you are convinced that a BOE will occur when the ice gets very thin, the perhaps you should choose thickness as the measure to be looked at if you want to extrapolate.  The only reason that the two-dimensional measures give too high a value, is you think it should be lower.  I think that is a rather biased reason.  But, to each his own.
Title: Re: When will the Arctic Go Ice Free?
Post by: DavidR on October 08, 2018, 09:35:47 AM
You are convinced that a BOE will occur when the ice gets very thin, the perhaps you should choose thickness as the measure to be looked at if you want to extrapolate.  The only reason that the two-dimensional measures give too high a value, is you think it should be lower.  I think that is a rather biased reason.  But, to each his own.
That's an odd argument if you ask me. The thickness is estimated by dividing area or extent by  volume. There is a lot of thin ice at the start of the season and a little bit of thick ice regardless of the overall extent.  As volume and extent decline the average thickness doesn't vary much. Thickness is probably a worse indicator than extent or area.  Volume seems a much more likely  measure because it measures the amount of ice lost each year.

Volume declines based on the difference between the ice formed in the freezing  season and the ice melting in the melting season. This has meant an average loss of about about 320 km^3 per year since 1988 but about 500 Km^3 per year since 2000 this appears to  be increasing exponentially  as warmer waters move into the Arctic.  With only  5000 Km^3 at minimum this year it seems highly likely  that within 10 years we will see a BOE in September. Extrapolating from extent,  thickness or area gives a much later date.
Title: Re: When will the Arctic Go Ice Free?
Post by: El Cid on October 08, 2018, 10:02:04 AM
I'm amazed that people can still take extrapolations seriously. If you had extrapolated in 2007, 8, or 12 based on either extent or volume or whatever, we should already be ice free. We are not, which proves the point: extrapolation does not work. It doesn't work, beacuse it is a nonlinear system, and melting the shelf is not the same as melting the central pack. Therefore extrapolations are rather a waste of time.

Even if you wanted to extrapolate I would urge to disregard anything other than the central pack, as most everything else melts out anyway, and extrapolate just the central pack going down to zero. Even this is probably close to useless but much better than using the total volume or extent numbers.
Title: Re: When will the Arctic Go Ice Free?
Post by: El Cid on October 08, 2018, 10:18:48 AM
So this is the rolling average past 12 month piomas volume of the CAB (based on Wipneus' file, attached). You can see that we lost cca 5000km3 from 1995 to 2011 (annual average loss of cca 300+ km3, which lineary extrapolated should have pointed to 0km3 remaining by around 2030), but it has been moving sideways in the past 7 years. The central pack is a hard nut to crack. We might see another 10 yrs of sideways movement or we might see a huge decline even the next few years. It is impossible to say. But extrapolation will not help.

I also attach an extrapolation from 2010 to 2018. It was such a nice fit, and still  it was a huge miss! Based on 2010 extrapolations, we should be around 5000 km3 average volume, whereas in realitywe are at 7400

 
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on October 08, 2018, 02:54:43 PM
which proves the point: extrapolation does not work. It doesn't work, beacuse it is a nonlinear system, and melting the shelf is not the same as melting the central pack. Therefore extrapolations are rather a waste of time.

Seems a bit sweeping to me. It certainly doesn't work when a new trend is emerging or when you use the wrong curve type or when trying to predict a long way outside the data range. Using exponential when the models suggest something more like gompertz was asking for big miss and even more so when the trend was beginning to show a levelling off and there were explanations in the literature to explain an acceleration and deceleration.

You pick out two reasons: non linear and central vs shelf. Certainly it is much easier to extrapolate with a linear system and I also agree re central vs shelf. But I would suggest that there are other reasons and maybe the two you picked alone wouldn't automatically mean that extrapolations will always fail.
Title: Re: When will the Arctic Go Ice Free?
Post by: El Cid on October 08, 2018, 03:33:14 PM
which proves the point: extrapolation does not work. It doesn't work, beacuse it is a nonlinear system, and melting the shelf is not the same as melting the central pack. Therefore extrapolations are rather a waste of time.

Seems a bit sweeping to me. ...

You pick out two reasons: non linear and central vs shelf. Certainly it is much easier to extrapolate with a linear system and I also agree re central vs shelf. But I would suggest that there are other reasons and maybe the two you picked alone wouldn't automatically mean that extrapolations will always fail.

Crandles, you are absolutely right. I consciously oversimplified the question just like extrapolation is IMO a very serious oversimplification of such an amazingly complex system. Nonetheless, we are definitely progressing towards a (more or less) ice free Arctic, and I just wanted to emphasize that forecasting the timing of a BOE (or any other state) is nigh impossible, no matter how much we would like to...
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on October 08, 2018, 03:40:46 PM
Speaking of useless extrapolations...


The first attachment uses maximum volume and the complete data set of the melting season volume loss to estimate the first ice free arctic.

The second attachment shows the maximum volume to volume loss ratio. There is a very good evidence that after 2007 there was a step change in the Arctic. This is supported by significant increase of the average losses. 

The third attachment uses the losses only from 2007-2018 with the justification that the system changed.
Title: Re: When will the Arctic Go Ice Free?
Post by: Pmt111500 on October 08, 2018, 05:16:03 PM
Yay Archimid! That looks like if the system change of 2010-2014 is the real change, and all other measurements are in error ice will never go away! Nice example of real problems in selecting anything other than a linear function for an extrapolation.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on October 08, 2018, 05:53:42 PM
Yay Archimid! That looks like if the system change of 2010-2014 is the real change, and all other measurements are in error ice will never go away! Nice example of real problems in selecting anything other than a linear function for an extrapolation.

Curve fitting can sometimes be an exercise in futility.  It looks nice, but does it describe the true situation.  Hard to imagine maximum ice volume approaching zero in an environment that is 20C below freezing.
Title: Re: When will the Arctic Go Ice Free?
Post by: Rodius on October 09, 2018, 01:08:02 AM


Curve fitting can sometimes be an exercise in futility.  It looks nice, but does it describe the true situation.  Hard to imagine maximum ice volume approaching zero in an environment that is 20C below freezing.
[/quote]

You say this, yet the Arctic has been ice free multiple times before
Title: Re: When will the Arctic Go Ice Free?
Post by: Sam on October 09, 2018, 01:38:48 AM
Interesting plots and extrapolations.

Yes, it is always important to be careful with extrapolations. That said, these two extrapolations lend at least some credence and support for my informal projection that we may see an ice free Arctic year round by 2035, and certainly not later than 2050.

As far as the idea that at -20 C the Arctic cannot be ice free....

That presumes without basis the idea that the Arctic system will remain as it is today despite the absence of the ice. Clearly it won't. How will it behave? We simply do not know.

We know the Arctic has gone ice free through quite a long part of geologic history. We know even that it has been quite warm, supporting subtropical plants and creatures as far north as Ellesmere and southern Greenland.

So how is this possible? That is a vastly better question, than the presumption contrary to known history that it will remain the same as now, and therefor cannot go ice free. That argument is circular and clearly wrong.

So, how?

We don't know. But we are about to find out. One plausible answer is that with the loss of the cold pole (no ice), and the dramatic shifts in atmospheric circulation, that at least two new things happen. 

First, the warm oceans and land support higher humidity that supports deep clouds through the Arctic winter insulating the pole from radiative heat loss.

Second, that the single circulation band and increased height of the tropopause drive heat migration northward via the atmosphere in a slower flow pattern.  The current three cell system acts as a block preventing that. With the loss of the three cell system, the circulation will likely look more like what we see on Venus.

Conditions there are so radically different from those on Earth, that we likely cannot learn too much from Venus as an exemplar. It does though give us a crude framework to consider.

Sam
Title: Re: When will the Arctic Go Ice Free?
Post by: SteveMDFP on October 09, 2018, 01:48:19 AM
The current three cell system acts as a block preventing that. With the loss of the three cell system, the circulation will likely look more like what we see on Venus.

Conditions there are so radically different from those on Earth, that we likely cannot learn too much from Venus as an exemplar. It does though give us a crude framework to consider.

Sam

Thanks for that, Sam.  I didn't know that we knew the atmospheric circulation patterns on Venus.  Can you elaborate?  It might indeed be relevant, and I don't know that the subject has ever come up on this forum.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on October 09, 2018, 02:59:35 AM


Curve fitting can sometimes be an exercise in futility.  It looks nice, but does it describe the true situation.  Hard to imagine maximum ice volume approaching zero in an environment that is 20C below freezing.

You say this, yet the Arctic has been ice free multiple times before
[/quote]

Yes, during those times when the temperature was warming, preventing freezing.  Simple physics.
Title: Re: When will the Arctic Go Ice Free?
Post by: Sam on October 09, 2018, 04:47:48 AM
Steve,

I've not tried posting links before. We will see how this goes.

Here are a couple of "simpler" articles on the subject.

https://www.lpi.usra.edu/vexag/chapman_conf/presentations/limaye.pdf (https://www.lpi.usra.edu/vexag/chapman_conf/presentations/limaye.pdf)

http://lasp.colorado.edu/~espoclass/ASTR_5835_2015_Readings_Notes/Notes_presentations/Schiff_Nov17-superrotation_presentation-expanded.pdf (http://lasp.colorado.edu/~espoclass/ASTR_5835_2015_Readings_Notes/Notes_presentations/Schiff_Nov17-superrotation_presentation-expanded.pdf)

And a more intense General one on exoplanets generally, especially others bodies in our system.

https://www.lpl.arizona.edu/~showman/publications/showman-etal-exoplanets-review-revised.pdf (https://www.lpl.arizona.edu/~showman/publications/showman-etal-exoplanets-review-revised.pdf)

Venus is an attractive case because it is our near twin. It is also has a series of problems for trying to relate it to Earth. Venus lacks a moon (and tidal forces). It has a tremendously dense hot and very different atmosphere. And it has a very slow retrograde rotation. Th atmosphere on Venus rotates in the direction of the planet, but much faster (super rotation).

Venus has massive storms over both poles that are persistent structures similar to those on Saturn.

Those might be suggestive of what our future may hold in store (Earth's distant past too).

Sam
Title: Re: When will the Arctic Go Ice Free?
Post by: Rodius on October 09, 2018, 04:48:23 AM


Curve fitting can sometimes be an exercise in futility.  It looks nice, but does it describe the true situation.  Hard to imagine maximum ice volume approaching zero in an environment that is 20C below freezing.

You say this, yet the Arctic has been ice free multiple times before

Yes, during those times when the temperature was warming, preventing freezing.  Simple physics.
[/quote]

What do you think is happening at the moment?
Are you suggesting the Arctic is not warming?
Title: Re: When will the Arctic Go Ice Free?
Post by: Sam on October 09, 2018, 04:58:52 AM
Steve,

Here is a bit clearer explanation. Skip to page 26-28. Lots of fascinating data and information.

https://spaceflightsystems.grc.nasa.gov/SSPO/SP/VenusUpper/Presentations/Crisp_1_What_We_Know_Today_Venus_STIM_20130124.pdf (https://spaceflightsystems.grc.nasa.gov/SSPO/SP/VenusUpper/Presentations/Crisp_1_What_We_Know_Today_Venus_STIM_20130124.pdf)

Sam
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on October 09, 2018, 02:40:17 PM


Curve fitting can sometimes be an exercise in futility.  It looks nice, but does it describe the true situation.  Hard to imagine maximum ice volume approaching zero in an environment that is 20C below freezing.

You say this, yet the Arctic has been ice free multiple times before

Yes, during those times when the temperature was warming, preventing freezing.  Simple physics.

What do you think is happening at the moment?
Are you suggesting the Arctic is not warming?
[/quote]

Not at all.  Should the Arctic temperature increase another 5C, then complete melting of the ice is certainly possible.  That is the estimated temperature the last time the Arctic was ice-free.
Title: Re: When will the Arctic Go Ice Free?
Post by: mostly_lurking on October 09, 2018, 02:56:12 PM
...snip


Not at all.  Should the Arctic temperature increase another 5C, then complete melting of the ice is certainly possible.  That is the estimated temperature the last time the Arctic was ice-free.

In the summer?
Title: Re: When will the Arctic Go Ice Free?
Post by: binntho on October 09, 2018, 02:57:06 PM
Should the Arctic temperature increase another 5C, then complete melting of the ice is certainly possible.  That is the estimated temperature the last time the Arctic was ice-free.

Well, there are different opinions as to when the arctic was last ice-free, at least seasonally (i.e. during summer). Quite possibly the last time was during the holocenene maximum when temperatures were not significantly higher than they are now.

https://www.sciencedirect.com/science/article/pii/S0277379113004162
Title: Re: When will the Arctic Go Ice Free?
Post by: jdallen on October 09, 2018, 04:13:33 PM
You are convinced that a BOE will occur when the ice gets very thin, the perhaps you should choose thickness as the measure to be looked at if you want to extrapolate.  The only reason that the two-dimensional measures give too high a value, is you think it should be lower.  I think that is a rather biased reason.  But, to each his own.
That's an odd argument if you ask me. The thickness is estimated by dividing area or extent by  volume. There is a lot of thin ice at the start of the season and a little bit of thick ice regardless of the overall extent.  As volume and extent decline the average thickness doesn't vary much. Thickness is probably a worse indicator than extent or area.  Volume seems a much more likely  measure because it measures the amount of ice lost each year.

Volume declines based on the difference between the ice formed in the freezing  season and the ice melting in the melting season. This has meant an average loss of about about 320 km^3 per year since 1988 but about 500 Km^3 per year since 2000 this appears to  be increasing exponentially  as warmer waters move into the Arctic.  With only  5000 Km^3 at minimum this year it seems highly likely  that within 10 years we will see a BOE in September. Extrapolating from extent,  thickness or area gives a much later date.
Volume is the key metric, as it is the primary expression of over-all heat exchange and total enthalpy in the system.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on October 09, 2018, 05:03:15 PM
You are convinced that a BOE will occur when the ice gets very thin, the perhaps you should choose thickness as the measure to be looked at if you want to extrapolate.  The only reason that the two-dimensional measures give too high a value, is you think it should be lower.  I think that is a rather biased reason.  But, to each his own.
That's an odd argument if you ask me. The thickness is estimated by dividing area or extent by  volume. There is a lot of thin ice at the start of the season and a little bit of thick ice regardless of the overall extent.  As volume and extent decline the average thickness doesn't vary much. Thickness is probably a worse indicator than extent or area.  Volume seems a much more likely  measure because it measures the amount of ice lost each year.

Volume declines based on the difference between the ice formed in the freezing  season and the ice melting in the melting season. This has meant an average loss of about about 320 km^3 per year since 1988 but about 500 Km^3 per year since 2000 this appears to  be increasing exponentially  as warmer waters move into the Arctic.  With only  5000 Km^3 at minimum this year it seems highly likely  that within 10 years we will see a BOE in September. Extrapolating from extent,  thickness or area gives a much later date.

Not sure where you are getting your determinations from, but volume is the estimated parameter, and calculated by multiplying the thickness by the area.  Thickness is determined by averaging the modeled thickness in each gridded cell.  Hence volume has thickness plus area uncertainty incorporated into its calculation.  Also, if both area (2-dimensions) and thickness (1-dimension) are decreasing, the volume (3-dimension) must decrease faster.  Hence, volume will always show a faster rate of decline than either area or thickness, but will slow down as the other parameters catch up.
Title: Re: When will the Arctic Go Ice Free?
Post by: Tor Bejnar on October 09, 2018, 05:56:41 PM
Quote
volume will always show a faster rate of decline than either area or thickness, but will slow down as the other parameters catch up.
I'm not sure this is always true, but I'm not a thermodynamics anything (not an expert nor even particularly knowledgeable).  If a significant cause of ice melt is bottom melt (which will likely increase as thickness decreases, as solar input into this process increases with ice thinness), then declining thickness will accelerate as zero volume approaches, while area remains fairly unchanged.  If area decreases 'at all', it might be a 'fact' that volume will decrease at a lower rate than does thickness (although faster than the area decline).  But I think this doesn't require volume declines to actually "slow down".
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on October 09, 2018, 07:43:00 PM
Quote
volume will always show a faster rate of decline than either area or thickness, but will slow down as the other parameters catch up.
I'm not sure this is always true, but I'm not a thermodynamics anything (not an expert nor even particularly knowledgeable).  If a significant cause of ice melt is bottom melt (which will likely increase as thickness decreases, as solar input into this process increases with ice thinness), then declining thickness will accelerate as zero volume approaches, while area remains fairly unchanged.  If area decreases 'at all', it might be a 'fact' that volume will decrease at a lower rate than does thickness (although faster than the area decline).  But I think this doesn't require volume declines to actually "slow down".

It is a case of simple mathematics.  The current minimum sea ice extent is ~60% of the extent measured in 1980.  The minimum volume is ~30% of 1980.  The thickness is ~50% of 1980.  Volume is just a product of these two; and since both are decreasing, the volume must decrease faster.  As extent and thickness decrease, the volume loss will slow because there is less volume to lose. 

This is different from the typical ice cube in a glass experiment, whereby all sides melt equally.  The large disproportionate dimensions leads to a difference in the physical melting properties.  The larger extent (or area) dominates the melting characteristic. 

If one were to assume that volume is the key parameter, and volume continues to decrease at its current rate, then the decline in thickness would need to double and the decline in extent more than triple, so that all three parameters reach zero simultaneously.  That is not what we are experiencing currently.
Title: Re: When will the Arctic Go Ice Free?
Post by: Sam on October 09, 2018, 08:16:11 PM
Klondike Kat,

I fear that you may have fallen victim to a variation of Zeno's paradox. (Ice volume decrease slow down)

Common experience suggests just the opposite. As anyone who has every drunk anything with ice in it can attest - the ice lasts and lasts and lasts, until near the end. As the volume of ice approaches zero, the exposed surface area increases and the melt rate increases with it, or ----- it at least seems to. I suspect the latter is the truth.

Rather than slowing down, I suspect that the volumetric loss rate would remain the same, all other factors remaining constant. But they aren't remaining constant. The heat input to the Arctic waters is increasing through direct solar absorption, through warmer fresh water inputs from rivers, and through intrusion of warmer waters from the Atlantic and Pacific. This is to some degree countered by increasing flows of cold (above freezing) water from Greenland melt.

At the same time, with the loss of ice, wind and wave action is increasing. This sloshing and stirring has to also be increasing the melt rate. Ditto for mixing of the Arctic Ocean bringing warmer and more saline waters into greater contact with the ice. Both increase the melt rate.

I fully expect the ice melt rate to increase as the ice volume nears zero. This I suspect will show up as increasing thinning, loss of multi year ice, shattering and dispersion of the ice, and formation of more vulnerable saline first year ice. And that is what we have seen.

Unsurprisingly, this is causing the extent to at least appear to increase compared to expectations due to the shattering and dispersion of the ice pack, coupled with the arbitrary rule that any area of Ocean that is covered by 15% or greater of ice is counted as being 100% covered.

That rule worked reasonably to smooth the edge of the intact ice sheet. It does not work at all well with a shattered ice sheet. To the contrary, it lies to us and causes us to falsely believe that conditions are no where near as bad as they really are.

And all of that leaves us vulnerable to seeing all of the ice seeming to go "poof!" over a short time span and making everyone involved look silly.

Sam
Title: Re: When will the Arctic Go Ice Free?
Post by: Ned W on October 09, 2018, 09:25:04 PM
I fully expect the ice melt rate to increase as the ice volume nears zero.

Except that doesn't seem to be what's happening:

(https://i.imgur.com/WyRGerv.jpg)

So perhaps intuition, and analogizing the Arctic to ice cubes in a drinking glass, aren't all that helpful?  Reality sure looks more like one of crandles's Gompertz curves.

Credit: Wipneus's monthly PIOMAS regional volume data.
Title: Re: When will the Arctic Go Ice Free?
Post by: Sam on October 09, 2018, 10:59:06 PM
Quote
Except that doesn't seem to be what's happening:

snip...

So perhaps intuition, and analogizing the Arctic to ice cubes in a drinking glass, aren't all that helpful?  Reality sure looks more like one of crandles's Gompertz curves.

More than perhaps. We all of us are to a good degree - whistling in the dark. The dynamics of the current and future conditions are unlike anything we have good evidence or models for. There are far too many uncertainties to have high confidence in predictions.

However, we can be sure that the difference in consequences is important in how we plan for our future. The consequences of an ice free Arctic to atmospheric and oceanic processes are enormous for humans and all creatures on Earth. Hoping or planning for less consequential outcomes runs the risk of triggering horrific outcomes.

Also, though at least in the short term the model projected ice volume appears to be following something like a Gompertz curve, it is important to be mindful of a couple of things.

First, the PIOMAS volume, useful as it is, is a modelled result. It may be wrong.

Second, within any data set like this there is statistical noise as well as potential systematic errors that have escaped recognition. The statistical noise can lead to misleading projections. Time will tell.

Third, there may be self referential (circular) errors involved where the fundamentals of how PIOMAS works may be misleading.

Sam
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on October 09, 2018, 11:23:34 PM
There is a hiatus in the minimum but there is no hiatus in the maximum volume. To me this means that the hiatus of the minimum will continue until the maximum is low enough to push the minimum down.

I think 2030 is the  most the Arctic has left. The last few KM3 will probably puff out of existence.
Title: Re: When will the Arctic Go Ice Free?
Post by: DavidR on October 10, 2018, 09:36:38 AM
Quote
volume will always show a faster rate of decline than either area or thickness, but will slow down as the other parameters catch up.
I'm not sure this is always true, but I'm not a thermodynamics anything (not an expert nor even particularly knowledgeable).  If a significant cause of ice melt is bottom melt (which will likely increase as thickness decreases, as solar input into this process increases with ice thinness), then declining thickness will accelerate as zero volume approaches, while area remains fairly unchanged.  If area decreases 'at all', it might be a 'fact' that volume will decrease at a lower rate than does thickness (although faster than the area decline).  But I think this doesn't require volume declines to actually "slow down".

It is a case of simple mathematics.  The current minimum sea ice extent is ~60% of the extent measured in 1980.  The minimum volume is ~30% of 1980.  The thickness is ~50% of 1980.  Volume is just a product of these two; and since both are decreasing, the volume must decrease faster.  As extent and thickness decrease, the volume loss will slow because there is less volume to lose. 

This is different from the typical ice cube in a glass experiment, whereby all sides melt equally.  The large disproportionate dimensions leads to a difference in the physical melting properties.  The larger extent (or area) dominates the melting characteristic. 

If one were to assume that volume is the key parameter, and volume continues to decrease at its current rate, then the decline in thickness would need to double and the decline in extent more than triple, so that all three parameters reach zero simultaneously.  That is not what we are experiencing currently.
The key  point  you  are missing is that the thickness is an average measure over the entire ice cap.  The area that is less than 20cm thick at maximum is 20 - 30  times greater than the are that is 2 m thick for the same volume. The simple formula V=A*T  only  works for a single cell.

Over the entire cap the  AverageThickness = sum(( T  * N ) / Total(N))  for all thicknesses where N is the number of cells of a given thickness.  As the ice melts the ratios between the various N's doesn't change much  so the average thickness doesn't change either.

Simple example; there are 100 cells at thickness 0.1m and 10 at  thickness 1m;  after massive melting the number of cells has reduced to 10 at 0.1m and 1 at 1m.  The ratio hasn't changed and the average thickness hasn't changed despite area declining by 90%. 

Title: Re: When will the Arctic Go Ice Free?
Post by: johnm33 on October 10, 2018, 10:28:50 AM
I think there's a threshold that needs forcing through, whilst there's enough ice around the pole to preserve an ice desert the ice will always regenerate and expand. The ice around the pole has to be accelerated to force it south, 0kph at the pole @175kph at the northernmost tip of Greenland, any wind powerful enough to do that also serves to enhance the ice deserts regenerative ability. The warm currents entering the Arctic either fall into the deeps or have too much inertia to move towards the pole, mostly both. We may have to wait until the temperature  of the ocean itself has the energy to cause bottom melt in the CAB.
 Looking at the various animations this year [thanks everyone] it seems pretty clear that the ice is expanding from the center out towards either the exits or to be destroyed by wave action, with the possible exception of ESS where there was thick ice left over from last season in sufficient quantity to almost serve as it's own ice desert. At the moment I can't see how a seperate area of thick ice could be established, so we may see the CAB under siege on all fronts. 
Title: Re: When will the Arctic Go Ice Free?
Post by: Pmt111500 on October 10, 2018, 01:49:05 PM
As the thickening of ice on the late freezing season stops so does the generation of thick first year ice which is essential to the production of two-year/old ice. Maybe the year this happens could be estimated. Last three winters the ESS-CAB assisted by CAA channels have done this stuff. Possibly assisted, paradoxically, by the diminished export to Fram made by the sub-polar gyre expansion to former arctic realm.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on October 10, 2018, 02:04:23 PM
Quote
volume will always show a faster rate of decline than either area or thickness, but will slow down as the other parameters catch up.
I'm not sure this is always true, but I'm not a thermodynamics anything (not an expert nor even particularly knowledgeable).  If a significant cause of ice melt is bottom melt (which will likely increase as thickness decreases, as solar input into this process increases with ice thinness), then declining thickness will accelerate as zero volume approaches, while area remains fairly unchanged.  If area decreases 'at all', it might be a 'fact' that volume will decrease at a lower rate than does thickness (although faster than the area decline).  But I think this doesn't require volume declines to actually "slow down".

It is a case of simple mathematics.  The current minimum sea ice extent is ~60% of the extent measured in 1980.  The minimum volume is ~30% of 1980.  The thickness is ~50% of 1980.  Volume is just a product of these two; and since both are decreasing, the volume must decrease faster.  As extent and thickness decrease, the volume loss will slow because there is less volume to lose. 

This is different from the typical ice cube in a glass experiment, whereby all sides melt equally.  The large disproportionate dimensions leads to a difference in the physical melting properties.  The larger extent (or area) dominates the melting characteristic. 

If one were to assume that volume is the key parameter, and volume continues to decrease at its current rate, then the decline in thickness would need to double and the decline in extent more than triple, so that all three parameters reach zero simultaneously.  That is not what we are experiencing currently.
The key  point  you  are missing is that the thickness is an average measure over the entire ice cap.  The area that is less than 20cm thick at maximum is 20 - 30  times greater than the are that is 2 m thick for the same volume. The simple formula V=A*T  only  works for a single cell.

Over the entire cap the  AverageThickness = sum(( T  * N ) / Total(N))  for all thicknesses where N is the number of cells of a given thickness.  As the ice melts the ratios between the various N's doesn't change much  so the average thickness doesn't change either.

Simple example; there are 100 cells at thickness 0.1m and 10 at  thickness 1m;  after massive melting the number of cells has reduced to 10 at 0.1m and 1 at 1m.  The ratio hasn't changed and the average thickness hasn't changed despite area declining by 90%.

Which is another reason to be skeptical of the volume calculations.  Using this average thickness to calculate volume, introducing more error into the equation.  Hence, the reason that I prefer extent to the other parameters.  Sure, it is not perfect.  However, it is the most consistent and reliable parameter currently available. 
Title: Re: When will the Arctic Go Ice Free?
Post by: Stephan on October 10, 2018, 04:47:35 PM
Just a question for us all.
We already have seas that melt out completely (like Hudson or Kara). Would these seas be an example for a BOE? And has anyone ever monitored the rates of volume, thickness and area decline close before the end and compared these rates with the rates at about 30, 50, 70 % of ice coverage? This analysis (also the relation of the rates) could help to answer the questions that arose in this thread.
Title: Re: When will the Arctic Go Ice Free?
Post by: GoSouthYoungins on October 10, 2018, 05:07:55 PM
Just a question for us all.
We already have seas that melt out completely (like Hudson or Kara). Would these seas be an example for a BOE? And has anyone ever monitored the rates of volume, thickness and area decline close before the end and compared these rates with the rates at about 30, 50, 70 % of ice coverage? This analysis (also the relation of the rates) could help to answer the questions that arose in this thread.

The seas are too different to be very informative. The central arctic (and greenland) is/are the Northern Hemisphere's ice cap. It is the lynch pin of half the world's weather. The dynamics as it starts to disappear are very odd and very complex and everyone is just guessing with varying levels of educatedness.
Title: Re: When will the Arctic Go Ice Free?
Post by: magnamentis on October 10, 2018, 05:27:02 PM
Just a question for us all.
We already have seas that melt out completely (like Hudson or Kara). Would these seas be an example for a BOE? And has anyone ever monitored the rates of volume, thickness and area decline close before the end and compared these rates with the rates at about 30, 50, 70 % of ice coverage? This analysis (also the relation of the rates) could help to answer the questions that arose in this thread.

a very interesting approach and to a certain extent a comparison might be valid. one thing that we see quite often is that some remaining ice is very persisting (reluctant to melt) and ultimately caves in within a few days.

i suspect that the preparation for a BOE is very similar and that below a certain amount of remaining ice we gonne be caught by surprise how quickly the rest will go.

all guesswork of course, but i think things gonna unfold somehow along such a line.
Title: Re: When will the Arctic Go Ice Free?
Post by: Dharma Rupa on October 10, 2018, 05:29:57 PM
We already have seas that melt out completely (like Hudson or Kara). Would these seas be an example for a BOE?

I kind of doubt it, with the main distinction being that they have the CAB next to them and the CAB has nothing (other than a bit of Greenland).
Title: Re: When will the Arctic Go Ice Free?
Post by: oren on October 10, 2018, 11:49:17 PM
I once made an animation of the Chukchi as it went from perennial ice cover to seasonally ice-free ("BOE"). I'll dig it up and repost it. Hudson ans Kara are not very similar to the CAB. The Chukchi is more similar but still quite different as it has a sea ice repository next to it, while the CAB does not.
Title: Re: When will the Arctic Go Ice Free?
Post by: oren on October 12, 2018, 03:48:45 AM
Here is the animation I mentioned. It focuses on the behavior of the Chukchi on its way to being seasonally ice-free. Before 1990 the Chukchi was rather stable, with about half of it melting each year. But then changes came along - earlier melt onset, a higher percentage of melt culminated by the first BOE in 2007, a later refreeze onset, and a later refreeze completion. The process wasn't immediate, but over two decades the changes are enormous. The length of time in which the Chukchi is less than fully ice-covered has increased from ~5 months to ~8 months.
I believe the CAB will undergo a quite similar process, though hopefully longer. The process has already started, and 2012 and 2016 proved a lot of the CAB is vulnerable, while 2018 is proving that the refreeze can be delayed significantly.

Notable years pushing the Chukchi envelope:
1991 (late refreeze)
1993 (new minimum)
1998 (new minimum)
2004 (new minimum)
2006 (late refreeze)
2007 (new minimum near zero, late refreeze)
2012 (earlier near zero)
2016 (late final refreeze, first into January)
2017 (early melt, late refreeze)

Notes: January of the following year is appended to each year. The date range shown is April 15th to January 20th. Data is NSIDC extent.
Title: Re: When will the Arctic Go Ice Free?
Post by: Pmt111500 on October 12, 2018, 04:57:54 AM
Thanks Oren. Here at forum, it's easy to pick up some alarmistic views as people present their pet theories. It's easy to forget main stream science has some very good arguments too.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on October 12, 2018, 01:47:44 PM
Yes, very nice.  The trend is clearly towards less ice, but once ice-free, there is nothing preventing refreezing.  I suspect the CAB will follow suit - hopefully longer as Oren stated.
Title: Re: When will the Arctic Go Ice Free?
Post by: Stephan on October 12, 2018, 05:26:20 PM
Thank you oren for this animation.
I am willing to investigate the area/extent, thickness and volume changes over the years and to look at "BOE" predictions derived from area/extent, thickness and volume. Can anyone send me the .xls or .csv files of area/extent, thickness and/or volume for Kara, Chukchi and Hudson Sea? Would be nice, thanks in advance.
Title: Re: When will the Arctic Go Ice Free?
Post by: GoSouthYoungins on October 12, 2018, 08:48:18 PM
Thanks Oren. Here at forum, it's easy to pick up some alarmistic views as people present their pet theories. It's easy to forget main stream science has some very good arguments too.

There are times when an alarm is supposed to go off. This is one of those times. It is not possible to be "alarmistic" currently.

The Pacific and Atlantic have drastically encroached on the Arctic Sea Ice. 2014,2015,2016 set consecutive heat records. 2017 and 2018 experienced a slight reprieve due to la nina. 2019 will be absurdly hot again. CO2 levels are 10% higher relative to baseline than they were in the beginning of 2014.

There is a significant lag if the heating effect from GHG emissions. The is also a significant lag in developing the physical and institutional infrastructure necessary to substantially reduce emissions. Thus we are almost certain to experience about twice the warming from emissions we have felt thus far.

Throw in a couple positive feedbacks, most notably the melting of the northern hemispheres ice cap, and we are quite clearly headed towards a drastically different climate system in the next decade or two.

BE ALARMED
Title: Re: When will the Arctic Go Ice Free?
Post by: Stephan on October 12, 2018, 09:18:20 PM
(This post is in the wrong thread but it must be said)
Here in Germany we suffer almost without exception from a too warm and too dry summer since beginning of April. We had almost no rain throughout June to October with a lot of crop failure and forest fires. And tomorrow daily max. temp is forecasted to be 27-29°C almost nationwide. Many people are alarmed, and the green party is really up in public polls. Diesel discussion and the end of coal mining is in every news show...
Title: Re: When will the Arctic Go Ice Free?
Post by: oren on October 15, 2018, 03:16:41 AM
Thank you oren for this animation.
I am willing to investigate the area/extent, thickness and volume changes over the years and to look at "BOE" predictions derived from area/extent, thickness and volume. Can anyone send me the .xls or .csv files of area/extent, thickness and/or volume for Kara, Chukchi and Hudson Sea? Would be nice, thanks in advance.
Apologies for the delay in responding.
The best is to download the data from the appropriate sources that you should bookmark, and plug them into a spreadsheet that fits the analysis you want to do.
My (very messy!) Excel workbooks normally have a worksheet where I paste the raw data, and other worksheets that build on that data using index/if functions, so as time goes by and the data becomes longer I am ready to go, though I still need to change the scale of the graphs to use all the new data.
Data fro text files (Wipneus) is pasted into a single column, then the function "text to columns" with delimited-space is used to unpack it into useful spreadsheet form.

The best source is ArctischePinguin - Wipneus' site, without it nothing would get done.
Regional daily PIOMAS data (since 2000)
https://sites.google.com/site/arctischepinguin/home/piomas/data/PIOMAS-regional.txt.gz?attredirects=0 (https://sites.google.com/site/arctischepinguin/home/piomas/data/PIOMAS-regional.txt.gz?attredirects=0)

"Home brew" regional AMSR2 extent and area (since 2012).
https://sites.google.com/site/arctischepinguin/home/amsr2/data/Jaxa_AMSR2_L3_10km_Area_Extent-v0.0.txt?attredirects=0&d=1 (https://sites.google.com/site/arctischepinguin/home/amsr2/data/Jaxa_AMSR2_L3_10km_Area_Extent-v0.0.txt?attredirects=0&d=1)

NSIDC regional daily data for both extent and area. But for area data of the CAB you must add back the size of the pole hole, varying by year.
Quote
ftp://sidads.colorado.edu/DATASETS/NOAA/G02135/seaice_analysis/Sea_Ice_Index_Regional_Daily_Data_G02135_v3.0.xlsx

NSIDC documentation of the sea ice index, including explanation of the pole hole on page 37 and its sizes on page 38.
https://nsidc.org/data/g02135 (https://nsidc.org/data/g02135)

I hope I haven't missed anything. Browse the data parts of ArctischePinguin for various other files.
https://sites.google.com/site/arctischepinguin/site (https://sites.google.com/site/arctischepinguin/site)

I really hope all this helps. I can try to locate sample workbooks that I use, but it is one big mess so if you can build your own you will have a much better chance of success.
Title: Re: When will the Arctic Go Ice Free?
Post by: Stephan on November 05, 2018, 08:52:56 PM
It is time for the monthly update of my extrapolation when the extent [Extent], volume [Volumen] and thickness [Dicke] will reach zero. The extrapolation occured linearly and by a logarithmic function; the latter one almost constantly resulting in earlier times. October value now includes 2018, and BOE for October seems to appear much earlier than extrapolated last year (up to 9 years difference than last year (!), see my last posting on Sep 09 in this thread), mostly due to the late minimum in September 2018 compared to 2017 and the delayed refreezing in the first half of October (see for details the sea ice area and extent thread). According to thickness October is the earliest month of the year compared to all other months.
Please note that this is not a forecast but a trend!
See attached table.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on November 05, 2018, 10:32:40 PM
That 2070 timeframe looks about right.
Title: Re: When will the Arctic Go Ice Free?
Post by: magnamentis on November 05, 2018, 11:18:11 PM
That 2070 timeframe looks about right.

+1

and i'm glad he calculated zero.

unfortunately some impatient observers who want to witness ice-free under all circumstances or seek headlines will come up with all kinds of arbitrary values that should serve as "ice-free"

the most common of such numbers at the moment is < 1'000'000 km2 of extent which i find ridiculous, 1M km2 is a lot of ice and visible with the naked ice as well as it will be a kind of homogeneous mass, at least in parts.

ice-free = zero ice and zero is 0-0.999999999999....... IMO
Title: Re: When will the Arctic Go Ice Free?
Post by: Alison on November 06, 2018, 01:31:30 AM
Quote
impatient observers who want to witness ice-free

Given it is unfortunately going to happen, I’d like to see it. I’ll be a deceased observer by 2070, so perhaps you could forgive a little impatience :)
Title: Re: When will the Arctic Go Ice Free?
Post by: Sleepy on November 06, 2018, 06:50:08 AM
unfortunately some impatient observers who want to witness ice-free under all circumstances or seek headlines will come up with all kinds of arbitrary values that should serve as "ice-free"

the most common of such numbers at the moment is < 1'000'000 km2 of extent which i find ridiculous
Heh, the Arctic Ocean is ~14,000,000 km² and the origin of that number is:

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fwww.climatechange2013.org%2Fimages%2Ffigures%2FWGI_AR5_FigSPM-7.jpg&hash=a8664d944efa8a534a30dee9a033a535)
The dashed line represents nearly ice-free conditions (i.e., when sea ice extent is less than 106 km² for at least five consecutive years). For further technical details see the
Technical Summary Supplementary Material {Figures 6.28, 12.5, and 12.28–12.31; Figures TS.15, TS.17, and TS.20}
Title: Re: When will the Arctic Go Ice Free?
Post by: gerontocrat on November 29, 2018, 02:58:21 PM
Extract from a post by AbruptSLR.
https://forum.arctic-sea-ice.net/index.php/topic,2205.msg182527.html#msg182527

Goodbye snow, hullo rain. That would tend to slow down winter sea ice formation?
(And not do bbr's hypothesis a lot of good).

Quote
Towards a rain-dominated Arctic
Richard Bintanja and Olivier Andry
Royal Netherlands Meteorological Institute (KNMI), De Bilt, Netherlands (bintanja@knmi.nl)
Current climate models project a strong increase in Arctic precipitation over the coming century, which has been attributed primarily to enhanced surface evaporation associated with sea-ice retreat. Since the Arctic is still quite cold, especially in winter, it is often (implicitly) assumed that the additional precipitation will fall mostly as snow.

However, very little is known about future changes in rain/snow distribution in the Arctic, notwithstanding the importance for hydrology and biology. Here we use 37 state-of-the-art climate models in standardised twenty-firstcentury (2006–2100) simulations to show that 70◦ – 90◦N average annual Arctic snowfall will actually decrease, despite the strong increase in precipitation, and that most of the additional precipitation in the future (2091–2100) will fall as rain. In fact, rain is even projected to become the dominant form of precipitation in the Arctic
region. This is because Arctic atmospheric warming causes a greater fraction of snowfall to melt before it reaches the surface, in particular over the North Atlantic and the Barents Sea. The reduction in Arctic snowfall is most pronounced during summer and autumn when temperatures are close to the melting point, but also winter rainfall is found to intensify considerably. Projected (seasonal) trends in rain/snowfall will heavily impact Arctic hydrology (e.g. river discharge, permafrost melt), climatology (e.g. snow, sea ice albedo and melt) and ecology (e.g. water and food availability).
Title: Re: When will the Arctic Go Ice Free?
Post by: Dharma Rupa on November 29, 2018, 10:03:33 PM
Extract from a post by AbruptSLR.
https://forum.arctic-sea-ice.net/index.php/topic,2205.msg182527.html#msg182527

Goodbye snow, hullo rain. That would tend to slow down winter sea ice formation?
(And not do bbr's hypothesis a lot of good).

Quote
Towards a rain-dominated Arctic
Richard Bintanja and Olivier Andry
Royal Netherlands Meteorological Institute (KNMI), De Bilt, Netherlands (bintanja@knmi.nl)
Current climate models project a strong increase in Arctic precipitation over the coming century, which has been attributed primarily to enhanced surface evaporation associated with sea-ice retreat. Since the Arctic is still quite cold, especially in winter, it is often (implicitly) assumed that the additional precipitation will fall mostly as snow.

However, very little is known about future changes in rain/snow distribution in the Arctic, notwithstanding the importance for hydrology and biology. Here we use 37 state-of-the-art climate models in standardised twenty-firstcentury (2006–2100) simulations to show that 70◦ – 90◦N average annual Arctic snowfall will actually decrease, despite the strong increase in precipitation, and that most of the additional precipitation in the future (2091–2100) will fall as rain. In fact, rain is even projected to become the dominant form of precipitation in the Arctic
region. This is because Arctic atmospheric warming causes a greater fraction of snowfall to melt before it reaches the surface, in particular over the North Atlantic and the Barents Sea. The reduction in Arctic snowfall is most pronounced during summer and autumn when temperatures are close to the melting point, but also winter rainfall is found to intensify considerably. Projected (seasonal) trends in rain/snowfall will heavily impact Arctic hydrology (e.g. river discharge, permafrost melt), climatology (e.g. snow, sea ice albedo and melt) and ecology (e.g. water and food availability).

While I do tend to agree with their projection, I object to their use of words like "will" rather than "might".  The models simply do not have the demonstrated skill which warrants definitive pronouncements.

Yes, I do expect the snow to change to rain....but I don't KNOW it will.
Title: Re: When will the Arctic Go Ice Free?
Post by: Stephan on December 06, 2018, 10:24:14 PM
It is time for the monthly update of my extrapolation when the extent [Extent], volume [Volumen] and thickness [Dicke] will reach zero. The extrapolation occured linearly and by a logarithmic function; the latter one almost constantly resulting in earlier times. November value now includes 2018. In contrast to October (see my post on Nov. 05) November 2018 showed a rapid freezing higher than average which also results in values above the linear trend line from 1979 to 2018. This results in slightly higher values of when zero will be reached, but not much of a difference compared to last year.
Please note that this is not a forecast but a trend!
See attached table.
Title: Re: When will the Arctic Go Ice Free?
Post by: oren on December 06, 2018, 11:51:29 PM
Stephan, can you extrapolate to 1M km2 of extent as well? The "nearly ice free" criterion.
Title: Re: When will the Arctic Go Ice Free?
Post by: El Cid on December 07, 2018, 10:25:28 AM
I don't want to be mean or nasty but these extrapolations are probably totally pointless. Extrapolations like this from around 2010 showed that we should already be ice free. The reason we are not - I believe - is that the Arctic has two distinct parts: the Central Arctic with deep seas below it and the periphery (mostly everything else) with shallow seas. It seems that these shallower seas have become mixed enough to either stay icefree even during the winter or to melt relatively quickly during the summer regardless of the weather. The Center, however, still holds. Only very favourable (for ice loss) weather can melt it partially during some exceptional summers (like 2012) and even then it freezes back quickly during autumn. Unless the Central Arctic Atlantifies - which will be hard due to bathymetry - I do not see it melting out soon.

So my point is that you can not project from total Arctic extent/volume/etc because the 2 parts of the Arctic are completely different and behave completely differently - probably because of bathymetry.   
Title: Re: When will the Arctic Go Ice Free?
Post by: El Cid on December 07, 2018, 10:28:33 AM
By the way, I believe that the above is the explanation for the "stall" since 2007: the shallow parts have entered a new era (system change) but the Central Arctic has not. When it will do so, I do not know. It could be next year (I very much doubt it ) but it also might stay like that for another 30 years
Title: Re: When will the Arctic Go Ice Free?
Post by: oren on December 07, 2018, 10:46:09 AM
The "stall" since 2007 is not a stall, yet. Check out 5-year and 10-year averages. Check out area instead of extent. Check out winter volume. The bad trend continues. Had 2012 weather happened in 2016 or 2017 a new record would have easily happened. As Neven said back then, we dodged a cannonball.
It's true though that the arctic is more complex than just the headline numbers: the bathymetry you mentioned, MYI causing an easy reduction in volume but now FYI makes it harder (the "slow transition" prediction), and the melting season is much shorter in the higher latitudes. So the linear trend may not happen just like that. But I still expect the coming decade to bring about at least one "outlier" year of nearly ice-free conditions in September.
Bear in mind the melting weather is a lot about prevailing wind and export, not just sunny vs. cloudy and warm vs. cold. Should the Central Arctic start flowing towards the Fram and the unlimited-capacity Atlantic front in earnest, as it did in parts of 2016 (and 2007), the melting season will have a much easier time than when the prevailing export of thick central ice is towards the limited-capacity Beaufort (as happened this year).
Title: Re: When will the Arctic Go Ice Free?
Post by: Stephan on December 07, 2018, 06:07:28 PM
Stephan, can you extrapolate to 1M km2 of extent as well? The "nearly ice free" criterion.
Here is the table (the right one with extrapolation to 1M).
I did it only for extent as I am not sure which volume should be attributed to the "1M km²" extent. The values are (of course) lower by 6 to 28 years.
The steeper the slope ("stg") the smaller is the difference until 1M is reached in comparison to 0M km²
Title: Re: When will the Arctic Go Ice Free?
Post by: Stephan on December 07, 2018, 06:19:19 PM
By the way, I believe that the above is the explanation for the "stall" since 2007: the shallow parts have entered a new era (system change) but the Central Arctic has not. When it will do so, I do not know. It could be next year (I very much doubt it ) but it also might stay like that for another 30 years
Please check my 5 year averages I posted yesterday in the "latest PIOMAS" thread. There is no stall, only the volume has not further decreased in the years 2014-2018 compared to 2009-2013. (Re: Latest PIOMAS update (December)
« Reply #2680 on: December 06, 2018, 11:00:25 PM )
Title: Re: When will the Arctic Go Ice Free?
Post by: El Cid on December 07, 2018, 09:53:56 PM

[/quote]
 There is no stall, only the volume has not further decreased
[/quote]

That's a good one. No stall, only the volume stopped decreasing :)
Title: Re: When will the Arctic Go Ice Free?
Post by: jdallen on December 08, 2018, 08:07:10 AM

There is no stall, only the volume has not further decreased
[/quote]

That's a good one. No stall, only the volume stopped decreasing :)
[/quote]
The whole row over stall vs. non-stall strikes me as being akin to mistaking "weather" for "climate".

Metaphor - California had some pretty serious rainfall over the last few months.  However, most of the state *still* is in moderate to severe drought. 

The "stall" is a statistical construct, one created solely by how narrowly one decides to view the data.  It has no more relevance to what is happening in the Arctic than weather two weeks ago has on what will happen here tomorrow.
Title: Re: When will the Arctic Go Ice Free?
Post by: El Cid on December 08, 2018, 08:47:47 AM
Maybe the "stall" is a statistical construct. Or maybe (a heresy to say on this site it seems) after the periphery melt out relatively quickly, the Central Arctic has different characteristics and will be a much harder nut to crack. In my opinion the "stall" is due to that the "easy" ice is gone and it is more difficult to melt the central parts. That is why you can not extrapolate from the past few years. The Central Arctic will be gone for (almost) sure but it is hard to model when in my view. Let me attach a picture how I see this whole process...

...the point is that the seeming stall could last only a very few but even a good many years as well
Title: Re: When will the Arctic Go Ice Free?
Post by: gerontocrat on December 08, 2018, 09:04:15 PM
Maybe the "stall" is a statistical construct. Or maybe (a heresy to say on this site it seems) after the periphery melt out relatively quickly, the Central Arctic has different characteristics and will be a much harder nut to crack. In my opinion the "stall" is due to that the "easy" ice is gone and it is more difficult to melt the central parts. That is why you can not extrapolate from the past few years. The Central Arctic will be gone for (almost) sure but it is hard to model when in my view. Let me attach a picture how I see this whole process...

There is a new paper that I think supports your contention. Basically it says that increased ocean heat transport (OHT) affects the Arctic seas over the continental shelves while it is the atmosphere that drives SIE in  the central arctic (over the deep ocean). (I can't access the full paper)

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018JC014525
The role of ocean heat transport in rapid sea ice declines in the Community Earth System Model Large Ensemble
Quote
Abstract
Many climate models, including the the Community Earth System Model Large Ensemble (CESM‐LE), predict future rapid sea ice declines in the Arctic linked with anomalous northward Ocean Heat Transport (OHT). Using CESM‐LE, we find that the partitioning of the poleward OHT between the different Arctic gates (Barents Sea Opening (BSO), Bering Strait and Fram Strait) is key to this link with the rapid declines. 64 of the 79 rapid declines in CESM‐LE are correlated with the anomalous OHT through one of the gates. Rapid declines that happen earlier in the simulations when the sea ice covers the continental shelves are correlated with anomalous OHT. The interaction between OHT and sea ice happens mainly over continental shelves since most rapid declines are correlated with the BSO or Bering Strait OHTs and only a few with the Fram Strait OHT (often also correlated with BSO or Bering Strait OHTs). In most rapid rapid declines not correlated with OHT, the September Sea Ice Extent (SIE) prior to the decline is smaller than the area covered by the deep basins. Those are associated with surface heat flux since the ice‐atmosphere heat fluxes are more strongly correlated with the sea ice concentrations over the deep basins than the ice‐ocean heat fluxes. Our results suggest that OHTs are causing rapid sea ice declines when the SIE is large enough to cover the continental shelves and that the atmosphere is the main driver when the initial SIE is located only over the deep basins.

Plain Language Summary
A significant decrease in the minimum sea ice extent has been observed since the beginning of the satellite era in the late seventies. Several climate models simulate drastically different future evolution of the minimum sea ice extent. In this study, we use output diagnostics from the Community Earth System Model Large Ensemble to verify if the pathway of ocean heat transport entering the Arctic has an impact on the presence or absence of rapid sea ice declines. We find that the interaction between ocean heat transport and sea ice happens mainly over the shallow continental shelves. There, ocean heat transport can contribute to the melting of the sea ice. This melting is afterward enhance by positive feedbacks, such as the ice‐albedo feedback, and can lead to a rapid decline of the Arctic sea ice cover. In the central Arctic, the sea ice is more sensitive to atmospheric heat than to ocean heat.
Title: Re: When will the Arctic Go Ice Free?
Post by: magnamentis on December 08, 2018, 10:05:31 PM
Maybe the "stall" is a statistical construct. Or maybe (a heresy to say on this site it seems) after the periphery melt out relatively quickly, the Central Arctic has different characteristics and will be a much harder nut to crack. In my opinion the "stall" is due to that the "easy" ice is gone and it is more difficult to melt the central parts. That is why you can not extrapolate from the past few years. The Central Arctic will be gone for (almost) sure but it is hard to model when in my view. Let me attach a picture how I see this whole process...

...the point is that the seeming stall could last only a very few but even a good many years as well

100% +1
Title: Re: When will the Arctic Go Ice Free?
Post by: El Cid on December 08, 2018, 10:55:32 PM
Maybe the "stall" is a statistical construct. Or maybe (a heresy to say on this site it seems) after the periphery melt out relatively quickly, the Central Arctic has different characteristics and will be a much harder nut to crack. In my opinion the "stall" is due to that the "easy" ice is gone and it is more difficult to melt the central parts.

There is a new paper that I think supports your contention. Basically it says that increased ocean heat transport (OHT) affects the Arctic seas over the continental shelves while it is the atmosphere that drives SIE in  the central arctic (over the deep ocean). [/size]
[/quote]

Exactly! Although I am not a climate scientist, that is what I suspect: shallow seas are prone to ocean heat transport but the deep Arctic Center is not...although the quickly melting and more and more open periphery is probably chipping away the Center so it will eventually yield. To melt the Center we need exceptional weather currently. Maybe it will not be so in 10,20,30 yrs time, but it is probably so now.
Title: Re: When will the Arctic Go Ice Free?
Post by: Avalonian on December 09, 2018, 12:12:30 AM
The problem I have with this idea is that the deep water shouldn't come into play since there is a pycnocline at (iirc) around 70 m down - equivalent to the outer shelf depth. Warm water resulting in OHT to the central basin will be limited to flowing over this pycnocline (if that breaks down, then everything melts due to the heat of the deep saline water being mixed upwards). Of course, the warm water will cool as it heads north, but this effect is reduced the less peripheral ice there is remaining. Unless it can spread into a much thicker (deeper) layer, this OHT surely has just as much potential for melting the CAB ice as it does the peripheral seas.

I'm very willing to hear that I'm missing something fundamental here, but can anyone tell me what it is?
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on December 09, 2018, 01:57:49 AM
Can anyone comment on the short term, local impact that these "burps" have on local temperatures? There is a lot of talk about the the global impact but the local impact on temperatures might have global consequences that global radiative forcing might not account for.
Title: Re: When will the Arctic Go Ice Free?
Post by: jdallen on December 09, 2018, 02:13:03 AM
Possibly relevant to this discussion, certainly prompted by it, I just posted an analysis of volume changes over on the volume and thickness thread Here:

https://forum.arctic-sea-ice.net/index.php/topic,2268.msg183686.html#msg183686
Title: Re: When will the Arctic Go Ice Free?
Post by: oren on December 09, 2018, 09:07:29 AM
The central arctic is less prone to OHT but is very vulnerable to export through the very gates mentioned above, especially once the adjacent seas (the continental shelves) are cleared.
Incoming OHT tends to sink (warm and saline), but outgoing ice floats, so the water depth cannot save it, as it meets the OHT on the surface.
2016 winter and spring were a great example, and I think only luck brought about a stall in export further into the season, or we would have gotten a new record.
Title: Re: When will the Arctic Go Ice Free?
Post by: El Cid on December 09, 2018, 01:03:13 PM
Great points everone! Much to think about. I have not much else to add. The trillion dollar question to me is: can and will mixing occur in the Central Arctic? If not, then export will probably be a slow way to get rid of all the ice and make the Central Arctic ice free.
Title: Re: When will the Arctic Go Ice Free?
Post by: Shared Humanity on December 09, 2018, 02:24:57 PM
Maybe the "stall" is a statistical construct. Or maybe (a heresy to say on this site it seems) after the periphery melt out relatively quickly, the Central Arctic has different characteristics and will be a much harder nut to crack. In my opinion the "stall" is due to that the "easy" ice is gone and it is more difficult to melt the central parts.

There is a new paper that I think supports your contention. Basically it says that increased ocean heat transport (OHT) affects the Arctic seas over the continental shelves while it is the atmosphere that drives SIE in  the central arctic (over the deep ocean). [/size]

Exactly! Although I am not a climate scientist, that is what I suspect: shallow seas are prone to ocean heat transport but the deep Arctic Center is not...although the quickly melting and more and more open periphery is probably chipping away the Center so it will eventually yield. To melt the Center we need exceptional weather currently. Maybe it will not be so in 10,20,30 yrs time, but it is probably so now.
[/quote]

I agree. I don't think it is entirely a coincidence that annual minimum ice cover appears to mimic the bathymetry of the Arctic Ocean.
Title: Re: When will the Arctic Go Ice Free?
Post by: Shared Humanity on December 09, 2018, 02:28:41 PM
Great points everone! Much to think about. I have not much else to add. The trillion dollar question to me is: can and will mixing occur in the Central Arctic? If not, then export will probably be a slow way to get rid of all the ice and make the Central Arctic ice free.

Dispersion into the shallower seas due to a stormy Arctic will help.
Title: Re: When will the Arctic Go Ice Free?
Post by: Shared Humanity on December 09, 2018, 02:33:27 PM
That Ocean Heat Transport is a primary contributor to melt and reduced SIE in shallow, peripheral seas might explain the dramatic changes in what use to be the refuge for some of the thickest MYI along the north of Greenland and the CAA.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on December 09, 2018, 07:35:17 PM
That would certainly explain the steep drop in sea ice during the 90s, and the slower decrease in recent years.
Title: Re: When will the Arctic Go Ice Free?
Post by: Stephan on February 10, 2019, 10:14:10 PM
It is time for the monthly update of my extrapolation when the extent [Extent], volume [Volumen] and thickness [Dicke] will reach zero. The extrapolation occured linearly and by a logarithmic function; the latter one almost constantly resulting in earlier times. Volume is the first to reach zero.
Due to long unavailable data for December I present Dec 1979-2018 and Jan 1979-2019 in one new post.
As both months lay above the long term linear trend (see my posting today on the sea ice area and extent data) the slopes have decreased very slightly, leading to slightly later values compared to the two months one year ago.
Please note that this is not a forecast but a trend!
See attached table.
Title: Re: When will the Arctic Go Ice Free?
Post by: vox_mundi on February 27, 2019, 06:29:21 PM
Ice-Free Arctic Summers Could Happen On Earlier Side of Predictions
https://www.eurekalert.org/pub_releases/2019-02/agu-ias022719.php

WASHINGTON -- The Arctic Ocean could become ice-free in the summer in the next 20 years due to a natural, long-term warming phase in the tropical Pacific that adds to human-caused warming, according to a new study.

The climate model used in the new study predicts an ice-free Arctic summer sometime between 2030 and 2050, if greenhouse gases continue to rise.

By accounting for a long-term warming phase in the tropical Pacific, the new research shows an ice-free Arctic is more likely to occur on the earlier side of that window, closer to 2030 than 2050.


Around five years ago, the Pacific began to switch from the cold to warm phase of the IPO. Screen and his co-author plotted predictions of when an ice-free Arctic would occur in model experiments where the IPO was shifting in the same direction as the real world. They compared these to predictions where the IPO was moving in the opposite direction, that is, switching from a warm to cold phase.

They found model predictions that were in sync with actual conditions showed an earlier ice-free Arctic, by seven years on average, than those predictions that were out of step with reality.

(https://wol-prod-cdn.literatumonline.com/cms/attachment/77bb4562-df09-49f8-9094-a4a6999b2d95/grl58618-fig-0001-m.png)

...our results do not contradict a contributing role of the negatively trending IPO in the accelerated winter sea‐ice loss from 2000 to 2014 in the Barents Sea. They suggest, however, that in the future, IPO‐associated sea‐ice changes in the Pacific sector may dominate over opposite‐signed sea‐ice changes in the Atlantic sector.

Open Access: J. A. Screen, et.al., Pacific Ocean Variability Influences the Time of Emergence of a Seasonally Ice‐Free Arctic Ocean (https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2018GL081393), Geophysical Research Letters, 05 February 2019
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on February 28, 2019, 03:04:07 PM
This seems to contradict the opinion of most that the Atlantic has the greater influence on Arctic sea ice. 
Title: Re: When will the Arctic Go Ice Free?
Post by: Gray-Wolf on February 28, 2019, 06:37:07 PM
I think we need sit up and pay attention to the I.P.O. if what we have seen occurring around Antarctica since the flip in 2014 is anything to go on!

We have also seen this 'drop off' in Bering ice over the similar time frame and further Pacification of that side of the basin?

You need also bear in mind the rapid changes to the Dimming China had placed over portions of the Tropical/Temperate Pacific basin?

We are set to see a 'natural' 0.5c upswing in sst's plus the impacts of the dimming over portions of the basin along with the impacts of the past 150 years of warming.

The first ever northern hemisphere cat 5 cyclone in Feb might give you a wake up to the direction of travel?

EDIT: This is what I class as the 'drip,drip' pathway and not the 'perfect melt storm' kind of one off event?

We could still go ice free this summer if we saw another 07' rolling on by?
Title: Re: When will the Arctic Go Ice Free?
Post by: Stephan on March 05, 2019, 10:22:45 PM
It is time for the monthly update of my extrapolation when the extent [Extent], volume [Volumen] and thickness [Dicke] will reach zero. The extrapolation occured linearly and by a logarithmic function; the latter one almost constantly resulting in earlier times. February value now includes 2019.
As extent, volume and thickness in February 2019 lie above the long-term trend lines it is clear that the BOE for February will take place a few years later than calculated last February. All slopes decreased slightly.

Please note that this is not a forecast but a trend!
See attached table.
Title: Re: When will the Arctic Go Ice Free?
Post by: Juan C. García on March 06, 2019, 05:54:22 AM
Please note that this is not a forecast but a trend!
See attached table.
Great table Stephan!

Of course (as my signature says), I believe that volumen has the real trend, extent and thickness are just partial views of reality. Even so, I think that some negative feedbacks will start to slow down the volume melting trend. So I thinking that we will have a BOE on September until 2040+.
Maybe it is just a good wish, and positive feedbacks will rule the near future.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on March 06, 2019, 04:38:05 PM
Please note that this is not a forecast but a trend!
See attached table.
Great table Stephan!

Of course (as my signature says), I believe that volumen has the real trend, extent and thickness are just partial views of reality. Even so, I think that some negative feedbacks will start to slow down the volume melting trend. So I thinking that we will have a BOE on September until 2040+.
Maybe it is just a good wish, and positive feedbacks will rule the near future.

I would state that volume is the aberration here.  This is largely a two-dimensional system, the ice tends to freeze and melt from above and below, with very little influence from the third thickness dimension.  In any time of three dimension object, volume will also change faster than area, simple mathematics.  Hence volume and area (or extent) cannot change at the same rate, unless the thickness remains unchanged.  Therefore, I would lean much more towards the two-dimension trends, and state that an ice-free (not necessary BOE) condition will not occur until after 2050, perhaps much later.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on March 06, 2019, 05:51:20 PM
Quote
This is largely a two-dimensional system.

Really?

Quote
I would state that volume is the aberration here.

There is no aberration here. Area, volume and thickness are all valid variables, dependent on each other, and they all reveal different aspects of the ice. It would serve us well to completely understand how they change relative to each other and  relative to the other thousand variables out there.
Title: Re: When will the Arctic Go Ice Free?
Post by: oren on March 06, 2019, 06:01:10 PM
I agree, volume is more important.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on March 06, 2019, 08:12:21 PM
Quote
This is largely a two-dimensional system.

Really?

Quote
I would state that volume is the aberration here.

There is no aberration here. Area, volume and thickness are all valid variables, dependent on each other, and they all reveal different aspects of the ice. It would serve us well to completely understand how they change relative to each other and  relative to the other thousand variables out there.

Considering that the area or extent varies from 4 to 15 square km annually, while the thickness varies from 2 to 3 meters, the thickness is no more than 0.1% of each of the other two dimension.  The thickness is also an estimated value based on models, compared to the other measured values.  Physically, changes in area have a dramatically greater effect on albedo than changes in thickness.  Unless this small dimension can be shown to influence the sea ice to much greater degree than the others, I tend to ignore its effect.
Title: Re: When will the Arctic Go Ice Free?
Post by: wdmn on March 06, 2019, 08:48:23 PM
Quote
This is largely a two-dimensional system.

Really?

Quote
I would state that volume is the aberration here.

There is no aberration here. Area, volume and thickness are all valid variables, dependent on each other, and they all reveal different aspects of the ice. It would serve us well to completely understand how they change relative to each other and  relative to the other thousand variables out there.

Considering that the area or extent varies from 4 to 15 square km annually, while the thickness varies from 2 to 3 meters, the thickness is no more than 0.1% of each of the other two dimension.  The thickness is also an estimated value based on models, compared to the other measured values.  Physically, changes in area have a dramatically greater effect on albedo than changes in thickness.  Unless this small dimension can be shown to influence the sea ice to much greater degree than the others, I tend to ignore its effect.

The energy required to melt ice doesn't differentiate between area and volume, however, area cannot decrease until all of the thickness below the surface has been melted, therefore volume is initially more responsive to increases in energy than area. As volume declines more energy is available to both melt area, and restrict its growth (ignoring potential short term negative feedbacks from melt water).

Seems pretty straight forward to me, though, geography does matter.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on March 06, 2019, 09:02:05 PM
Thickness is not the same as volume, and volume varies more than Area, whatever that means.

I challenge you to define "ice" without volume. Volume of water at below freezing is the very definition of ice. A 2 dimensional representation ice is a very useful number, but it represents the area ice occupies, not ice. Useful and important, but not ice.
Title: Re: When will the Arctic Go Ice Free?
Post by: Paddy on March 06, 2019, 10:12:34 PM
I never did vote on this poll, but I'd like to hazard a very tardy conservative guess at 2031-2040. (Partly just because it's a ten year wide stab in the dark rather than a five-year-wide one).
Title: Re: When will the Arctic Go Ice Free?
Post by: interstitial on March 06, 2019, 10:25:28 PM
My initial reaction was volume is more important. I was thinking more of glaciers and the cooling effect of all that ice. Ultimately they both have advantages and disadvantages. Fundamentally they are different and both are needed to fully understand the system. In gerontocrat's post #301 in 2019 sea ice area and extent data he ruminates.

Quote
I am still wondering how much of the recent strong extent gains and losses is from freezing / melting  and how much from existing ice being spread out or pushed together due to winds and waves.
Quote

I think one needs to consider area and volume to better understand this system. Though area/extent and volume are related they tell you different things.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on March 06, 2019, 10:44:05 PM
Quote
This is largely a two-dimensional system.

Really?

Quote
I would state that volume is the aberration here.

There is no aberration here. Area, volume and thickness are all valid variables, dependent on each other, and they all reveal different aspects of the ice. It would serve us well to completely understand how they change relative to each other and  relative to the other thousand variables out there.

Considering that the area or extent varies from 4 to 15 square km annually, while the thickness varies from 2 to 3 meters, the thickness is no more than 0.1% of each of the other two dimension.  The thickness is also an estimated value based on models, compared to the other measured values.  Physically, changes in area have a dramatically greater effect on albedo than changes in thickness.  Unless this small dimension can be shown to influence the sea ice to much greater degree than the others, I tend to ignore its effect.

The energy required to melt ice doesn't differentiate between area and volume, however, area cannot decrease until all of the thickness below the surface has been melted, therefore volume is initially more responsive to increases in energy than area. As volume declines more energy is available to both melt area, and restrict its growth (ignoring potential short term negative feedbacks from melt water).

Seems pretty straight forward to me, though, geography does matter.

While it is certainly true that the energy required does not differentiate, the amount of energy absorbed is dependent on the surface area.  Solar energy will only penetrate so far, and subsurface water only contracts one side.  Ice forms and melts in sheets, not clumps.  Remember, sea ice more closely resembles a sheet of glass, rather than an ice cube. 
Title: Re: When will the Arctic Go Ice Free?
Post by: magnamentis on March 07, 2019, 02:12:22 AM
This is largely a two-dimensional system,

it's about energy and how much energy is needed to melt how much ice is mostly about volume.

of course area plays a role when it comes to insolation and air-flow but nevertheless it's about how much energy is needed to melt a given amount of ice and "amount" is equivalent to volume.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on March 07, 2019, 02:15:26 AM
This is largely a two-dimensional system,

it's about energy and how much energy is needed to melt how much ice is mostly about volume.

of course area plays a role when it comes to insolation and air-flow but nevertheless it's about how much energy is needed to melt a given amount of ice and "amount" is equivalent to volume.

And greater surface area absorbs more energy.
Title: Re: When will the Arctic Go Ice Free?
Post by: Juan C. García on March 07, 2019, 03:55:20 AM
Let’s assume that on June 1st, 2022 we will have a new record of only 9.5 million km2 of ASI extent and the weather is going to promote melting for the following 2 months, with a high pressure system all around the Arctic. Then on August, we are going to have some Great Arctic Cyclones, like the one we have on 2012.

Let’s assume two settings for June 1st, 2022:

1. On the first one, we are going to have an average ice thickness of 2.6 meters, like the one we had on 1980, with 90% of the ice being 5+ years old (yes, I know it is not going to happen  ;) ).

2. On the second setting, we are going to have an average thickness of 1.5 meters, like the one that we had on 2017. Let’s assume that 80% of the ice is 1st year old.

Well, we start with the same extent on both settings, but IMHO, at the end of August we could be having something close to a BOE in the second setting, but not on the first.

So, it is important the volume and also the quality of the ice that we have.
Title: Re: When will the Arctic Go Ice Free?
Post by: Adam Ash on March 07, 2019, 05:03:09 AM
If 1980 was 2.6 m thick, and 2017 1.5 m thick, then the linear thickness loss rate is about 0.3 m per year.  With 1.5 m remaining, then extrapolating a linear trend we find zero thickness in about 2068.  But nothing in the Arctic is linear.
Title: Re: When will the Arctic Go Ice Free?
Post by: oren on March 07, 2019, 06:10:43 AM
JCG's numbers were for June, so you'd get for zero in Sept much earlier than 2068. With these assumptions it should be somewhere around 2048. But an average thickness cannot capture all the required information even for a very basic extrapolation. For that you would need the distribution of thicknesses, compared to the typical melt over the season. If 90% of the April or May ice is less thick than a season's worth of top+bottom melting, you would get a BOE as traditionally defined.

Note this is regardless of trends in extent or area, which could severely lag the drops in volume until the BOE arrives by surprise. This is because winter extent is limited by the geography of the Arctic ocean, surrounded by land on most sides, while winter thickness is dictated by freezing season temperatures. So volume is much more variable (and vulnerable) than extent/area.
High/low max extent is dictated by Okhotsk, Bering, Baffin and Barents - all are external to the Arctic Ocean and completely melt every summer. High/low max volume is sensitive to thickness in the Arctic Ocean itself. So ignoring volume is very risky.
Title: Re: When will the Arctic Go Ice Free?
Post by: interstitial on March 07, 2019, 06:22:15 AM
Two points is enough to define a line but it is not nearly enough to even consider defining a trend. Maybe it wasn't intentional but that is cherry picking the data and can be used to say practically anything.  :)
Title: Re: When will the Arctic Go Ice Free?
Post by: magnamentis on March 07, 2019, 12:53:37 PM
This is largely a two-dimensional system,

it's about energy and how much energy is needed to melt how much ice is mostly about volume.

of course area plays a role when it comes to insolation and air-flow but nevertheless it's about how much energy is needed to melt a given amount of ice and "amount" is equivalent to volume.

And greater surface area absorbs more energy.

or reflects ;)
Title: Re: When will the Arctic Go Ice Free?
Post by: Stephan on March 07, 2019, 07:48:24 PM
If 1980 was 2.6 m thick, and 2017 1.5 m thick, then the linear thickness loss rate is about 0.3 m per year.  With 1.5 m remaining, then extrapolating a linear trend we find zero thickness in about 2068.  But nothing in the Arctic is linear.
If I go back to my table and define June 1st just as a 1:1 "mixture" of May and June, we'll end up with a BOE at around 2103 (log evaluation) and 2112 (lin evaluation), which shows that there is no big difference between these two ways of evaluation, which implies an acceptable assumption of linearity. Noone of us will have the chance to prove that unless BOE happens much earlier than around the start of the next century.

[PS: The loss rate per year is around 0.03 m, not 0.3 m]
Title: Re: When will the Arctic Go Ice Free?
Post by: Tor Bejnar on March 07, 2019, 09:10:57 PM
If 1980 was 2.6 m thick, and 2017 1.5 m thick, then the linear thickness loss rate is about [edit: 0.03] m per year.  With 1.5 m remaining, then extrapolating a linear trend we find zero thickness in about 2068.  But nothing in the Arctic is linear.
I have three comments about this simplistic projection.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on March 07, 2019, 10:17:16 PM
Nothing in th Arctic tends to proceed in a linear fashion, and once we start to think we understand the system, it changes.  Who would have thought that the summer minimum would cease to drop over the last decade?  Many recent publications have sought to explain this.  I tend to agree that I will not live long enough to witness a BOE.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on March 07, 2019, 10:42:32 PM
Quote
Who would have thought that the summer minimum would cease to drop over the last decade?

See the Slow Transition and many threads in this forum. Half the people here were predicting a slow down of the minimum drop before it happened. I was not one of them, but it is not true that this  slowdown was not expected by many if not most. I still think it will be faster than even the Slow transition predicts and the drops will increase soon.
Title: Re: When will the Arctic Go Ice Free?
Post by: Juan C. García on March 07, 2019, 11:19:21 PM
Who would have thought that the summer minimum would cease to drop over the last decade?  Many recent publications have sought to explain this.  I tend to agree that I will not live long enough to witness a BOE.

There has been a "cease to drop" on extent, but not necessarily is the same on volume:

On extent, the ASI has not even able to break the 2007 record, not to mention the 2012 record. So, there are some people saying that 2012 is an outlier and even 2007 will be difficult to break. But I don’t like extent! Yes, it is important to measure the effect of the Arctic Ocean albedo. But to measure the ASI drop, I am convinced that we should use volume, even if it is harder to measure than extent.

So, what do I see on volume?

First, volume on 2007 has been broken several times. On volume, [September] 2007 is the ninth lowest on record! And even that September 2012 is still the lowest, the difference between 2012 with 2010-2011 and 2016-17 is not that big.

The 39.5% ice that we have on 2010-18, versus the 1979-2000 baseline, is climate change, not just one year, not weather change.
Title: Re: When will the Arctic Go Ice Free?
Post by: jai mitchell on March 08, 2019, 02:19:15 AM
h/t to AbruptSLR for pulling this one out.  It shows how the Arctic is being cooled by2.4 to 5.5 (median estimate 3.0) Celsius from aerosols

Title: "Arctic Clouds Highly Sensitive to Air Pollution"

https://eos.org/scientific-press/arctic-clouds-highly-sensitive-to-air-pollution


Q. Coopman et al. (09 November 2017), "High Sensitivity of Arctic Liquid Clouds to Long‐Range Anthropogenic Aerosol Transport", Geophysical Research Letters, https://doi.org/10.1002/2017GL075795

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2017GL075795


Abstract

The rate of warming in the Arctic depends upon the response of low‐level microphysical and radiative cloud properties to aerosols advected from distant anthropogenic and biomass‐burning sources. Cloud droplet cross‐section density increases with higher concentrations of cloud condensation nuclei, leading to an increase of cloud droplet absorption and scattering radiative cross sections. The challenge of assessing the magnitude of the effect has been decoupling the aerosol impacts on clouds from how clouds change solely due to natural meteorological variability. Here we address this issue with large, multi‐year satellite, meteorological, and tracer transport model data sets to show that the response of low‐level clouds in the Arctic to anthropogenic aerosols lies close to a theoretical maximum and is between 2 and 8 times higher than has been observed elsewhere. However, a previously described response of arctic clouds to biomass‐burning plumes appears to be overstated because the interactions are rare and modification of cloud radiative properties appears better explained by coincident changes in temperature, humidity, and atmospheric stability.

image below from a different study that (apparently) underestimated the arctic cooling from aerosols.
Title: Re: When will the Arctic Go Ice Free?
Post by: Dharma Rupa on March 09, 2019, 03:15:45 PM
If 1980 was 2.6 m thick, and 2017 1.5 m thick, then the linear thickness loss rate is about [edit: 0.03] m per year.  With 1.5 m remaining, then extrapolating a linear trend we find zero thickness in about 2068.  But nothing in the Arctic is linear.
I have three comments about this simplistic projection.
  • Much of the larger 1980's thickness was associated with thick multi-year ice that has drifted out The Fram (mostly) over 30+ years and has been replaced with younger ice, which in turn is replaced with about the same age of young ice, so the future decline rate is likely to be less ("Slow Transition (https://forum.arctic-sea-ice.net/index.php/topic,933.msg32299.html#msg32299)" thread).
  • I expect Arctic ice to crumple to nothingness after it gets to 10 or 20 cm thick, due to waves (https://forum.arctic-sea-ice.net/index.php/topic,1222.msg49706.html#msg49706), etc., so the final decline may be fast.
  • I used to have an opinion about when 'ice freedom' would occur; now I don't.

I've no idea on point 1, but I agree totally with points 2 and 3.  It's very unclear when the BOE will happen, but when it does the end will come suddenly.
Title: Re: When will the Arctic Go Ice Free?
Post by: jdallen on March 09, 2019, 10:17:55 PM
If 1980 was 2.6 m thick, and 2017 1.5 m thick, then the linear thickness loss rate is about [edit: 0.03] m per year.  With 1.5 m remaining, then extrapolating a linear trend we find zero thickness in about 2068.  But nothing in the Arctic is linear.
I have three comments about this simplistic projection.
  • Much of the larger 1980's thickness was associated with thick multi-year ice that has drifted out The Fram (mostly) over 30+ years and has been replaced with younger ice, which in turn is replaced with about the same age of young ice, so the future decline rate is likely to be less ("Slow Transition (https://forum.arctic-sea-ice.net/index.php/topic,933.msg32299.html#msg32299)" thread).
  • I expect Arctic ice to crumple to nothingness after it gets to 10 or 20 cm thick, due to waves (https://forum.arctic-sea-ice.net/index.php/topic,1222.msg49706.html#msg49706), etc., so the final decline may be fast.
  • I used to have an opinion about when 'ice freedom' would occur; now I don't.

I've no idea on point 1, but I agree totally with points 2 and 3.  It's very unclear when the BOE will happen, but when it does the end will come suddenly.
Speaking to point 2 I think volume will be the driver. I think the I think the tip over point will occur at somewhere around 2000KM3 volume. When the Arctic ice reaches that threshold I think the other mechanical forces we are thinking about will come into play and will overwhelm the remaining extent very quickly.
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on March 09, 2019, 10:56:32 PM
Is there any reason for thinking that a lot of area will suddenly go below some critical threshold whether between 10 and 20cm or some other particular thickness?

Why aren't people considering the ice to be more like a wedge as the minimum is approached with the thickest parts nearest Greenland/CAA? And there are, in any year, always some bits going below that critical thickness?

Is it just because that doesn't fit with personal beliefs that when the end comes it will happen suddenly? Can you see how this sounds like, I want this fast end collapse conclusion and therefore I am going to believe in this sudden collapse once it goes under a certain threshold rather than working with what we would expect to ultimately arrive at a conclusion?

If you have worked it the other way, considered the wedge as explained above and have reasons for dismissing it, then that is fine, you will be able to explain your reasoning as to why you reached that conclusion and won't find this post annoying. If you just find this post annoying then ....
Title: Re: When will the Arctic Go Ice Free?
Post by: wdmn on March 09, 2019, 11:44:30 PM
@Crandles,

I think the wedge point is a fair one, but all it does it is reaffirm the argument for why volume is more important than extent. Not just average volume though, since location matters.

That said, there's a clear reason for seeing how extent can lag behind volume, just by comparing the shape of the decline for both volume and extent.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on March 10, 2019, 12:35:14 AM
Quote
Why aren't people considering the ice to be more like a wedge as the minimum is approached with the thickest parts nearest Greenland/CAA? And there are, in any year, always some bits going below that critical thickness?

Reviving an old A-Team image. This is what extent hides:

(https://forum.arctic-sea-ice.net/index.php?action=dlattach;topic=119.0;attach=72424;image)

The images above are the September minimum with ice <1.5m removed from 1978-2016. 

The thick ice is not just melting, it is being exported through the garlic press and fram (Now replaced by the kill zone north of Svalbard). That thick ice is barely being replaced.

Quote
Is there any reason for thinking that a lot of area will suddenly go below some critical threshold whether between 10 and 20cm or some other particular thickness?

Thinner ice melts faster, but usually by the time most of the thin ice is gone is August or September and the sun works in our favor. A weak freezing season with a low max volume ( like 2017, 20.782 maximum volume) coupled with a strong melting season (like 2012, 19,692 volume loss) is already enough to get us to an ice free state (20.782-19,692= 1,091, virtually ice free). No threshold needed, only bad climate luck.

Quote
Is it just because that doesn't fit with personal beliefs that when the end comes it will happen suddenly?

In my case is because nature likes abrupt change. Systems are stable until they are sufficiently modified and then they can change to completely different states. The Arctic seems an awful lot like the kind of system that will abruptly change once sufficiently disturbed, the same for the atmospheric and oceanic currents affected by the presence of ice.

Quote
Can you see how this sounds like, I want this fast end collapse conclusion and therefore I am going to believe in this sudden collapse once it goes under a certain threshold rather than working with what we would expect to ultimately arrive at a conclusion?

Can you see the other way tho? Can you acknowledge the implication of a fast Arctic collapse on the world that we live? Can you acknowledge how difficult it would be for scientists to claim that the world might end in just a few decades? They can't. If they do they will be called crazy. Are you familiar with double blind experiments? DO you know why they do it? Do you realize that climate science there is no double blind experimentation because the science directly affects the scientist?
Title: Re: When will the Arctic Go Ice Free?
Post by: jdallen on March 10, 2019, 01:55:17 AM
Is there any reason for thinking that a lot of area will suddenly go below some critical threshold whether between 10 and 20cm or some other particular thickness?

Why aren't people considering the ice to be more like a wedge as the minimum is approached with the thickest parts nearest Greenland/CAA? And there are, in any year, always some bits going below that critical thickness?

Is it just because that doesn't fit with personal beliefs that when the end comes it will happen suddenly? Can you see how this sounds like, I want this fast end collapse conclusion and therefore I am going to believe in this sudden collapse once it goes under a certain threshold rather than working with what we would expect to ultimately arrive at a conclusion?

If you have worked it the other way, considered the wedge as explained above and have reasons for dismissing it, then that is fine, you will be able to explain your reasoning as to why you reached that conclusion and won't find this post annoying. If you just find this post annoying then ....
I don't *want* a fast collapse conclusion, Crandles.  My understanding of the system dynamics tends to support that kind of event.

I'm not denying that thicker ice will still make up a significant portion of that volume; in fact I expect it - exactly from some of the sources like Greenland that you're thinking of.

However comparatively that ice will make up a comparatively small extent and area - likely under  the 1 million KM2 metric a lot of people are thinking of.

That ice *will* be durable and will be around for centuries, but it won't be near enough to prevent the massive changes in system dynamics that will take place once we start loosing most of the CAB extent.  That's what I'm thinking about when I talk about a tip over point.
Title: Re: When will the Arctic Go Ice Free?
Post by: Tor Bejnar on March 10, 2019, 02:05:52 AM
I recall a 'flash melting' due to a GAC (great Arctic Cyclone).  I expect more in the future.  Yes, there will be thicker ice that won't flash disappear, until there isn't.  As I don't have any of that 'magical' Chinese elixir (https://forum.arctic-sea-ice.net/index.php/topic,2470.msg191592.html#msg191592), I may well not see that day.
Title: Re: When will the Arctic Go Ice Free?
Post by: oren on March 10, 2019, 10:09:50 AM
Yes, I recall two GACs. 2016 showed 2012 was not a fluke, especially when looking at high-resolution metrics such as AMSR2 area, and the state of the ice around the Pole.
I expect the first BOE season to also have a GAC, which provides an extra punch right there at the end, when the sun is weak but the water is relatively warm and the surviving ice quite vulnerable.
Title: Re: When will the Arctic Go Ice Free?
Post by: Peter Ellis on March 12, 2019, 03:00:25 PM
Discussions of fast crashes when thickness gets below a given threshold always strike me as conflating two UTTERLY different things.

The first is the kinetics of how the thickness of a given piece of ice melts during the course of a season.  As it gets thinner, eventually there comes to be a point where it's too thin to maintain structural integrity, fragments and rapidly melts.

The second is the kinetics of how the average statistical distribution of ice thickness changes from year to year.
Title: Re: When will the Arctic Go Ice Free?
Post by: jdallen on March 13, 2019, 06:25:43 AM
Discussions of fast crashes when thickness gets below a given threshold always strike me as conflating two UTTERLY different things.
<snippage>
(summarized: melting behavior and distribution)
Good point.

Between the two of them, I think volume is the unifying factor, rather than either one of those on its own.
Title: Re: When will the Arctic Go Ice Free?
Post by: El Cid on March 13, 2019, 09:34:45 AM
I think using generalized volume is a simplification because the periphery and the central arctic behaves quite differently (probably due to bathymetry). Attached is the volume for the CAB only.

It seems to me that we currently have a new "balance" in the CAB (circled) which will probably last until Atlantic warm water intrudes and finally mixes well and then the CAB will be gone. I think it is impossible to know when this will happen  and linear/polynomial, etc. projections are not useful
Title: Re: When will the Arctic Go Ice Free?
Post by: uniquorn on March 13, 2019, 10:32:43 AM
Attached is the volume for the CAB only. <snippage>
Nice chart, are they piomas numbers?
This may not be a 'balance' but a temporary pause while MYI and 2 year ice is flushed out.
Title: Re: When will the Arctic Go Ice Free?
Post by: oren on March 13, 2019, 11:04:32 AM
Nice chart indeed.
The fact that a new lower max was set in early 2017 hints that the process is not really over, so I am not sure this is a balance. But certainly the CAB will be more resilient, with its consistent winter freezing and short melting season.
Title: Re: When will the Arctic Go Ice Free?
Post by: echoughton on March 13, 2019, 12:06:30 PM
Missed the vote...by 6 months...lol.
Seeing 12 members voted for this season tells me alarm is alive and well. Sorry, don't see it in the data at all. Decent volume, extent not too bad...better than last few years. Maybe in 50-100 years. About the same time frame it will logical and feasibly take to make the complete switch...or nearly so...to renewable energy
Title: Re: When will the Arctic Go Ice Free?
Post by: El Cid on March 13, 2019, 12:48:47 PM
Attached is the volume for the CAB only. <snippage>
Nice chart, are they piomas numbers?

Yes, piomas data from Wipneus' page.

I think increased ocean heat is nibbling at the CAB and eventually this will lead to a collapse. Could happen next year or in 2050 for all we know.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on March 13, 2019, 02:46:48 PM
Nice chart indeed.
The fact that a new lower max was set in early 2017 hints that the process is not really over, so I am not sure this is a balance. But certainly the CAB will be more resilient, with its consistent winter freezing and short melting season.

Except that poimas volume has returned to the previous years.  I agree with El Cid (thank you for the chart, by the way), and that we are in a new balance, and impossible to say how long it will last.
Title: Re: When will the Arctic Go Ice Free?
Post by: Gray-Wolf on March 13, 2019, 04:42:19 PM
Sorry, don't see it in the data at all.

said most cryosphere scientists in Sept 2007!

I know we focus in on the Basin but there is a big old world beyond that and since the Pacific naturals flip in 2014 I believe we are seeing the rates of warming increase up and beyond that seen through the 80's/90's?

The Super Nino might have messed with the new patterns settling in but the past year has seen them look much more settled?

If the record heat from the South of the planet merely passes across the equator with the sun around the 21st then we could be in for a heck of a summer what with Yamal ready to go pop and the sea ice ground down into ever smaller individual floes glued together by younger ice and with us also in the return period for the 'perfect melt storm'............ plenty of potential for an " Oh! Shite!" moment!

Title: Re: When will the Arctic Go Ice Free?
Post by: El Cid on March 13, 2019, 05:03:37 PM
Sorry, don't see it in the data at all.


I know we focus in on the Basin but there is a big old world beyond that and since the Pacific naturals flip in 2014 I believe we are seeing the rates of warming increase up and beyond that seen through the 80's/90's?

The Pacific might have "flipped" in 2014. I attach a picture of 2014-18  winter temp anomaly vs 2000-2010.

It is obvious that the Bering region warmed up very much and sucked in warm air from the south - probably creating string ridging and an anomalously cold Hudson region as the cold was "pushed out" into that region. The same thing happened in 2019 (not on pic), so we could call it a trend.
The consequence (other than bitter winter cold intrusions for NA) is probably a weak Bering/Chukchi which could dissipate fast come summer. Will that be enough to break the new CAB volume "balance"? I do not know.
Title: Re: When will the Arctic Go Ice Free?
Post by: oren on March 29, 2019, 10:58:28 AM
https://cryospherecomputing.tk/IceFreeDays (https://cryospherecomputing.tk/IceFreeDays)
Parts of the arctic have already gone partially ice-free. Here is an image from a new visualization tool by Tealight (a.k.a Nico Sun) showing the anomaly of ice-free days in 2017 compared to the long term average. You can clearly see the two-pronged advance of the Atlantic and the Pacific into the Arctic.
One doesn't need a blue ocean event to have far-reaching consequences.
(https://cryospherecomputing.tk/IceFreeDays/Arctic_IceFreeDays__anom_2017.png)

Note: Bear in mind the anomaly is limited by the number of ice-covered days each pixel had to begin with.
Title: Re: When will the Arctic Go Ice Free?
Post by: Aluminium on April 02, 2019, 10:27:49 AM
Based on minimums 1979-2018 and linear regression, I calculated probabilities to get minimum below 2012 in 2019-2035 (blue dots). Also cumulative probability (red dots) and probability to get minimum below 2012 first time that year (green dots).

Title: Re: When will the Arctic Go Ice Free?
Post by: kassy on April 02, 2019, 01:15:14 PM
The Transpolar Drift is faltering -- sea ice is now melting before it can leave the nursery


The dramatic loss of ice in the Arctic is influencing sea-ice transport across the Arctic Ocean. As experts from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research report in a new study, today only 20 percent of the sea ice that forms in the shallow Russian marginal seas of the Arctic Ocean actually reaches the Central Arctic, where it joins the Transpolar Drift; the remaining 80 percent of the young ice melts before it has a chance to leave its 'nursery'. Before 2000, that number was only 50 percent. According to the researchers, this development not only takes us one step closer to an ice-free summer in the Arctic; as the sea ice dwindles, the Arctic Ocean stands to lose an important means of transporting nutrients, algae and sediments. The new study will be released as a freely accessible Open Access article in the online journal Scientific Reports on 2 April 2019.

...

"Our study shows extreme changes in the Arctic: the melting of sea ice in the Kara Sea, Laptev Sea and East Siberian Sea is now so rapid and widespread that we're seeing a lasting reduction in the amount of new ice for the Transpolar Drift. Now, most of the ice that still reaches the Fram Strait isn't formed in the marginal seas, but comes from the Central Arctic. What we're witnessing is a major transport current faltering, which is bringing the world one major step closer to a sea-ice-free summer in the Arctic," says first author Dr Thomas Krumpen, a sea-ice physicist at the Alfred Wegener Institute.

This trend has been confirmed by the outcomes of sea-ice thickness measurements taken in the Fram Strait, which the AWI sea-ice physicists gather on a regular basis. "The ice now leaving the Arctic through the Fram Strait is, on average, 30 percent thinner than it was 15 years ago. The reasons: on the one hand, rising winter temperatures in the Arctic and a melting season that now begins much earlier; on the other, this ice is no longer formed in the shelf seas, but much farther north. As a result, it has far less time to drift through the Arctic and grow into thicker pack ice," Thomas Krumpen explains.

...

https://www.brightsurf.com/news/article/040219479881/the-transpolar-drift-is-faltering-sea-ice-is-now-melting-before-it-can-leave-the-nursery.html
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on April 02, 2019, 02:17:17 PM
Based on minimums 1979-2018 and linear regression, I calculated probabilities to get minimum below 2012 in 2019-2035 (blue dots). Also cumulative probability (red dots) and probability to get minimum below 2012 first time that year (green dots).

Using linear regression for predictions in a non-linear system may not be the best.  Hence, I think you have over-estimated the probabilities.
Title: Re: When will the Arctic Go Ice Free?
Post by: oren on April 02, 2019, 02:46:05 PM
Based on minimums 1979-2018 and linear regression, I calculated probabilities to get minimum below 2012 in 2019-2035 (blue dots). Also cumulative probability (red dots) and probability to get minimum below 2012 first time that year (green dots).

Using linear regression for predictions in a non-linear system may not be the best.  Hence, I think you have over-estimated the probabilities.
Or under-estimated.
I think the odds of 2019 producing a minimum below 2012 are much higher than the ~7% (1:14) shown in the graph. Probably double that at 1:7. OTOH I think the odds for 2020, 2021, 2022... are not materially different, unlike the trend shown in the graph.
In essence I think the linear ice loss trend is less reliable for predictions, but that there is much greater volatility enabling any given year to set a new record minimum, with a little cooperation from the weather and maybe an August GAC. The dice are heavily loaded.
Title: Re: When will the Arctic Go Ice Free?
Post by: Aluminium on April 02, 2019, 02:59:31 PM
It was not about ice free Arctic. Results for minimum under 106 km2 see below.
Title: Re: When will the Arctic Go Ice Free?
Post by: gerontocrat on April 02, 2019, 05:45:33 PM
Some years before a BOE becomes anything like normal, will we have to change the maps vis a vis where the Atlantic ends and the Arctic begins?

I can see an International Conference looming by about 2030 (or before?) ?
Title: Re: When will the Arctic Go Ice Free?
Post by: Stephan on April 02, 2019, 06:40:53 PM
Based on minimums 1979-2018 and linear regression, I calculated probabilities to get minimum below 2012 in 2019-2035 (blue dots). Also cumulative probability (red dots) and probability to get minimum below 2012 first time that year (green dots).
From linear regression of the Sep averages an area of 3,50 M km² will be reached around 2030.
Title: Re: When will the Arctic Go Ice Free?
Post by: Viggy on April 02, 2019, 07:53:30 PM
Some years before a BOE becomes anything like normal, will we have to change the maps vis a vis where the Atlantic ends and the Arctic begins?

I can see an International Conference looming by about 2030 (or before?) ?

Russia's about to get a NATO invite in the mail
Title: Re: When will the Arctic Go Ice Free?
Post by: gerontocrat on April 02, 2019, 08:03:04 PM
I was thinking more along the lines of that when a sea is more or less ice-free (say less than 10% area) for more than 6 months of the year, its nature is more of an open water sea than an Arctic Sea.

Then I might argue that this is Atlantification beyond the point of no return, and is more a part of the Atlantic Ocean than the Arctic Ocean.

As the graph attached shows, on the Atlantic Front the Barents Sea is on the point of no return of Atlantification, the ice-free days (less than 10 % area) increasing from about 100 days in the 1980's to around 200 days now.

Tealight and his alter ego Nico Sun shows the same thing graphically.

The opportunities for argument about defining an open water sea are no doubt tending to the infinite. "But this is my definition that belongs to me"
Title: Re: When will the Arctic Go Ice Free?
Post by: Stephan on April 07, 2019, 10:10:41 PM
It is time for the monthly update of my extrapolation when the extent [Extent], volume [Volumen] and thickness [Dicke] will reach zero. The extrapolation occured linearly and by a logarithmic function; the latter one almost constantly resulting in earlier times. March value now includes 2019.
As extent, volume and thickness in March 2019 lie all above the long-term linear trend lines it is clear that the BOE for March will take place a few years later than calculated last March. All slopes decreased slightly, and March has, together with April, the smallest slope.

Please note that this is not a forecast but a trend!
See attached table.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on May 05, 2019, 03:23:51 PM
It seems maximum volume was reached in day 110. I will update the model that belongs to me for when the Arctic will go ice free every tic. That is, for every minimum and maximum volume I will update the trendlines and averages and combine them into an animation.

I will do one assuming the minimum hit a new state in 2007 and another one using the whole satellite data set. Let me know what you think.
Title: Re: When will the Arctic Go Ice Free?
Post by: jdallen on May 06, 2019, 08:57:09 AM
It seems maximum volume was reached in day 110. I will update the model that belongs to me for when the Arctic will go ice free every tic. That is, for every minimum and maximum volume I will update the trendlines and averages and combine them into an animation.

I will do one assuming the minimum hit a new state in 2007 and another one using the whole satellite data set. Let me know what you think.
The bottom trendline bothers me, for a specific reason; it's a proxy for the annual heat entering the Arctic.

That isn't decreasing, *can't* decrease past a hard limit described by that total insolation + other heat inflows.

I'd be highly surprised if it really could drop below 17,000km3/year.  I doubt it can remain consistently below 18,000km3/year.

That's the value I'm actually watching to determine when we hit "ice free".
Title: Re: When will the Arctic Go Ice Free?
Post by: El Cid on May 06, 2019, 10:20:57 AM
Nice charts Archimid!

2030ish seems believable.

Although, who knows? Could happen even this year for all we know
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on May 06, 2019, 01:30:10 PM

The bottom trendline bothers me, for a specific reason; it's a proxy for the annual heat entering the Arctic.

That isn't decreasing, *can't* decrease past a hard limit described by that total insolation + other heat inflows.

I'd be highly surprised if it really could drop below 17,000km3/year.  I doubt it can remain consistently below 18,000km3/year.

That's the value I'm actually watching to determine when we hit "ice free".

>"*can't* decrease past a hard limit"

Alternatively, you could (more correctly?) argue it *can't* be above max volume.

Anyway there appears an issue with your version: If the ice gathers heat from the same area then "total insolation + other heat inflows" will not go down seems sensible. However if the ice shrinks to a smaller area then isn't it logical that the heat energy that the ice can gather from "total insolation + other heat inflows" is also likely to go down?

Same area but thinner and the energy gathered by the ice is likely to go up not stay steady or go down. We have had a lot of this as thick MYI disappeared. (~2000-2012?) We have reached the end of this rapid thinning and now we are getting more of the area shrinkage with volume.

So is a horizontal or straight line extrapolation appropriate?
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on May 06, 2019, 02:16:31 PM
The bottom trendline bothers me, for a specific reason; it's a proxy for the annual heat entering the Arctic.

That's how I like to look at it.

Quote
That isn't decreasing, *can't* decrease past a hard limit described by that total insolation + other heat inflows.

I suppose that the hard limit is the minimum value for loss in the satellite set. That value is 13.9 and happened in 1996. The graph starts at 14. So all the values that have been proven possible are present in the graph

Quote
I'd be highly surprised if it really could drop below 17,000km3/year.  I doubt it can remain consistently below 18,000km3/year.

I think clouds are the only thing that can possibly bring the value down to lower levels, but so far they haven't.

Quote
That's the value I'm actually watching to determine when we hit "ice free".

I think we will have a record loss year soon, even if the ice is harder to melt because of geometry or clouds. Next strong El Niño year will likely be the first BOE.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on May 06, 2019, 03:19:20 PM
Alternatively, you could (more correctly?) argue it *can't* be above max volume.

It can't go above max volume in terms of water volume. In term of heat it can certainly go past max negative heat.

Quote
However, if the ice shrinks to a smaller area then isn't it logical that the heat energy that the ice can gather from "total insolation + other heat inflows" is also likely to go down?

It is not just likely. Direct "total insolation" will go down with area as sure as the Earth is round.  The question is, will it go down enough to offset the increase in "other heat inflows"?

Quote
Same area but thinner and the energy gathered by the ice is likely to go up not stay steady or go down. We have had a lot of this as thick MYI disappeared. (~2000-2012?) We have reached the end of this rapid thinning and now we are getting more of the area shrinkage with volume.

The graph showing losses for 2007-2018 already takes that mechanical feature of Arctic melt somewhat into account as it doesn't include the years when ice was significantly thicker. Even so, losses are greater now that the ice is thin than when the ice was thick.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fgreatwhitecon.info%2Fwp-content%2Fuploads%2F2019%2F03%2FSeaIceAgeV4.png&hash=2f9b1e1c1a5379315e3290da7c964184)

Quote
So is a horizontal or straight line extrapolation appropriate?

For the Maximum volume a linear extrapolation works very well. For the minimum it doesn't. That's why I include two versions. One takes the satellite data set as the Arctic system, the other assumes there was a state change in 2007 and data before that is meaningless. Hopefully, we get to see how they change over time.

A less technical answer would be that  linear extrapolation is what it is. It assumes that exactly what happened in the past will happen in the future. It is naive because it is a fact of life that things change. But it is insightful because it is also a fact of life that things tend to repeat.

Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on May 06, 2019, 06:31:52 PM
Alternatively, you could (more correctly?) argue it *can't* be above max volume.

It can't go above max volume in terms of water volume. In term of heat it can certainly go past max negative heat.
Fair point. The graph referred to is showing ice volume change.

"will it go down enough to offset the increase in "other heat inflows"?" is also a good point.

Quote
Quote
Same area but thinner and the energy gathered by the ice is likely to go up not stay steady or go down. We have had a lot of this as thick MYI disappeared. (~2000-2012?) We have reached the end of this rapid thinning and now we are getting more of the area shrinkage with volume.

The graph showing losses for 2007-2018 already takes that mechanical feature of Arctic melt somewhat into account as it doesn't include the years when ice was significantly thicker. Even so, losses are greater now that the ice is thin than when the ice was thick.

I wasn't particularly referring to mechanical strength. Thinner ice converts to open water more easily and that has albedo consequences meaning much more of the insolation is captured. Then if ice is nearby, currents are likely to move the heat to the ice. But if the ice is a long way away then then likelihood of that heat being transferred to the ice is much reduced.


Quote
For the Maximum volume a linear extrapolation works very well. For the minimum it doesn't. That's why I include two versions. One takes the satellite data set as the Arctic system, the other assumes there was a state change in 2007 and data before that is meaningless. Hopefully, we get to see how they change over time.

A less technical answer would be that  linear extrapolation is what it is. It assumes that exactly what happened in the past will happen in the future. It is naive because it is a fact of life that things change. But it is insightful because it is also a fact of life that things tend to repeat.

Straight line is sensible when you expect the same physics to be in play or has shown to work well and there is no reason to expect change ....
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on May 06, 2019, 11:31:52 PM
Quote
I wasn't particularly referring to mechanical strength.


I should have said geometric feature instead of mechanical feature. The interactions between reduction of area and albedo are more geometric than mechanical. I was not talking about mechanical strength.

Quote
Thinner ice converts to open water more easily and that has albedo consequences meaning much more of the insolation is captured. Then if ice is nearby, currents are likely to move the heat to the ice. But if the ice is a long way away then then likelihood of that heat being transferred to the ice is much reduced.

yes, but so far the effect has been masked by the sum of all other factors. Volume losses are higher even when there is less volume and less area to lose. Although the losses decreased in recent years they are still above the average of the losses before 2007.

Quote
Straight line is sensible when you expect the same physics to be in play or has shown to work well and there is no reason to expect change ....

Yep. That's why I used 2 graphs. One with a straight line through the satellite set representing no change in the system and one that only uses a line through the latest years representing a changed system. Not only that, but the lines will be changing with each new entry, reflecting the change overtime.

Title: Re: When will the Arctic Go Ice Free?
Post by: Tom_Mazanec on May 09, 2019, 12:59:02 AM
I find it interesting that three people voted for next century or later, while a dozen voted for a year or two.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on May 09, 2019, 03:54:09 AM
I find it interesting that three people voted for next century or later, while a dozen voted for a year or two.

Just shows the wide breadth of opinions.  I am really more surprised that so many thought the Arctic would be ice-free by this year.
Title: Re: When will the Arctic Go Ice Free?
Post by: oren on May 09, 2019, 04:29:21 AM
2018-2019 was a roll of the dice, with low chances (5% per year?). Some people chose to take the gamble, knowing it cost them nothing.
But I am personally much more surprised by those who truly believe that the answer to "When will the Arctic Extent dip below 1,000,000 Km^2" is 2100 and beyond, after the crazy drops we saw in summer 2012 and spring 2016. Even random year-over-year variability could get us there this century. And 80 years of Arctic amplification will surely make matters much worse.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on May 09, 2019, 04:31:41 AM
It could have been ice free in 2016, but we got lucky. Not a lot of luck was needed.Unluckily, luck will decrease every year the planet keeps warming.
Title: Re: When will the Arctic Go Ice Free?
Post by: miki on May 09, 2019, 05:04:15 AM
Just shows the wide breadth of opinions.  I am really more surprised that so many thought the Arctic would be ice-free by this year.

You speak as this year is already done. 2019 is still in the game, IMO.
Title: Re: When will the Arctic Go Ice Free?
Post by: interstitial on May 09, 2019, 05:04:53 AM
In the spring of 2012 I started following JAXA extent graph. Just from that one graph I figured BOE was going to be 2035 plus or minus five years for weather. Since then from this site and satellite images i have learned quite a bit. I still am just an amateur but until this year I thought my original guess was on target. I still think plus or minus five years for weather is appropriate for any guess further out than the current year. Now I am thinking 2030 plus or minus 5 years for BOE. What changed? Extent record is still 2012 but volume bottomed out in 2016 or 2017 depending on which graph you prefer. I think volume is a better indicator of when to expect BOE because extent can change dramatically with a shift in winds. To my eyes no area on worldview looks to have ice in much worse condition than this year except Barents sea in 2012.
Title: Re: When will the Arctic Go Ice Free?
Post by: Pmt111500 on May 09, 2019, 06:24:56 AM
Just shows the wide breadth of opinions.  I am really more surprised that so many thought the Arctic would be ice-free by this year.

You speak as this year is already done. 2019 is still in the game, IMO.
Maybe KK thought this meant the average of the whole year. Dipping to me is though crossing the point at any time.
Title: Re: When will the Arctic Go Ice Free?
Post by: Sleepy on May 09, 2019, 07:02:38 AM
The ASI is a zombie, all the heat needed is already up there. Halocline heat content has doubled over the last three decades in the gyre, I will be surprised if we don't see a dip below 1M before 2025.

Edit; adding some colourful support.

(https://www.nodc.noaa.gov/OC5/3M_HEAT_CONTENT/heat_content2000m.png)

(https://www.esrl.noaa.gov/gmd/aggi/aggi.fig3.png)
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on May 09, 2019, 03:06:21 PM
Just shows the wide breadth of opinions.  I am really more surprised that so many thought the Arctic would be ice-free by this year.

You speak as this year is already done. 2019 is still in the game, IMO.

Of course it is.  However, after a fast start to the melt season, the ice loss has slowed dramatically this year.  The 30-day melt is one of the lowest in the satellite data (only six years have shown less).    At this point in 2012, the ice melt was already taking off, and the aforementioned 2016 (which was lower on this date) also experienced large losses.  The multiple reports of greater thickness this year, is not indicative of an ice-free minimum this year.  Over the past dozen years, the trend in sea ice minima has been relatively flat.  It would take an extraordinary event (much more than observed in 2012) to cross the point at any time (No, miki I was not talking about average the whole year).  Until we start seeing lower minima, I think that the later decades are more likely. 
Title: Re: When will the Arctic Go Ice Free?
Post by: miki on May 09, 2019, 04:58:34 PM
Just shows the wide breadth of opinions.  I am really more surprised that so many thought the Arctic would be ice-free by this year.

You speak as this year is already done. 2019 is still in the game, IMO.

Of course it is.  However, after a fast start to the melt season, the ice loss has slowed dramatically this year.  The 30-day melt is one of the lowest in the satellite data (only six years have shown less).    At this point in 2012, the ice melt was already taking off, and the aforementioned 2016 (which was lower on this date) also experienced large losses.  The multiple reports of greater thickness this year, is not indicative of an ice-free minimum this year.  Over the past dozen years, the trend in sea ice minima has been relatively flat.  It would take an extraordinary event (much more than observed in 2012) to cross the point at any time (No, miki I was not talking about average the whole year).  Until we start seeing lower minima, I think that the later decades are more likely.
I don't know.

My main concern is the rapid change of the whole Arctic ecosystem that is happening right now.
My guess for the dip, given all, is that it may likely happen in the early twenties. However, at this point, I do not discard any year. The fact that a season can be determined by the absence or presence of smoke coming from the burning Tundra in Siberia, or by a couple of storms coming in from the Pacific, makes me really wonder and worry. We may be here one of these coming years, still discussing about thickness, and then we turn our head and the ice is gone.
Title: Re: When will the Arctic Go Ice Free?
Post by: Stephan on May 10, 2019, 05:31:11 PM
It is time for the monthly update of my extrapolation when the extent [Extent], volume [Volumen] and thickness [Dicke] will reach zero. The extrapolation occured linearly and by a logarithmic function; the latter one almost constantly resulting in earlier times. April value now includes 2019.
As volume and thickness in April 2019 lie above the long-term linear trend lines it is clear that the BOE for April will take place a few years later than calculated last April. The extent in April 2019 was the lowest ever measured and below the long-term trend line, this also means that with volume above the long term trend line the thickness is also bigger than last years. In fact - apart from 2015 - the thickness is the largest since 2009! Was this the cold winter and the mostly missing warm intrusions between Nov and March?
The low extent did not effect the "BOE" value for April in the extent part of the table.
All slopes decreased slightly, and April has, together with March, the smallest slope of all months ("Stg" in the attached table).

Please note that this is not a forecast but a trend!
See attached table.
Title: Re: When will the Arctic Go Ice Free?
Post by: Reallybigbunny on May 11, 2019, 05:39:05 AM
In this highly interesting interview published on May 08, 2019, Wieslaw Maslowski talks with Guy McPherson about Arctic Ice. You might recall In 2012 Maslowski published a paper projecting the arctic would be ice free in 2016 + or - 3 years.

https://www.youtube.com/watch?v=yoy4U7MGIdo
Title: Re: When will the Arctic Go Ice Free?
Post by: Pmt111500 on May 11, 2019, 06:26:05 AM
In this highly interesting interview published on May 08, 2019, Wieslaw Maslowski talks with Guy McPherson about Arctic Ice. You might recall In 2012 Maslowski published a paper projecting the arctic would be ice free in 2016 + or - 3 years.


If this doesn't happen, we might conclude Maslowski didn't have enough info of the future weather, though his projection was valid for exponential decrease of ice. We might try to add up the drops in Antarctic in the recent three years to the Arctic decrease and see how little there would be ice in Arctic if all the decrease had happened up there. SH was projected to be spared of the faster effects of CC due the higher ocean proportion and the protective function of ACC back then.
Title: Re: When will the Arctic Go Ice Free?
Post by: sark on May 11, 2019, 06:43:26 AM
not interesting
Title: Re: When will the Arctic Go Ice Free?
Post by: Sleepy on May 11, 2019, 06:59:12 AM
There's something to learn from everyone.
Title: Re: When will the Arctic Go Ice Free?
Post by: Sterks on May 11, 2019, 12:49:56 PM
Yes, for some scientists to learn: avoid dissemination of catastrophic alarmist results if they don't have an extremely solid basis. 10-year linear trends? WTF?

Many deniers nowadays are using to discredit AGW claims from the 80's that were based on worst case scenarios and that did not come to happen.

I find alarmist scientists absolutely reckless. Fattening career and fame with +3sigma claims as baseline. As reckless as denier scientists paid with gold by the Cato Institute

Fortunately most of scientists take a more humble, more rigorous approach, something that is seen by some in forums like this as "coward" "staying in an ivory tower" "irresponsible" "slow science supports deniers" etc etc
Title: Re: When will the Arctic Go Ice Free?
Post by: oren on May 11, 2019, 01:45:11 PM
Guy McPherson? I'll pass.
Title: Re: When will the Arctic Go Ice Free?
Post by: Sleepy on May 11, 2019, 02:21:41 PM
Yes, for some scientists to learn>snip>
I commented the previous poster, just like you did I guess? It also stands in general.

Good or bad, kind or evil, silent or loud, there's still something to learn from everyone.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on May 11, 2019, 02:28:29 PM
Yes, for some scientists to learn: avoid dissemination of catastrophic alarmist results if they don't have an extremely solid basis. 10-year linear trends? WTF?

Many deniers nowadays are using to discredit AGW claims from the 80's that were based on worst case scenarios and that did not come to happen.

I find alarmist scientists absolutely reckless. Fattening career and fame with +3sigma claims as baseline. As reckless as denier scientists paid with gold by the Cato Institute

Fortunately most of scientists take a more humble, more rigorous approach, something that is seen by some in forums like this as "coward" "staying in an ivory tower" "irresponsible" "slow science supports deniers" etc etc

I agree completely.  The reckless nature of these scientists have given ammo do those who wish to discredit the entire theory.  Many posters here seemed to hail these claims, as the number voting for an ice-free Arctic in the very near future exemplifies. 

Unfortunately, these claims are not restricted to the Arctic.  I remember after 2005, how some had claimed that this would be the “new normal” for hurricanes, only to be followed by a prolonged lull in activity.  Droughts and starvation appear to be another common meme, that has failed to materialize.  Although in the U.S., it has been replaced by flooding, as drought is at an all time low.  Yes, I tend to listen to the more humble scientists, and their thorough research, rather than those garnering headlines in the papers, which tend to amplify the further left and right positions.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on May 11, 2019, 02:30:07 PM
Quote
Yes, for some scientists to learn: avoid dissemination of catastrophic alarmist results if they don't have an extremely solid basis. 10-year linear trends? WTF?

Given what is known, and worse, what is not known about climate change, any climate scientist not being alarmist has succumbed to fear. Climate change is real. Climate change is worse than predictions. Abrupt climate change is very likely.

The lack of alarmism produces inaction.


Quote
Many deniers nowadays are using to discredit AGW claims from the 80's that were based on worst case scenarios and that did not come to happen.

Deniers say NASA is lying about the temperature data set. Deniers take the painstaking and rigorous work of revising data and makes it look like fraud to anyone not versed in science (95% of people). There is nothing you can say that cowardly deniers won't twist for their own cowardly purposes.

What you should be worried about is giving the world the best risk assessment possible and the best science possible regardless of what others may think. That is very difficult, specially for people of science.

Slow climate change proponents are giving the world the wrong risk assessment.

Quote
Fattening career and fame with +3sigma claims as baseline. As reckless as denier scientists paid with gold by the Cato Institute

What scientist is "fattening" their career? Scientist that make alarmists predictions are immediately shunned by peers and the media, just like you are doing here.  People don't want to hear that our world is ending unless we make significant changes to how we lead our lives. Scientists are people and they suffer the same defect* as people do. They don't want to talk about the end of our world.
 
Quote
I find alarmist scientists absolutely reckless.

I find scientists that pretend "everything is ok, nothing to worry about until 2100" absolutely reckless. Although "scientists" may not be the best way to describe them. The whole "climate change will be slow"  theory has no basis in science. Zero. Nada. Climate change at the scale humans are producing is unprecedented. Any claim of safety is pure speculation. Bad speculation at that. Past mass extinction happened over thousands of years. What we are doing to Earth is happening over decades.

Your Conservatism is fake science.

Quote
Fortunately most of scientists take a more humble, more rigorous approach, something that is seen by some in forums like this as "coward" "staying in an ivory tower" "irresponsible" "slow science supports deniers" etc etc

They are not being rigorous. They are supposing a stable climate as a given and ignoring evidence that is scary.


*Defect only in terms of security and correct risk assesment. In terms of everyday life, denying the fragility of our world and the impact we are having on it is a feature that keeps us sane. Climate scientist do not have the choice of double blind experimentation.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on May 11, 2019, 02:48:33 PM

Thanks for the examples in cowardliness:

Quote
remember after 2005, how some had claimed that this would be the “new normal” for hurricanes, only to be followed by a prolonged lull in activity.

The last three years of hurricanes were record losses, yet you cherry pick a small lull after 2005 to justify your point

Quote
I  Droughts and starvation appear to be another common meme, that has failed to materialize.

This coward conveniently forgot about the years before 2015-2016. Drought was dangerously closing into many parts of the world as the world was undergoing a warm/dry spell. This warm/dry spell was replaced by a warm/wet spell we are currently on. Is warm/dry returning? I don't know, but I dare not to assume that it won't. And if it does, due to CO2, it will be even warmer with more flash droughts.

Quote
Although in the U.S., it has been replaced by flooding, as drought is at an all time low.

I mean listen to yourself. You know the extreme drought was replaced by extreme flood, and you may know that the world is going to get warmer. Yet you ignore the danger happily and with pride.


Pure madness.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on May 11, 2019, 03:54:31 PM
Yes, after a prolonged lull, hurricane activity returned to near average levels, neither high (alarmist), nor low (denialist).

Droughts ebb and flow.  After every drought, some alarmist proclaims they are getting worse.  Historically, droughts have been much worse.  You are confusing cowardice with accuracy.  Even the U.S. drought was not as bad as previously 20th droughts.  Recent flooding is no worse either.

Obviously, you are encouraging alarmist and further food for the denialist machine.  What is so wrong with accurate portrayal of the climate?
Title: Re: When will the Arctic Go Ice Free?
Post by: Dharma Rupa on May 11, 2019, 04:44:13 PM
Slow climate change proponents are giving the world the wrong risk assessment.

While I am not particularly interested in the alarmist/denier debate, I have to agree with this in terms of risk assessment.

The past evidence is that there can be sudden climate change, therefore in terms of risk assessment, you must plan for abrupt changes.  The slow change proponents, unless they can demonstrate a very high level of skill in their predictions, are doing society a disservice.
Title: Re: When will the Arctic Go Ice Free?
Post by: magnamentis on May 11, 2019, 05:32:29 PM
In this highly interesting interview published on May 08, 2019, Wieslaw Maslowski talks with Guy McPherson about Arctic Ice. You might recall In 2012 Maslowski published a paper projecting the arctic would be ice free in 2016 + or - 3 years.


If this doesn't happen, we might conclude Maslowski didn't have enough info of the future weather, though his projection was valid for exponential decrease of ice. We might try to add up the drops in Antarctic in the recent three years to the Arctic decrease and see how little there would be ice in Arctic if all the decrease had happened up there. SH was projected to be spared of the faster effects of CC due the higher ocean proportion and the protective function of ACC back then.

why defend or try to explain anything, he was wrong, i was wrong and many others were wrong with many of our projections (predictions) and so what, learning and keeping goin' that's it.

Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on May 11, 2019, 06:29:32 PM
The good scientist admits when he is wrong, acknowledges those who are right, learns from them, and moves on.  Scientists are often wrong.  There is nothing shameful in that, unless they try to claim they were actually right, only something else overwhelmed their rightness.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on May 11, 2019, 07:26:41 PM
Yes, after a prolonged lull, hurricane activity returned to near average levels, neither high (alarmist), nor low (denialist).

False, See attachment. After 2005 cyclonic activity in the Atlantic remained at very high levels. Lately, rapid intensification is becoming a very bad trend.

What you are doing is yet another version of "no warming since 1998".

Quote
Droughts ebb and flow.  After every drought, some alarmist proclaims they are getting worse.  Historically, droughts have been much worse.
 

Drought is tricky. A warmer world means a wetter world, but during dry days, higher temperatures hasten droughts.

I can certainly believe that droughts of the past were longer lasting and over wider areas. Climate changes much faster now so prolonged droughts may become rarer.  However, the extra warmth in the system makes drought conditions faster and in many more places. 

Quote
Recent flooding is no worse either.

 Recent flooding across the world is historic in more ways than one. Pray it subsides and doesn't get worse.  Or instead of praying you could act and demand action to stop the warming of the world and the floods that come with it.

Quote
Obviously, you are encouraging alarmist and further food for the denialist machine.  What is so wrong with accurate portrayal of the climate?

You are misrepresenting current climate conditions to fit your cowardly beliefs. I would call what you are doing lies, but apparently lies require ill intent. If you understood the danger we (yes, you included) are in you wouldn't be doing this.

Quote
The good scientist admits when he is wrong, acknowledges those who are right, learns from them, and moves on.

Yep.
Title: Re: When will the Arctic Go Ice Free?
Post by: Wherestheice on May 11, 2019, 10:17:56 PM
Lets get back on topic, If you want to create a thread for who's right Mann or McPherson please do so.
Title: Re: When will the Arctic Go Ice Free?
Post by: Reallybigbunny on May 11, 2019, 10:55:34 PM
#Tim thanks for watching the video! It was really worth watching. Plays with your preconceptions of the participants.
Title: Re: When will the Arctic Go Ice Free?
Post by: oren on May 11, 2019, 11:07:15 PM
I normally avoid watching videos of people talking, I prefer to better utilize my time reading, I find it to be much quicker and less biased. Stuff by Guy M I have read in the past led me to the conclusion that he is an unscientific alarmist, I actually prefer alarmists to lukewarmists but without science it's all just nonsense. But in any case, thanks for your summary of the video Tim. I did read it!
Title: Re: When will the Arctic Go Ice Free?
Post by: Human Habitat Index on May 12, 2019, 01:25:06 AM
I normally avoid watching videos of people talking, I prefer to better utilize my time reading, I find it to be much quicker and less biased. Stuff by Guy M I have read in the past led me to the conclusion that he is an unscientific alarmist, I actually prefer alarmists to lukewarmists but without science it's all just nonsense. But in any case, thanks for your summary of the video Tim. I did read it!

Why don't you debunk Guy M scientifically - a lot of people would appreciate it.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on May 12, 2019, 05:46:33 AM
Tim,
No, I did not watch the video, nor was I commenting about it.  Hence, your post about my presumption is way off target.  Additionally, I never mentioned hurricane frequency.  I suspect you may be referring to the graph in the post by arachimid.  Somehow you mixed up my post with others, but chose to comment on my post, based on your presumptions.
Title: Re: When will the Arctic Go Ice Free?
Post by: Shared Humanity on May 12, 2019, 02:21:15 PM
Any scientist who goes on the record that we are a decade away from human extinction will not be taken seriously by me. In fact, (adjusts tin foil cap) a purported scientist who goes on the record saying this does tremendous damage to real climate science, undermines the real threat that AGW presents to human civilization and causes me to suspect that he is actually being paid by the far right to do just this.
Title: Re: When will the Arctic Go Ice Free?
Post by: dnem on May 12, 2019, 03:39:45 PM
Any scientist who goes on the record that we are a decade away from human extinction will not be taken seriously by me. In fact, (adjusts tin foil cap) a purported scientist who goes on the record saying this does tremendous damage to real climate science, undermines the real threat that AGW presents to human civilization and causes me to suspect that he is actually being paid by the far right to do just this.

McPherson strikes me more as a deeply troubled person than a paid double agent.
Title: Re: When will the Arctic Go Ice Free?
Post by: Sterks on May 13, 2019, 01:54:46 AM
I normally avoid watching videos of people talking, I prefer to better utilize my time reading, I find it to be much quicker and less biased. Stuff by Guy M I have read in the past led me to the conclusion that he is an unscientific alarmist, I actually prefer alarmists to lukewarmists but without science it's all just nonsense. But in any case, thanks for your summary of the video Tim. I did read it!

Why don't you debunk Guy M scientifically - a lot of people would appreciate it.
I’ll do, I’ll give you the rebuttal in 2030
Title: Re: When will the Arctic Go Ice Free?
Post by: kiwichick16 on May 13, 2019, 10:55:58 AM
not sure if this is the right place but.......CO2  has hit 415 ppm at Mauna Loa for the first time ever

https://scripps.ucsd.edu/programs/keelingcurve/
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on May 13, 2019, 03:01:48 PM
I normally avoid watching videos of people talking, I prefer to better utilize my time reading, I find it to be much quicker and less biased. Stuff by Guy M I have read in the past led me to the conclusion that he is an unscientific alarmist, I actually prefer alarmists to lukewarmists but without science it's all just nonsense. But in any case, thanks for your summary of the video Tim. I did read it!

I finally took the time to watch the video.  It is longer than it needs to be.  In any case, Maslowski admitted that his projection was based on the trend from the late 1990s to 2007, which was the steepest decline in the satellite era, and which has not continued to date.  McPherson stated that the ice has leveled out after that time, and Maslowksi agreed.  Maslowski admitting that he made his projection based on too short a timeframe.  He downplayed his projection as a sound scientific tool.  He now says we can make Arctic predictions out to six months, and the Arctic will not be ice-free this year.  Maslowski stated that modeled results, with slightly tweaked parameters different experiments, show that ice thickness varies by a factor of three.  Consequently, he is hesitant to make any new ice-free projections.
Title: Re: When will the Arctic Go Ice Free?
Post by: Maven on May 13, 2019, 05:44:58 PM
  Consequently, he is hesitant to make any new ice-free projections.

He's hesitant to make any specific ice-free projections, but he does think that it will be sooner than 2030.
Title: Re: When will the Arctic Go Ice Free?
Post by: Tor Bejnar on May 14, 2019, 01:28:35 AM
Welcome, Maven, to the ASIF!
I hope you are as likeable as you are liking.  :)
Title: Re: When will the Arctic Go Ice Free?
Post by: Human Habitat Index on May 14, 2019, 03:29:37 AM
I normally avoid watching videos of people talking, I prefer to better utilize my time reading, I find it to be much quicker and less biased. Stuff by Guy M I have read in the past led me to the conclusion that he is an unscientific alarmist, I actually prefer alarmists to lukewarmists but without science it's all just nonsense. But in any case, thanks for your summary of the video Tim. I did read it!



Why don't you debunk Guy M scientifically - a lot of people would appreciate it.
I’ll do, I’ll give you the rebuttal in 2030

I'll be dead by 2030.
Title: Re: When will the Arctic Go Ice Free?
Post by: Tom_Mazanec on May 14, 2019, 01:54:22 PM
I normally avoid watching videos of people talking, I prefer to better utilize my time reading, I find it to be much quicker and less biased. Stuff by Guy M I have read in the past led me to the conclusion that he is an unscientific alarmist, I actually prefer alarmists to lukewarmists but without science it's all just nonsense. But in any case, thanks for your summary of the video Tim. I did read it!



Why don't you debunk Guy M scientifically - a lot of people would appreciate it.
I’ll do, I’ll give you the rebuttal in 2030

I'll be dead by 2030.

Why? Are you very elderly? Terminally ill? A uberdoomer?
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on May 14, 2019, 02:04:30 PM
  Consequently, he is hesitant to make any new ice-free projections.

He's hesitant to make any specific ice-free projections, but he does think that it will be sooner than 2030.

No, he never said that.  Only that it might.
Title: Re: When will the Arctic Go Ice Free?
Post by: Maven on May 14, 2019, 08:52:40 PM
@Tor - Thanks!  We will see.



  Consequently, he is hesitant to make any new ice-free projections.

He's hesitant to make any specific ice-free projections, but he does think that it will be sooner than 2030.

No, he never said that.  Only that it might.

Well, if you start from right here in the video - https://youtu.be/yoy4U7MGIdo?t=1103

Here's some of the dialogue -

Wiselaw:
"There are some publications now, peer-reviewed publications which are using the global climate and Earth system models and, uh, hand picked some of them for their better representation of the Arctic ice area and they provided the estimate of ice disappearance roughly between 2030 and 2040."

Guy:
"And what do you think about that?"

Wiselaw:
"I would still think that it might happen sooner than that but I would hesitate to provide a specific date basically because the system is so complex and so nonlinear."


¯\_(ツ)_/¯

Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on May 14, 2019, 10:00:02 PM
Exactly!  He said it might happen.
Title: Re: When will the Arctic Go Ice Free?
Post by: Maven on May 14, 2019, 11:03:53 PM
Exactly!  He said it might happen.

Wow, srsly?

At the risk of beating a dead horse -


might1
/mīt/
3.   used to express possibility or make a suggestion.
"this might be true"


I don't see why you contended with what I said initially.  He does think it might happen before 2030 which also means sooner than 2030.

IMO, leaving the word 'might' out doesn't really change the meaning of the sentence.  If 'might' was left out of what he said initially it would've been inferred anyway since he cannot absolutely know what will happen in the future.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on May 14, 2019, 11:40:11 PM
Exactly!  He said it might happen.

Wow, srsly?

At the risk of beating a dead horse -


might1
/mīt/
3.   used to express possibility or make a suggestion.
"this might be true"


I don't see why you contended with what I said initially.  He does think it might happen before 2030 which also means sooner than 2030.

IMO, leaving the word 'might' out doesn't really change the meaning of the sentence.  If 'might' was left out of what he said initially it would've been inferred anyway since he cannot absolutely know what will happen in the future.
[/
Initially, you said he thinks it will happen.  Will indicates certainty.  That is a big different from might, which [from your definition] indicates a possibility.  Inferring from the video that he thinks it will happen is quite the stretch.  Now, leave the horse alone.
Title: Re: When will the Arctic Go Ice Free?
Post by: FishOutofWater on May 15, 2019, 12:26:25 AM
A lot of less than spectacular stuff in this thread...

Global hurricane activity and energy release is tied to Pacific El Niño cycles because the western Pacific has the largest area of warm tropical and subtropical water on earth. Strong Asian monsoons cause wind shear that dampens westpac hurricane activity in the summer months. Thus is is true that global measures of hurricane energy release such as ACE do not show significant increases.

However, Atlantic hurricane energy release went way up after the 1997 El Niño. It correlates with increasing heat content in the tropical and subtropical north Atlantic basin. Some folks have theorized that the Atlantic has now gone into a cool phase of a so called cycle, but the apparent cycle was caused by aerosol cooling of the north Atlantic in the 60s and 70s. The apparent cycle is probably an artifact of that cooling episode.

As to the "slow down" in melting over the past 30 days, it happened because of the early melt out of the Pacific seas. The recent heat has melted Baffin island snow and the Labrador sea is about to go, but the central Arctic basin takes time to show the effects of unseasonable warmth.

Klondike wrote (in green):
 However, after a fast start to the melt season, the ice loss has slowed dramatically this year.  The 30-day melt is one of the lowest in the satellite data (only six years have shown less).
 
The weather developing right now is exceedingly unfavorable for sea ice and melting is going to speed up. However, I think there's too much volume to melt to get a blue ocean event this year. We could luck out again as we did in 2016 with a period of cool stormy weather in July. However, I think we will see a new record minimum because of what's going to happen over the next 2 weeks. Time will tell.
Title: Re: When will the Arctic Go Ice Free?
Post by: Human Habitat Index on May 15, 2019, 01:10:39 AM
I normally avoid watching videos of people talking, I prefer to better utilize my time reading, I find it to be much quicker and less biased. Stuff by Guy M I have read in the past led me to the conclusion that he is an unscientific alarmist, I actually prefer alarmists to lukewarmists but without science it's all just nonsense. But in any case, thanks for your summary of the video Tim. I did read it!



Why don't you debunk Guy M scientifically - a lot of people would appreciate it.
I’ll do, I’ll give you the rebuttal in 2030

I'll be dead by 2030.

Why? Are you very elderly? Terminally ill? A uberdoomer?

https://guymcpherson.com/climate-chaos/climate-change-summary-and-update/
Title: Re: When will the Arctic Go Ice Free?
Post by: Wherestheice on May 15, 2019, 01:52:27 AM
Saying the arctic will go ice free before 2030 is just as valid as saying it won’t
Title: Re: When will the Arctic Go Ice Free?
Post by: be cause on May 15, 2019, 02:13:11 AM
when the ice goes I may still be 59 ! .. b.c.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on May 15, 2019, 02:36:17 AM
Saying the arctic will go ice free before 2030 is just as valid as saying it won’t

That is because at this point, it has not happened.  So neither is right or wrong, and the no one can accurately calculate the odds.
Title: Re: When will the Arctic Go Ice Free?
Post by: b_lumenkraft on May 15, 2019, 06:42:15 AM
Schrödinger's sea ice!
Title: Re: When will the Arctic Go Ice Free?
Post by: wdmn on May 15, 2019, 06:58:21 AM
This is generally a fact about probability:

Propositions expressing probabilities have a grammar that sets the criteria
for their verification or falsification on past events. Such a proposition says
something about the current state of affairs by connecting it to past events, based
on induction. This holds whether the sentence is given as:

The weather looks like it will rain tomorrow. Or,
There’s a 70% chance of showers tomorrow.

Neither proposition says anything about the future weather (in the sense that they
can be falsified or verified by what actually happens). We are only inclined to think
they do because of the ‘surface’ grammar. The second example may be based on
specific measurements about how often rain follows a certain weather pattern,
whereas the first sentence is a more general empirical proposition.

In other words, you can be correct to say, "there's a 99% chance of rain tomorrow" even if it doesn't end up raining. The truth of your statement is based on past events (patterns) and not on what actually comes to pass.

This is what makes the IPCC, and for that matter, all model pathways, of limited value. Since our knowledge is extremely limited on these matters. It can be correct to consider something improbable even if it ends up happening. That is why ASLR is always talking about "fat tailed risk" and the precautionary principle.
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on May 15, 2019, 09:53:52 AM

In other words, you can be correct to say, "there's a 99% chance of rain tomorrow" even if it doesn't end up raining. The truth of your statement is based on past events (patterns) and not on what actually comes to pass.

This is what makes the IPCC, and for that matter, all model pathways, of limited value. Since our knowledge is extremely limited on these matters. It can be correct to consider something improbable even if it ends up happening. That is why ASLR is always talking about "fat tailed risk" and the precautionary principle.

'Correct to say' is an odd term to use in this situation when it cannot be falsified and moreover someone else might have a better model that predicts a different percentage.

A single probability percentage prediction is unfalsifyable but I used term 'better model'. This relies on testing a lot of random situations which might not be indicative of skill at the current situation so is still somewhat problematic but it might be a reasonable indication. In this sense, one model may appear better than another model. 'Correct' is likely to be unobtainable because it is always possible that someone could find some other factors to use in some currently unknown way to improve the skill of your model.

'Makes the IPCC of limited value'
Think I disagree here too, at least to some extent. There is a danger that what you said conflates chaotic weather and fairly stable climate. With chaotic weather, a better model than a random guess might be practically impossible, whereas with fairly stable boundary issue problem, progress may well be possible and using best models may well yield more reliable results. Then using the most expert models is sensible.

There is also the one prediction unfalsifyable but can test a large number of predictions to get a sense of which model is better.

Also, It is only possible to talk about 'fat tail risk' in a situation where you can compare models.


So, I am getting impression that you are implying too much from a single prediction being unfalsifyable but maybe that is me inferring too much from what you said.
Title: Re: When will the Arctic Go Ice Free?
Post by: wdmn on May 15, 2019, 01:12:13 PM
"'Correct to say' is an odd term to use in this situation when it cannot be falsified and moreover someone else might have a better model that predicts a different percentage."

Yes there is a difference. In the case of the predictions being made here, when comparing them, we are better of saying "it's more or less defensible to say."

"A single probability percentage prediction is unfalsifyable..."

That is not true. If you have a good statistical probability for an event, then your proposition is verified or falsified by those statistics. The proposition is about your reading of those statistics, and the truth or falsity of it depends on whether or not you've read them correctly.

When the predictions are based off of model projections, the best we can do is defend one or another projection, and the propositions to be assessed will be the propositions we make in defense.

We can also, of course, make statements that are verifiable or falsifiable within any given projection (or aggregate of them). Such as, "according to this (or these) model(s), the probability of such and such an event is 60%." We could also be less specific, and say something like, "according to these models the likelihood of this happening is very high." All of these propositions can be verified or falsified.

When it can be shown that our projections have left out many relevant factors, then the value of our projections goes down.

When the risks involved are very high, and the timeframes are relatively short, then using the probability distribution of one of these models, or an aggregate of these models (as is very often done when discussing pathways, say to 1.5 or 2C warming), is extremely risky.

So we have AR5 give a median ECS of 3C (you can verify this proposition), and CMIP6 (so far) give a median ECS of 4.3C. This difference is enough to suggest that most of the projected pathways to 1.5 or 2C of warming are worse than useless, since they may have resulted in us under appreciating the risks involved...

I should be clear that it was these pathways that I had in mind, though I didn't make that entirely clear.

There is greater value to lots of the other projections made by models, including those incorporated into IPCC reports.

Of course, it is also possible to say, even without any models, that the risks of rapidly altering the concentration of co2 (and other GHGs) in the atmosphere are great. And we could defend this claim well enough that it would be called "true."
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on May 15, 2019, 01:46:19 PM
"Correct to say" is a fine term, and probabilities based on mathematics is accurate.  If you flip a coin 10 times, there is a 99% probability that it will comes up heads at least once.  However, there is a finite possibility that it will not.  The outcome, in no way chances the odds, nor does it falsify them.

When talking about the weather or climate, the probabilities are a bit more nebulous.  When a forecaster gives a percentage chance of rain, it is not based on strict mathematics, but on past data.  The less data available (or factors omitted), the less reliable are the projections.  Additionally, there are unknowns that may influence the system, before the time arrives, changing the potential outcome. 
Title: Re: When will the Arctic Go Ice Free?
Post by: Tom_Mazanec on May 15, 2019, 02:01:20 PM
Human Habitat Index:
Thanks! Bookmarked article.
Title: Re: When will the Arctic Go Ice Free?
Post by: Dharma Rupa on May 16, 2019, 10:34:06 PM
...There is a danger that what you said conflates chaotic weather and fairly stable climate...

Climate is just as chaotic as weather but on a (slightly) longer timescale.
Title: Re: When will the Arctic Go Ice Free?
Post by: gerontocrat on May 18, 2019, 08:03:36 PM
NSIDC Data

A couple of graphs looking at the Arctic Central Seas only, about what melt is required for a BOE of < 1 million km2 extent. The peripheral seas are ignored as they always melt out completely to the extent as makes no difference.

Currently a BOE requires an extent loss from now of circa 7.5 million km2 compared with an average of circa 4.5 million, i.e. circa 65% above average. The most that happened was in 2012, when extent loss from now was circa 20% above average.

So a BOE currently requires a series of circumstances (tipping points?) completely outside and beyond previous experience.

____________________________________________________________
Area data gives similar results. Note that at minimum area is usually about 65% of extent. So a BOE of 1 million km2 extent might be about 0.65 million km2 area.
Title: Re: When will the Arctic Go Ice Free?
Post by: Sam on May 18, 2019, 09:03:40 PM
"Correct to say" is a fine term, and probabilities based on mathematics is accurate.  If you flip a coin 10 times, there is a 99% probability that it will comes up heads at least once.  However, there is a finite possibility that it will not.  The outcome, in no way chances the odds, nor does it falsify them.

When talking about the weather or climate, the probabilities are a bit more nebulous.  When a forecaster gives a percentage chance of rain, it is not based on strict mathematics, but on past data.  The less data available (or factors omitted), the less reliable are the projections.  Additionally, there are unknowns that may influence the system, before the time arrives, changing the potential outcome.

With a truly random system and truly even random odds, you need only flip the coin 7 times to have a >99% chance that at least one of those times would come up heads. On average in a long series of trials 1 time in about 128 the coin will come up heads only once, with all of the rest being tails.

With 10 coin flips the odds are ~ 99.93%

However - and this is a huge however - it is unfortunately common for odds to not apply at all in studies, or for the situation to not be balanced, fully known and free of external influences.

Quite often systems may behave similarly to random processes, yet not be such at all. In those cases, statistical tests and bounds may be useful, but also be wrong. They can mislead us greatly.

Chaotic systems may for a time exhibit quasi random statistical like behavior within certain bounds. Deviate slightly and the statistics may suddenly not work at all.

Some systems exhibit what appears to be statistical noise and random behavior only to exhibit wildly non-random behavior that far exceeds the statistical bounds. So-called "stiff" equations in chemical engineering behave this way. They appear stable for long periods before some small input accumulates in effects and drives wild changes in the results.

Systems with unrecognized, hidden, or ignored state changes may also exhibit either true or apparent random behavior about a mean, but with changes in the underlying conditions, or slight changes in the mean can walk across a system boundary and suddenly completely change behaviors completely outside any statistical analysis of the previous behavior to that point. These are actually quite common. Traffic jams are one such example. With minor changes in the traffic volume, a sudden state change can occur. The traffic that previous flowed in ways that could be modeled like a gas, now behaves like a liquid, or even a highly viscous liquid, or a true solid.

Many of the parameters that we routinely use also have strange behaviors in conditions away from the usual. It is common in modeling to treat collections of discrete objects as a uniform flow field of a quasi-fluid. Tensor analysis often falls victim to this flaw. The usual examples are far from the common world, but are informative.

For example, though gases behave like a quasi-fluid flow field and are easily modeled as such, and even though they exhibit properties like temperature (the kinetic energy of the particles in the fluid); when the flow conditions change to rarified conditions, the energy transfer between the discrete particles breaks down. When that happens, simple ideas like temperature are revealed not to be static values, nor vectors, nor even tensor gradients. The temperature of gases under near vacuum conditions are one such example. They become highly directional, often with little or no correlation at large angles to the main flow direction.

The assumptions and presumptions that go into building an assessment or model are critically important for understanding the limitations of the results. Far too often in my experience researchers leave these unstated, and often unknown.

These ideas are often forgotten, neglected, ignored or dismissed in examining real world systems. And that error can be at our great peril.

To quote Monty Python, "Nobody expects the Spanish Inquisition!".

With the ice loss in the Arctic, there are a large number of unknown factors and variables. The changes from year to year exhibit quasi-random behavior around a moving mean. But that is a fiction. The reality is that it is a mostly deterministic system with random variation in many parameters, and chaotic inputs of many types. These all interact to exhibit the behavior we see and that we interpret as randomness. And that is useful, even though it is wrong.

We can over short timespans extrapolate from past behavior to anticipate future likely behavior. However, it is not a truly random variation, and these variations only act and appear random. We must always bear that in mind.

Additionally, our choice of definitions play large roles in what we see. We have arbitrarily decided to define what portion of ice cover in a given area constitutes being ice covered - essentially treated as 100% ice. Our usual rule for that is that if the area in question is 15% ice covered, then we treat it as 100% ice covered.

This then leads to strange results. If we take the same large segment of ice and shatter it, moving the shattered parts away from each other, the ice area remains the same, while the extent can increase dramatically.

Here near the end of the ice, as the ice thins, we see this playing out over large areas. The extent artificially remains much higher than it would have as a comparison to ice area in decades gone by.

While it made sense to have such a rule when the only place it applied was around the edges of the ice sheet, the rule now serves to mislead us when the whole of the ice sheet is disintegrating. That misleading statistic then can lead us to erroneously project that the ice will last longer that other metrics like ice volume and thickness imply.

Sam
Title: Re: When will the Arctic Go Ice Free?
Post by: Tor Bejnar on May 18, 2019, 09:38:17 PM
Sam,
Thanks for the statistics tutorial.

Concerning the use of "extent", remote sensing can still not discern the difference between a melt pond and sea water, so even as extent gets progressively more inaccurate, there is not a lot of alternative.  At some point in time, detection of the several centimeters difference in height may become possible...
Title: Re: When will the Arctic Go Ice Free?
Post by: gerontocrat on May 18, 2019, 09:46:33 PM
Sam,
Thanks for the statistics tutorial.

Concerning the use of "extent", remote sensing can still not discern the difference between a melt pond and sea water, so even as extent gets progressively more inaccurate, there is not a lot of alternative.  At some point in time, detection of the several centimeters difference in height may become possible...
I thought IceSat2 was getting pretty close to that.

I still say, no matter what measure one uses, the chances of a BOE this year are vanishingly small.
Title: Re: When will the Arctic Go Ice Free?
Post by: magnamentis on May 18, 2019, 10:12:47 PM
Sam,
Thanks for the statistics tutorial.

Concerning the use of "extent", remote sensing can still not discern the difference between a melt pond and sea water, so even as extent gets progressively more inaccurate, there is not a lot of alternative.  At some point in time, detection of the several centimeters difference in height may become possible...
I thought IceSat2 was getting pretty close to that.

I still say, no matter what measure one uses, the chances of a BOE this year are vanishingly small.

calculating the excess energy needed to melt the estimated reminder of sea-ice, that would be around 3 million km2 +/-1 million km2 it's not that bold to say it's "IMPOSSIBLE"

after all there remain the laws of physics and as long as we exclude extraordinary events like impacting asteroids and/or (non-existent) POLAR undersea-volcanoes we can conclude the impossibility of it.
Title: Re: When will the Arctic Go Ice Free?
Post by: be cause on May 18, 2019, 10:43:13 PM
  ' vanishingly small ' and ' IMPOSSIBLE '  ?   we shall see .. b.c.
Title: Re: When will the Arctic Go Ice Free?
Post by: HapHazard on May 19, 2019, 01:18:22 AM
RE: statistics:

I always viewed statistics in a very simplistic yet accurate way:

Statistics are like bikinis: what they reveal is interesting, but what they hide is crucial.
Title: Re: When will the Arctic Go Ice Free?
Post by: Rich on May 19, 2019, 01:26:30 AM
My hunch is that there is plenty of energy available to melt the ice, but there is a barrier between the ice and the energy beneath.

If that energy can find it's way to the surface......
Title: Re: When will the Arctic Go Ice Free?
Post by: magnamentis on May 19, 2019, 01:40:31 AM
My hunch is that there is plenty of energy available to melt the ice, but there is a barrier between the ice and the energy beneath.

If that energy can find it's way to the surface......

of course there is enough energy, one could assume the earth gets a bit closer to the sun and "bingo" only that it won't happen.

it does not make sense to state the obvious that is not going to happen. there has always been enough energy on planet earth to melt all the ice, only that it did not cross the various barriers.

same now, we can assume that the oceans won't turn upside down within the next 4 months.

BTW those barriers as well are subject to the laws of physics.

it's somehow interesting how some people like to stick out by gambling on the least probable scenario and try to make it sound realistic or make all others look stupid. I think we're all aware that there is enough heat/energy in the system, be it air, water, earth core, solar system and/or the universe. the point was whether it will happen this year and the answer is no to such a high degree that i suggest that those who like to gamble play poker or black jack.

Title: Re: When will the Arctic Go Ice Free?
Post by: oren on May 19, 2019, 02:11:33 AM
Vanishingly small? Not, IMHO.
First, I dislike the use of NSIDC data for fine distinctions, when we have the much more accurate and hi-res AMSR2, especially the UH 3.125km version, and especially with Wipneus' "home brew" algorithm that gets rid of various data problems.
Second, I think extent is a poor metric for September, as 2016 showed well.
I'll define my own version of "BOE" as <1M km2 of actual sea ice, namely Wipneus' AMSR2 area. This is not ice-free in any way, but is an important milestone.
For this BOE, I estimate a probability of 5-10% per year, with the odds rising slightly with time.
The variability in the system is high. 2012 showed that beyond a doubt, going from nearly last to first in about a month. 2016 showed that GACs are not so rare. The ice state is worse than it's ever been, looking at the MYI percentages and at the grinding and breakage in the Lincoln Sea refuge.
Take any year with low starting conditions, add sunny weather in May-June-July, especially weather that increases export towards the Atlantic, and add an August GAC. The BOE could easily follow.
I am not a weather expert, but a high pressure dome could do this from what I have read here. Both export and sunny skies. And I've also read here that high pressure is coming. Will it stay? I sure don't know. Can this year reach a BOE? Not totally impossible.
I will be highly surprised if a first BOE does not happen by 2030.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on May 19, 2019, 04:00:03 AM
Thanks for the graphs Gerontocrat.

First thing I notice is how the distance between each decadal minimum increases.

The second thing I notice is how far below the 2010 decadal average is the decadal minimum.

Then in my head I imagine where the 2020s decade average will be using the increasing gaps of the first observation.

And then I imagine the decadal minimum for the 2020s to be as far down from the average as the 2010s. If I'm not mistaken there is a very likely BOE there.
Title: Re: When will the Arctic Go Ice Free?
Post by: kiwichick16 on May 19, 2019, 06:55:01 AM
IF   .....the 2020 average drops to 2million sq kms  .....and we have an  extreme loss  .....similar to 2012 ...then we could be close to 1 million  sq kms  at the minimum.

The 2020's are only 7 months away.
Title: Re: When will the Arctic Go Ice Free?
Post by: wdmn on May 19, 2019, 07:13:34 AM
Quite often systems may behave similarly to random processes, yet not be such at all. In those cases, statistical tests and bounds may be useful, but also be wrong. They can mislead us greatly.

Chaotic systems may for a time exhibit quasi random statistical like behavior within certain bounds. Deviate slightly and the statistics may suddenly not work at all.

Some systems exhibit what appears to be statistical noise and random behavior only to exhibit wildly non-random behavior that far exceeds the statistical bounds. So-called "stiff" equations in chemical engineering behave this way. They appear stable for long periods before some small input accumulates in effects and drives wild changes in the results.

Systems with unrecognized, hidden, or ignored state changes may also exhibit either true or apparent random behavior about a mean, but with changes in the underlying conditions, or slight changes in the mean can walk across a system boundary and suddenly completely change behaviors completely outside any statistical analysis of the previous behavior to that point.

Thank you Sam for giving a detailed, expert explanation of what I could only generally describe.

My point -- which KK was in part responding to -- was that any probability, whether of coin flips or of "chaotic systems," can only legitimately be based on observed frequencies. That means that they can only be verified or refuted by reference to past observations (and the assumptions/presumptions that go with them).

But what does this mean for "chaotic systems?" It means that assigning numerical probabilities is dangerous and imprudent, precisely because it gives the appearance that we know more than we do. So, as I stated previously, I think that many of the pathways laid out for limiting warming are less than useless. They would be useless if they were so shrouded in uncertainty as to not give much direction in determining what to expect. They are worse than useless when this holds, and there is an extreme amount of risk should we end up being wrong, which the assigned probabilities cause us to not properly appreciate. It is even worse when we use models which give us the appearance of a statistical record, but are not actually based on observations, and so are not observed frequencies at all, but merely the figure of our assumptions being traced over and over again.

To me, this is the meaning of the precautionary principle. When we really don't know how things will play out, when we know that we have an incomplete picture about something with significant consequences, but we choose to assign a numerical probability that masks this uncertainty, we expose ourselves unnecessarily.

Without bashing any climate scientists too much, it is clear that the really capable ones appreciate this. James Hansen, for example, has been warning for a long time that are better to act sooner rather than later, because we don't properly understand all of the feedbacks (positive and negative), or ECS very well. Moreover, there's enough observational data (from the paleoclimate records) to suggest that what we have been doing with our emissions is potentially very dangerous. Early results from CMIP6 runs are now telling us that what we thought were pathways to 2C of warming over preindustrial, are likely insufficient.

I quote a recent study to support this:

“The massive analysis shows that meeting the 2C target is exceptionally difficult in all but the most optimistic climate scenarios. One pathway is to immediately and aggressively pursue carbon-neutral energy production by 2030 and hope that the atmosphere’s sensitivity to carbon emissions is relatively low, according to the study. If climate sensitivity is not low, the window to a tolerable future narrows and in some scenarios, may already be closed.

... If the climate sensitivity is greater than 3 Kelvin (median of assumed distribution), the pathway to a tolerable future is likely already closed.”

Source: https://phys.org/news/2019-03-pathways-climate-future-action.html

Given that the median value from the early results of CMIP6 runs is 4.3C we could be in a lot of trouble.

Forgive me where I am wrong. I've studied probability from a philosophical perspective, but am definitely not a statistician or even very good at maths.
Title: Re: When will the Arctic Go Ice Free?
Post by: Aluminium on May 19, 2019, 07:49:35 AM
after all there remain the laws of physics and as long as we exclude extraordinary events like impacting asteroids
How big should an asteroid be?
(https://pp.userapi.com/c845321/v845321893/20e947/Ey5TD7G5duc.jpg)
Title: Re: When will the Arctic Go Ice Free?
Post by: Shared Humanity on May 19, 2019, 02:14:56 PM
Can this year reach a BOE? Not totally impossible.
I will be highly surprised if a first BOE does not happen by 2030.

And even if we do not reach a true BOE before 2030, there will be little difference between a minimum of 1.8 M km2 vs. < 1.0 M km2 when we consider the impact it will have on climate.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on May 19, 2019, 02:20:25 PM
+1 SH
Title: Re: When will the Arctic Go Ice Free?
Post by: miki on May 19, 2019, 06:38:26 PM
+2 SH  ;)
Title: Re: When will the Arctic Go Ice Free?
Post by: magnamentis on May 19, 2019, 06:48:24 PM
Can this year reach a BOE? Not totally impossible.
I will be highly surprised if a first BOE does not happen by 2030.

And even if we do not reach a true BOE before 2030, there will be little difference between a minimum of 1.8 M km2 vs. < 1.0 M km2 when we consider the impact it will have on climate.

good point and has to be mentioned from time to time to bring talks back to what really matters.
Title: Re: When will the Arctic Go Ice Free?
Post by: Rich on May 19, 2019, 06:54:46 PM
Are people underappreciating the consequences of a BOE?

My understanding is that it takes 70-80x as much energy to convert a g of water from me ice to liquid as it does to raise the temp of water 1C.  When the ice is melted, we lose a buffer for more rapid heating. We also lose albedo. These are two important positive feedback effects associated with declining ice, no?
Title: Re: When will the Arctic Go Ice Free?
Post by: b_lumenkraft on May 19, 2019, 07:09:42 PM
Are people underappreciating the consequences of a BOE?

Yes. The mainstream does. This is why we are in this mess. If people would understand what's happening there, we'd have a carbon tax for 30 years.
Title: Re: When will the Arctic Go Ice Free?
Post by: Sam on May 19, 2019, 07:17:34 PM
Wdmn,

I believe you have it exactly correct.

The IPCC has begun hedging all of its analyses by using probabilities of success, and accepting lower probabilities precisely to avoid the most draconian actions required to avoid calamity. In doing so they forget or neglect several things, including:

1) how much we do not know
2) the time lags in the system
3) how humans react to directly sensed impacts and very poorly to delayed impacts
4) the chaotic nature of the systems
5) the severe consequences of step changes in physical behavior, points of no return, ...
6) how horrible people are at understanding probability and consequences, and reacting to those
7) just how hard it is to take large actions, how slow they are to start, and how slow they are to cause meaningful change
8 ) how resistant people are to sacrifice (no one wants to give up their toys)
9) how dependent society is on growth (even brief periods of stagnation, let alone negative growth, lead to problems, and negative growth of any significance leads to societal collapse)
10) the practical impossibility of achieving and sustaining the negative growth rates required to meet targets of less than 4 degrees C increase in temperature
11) people’s unwillingness to shrink population size, and in fact the in built bias reinforced in all societies and religions to expand population to out populate the “others” thereby winning by head count, and having the bodies needed to do war on the “others” to win in the battles of belief.
11) etc...

Number 10 is particularly troubling. If we consider what flat or negative growth has done to previous societies and civilizations, and use that as a guide to what we can do, it is hard to escape the conclusion that we have already lost the war in its entirety.

It is certainly possible to use renewables to do this. The Netherlands is a case example of success.  That is a slow process. And it has serious limits and problems that must be overcome. Many of these problems require societal changes to succeed, e.g. distributed power, high energetic efficiency in design, low waste, working near home, minimal travel, growing our food near where we each live, undoing much of the industrial revolution, ...  These are things people are highly resistant to surrendering.

Much of our population has little to no grasp on the importance of the wild world in maintaining the stability of the earths systems. They view population growth as an inherent good, and the wilds as just something to consume. Until we stand shoulder to shoulder unable to move, they cannot see a problem.

And all of these combined take us to an ice free earth in short order, with an ice free arctic being the first and most immediate hallmark.

The denial built into our societal and belief structures, our desire for a better life in the near term, with little or no understanding of the long term consequences, and almost no willingness to fight against the short sighted myopic financial interests that drive us to ruin in the near term, let alone the long term, lead us inexorably to a hothouse earth and to a very early ice free arctic.

Sam
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on May 19, 2019, 07:19:12 PM
Quote
These are two important positive feedback effects associated with declining ice, no?

Just think about it for a bit. The consequences are scary as hell. Unbelievable. If you speak of the consequences of such an event you will be called a madman. It is better to pretend that is not going to happen.
Title: Re: When will the Arctic Go Ice Free?
Post by: Aluminium on May 19, 2019, 07:47:59 PM
About albedo effect of BOE.
3.0 M km2, 102 W/m2, 107 s (~4 months of sunshine in year). This is enough to melt 9000 Gt per year. Currently, the volume loss is only about 400 km3 (~400 Gt) per year.
Title: Re: When will the Arctic Go Ice Free?
Post by: magnamentis on May 19, 2019, 07:57:09 PM
Wdmn,

I believe you have it exactly correct.

The IPCC has begun hedging all of its analyses by using probabilities of success, and accepting lower probabilities precisely to avoid the most draconian actions required to avoid calamity. In doing so they forget or neglect several things, including:

1) how much we do not know
2) the time lags in the system
3) how humans react to directly sensed impacts and very poorly to delayed impacts
4) the chaotic nature of the systems
5) the severe consequences of step changes in physical behavior, points of no return, ...
6) how horrible people are at understanding probability and consequences, and reacting to those
7) just how hard it is to take large actions, how slow they are to start, and how slow they are to cause meaningful change
8 ) how resistant people are to sacrifice (no one wants to give up their toys)
9) how dependent society is on growth (even brief periods of stagnation, let alone negative growth, lead to problems, and negative growth of any significance leads to societal collapse)
10) the practical impossibility of achieving and sustaining the negative growth rates required to meet targets of less than 4 degrees C increase in temperature
11) people’s unwillingness to shrink population size, and in fact the in built bias reinforced in all societies and religions to expand population to out populate the “others” thereby winning by head count, and having the bodies needed to do war on the “others” to win in the battles of belief.
11) etc...

Number 10 is particularly troubling. If we consider what flat or negative growth has done to previous societies and civilizations, and use that as a guide to what we can do, it is hard to escape the conclusion that we have already lost the war in its entirety.

It is certainly possible to use renewables to do this. The Netherlands is a case example of success.  That is a slow process. And it has serious limits and problems that must be overcome. Many of these problems require societal changes to succeed, e.g. distributed power, high energetic efficiency in design, low waste, working near home, minimal travel, growing our food near where we each live, undoing much of the industrial revolution, ...  These are things people are highly resistant to surrendering.

Much of our population has little to no grasp on the importance of the wild world in maintaining the stability of the earths systems. They view population growth as an inherent good, and the wilds as just something to consume. Until we stand shoulder to shoulder unable to move, they cannot see a problem.

And all of these combined take us to an ice free earth in short order, with an ice free arctic being the first and most immediate hallmark.

The denial built into our societal and belief structures, our desire for a better life in the near term, with little or no understanding of the long term consequences, and almost no willingness to fight against the short sighted myopic financial interests that drive us to ruin in the near term, let alone the long term, lead us inexorably to a hothouse earth and to a very early ice free arctic.

Sam

your list tell the entire story and makes it obvious where we are heading without a feasible way out.

also whoever is talking about human extinction, it won't be temps, storms or any of the natural impacts but it will be the consequences of forces measures as of paragraph 10 that have the potential to cause extinction of humanity.

in fact i prefer the term "drastic decimation" over extinction because i'm quite sure that there are places like those medium high and medium latitudes as well as surrounded by mountains that will allow a few to survive even most of the worst case scenarious.

before getting to much OT and distracted here just wanted to submit my kudos for the
list where one can find > 90% of what this is all about.
Title: Re: When will the Arctic Go Ice Free?
Post by: Ktb on May 20, 2019, 07:45:38 AM
NSIDC Data

A couple of graphs looking at the Arctic Central Seas only, about what melt is required for a BOE of < 1 million km2 extent. The peripheral seas are ignored as they always melt out completely to the extent as makes no difference.

Currently a BOE requires an extent loss from now of circa 7.5 million km2 compared with an average of circa 4.5 million, i.e. circa 65% above average. The most that happened was in 2012, when extent loss from now was circa 20% above average.

So a BOE currently requires a series of circumstances (tipping points?) completely outside and beyond previous experience.

____________________________________________________________
Area data gives similar results. Note that at minimum area is usually about 65% of extent. So a BOE of 1 million km2 extent might be about 0.65 million km2 area.



And this is why I began maintaining a BOE spreadsheet. I just don't think people realize how amazing a BOE year will have to be.
If we started doing daily drops to actually be on pace (averaging 88,232 km^2 per day), we would have the 2nd strongest may melt, the strongest June melt, an average July, the strongest August, and the strongest September to minimum.

2012 didn't even have the strongest July melt, averaging -91,753 km^2 per day, making it 5th place in the years 2007-2018.

That being said, I still voted for 2020-2025. We can't dodge cannonballs forever, and one year everything is going to line up just perfectly.
Title: Re: When will the Arctic Go Ice Free?
Post by: dnem on May 20, 2019, 02:26:18 PM
Are people underappreciating the consequences of a BOE?

My understanding is that it takes 70-80x as much energy to convert a g of water from me ice to liquid as it does to raise the temp of water 1C.  When the ice is melted, we lose a buffer for more rapid heating. We also lose albedo. These are two important positive feedback effects associated with declining ice, no?

Certainly true Rich, but when we first get to a BOE it will be at the very end of the melt season.  Some of that summer's energy will still have gone into overcoming the heat of fusion of melting the ice, and the albedo loss will be cumulative over the season and only reaching its maximum at the end.  And then the arctic night will come and there will be refreezing.  So it isn't quite right to think that once we get there, we'll be in a system with no ice to melt and no cover to reflect sunlight.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on May 20, 2019, 02:55:31 PM
I would like to comment on the precautionary principle, because it has been used quite often when discussing climate changes.  While this pathway is based on sound reasoning, it may not be the best approach.  This principle would actually prevent more action, than it would encourage.  While many view this as a positive step (preventing negative outcomes), it can also be viewed negatively (preventing positive outcomes).  The precautionary principle would block risky ventures, because they are not proven to be safe.  This contrasts normal human behavior, which tends to encourage behavior, until proven unsafe.  This is precisely how the EPA, OSHA, and other regulatory agencies operate.  Most inventors, explorers, and scientists in general, operate opposite to the precautionary principle.  Would  clinical trials ever exist, if medical practitioners followed this principle?  Would man have ever set foot on the moon, if NASA had followed this principle? 

As Sam said, "Many of the parameters that we routinely use also have strange behaviors in conditions away from the usual."  The only way to know for sure, is to test them.  This is where scientists tend to deviate from the average person.  The average person like to remain in their safe "known" environment, whereas the scientists is pushing the boundaries to new areas.  Sometimes they succeed, sometimes they fail.  Some make great discoveries (Marie Curie) only to succumb to the perils of their discovery.  Civilization would not be where it is today, if people of the past followed the precautionary principle.  Some view this as the best, others the worst.  Consider this:  when combating climate change, should we implement new technologies, before they are proven safe, or should we try them in the hopes of making grand changes? 

Research is a way of taking calculated risks to bring about incalculable consequences.
— Celia Green
Title: Re: When will the Arctic Go Ice Free?
Post by: SteveMDFP on May 20, 2019, 03:14:23 PM
I would like to comment on the precautionary principle, because it has been used quite often when discussing climate changes.  While this pathway is based on sound reasoning, it may not be the best approach.  This principle would actually prevent more action, than it would encourage.  While many view this as a positive step (preventing negative outcomes), it can also be viewed negatively (preventing positive outcomes).  The precautionary principle would block risky ventures, because they are not proven to be safe...

A thoughtful post, for which I'd offer a moderately contrasting perspective.
There may be some benefit in presenting a definition and discussion of what the Precautionary Principle entails:

The precautionary principle in environmental science.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1240435/ (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1240435/)

" The precautionary principle, proposed as a new guideline in environmental decision making, has four central components: taking preventive action in the face of uncertainty; shifting the burden of proof to the proponents of an activity; exploring a wide range of alternatives to possibly harmful actions; and increasing public participation in decision making..."
_____________________________________________

The difficulty may be less in the Precautionary Principle than how to apply it to societal decision-making.  I'd emphasize "taking preventive action in the face of uncertainty."  That is, if continuing BAU carries even a small risk of catastrophic consequences, such preventive action is necessary.  This wouldn't imply avoiding actions that might be beneficial, rather the opposite.

There's also the matter of what constitutes "action" or "activity."  Continuing the status quo must be considered an action.  The proposal to, say, burn another gigaton of fossil fuels should be weighed against whether to build a megawatt of solar power.  The solar power array shouldn't be viewed as the only "action" or "activity" in this choice.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on May 20, 2019, 03:28:41 PM
dnem makes an extremely important point.

The first BOE very likely happens in September. At that point, the power of the Sun over the Arctic is minimal. Let's start there.

Let's imagine a situation where the last few million square kilometers of ice poof out of existence creating the first BOE. Let's suppose that the thermodynamic balance of the arctic switches from Melt to Freeze at the instant the BOE happens. No heat accumulated in the atmosphere or the oceans. No enthalphy considerations. The freezing season begins.

What happens next?  The maximum volume of ice that the Arctic has created in a Freezing season is 19.66 (1000 km3). If the year after the first BOE the Arctic creates the maximum volume on record, then max volume in April will be 19.66 of thin, one year ice. The average Melt from 2006 to 2018 was 17.89, but included thick ice. The maximum let on record was 19.69, more than the Maximum gain.

 If everything stayed the same, it is very likely that the year following the first BOE is followed by another  BOE that happens earlier. Then you start the freezing season with negative ice, ending the following the freezing season with even less ice setting up the Arctic for another even earlier BOE.

This cycle will not go on for long before sea ice is gone by June and the northern hemisphere is a different world.
Title: Re: When will the Arctic Go Ice Free?
Post by: SteveMDFP on May 20, 2019, 03:40:34 PM
dnem makes an extremely important point.

The first BOE very likely happens in September. At that point, the power of the Sun over the Arctic is minimal. Let's start there.
...
If the year after the first BOE the Arctic creates the maximum volume on record, then max volume in April will be 19.66 of thin, one year ice. The average Melt from 2006 to 2018 was 17.89, but included thick ice. The maximum let on record was 19.69, more than the Maximum gain.

 If everything stayed the same, it is very likely that the year following the first BOE is followed by another 

A reasonable interpretation.  However, we shouldn't ignore a major negative feedback (against all the worrisome positive feedbacks).  A BOE leaves the arctic with vast open expanses of bare water going into the arctic night.  Open ocean radiates far more heat out into space during the night than ocean covered with ice and snow as an insulator.  I really would expect above-record refreezing after a BOE.  Enough to preclude a subsequent repeat BOE?  I don't know.   
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on May 20, 2019, 05:20:12 PM
I would like to comment on the precautionary principle, because it has been used quite often when discussing climate changes.  While this pathway is based on sound reasoning, it may not be the best approach.  This principle would actually prevent more action, than it would encourage.  While many view this as a positive step (preventing negative outcomes), it can also be viewed negatively (preventing positive outcomes).  The precautionary principle would block risky ventures, because they are not proven to be safe...

A thoughtful post, for which I'd offer a moderately contrasting perspective.
There may be some benefit in presenting a definition and discussion of what the Precautionary Principle entails:

The precautionary principle in environmental science.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1240435/ (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1240435/)

" The precautionary principle, proposed as a new guideline in environmental decision making, has four central components: taking preventive action in the face of uncertainty; shifting the burden of proof to the proponents of an activity; exploring a wide range of alternatives to possibly harmful actions; and increasing public participation in decision making..."
_____________________________________________

The difficulty may be less in the Precautionary Principle than how to apply it to societal decision-making.  I'd emphasize "taking preventive action in the face of uncertainty."  That is, if continuing BAU carries even a small risk of catastrophic consequences, such preventive action is necessary.  This wouldn't imply avoiding actions that might be beneficial, rather the opposite.

There's also the matter of what constitutes "action" or "activity."  Continuing the status quo must be considered an action.  The proposal to, say, burn another gigaton of fossil fuels should be weighed against whether to build a megawatt of solar power.  The solar power array shouldn't be viewed as the only "action" or "activity" in this choice.

That is true.  Perhaps I should have said something along the lines of new or novel activity.  Continuing the status quo is, of course, an action.  However, I would consider it more of a known action, even if the future has some unknowns attached.  That is why I mention that many people prefer to stay in their safe, known environments, rather than venture into something new.  Hence, I view maintaining the status quo of more an inaction, as nothing really changes.
Title: Re: When will the Arctic Go Ice Free?
Post by: GoSouthYoungins on May 20, 2019, 06:11:50 PM
A BOE leaves the arctic with vast open expanses of bare water going into the arctic night.  Open ocean radiates far more heat out into space during the night than ocean covered with ice and snow as an insulator.  I really would expect above-record refreezing after a BOE.  Enough to preclude a subsequent repeat BOE?  I don't know.

I think you are getting your wires crossed a bit here.  Heat can only get spaced into the black night if there is no ice. So once there is a thin layer of ice, the insulation begins. Thus it is impossible to get more ice from having less ice. (If you are only talking about extent increase from the minimum, I agree.)

The rate of refreeze would be epic. In a few weeks almost the entire arctic basin would be covered with ice. There would be parts of the Chukchi Sea that may not refreeze, and refreeze in the Bering would likely be minimal. Meanwhile, the Bering Strait will almost certainly freeze due to its proximity to very cold land.

The real problems start the year after a BOE. The thin ice will melt out in much of the arctic by the solstice. July and August would see incredible amounts of heat sunk into the ocean. That fall refreeze would be many weeks delayed, and the ice layer that forms would be substantially inferior to typical first year ice. The next summer much of the basin is ice free by June causing refreeze to be many more weeks delayed.

Archimid is correct: once a BOE occurs, the rate of change increases. And before long there is only winter and spring ice. What ice forms in the arctic night a decade or two after the first BOE is way to complicated to really even hypothesis at currently.
Title: Re: When will the Arctic Go Ice Free?
Post by: Tom_Mazanec on May 20, 2019, 07:01:36 PM
Was there a BOE in the Eemian? Maybe that will give us a clue as to what the consequences will be.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on May 22, 2019, 03:44:51 PM
A reasonable interpretation.  However, we shouldn't ignore a major negative feedback (against all the worrisome positive feedbacks).

I was attempting to ignore all possible positive or negative feedbacks to establish a statistical baseline. The baseline is what will happen if the system stays about the same.

I find it extremely unlikely that the system stays about the same. If the system changes then adding the sum of positive and negative feedbacks and forcings to the Maximum volume for the year that follows the first BOE.   

I'll try to address the feedbacks you mention.


Quote
A BOE leaves the arctic with vast open expanses of bare water going into the arctic night.

Correct. This vast expanse of water will warm while there is sunlight and cool when there isn't. In an attempt to ignore feedback and simplify analysis, I'm assuming that when the first BOE happens, the last of the heat will be used melting the last of the ice, thus water is as close to freezing temperature as possible. 


Quote
  Open ocean radiates far more heat out into space during the night than ocean covered with ice and snow as an insulator.

Heat is radiated into the atmosphere first, some of it interacts with gasses and water and the rest goes out into space.

Heat also escapes by convection into the atmosphere.

This means that all else being equal, because the atmosphere above the ocean is exposed to more radiation and convection the atmosphere will be warmer. This means that there will be a delay of freezing until the heat of the atmosphere can be dissipated. Thus freezing is delayed until that heat is dissipated.

How long it will take to dissipate that heat?

I don't know. I hope that 2016 DMI N80 is not an example, but I believe it is.
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fplots%2FmeanTarchive%2FmeanT_2016.png&hash=ed3bc1964e488b5d83cfae05c243a1bc)

It may takes weeks to dissipate enough heat from the lower atmosphere of the arctic before the sheer darkness of the Arctic night takes over. Add abundant clouds from the newly opened ocean and things get worse.

Quote
  I really would expect above-record refreezing after a BOE.  Enough to preclude a subsequent repeat BOE?  I don't know.

I also expect a record volume gain after the first BOE. Once the heat is dissipated (ignore the effects of waves and salinity)  freezing will begin with a vengeance, particularly in the Volume metric. Thin ice thickens extremely fast relative to thick ice. However I also expect the ocean opened for a lot longer, clouds hanging around a lot longer and a warm winter. Come April the ice will be weak and warm. Barely anything above 2m.

What might help the year after the first BOE is the snow.  I expect the continents to be hammered by snow in extraordinary ways, and that may lead to a mild melting season.
Title: Re: When will the Arctic Go Ice Free?
Post by: Tom_Mazanec on May 22, 2019, 04:18:22 PM
Of course, the important date is not first BOE, but when it becomes inevitable. That is almost certainly past.
Title: Re: When will the Arctic Go Ice Free?
Post by: Dharma Rupa on May 22, 2019, 04:47:40 PM
Of course, the important date is not first BOE, but when it becomes inevitable. That is almost certainly past.

I'm of the belief that date passed over 100 years ago.  This belief does not make me popular.
Title: Re: When will the Arctic Go Ice Free?
Post by: Rich on May 22, 2019, 06:13:21 PM

Of course, the important date is not first BOE, but when it becomes inevitable. That is almost certainly past.

I'm of the belief that date passed over 100 years ago.  This belief does not make me popular.
[/quote]

Don't sweat it. Popularity is overrated.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on May 22, 2019, 06:22:29 PM
Nothing is inevitable, except death and taxes  - Ben Franklin.
Title: Re: When will the Arctic Go Ice Free?
Post by: magnamentis on May 23, 2019, 03:48:39 AM
Nothing is inevitable, except death and taxes  - Ben Franklin.

totally not true, there are point of no returns even for things that have once been avoidable but are not anymore after a certain momentum in relation to the inertia of a given system has been reached.

Title: Re: When will the Arctic Go Ice Free?
Post by: Tom_Mazanec on May 23, 2019, 02:23:04 PM
Maybe it will be unlucky Friday the 13th in September? ;D
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on May 23, 2019, 04:59:00 PM
Nothing is inevitable, except death and taxes  - Ben Franklin.

totally not true, there are point of no returns even for things that have once been avoidable but are not anymore after a certain momentum in relation to the inertia of a given system has been reached.

If you are referring to the Arctic, there is no point of no return.  Even if we attain a BOE condition, the Arctic will re-freeze (and glaciers expand), if temperatures dictate such.  This is simple physics.
Title: Re: When will the Arctic Go Ice Free?
Post by: magnamentis on May 23, 2019, 06:07:57 PM
Nothing is inevitable, except death and taxes  - Ben Franklin.

totally not true, there are point of no returns even for things that have once been avoidable but are not anymore after a certain momentum in relation to the inertia of a given system has been reached.

If you are referring to the Arctic, there is no point of no return.  Even if we attain a BOE condition, the Arctic will re-freeze (and glaciers expand), if temperatures dictate such.  This is simple physics.

i refer to what you referred and then a return path that would exceed the live span of several generation and/or take longer than mankind exists is NOT a turnaround that deserves that term.

matter of factly, yes, there can be a next ice-age, we cannot discard the possibility, but it's obvious that this is now what is meant with "point of no return" it means that if we reduce pollution to zero today, that we probably won't live to see that turn-around and if the planet shall recover once we're extinct that was not the point that is discussed in the context of reverting the process be free will and human action or literally lack of action ;)

BTW i'm in the 2020-20125 ballpark while 2020-2030 would have been my favourite choice because it's almost impossible to make an educated guess that is more accurate than a decade.
Title: Re: When will the Arctic Go Ice Free?
Post by: Rich on May 23, 2019, 07:32:21 PM
Nothing is inevitable, except death and taxes  - Ben Franklin.

totally not true, there are point of no returns even for things that have once been avoidable but are not anymore after a certain momentum in relation to the inertia of a given system has been reached.

If you are referring to the Arctic, there is no point of no return.  Even if we attain a BOE condition, the Arctic will re-freeze (and glaciers expand), if temperatures dictate such.  This is simple physics.

I think it"s pretty clear that this thread is about predicting the next BOE. No one is suggesting that the next BOE will be the last one the earth will ever experience.

What's your prediction regarding the next BOE?
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on May 23, 2019, 08:04:27 PM
Nothing is inevitable, except death and taxes  - Ben Franklin.

totally not true, there are point of no returns even for things that have once been avoidable but are not anymore after a certain momentum in relation to the inertia of a given system has been reached.

I am one of the two that chose 2041-60.

If you are referring to the Arctic, there is no point of no return.  Even if we attain a BOE condition, the Arctic will re-freeze (and glaciers expand), if temperatures dictate such.  This is simple physics.

I think it"s pretty clear that this thread is about predicting the next BOE. No one is suggesting that the next BOE will be the last one the earth will ever experience.

What's your prediction regarding the next BOE?
Title: Re: When will the Arctic Go Ice Free?
Post by: ArcticMelt2 on May 24, 2019, 03:43:09 AM
This will be a disaster for polar bears. They will not be able to escape in Canada and Greenland, and all will drown near the North pole.

 :D

That's not going to happen. But there is no way that Arctic sea ice loss will be good for polar bears.

Why do you think this is unlikely? You wrote last year how the Northern shores of Greenland were cleared of ice at the end of August. It is obvious that there is a high probability that polar bears will fall into the ice trap in the Central Arctic and die.

google how far and how long polar bears can and do swim, even when they don't necessarily have to, you'll be surprised and know why this won't happen the way you describe.

neven's take on this is as spot on as it can get. bad for the bears but they won't drown in numbers.

Bears will be able to swim hundreds and thousands of kilometers, even in conditions of multimeter waves?

After all, most likely the complete melting of ice in the Arctic will happen after a powerful cyclone, like those that happened in August 2012 and 2016.

In such conditions, bears trapped will have very little chance of escape. It should be understood that only with warming in the Arctic increases the height of the waves, to which the bears will not have time to adapt.
Title: Re: When will the Arctic Go Ice Free?
Post by: ArcticMelt2 on May 24, 2019, 05:02:28 AM
When a bear swims, its head protrudes only 10 cm.

(https://secure.i.telegraph.co.uk/multimedia/archive/01810/Polarbear_1810939c.jpg)

In a strong storm, it is corny to choke.
Title: Re: When will the Arctic Go Ice Free?
Post by: oren on May 24, 2019, 09:02:12 AM
It would be best to move the polar bear discussions to the "effects on Arctic wildlife" thread.
Title: Re: When will the Arctic Go Ice Free?
Post by: be cause on May 24, 2019, 10:42:41 AM
answer to the original question .. in about 4 months .. b.c.
Title: Re: When will the Arctic Go Ice Free?
Post by: magnamentis on May 24, 2019, 02:46:22 PM
When a bear swims, its head protrudes only 10 cm.

(https://secure.i.telegraph.co.uk/multimedia/archive/01810/Polarbear_1810939c.jpg)

In a strong storm, it is corny to choke.

since the ice he stands on won't disappear withing a few hours he shall choose the moment to begin his journey carefully.

i feel it, that you have a point and wand recognition and if i do others do as well and others don't but either way it can become annoying.

what's next, after the storm argument?  the sun blinding him or anything of that kind.

fact is that all this sounded from the beginning like if we would gonna face a mass drowning which we most probably won't for the said reasons and everything is instisting blahhh... to be right.

there are many enough real catastrophies at hand, you can freely choose among them. exagerations have never been helpful to make a point LASTING.

short term effects can be achieved among the sheep but then once it doesn't happen the storm sawn is blowing back into the seeder's faces. backfiring for the cose so to say.

yes, the p'bears are at risk and they are losing out on space to feed and to procreate but they won't drown in masses for the reasons you stated because the reason won't happen that way any time soon and the effect won't be as you suggest.

over and out
Title: Re: When will the Arctic Go Ice Free?
Post by: Shared Humanity on May 24, 2019, 07:21:45 PM
Can we please stay on topic?
Title: Re: When will the Arctic Go Ice Free?
Post by: HapHazard on May 24, 2019, 08:46:07 PM
Can we please stay on topic?
No, everyone needs to have the last word first.  ::)
Title: Re: When will the Arctic Go Ice Free?
Post by: b_lumenkraft on June 02, 2019, 04:23:14 PM
For clarification, the header of the sea ice area chart indicates it's a 5 day moving average.

Since the loss reported for the day is 69k, up from the previous day of 60k, I'm inferring that the latest day total added to the 5 days average is 45k greater loss than the day that dropped out.

69*5 = 345
60*5 = 300

When comparing today's extent loss of 97k to today's area loss of 69k, I'd guess we need to factor in different techniques for measuring as well as a 5 day vs. 1 day measurement period.


Rich, can you talk about the numbers in this thread, please? Thank you.
Title: Re: When will the Arctic Go Ice Free?
Post by: gerontocrat on June 03, 2019, 03:02:17 PM
Tealight prompted me to do some extra work on the High Arctic (the 7 central seas), as that is where ice-free will happen last. (It was his stupendous work on Alebo Warming Potential that was the trigger).

So I updated my open-water graphs to add a "high arctic" trend graph.. I attach 2 graphs, on for the high arctic and one for the total Arctic.

The High Arctic graph shows that even at the peak of the melting season, open water only reached 50% by the year 2000, and also that these seas are still an icy desert in Winter, barely touched by global heating.

It is graphs like these that reinforce my conviction that:-
- decline in Arctic Sea Ice is remorseless and inevitable,
- the BOE is still a few years away,
- when a BOE arrives may be a function more of volume loss.

So I still plump for a BOE before 2030, but perhaps at the end of the 2020s.
Title: Re: When will the Arctic Go Ice Free?
Post by: binntho on June 03, 2019, 03:33:21 PM
(It was his stupebdous work on Alebo Warming Potential that was the trigger).

Checking if we're awake? I am, and I agree with your other points.
Title: Re: When will the Arctic Go Ice Free?
Post by: Tom_Mazanec on June 03, 2019, 04:37:56 PM
I joined too late to vote, but I think the most likely time is early Twenties.
Title: Re: When will the Arctic Go Ice Free?
Post by: b_lumenkraft on June 03, 2019, 04:42:44 PM
Joined too late too. :/

Would have voted the early 20s.
Title: Re: When will the Arctic Go Ice Free?
Post by: dnem on June 03, 2019, 06:16:54 PM
I would not be surprised if we have a year soon (any year including this year) where the numbers still say 2-3 million sq km at the end of the melt season, but the condition of the ice - fragmented, slushy, dispersed and mobile - is qualitatively unlike anything in the satellite record.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on June 03, 2019, 09:13:24 PM
Inspired by Gerontocrat's insightful graphs, I decided to see what the lines look like for the "High Seas"  in PIOMAS.

Edit: True to form the previously posted graphs only included 6 seas ( I mistakenly excluded the Kara sea). Then calamity happened and I lost all the formulas. Got to do it again... My apologies.

Edit: Fixed. the 7 seas are included.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on June 04, 2019, 03:25:39 PM
Nice graphs.  However, I question your trend lines.  Both the max and min were decreasing fairly constantly for the first decade.  However, both max and min have been flat over the past decade.
Title: Re: When will the Arctic Go Ice Free?
Post by: binntho on June 04, 2019, 04:57:00 PM
Nice graphs.  However, I question your trend lines.  Both the max and min were decreasing fairly constantly for the first decade.  However, both max and min have been flat over the past decade.

Max certainly hasn't been flat over the last decade, seems to be following the trendline pretty faithfully. And besides, trendlines are what trendlines do - and I doubt very much whether the difference between the last decade and the previous two is in any way statistically significant.
Title: Re: When will the Arctic Go Ice Free?
Post by: Shared Humanity on June 04, 2019, 04:59:09 PM
Nice graphs.  However, I question your trend lines.  Both the max and min were decreasing fairly constantly for the first decade.  However, both max and min have been flat over the past decade.

This is consistent with the observation made by Crandles that there was a state change in 2010 when the Arctic lost a ton of volume (the thickest ice) which was not fully reflected in the extent numbers. Since 2010 we have been in a relatively static condition where FYI is created each freeze season and melts out each melt season.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on June 05, 2019, 04:27:42 AM
This is very likely the same cherry as "No warming since 1998!" or the hiatus, but because the next state change hasn't happened I will do it.  All that needs to happen for this line to come true is that in a warming world Arctic ice doesn't melt faster. It could happen, but I wouldn't bet the fate of our civilization on it.

The state change can be appreciated on attachment one. From 2000-2012 the Loss to Max ratio increased almost monotonically, then after 2012 the Loss to Max Ratio flattens. I drew a 6 year moving average that shows the behavior I'm attempting to show.

It seems that in the "High Arctic" the state change began in 2012. Thus I'm ignoring all previous years to 2012 and I'm drawing the line using only the years after 2012. I'll update after the next minimum is reached.

(R2 value provided.)
Title: Re: When will the Arctic Go Ice Free?
Post by: binntho on June 05, 2019, 08:06:19 AM
I think we all see the same thing here: The loss flatlines and even seems to drop. Which may very well be indicative of a real state change and not a statistical fluke. I think it may very well be the former, but the datapoints are too few to statistically validate any change in trends.

You mention the "hiatus" that some people see in the warming data, and yes it's there and easy to see - but as  Tamino  (https://tamino.wordpress.com/)has pointed out, even with a dataset stretching over more than 100 years, a ten year "flatline" is not statistically significant.

Besides, the  constant drop in the max line does not show any state change, simply business as usual, so the theoretical state change does not show up in the max numbers? And yes, I do think there may very well have been a state change, but the numbers are not conclusive.
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on June 05, 2019, 12:05:16 PM
I think it is better to show data from beginning than selecting 2000 as starting point.

Note: I don't believe the completely flat trendline at the end, I think it will continue downwards but at a fairly slow rate.

Is it straight or curved? Perhaps not clear enough to be statistically significant, particularly with April.

While residuals are uncorrelated, I think there is still good reason to think shape of trendlines will be somewhat similar between April and Sept: Less volume means more area becomes thin ice and open water so albedo drops and more energy is absorbed ....

If curved then the way this shows seems to be the way it is going.

Also an understanding of the data and processes helps draw conclusions. When Piomas and other models were run with huge initial step change, half the ice thickness at beginning of melt season the models showed that some ice remained. So the models had very little ice loss in such a year. If this is where we are going then the curves I show (but still going a little down at the end) are more like what we should expect.

Title: Re: When will the Arctic Go Ice Free?
Post by: b_lumenkraft on June 05, 2019, 12:15:11 PM
Is it straight or curved?

For how i see this, a straight line would be magical.

We are at the beginning of a massive conversion event. Why would the sea ice find a new equilibrium this early in the process? Doesn't sound logical to me.
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on June 05, 2019, 12:22:00 PM
Is it straight or curved?

For how i see this, a straight line would be magical.

We are at the beginning of a massive conversion event. Why would the sea ice find a new equilibrium this early in the process? Doesn't sound logical to me.

horizontal extrapolation would indeed be magical, and I don't believe that as noted. This question was about shape of trendline not of the extrapolation. Which is better fit straight diagonal line though data or curve I have drawn? (obviously curve but that is of course capable of fitting data better with more parameters/degrees of freedom. Sorry if this wasn't clear.
Title: Re: When will the Arctic Go Ice Free?
Post by: b_lumenkraft on June 05, 2019, 12:31:58 PM
This question was about shape of trendline not of the extrapolation. Which is better fit straight diagonal line though data or curve I have drawn? (obviously curve but that is of course capable of fitting data better with more parameters/degrees of freedom. Sorry if this wasn't clear.

Oh, sorry, my fault Crandles. I think your trendline is fitting.
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on June 05, 2019, 01:15:29 PM

Oh, sorry, my fault Crandles. I think your trendline is fitting.

Fitting as in a good fit, or as in overfitting?

If overfitting, how many more years data with this being a better predictor than straight line is needed till you think that is the general shape?
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on June 05, 2019, 01:25:44 PM
I think it is better to show data from beginning than selecting 2000 as starting point.

PIOMAs regional starts on the year 2000, so I didn't select a starting point , I used all the data available to me.

Quote
Note: I don't believe the completely flat trendline at the end, I think it will continue downwards but at a fairly slow rate.

Is it straight or curved? Perhaps not clear enough to be statistically significant, particularly with April.

I think annual volume losses will go up slowly, while the max keeps steadily and linearly marching down. Then one year, when the ice is thin enough and we get unlucky with the weather then the September minimum will go to 0. After that minimum will hit 0 every year.

2012 was a record loss year, so starting the graph for the changed state on 2012 has the effect of creating an artificially declining slope. Attached the graph with the new trend line starting in 2013.

Quote
While residuals are uncorrelated, I think there is still good reason to think shape of trendlines will be somewhat similar between April and Sept: Less volume means more area becomes thin ice and open water so albedo drops and more energy is absorbed ....

They are mostly linear, the maximum showing very good linearity and the minimum staying within acceptable limits of linearity. This is so because the behavior of this system is due mostly to the Sun or lack thereof and Earth's orbit and tilt. For the purposes of Arctic freeze/melt cycles, that energy is mostly constant. The variation that we see year to year is mostly weather. The constant downtrend is due to GHG's

Quote
If curved then the way this shows seems to be the way it is going.

I think this is the exact opposite of what the physics indicate. The world is warmer, the ice is thinner, the water saltier and the pack has loss significant mechanical strength. I see no reason why losses should slowdown for much longer.

 Unless something changes drastically this melting season (very good chance for that), it seems your straight line case may get a mortal blow this year.
Title: Re: When will the Arctic Go Ice Free?
Post by: oren on June 05, 2019, 01:52:15 PM
As the volume goes down losses must go down. There is simply less ice to melt, and certainly less easy peripheral ice to melt.
With the disappearance of multi-year ice, volume loss must go down as well.
But all this doesn't mean that volume is expected to reach equilibrium. The curve will surely go down, only question is how quickly or slowly.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on June 05, 2019, 01:56:26 PM
Nice graphs.  However, I question your trend lines.  Both the max and min were decreasing fairly constantly for the first decade.  However, both max and min have been flat over the past decade.

However, both max and min have been flat over the past decade.

Neither max nor min have been flat for a decade. Min has been slightly flat but above the old average, and climbing for 6 years, likely waiting for volume to catch up before it resumes the march down.

Either acknowledge your "error" or substantiate your claim. That's what good scientist do, right?
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on June 05, 2019, 02:03:00 PM
As the volume goes down losses must go down. There is simply less ice to melt, and certainly less easy peripheral ice to melt.
With the disappearance of multi-year ice, volume loss must go down as well.


Only if you hold temperature, salinity, export and thickness constant. If the effect on the ice of any/all of these variable is of larger magnitude than the lack of ice to melt it must go up.

Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on June 05, 2019, 02:22:43 PM
Slow transition thread started in July 2014, and I think gompertz shapes were discussed well before that. Here are a couple of 2012 links that mention gompertz in 2013 and 2012 2011
https://forum.arctic-sea-ice.net/index.php?topic=540.0
http://www.realclimate.org/index.php/archives/2012/04/arctic-sea-ice-volume-piomas-prediction-and-the-perils-of-extrapolation/
https://neven1.typepad.com/blog/2011/04/trends-in-arctic-sea-ice-volume.html


Since such dates has gompertz or straight line been a better predictor?

.

As thickness at max reduces and approaches a meltable thickness, the loss goes up as albedo goes down. Once under the meltable thickness then the volume loss in that area goes down and temperature goes up. Over time more and more of the area gets under the meltable thickness so there is certainly the potential for the volume loss to go down. Temperature goes up but it is in wrong places to melt ice so it has to increasingly travel further. It isn't clear whether this temperature increase overcomes the reduction in available ice to lose effect. However the pattern seems to be that there was increase in volume loss but perhaps it is now going down.

I don't think this is conclusive either way, but if you think the loss will continually increase then the shape of the loss trends seems a bit odd (not definitely ruled out but a bit odd). If you think the loss will increase then decrease again there is nothing particularly odd in the shape of the volume loss data.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on June 05, 2019, 03:04:36 PM
As the volume goes down losses must go down. There is simply less ice to melt, and certainly less easy peripheral ice to melt.
With the disappearance of multi-year ice, volume loss must go down as well.
But all this doesn't mean that volume is expected to reach equilibrium. The curve will surely go down, only question is how quickly or slowly.

Exactly!  Piomas Sept. volume is one-third of what is was in 1980.  The Arctic simply does not have as much ice to lose.  Hence, volumetric losses will continue to decrease.  Equilibrium will not occur, unless the climate holds steady for a prolonged period.  The curve looks good, and likely to continue until a state change forces it to change.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on June 05, 2019, 03:20:52 PM
Nice graphs.  However, I question your trend lines.  Both the max and min were decreasing fairly constantly for the first decade.  However, both max and min have been flat over the past decade.

However, both max and min have been flat over the past decade.

Neither max nor min have been flat for a decade. Min has been slightly flat but above the old average, and climbing for 6 years, likely waiting for volume to catch up before it resumes the march down.

Either acknowledge your "error" or substantiate your claim. That's what good scientist do, right?

Using the PIOMAS data that you posted previously, the trend line for the minimum volume since summer 2010 is +0.06 / yr and the maximum is -0.14 / yr, and neither is significantly different than zero.  Considering that the linear trends for the previous decade were -0.73 and -0.46 for the min and max, I would say confidently that the recent trends are flat compared to the most recent declines.  Using your data, I cannot substantiate it any more than that.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on June 05, 2019, 03:28:29 PM
Quote
However the pattern seems to be that there was increase in volume loss but perhaps it is now going down.

Please, attempt to convince me it is currently going down. If we take 2013 as the starting point, a year firmly in the "new ice arctic" regime, it is going up. The melting season thread hints to going up even more.

In the mean time, I like to look at the following animation as a rough bounds for the possible futures.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on June 05, 2019, 04:42:47 PM
Quote
The maximum is -0.14 / yr, and neither is significantly different than zero.

Your characterization of the maximum is plain wrong. The maximum has kept a steady decline , significantly higher than zero, even when there is much less thick and easy ice to melt.

Quote
I would say confidently that the recent trends are flat compared to the most recent declines.

You can say it confidently with words, but not with numbers.

Max has been steadily going down even if we pick a very high starting point for the graph, like 2010. See attachment for lines, slopes and R2 of 2010 to present and 2001 to 2010. While it is true that if we pick 2010 the slope improved, it is marching steadily down, even in the absence of easy ice.
Title: Re: When will the Arctic Go Ice Free?
Post by: Shared Humanity on June 05, 2019, 07:28:53 PM
Quote
The maximum is -0.14 / yr, and neither is significantly different than zero.

Your characterization of the maximum is plain wrong. The maximum has kept a steady decline , significantly higher than zero, even when there is much less thick and easy ice to melt.

The maximum has kept a steady decline not because there is much less thick and easy ice to melt but that there is far more open stretches of water that has taken up additional heat from the sun to freeze.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on June 05, 2019, 08:02:21 PM
Quote
The maximum is -0.14 / yr, and neither is significantly different than zero.

Your characterization of the maximum is plain wrong. The maximum has kept a steady decline , significantly higher than zero, even when there is much less thick and easy ice to melt.

Quote
I would say confidently that the recent trends are flat compared to the most recent declines.

You can say it confidently with words, but not with numbers.

Max has been steadily going down even if we pick a very high starting point for the graph, like 2010. See attachment for lines, slopes and R2 of 2010 to present and 2001 to 2010. While it is true that if we pick 2010 the slope improved, it is marching steadily down, even in the absence of easy ice.

I am guessing that you are using daily ice volume, whereas I am using monthly.  That is the only reason that I can see for the discrepancy.
Title: Re: When will the Arctic Go Ice Free?
Post by: Sam on June 05, 2019, 08:42:54 PM
Max has been steadily going down even if we pick a very high starting point for the graph, like 2010. See attachment for lines, slopes and R2 of 2010 to present and 2001 to 2010. While it is true that if we pick 2010 the slope improved, it is marching steadily down, even in the absence of easy ice.

Archimid,

You are exactly correct about the maximum values being on a steady decline. I would be careful though in arguing that the annual decline is now shrinking. There may be actual dynamics at work, such as the loss of thick ice to melt. It may equally be that you are only seeing an apparent trend where there isn't one, due to the statistics variations and randomness, or some longer period oscillation. The entire time series of annual loss from 1979 to the present is slowly increasing. The last few years decline does not appear to definitively be significant. A single year with larger loss (2019 may be that year), would dramatically change the chart and the conclusions.

Sam
Title: Re: When will the Arctic Go Ice Free?
Post by: Stephan on June 05, 2019, 10:07:50 PM
It is time for the monthly update of my extrapolation when the extent [Extent], volume [Volumen] and thickness [Dicke] will reach zero. The extrapolation occured linearly and by a logarithmic function; the latter one almost constantly resulting in earlier times. May value now includes 2019.
Extent value for May 2019 lies below, volume and thickness lie above the long-term linear trend lines. As these anomalies aren't too large, the "BOE numbers" haven't changed significantly compared to last year.

Please note that this is not a forecast but a trend!
See attached table.
Title: Re: When will the Arctic Go Ice Free?
Post by: jdallen on June 05, 2019, 10:27:48 PM
I think we all see the same thing here: The loss flatlines and even seems to drop. Which may very well be indicative of a real state change and not a statistical fluke. I think it may very well be the former, but the datapoints are too few to statistically validate any change in trends.

I think the  loss flatlines (in the case of the Arctic) because total winter extent vs loss is reaching a hard limit - zero - as to how much ice is left over at the end of the melting season.

We have seen a decline in melt season total loss of extent and volume, but that remaining volume is (1) harder to reach and increasingly (2) isn't replaced during the refreeze.

The sun reaches the 80N at the same time, and has the same effect, but there is less ice at lower latitudes.

My instinct now is to watch the winter numbers more closely than summer's, as that's were I think the real harbingers to our first BoE will show up.
Title: Re: When will the Arctic Go Ice Free?
Post by: Tom_Mazanec on June 18, 2019, 11:04:45 PM
Well, here is a scientist who votes for 2022:
https://www.forbes.com/sites/jeffmcmahon/2018/01/15/carbon-pollution-has-shoved-the-climate-backward-at-least-12-million-years-harvard-scientist-says/#6bd5743b963e
Title: Re: When will the Arctic Go Ice Free?
Post by: Ardeus on June 18, 2019, 11:25:26 PM
Well, here is a scientist who votes for 2022:
https://www.forbes.com/sites/jeffmcmahon/2018/01/15/carbon-pollution-has-shoved-the-climate-backward-at-least-12-million-years-harvard-scientist-says/#6bd5743b963e

I talked with Peter Wadhams last year and he also described a similar scenario, both for the timing of the BOE and for the effects on weather patterns.

https://youtu.be/fPEUfc965i8

I did this interview for a doc about Lake Tanganyika, so part of the interview focuses on the effects in Africa.
Title: Re: When will the Arctic Go Ice Free?
Post by: DavidR on June 19, 2019, 01:49:19 AM
I think we all see the same thing here: The loss flatlines and even seems to drop. Which may very well be indicative of a real state change and not a statistical fluke. I think it may very well be the former, but the datapoints are too few to statistically validate any change in trends.

I think the  loss flatlines (in the case of the Arctic) because total winter extent vs loss is reaching a hard limit - zero - as to how much ice is left over at the end of the melting season.

We have seen a decline in melt season total loss of extent and volume, but that remaining volume is (1) harder to reach and increasingly (2) isn't replaced during the refreeze.

The sun reaches the 80N at the same time, and has the same effect, but there is less ice at lower latitudes.

My instinct now is to watch the winter numbers more closely than summer's, as that's were I think the real harbingers to our first BoE will show up.
Its worth reminding ourselves that "from the comparison with in situ observations  it appears that PIOMAS tends to overestimate thin ice and underestimates thick ice.  As the ice thins such systematic errors can affect the overall trend."

http://psc.apl.uw.edu/research/projects/arctic-sea-ice-volume-anomaly/validation/

This suggests that  the apparent flattening of the trend over recent years may be an illusion that is created by the model biases.
Title: Re: When will the Arctic Go Ice Free?
Post by: magnamentis on June 19, 2019, 03:37:59 PM
Its worth reminding ourselves that "from the comparison with in situ observations  it appears that PIOMAS tends to overestimate thin ice and underestimates thick ice. ...

the only thing that i know for sure is that PIOMAS overestimates any ice against no ice at all.

the current mid-month report shows ice north of point barrows that isn't there since 8th or 9th of June, depending on interpretation while currently there is a clear ice-free zone that is not showing at all in piomas maps.

this is not the only place, it's just a prominent, obvious and well know example since that spot has been subject to a poll an exiting race for the 7th that turned out to be the 8th IMO.
Title: Re: When will the Arctic Go Ice Free?
Post by: oren on June 19, 2019, 03:45:58 PM
PIOMAS is calibrated to NSIDC sea ice concentration, which has coarse resolution (25x25km). Perhaps NSIDC shows this area with some ice?
Title: Re: When will the Arctic Go Ice Free?
Post by: Pragma on June 19, 2019, 05:00:29 PM
PIOMAS is calibrated to NSIDC sea ice concentration, which has coarse resolution (25x25km). Perhaps NSIDC shows this area with some ice?

That it uses NSIDC concentration is good information.
I've been comparing the latest modeled ice thickness against concentration maps. I have some observations but unfortunately not much insight.

POIMAS definitely shows ice where NSIDC does not, but this could be explained by the 15% threshold. This is not conclusive at all, because posters have pointed out the area around Barrow as inconsistent.

However, it also ignores ice that NSIDC clearly shows, such as shore ice in the Bering Sea. The granularity of the PIOMAS chart is lower, so it could get lost in some sort of averaging, but I am not convinced of that.

As others have said, it seems to have problems with overestimating thinner ice, but I'm seeing it go both ways. It may have similar issues with thick ice, but that's tougher to tell using NSIDC concentration. There are short lived low concentrations (NSIDC) that move across the interior of the ice pack that are not reflected in the morphology of the PIOMAS map thicknesses. I am wondering if some sort of box car averaging is being used.

I am not trying to discredit PIOMAS, but it's important to understand it's limitations and I'm not there yet.

We are obviously moving towards thinner ice, so these anomalies will be more widespread, so if anyone has more insight, I am all ears. 
Title: Re: When will the Arctic Go Ice Free?
Post by: Dharma Rupa on June 19, 2019, 05:07:20 PM
I am not trying to discredit PIOMAS, but it's important to understand it's limitations and I'm not there yet.

PIOMAS is known to be:

1.  Not very accurate,

and

2.  Better than anything else we've got.
Title: Re: When will the Arctic Go Ice Free?
Post by: Pragma on June 19, 2019, 05:23:48 PM
LOL Thanks! (I think  :) )

That's about where I'm at right now.

I have a vision a few years from now, where PIOMAS will either still have volume when there is no ice left, or it will show that there is negative volume.  ;)
Title: Re: When will the Arctic Go Ice Free?
Post by: gerontocrat on June 19, 2019, 07:22:19 PM
I am not trying to discredit PIOMAS, but it's important to understand it's limitations and I'm not there yet.

PIOMAS is known to be:

1.  Not very accurate,

and

2.  Better than anything else we've got.
At the beginning of the month I posted some thickness graphs (PIOMAS volume divided by NSIDC Area) of some individual seas. It showed clearly that in at least some of the smaller seas as  summer advanced, the data started to look somewhat dodgy. But that when that starts to happen at least it does tell you that the sea is nearly kaput of ice.

So here are 4 thickness graphs.
The Chukchi - a fair sized sea that melts in a fairly orderly way.
The Greenland Sea - really messy,. so dependent on quantity and nature of what arrives from the Fram Strait
Baffin Bay Note the 2000 Average line. That I do NOT understand

High Arctic Seas- the 7 central seas as in Tealight's High Arctic**.

**Still a long way to go to melt out.
Title: Re: When will the Arctic Go Ice Free?
Post by: Pragma on June 19, 2019, 07:28:33 PM
Thanks, but I am only seeing one graph.

I look forward to the other three.

Cheers
Title: Re: When will the Arctic Go Ice Free?
Post by: gerontocrat on June 19, 2019, 09:00:05 PM
Thanks, but I am only seeing one graph.

I look forward to the other three.

Cheers
Look again...
Title: Re: When will the Arctic Go Ice Free?
Post by: Pragma on June 19, 2019, 10:48:54 PM
Thanks, but I am only seeing one graph.

I look forward to the other three.

Cheers
Look again...

Thanks very much for that. It gives more insight and my guess is that we are seeing the error bars of NSIDC fighting, or at least interacting, with the error bars of PIOMAS. It doesn't help that one is partially derived from the other. Further guessing, I think it's the limits of sensors and inherent noise swamping the signal as it gets to the limits of resolution.

In defence of PIOMAS, the model has refined by comparing previous surveys and I suspect that we are just not in Kansas anymore. I keep thinking of previous expeditions that, based on satellite data, expected solid ice, only to find huge areas of slush or porous and "rotten" ice.

Another area that I find suspect is how they keep track of multi-year ice. It's a daunting task, when thickness is not a reliable indicator of age, particularly along the north of the CAA and Greenland. Again, not a criticism, just a point to consider as it applies to PIOMAS.

As for the Baffin Bay chart, I spent quite a bit of time looking at old PIOMAS data and NSIDC data. I thought it might be due to Nares staying closed but I found nothing that would cause that anomaly in the 2000's. That decade was actually pretty predictable, compared to the 80's and 90"s and the fact that it's an average makes it all the more suspect. I think it must be a data set error or a quirk in the computation.

Unfortunately, I don't have a great eureka moment to share, I just know now to take PIOMAS with a large grain of salt, whatever that means.
Title: Re: When will the Arctic Go Ice Free?
Post by: oren on June 21, 2019, 10:34:24 AM
Baffin Bay Note the 2000 Average line. That I do NOT understand
The problem is with the PIOMAS data itself. While the volume in the 2000s was modeled as higher than the 2010s, the minimum NSIDC area was almost the same in both decades. In addition, the volume in the 2000s barely reduces for weeks around the minimum, while area continues shrinking. It seems that either PIOMAS did not calibrate itself properly by the NSIDC area data in Baffin Bay as it is supposed to do, or that PIOMAS modeled extremely thick ice in the bay, perhaps due to export from Nares or the CAA, and that ice was the only thing left in September according to the model. I really doubt the second explanation, as PIOMAS lacks the resolution to achieve that kind of result.
But in any case, that's what you get when you divide two small numbers. I think the PIOMAS/NSIDC thickness calculation is more indicative during winter than during summer, and more indicative in the CAB than in seas that are seasonally ice free.
Title: Re: When will the Arctic Go Ice Free?
Post by: Tor Bejnar on June 21, 2019, 03:43:06 PM
Quote
the volume in the 2000s barely reduces for weeks around the minimum, while area continues shrinking.
Just as CAB ice continues to thicken long after 'fringe' sea ice melts out (causing volume max to follow [and not follow closely] area/extent max), CAB ice will start thickening before the remaining pack stops melting at the edges.  The North Pole summer is shorter than the 80ºN summer - it starts later and ends sooner. 

Therefore, as 'fringe' volume (and total area) continued to decrease in September in the 2000s, North Pole volume started increasing. 

Today, I suspect (=deduce without looking at hard numbers = guess) the NP freezing season starts much later than it used to, while its melting season starts shortly before the time it used to.
Title: Re: When will the Arctic Go Ice Free?
Post by: oren on June 21, 2019, 05:59:08 PM
Good points Tor, but I was referring specifically to Baffin Bay volume, I should have been clearer.
Title: Re: When will the Arctic Go Ice Free?
Post by: Tor Bejnar on June 21, 2019, 06:07:10 PM
Yes, Baffin Bay volume data is puzzling.
Title: Re: When will the Arctic Go Ice Free?
Post by: gerontocrat on June 21, 2019, 09:09:07 PM
Baffin Bay is not the only sea by any means to show wobbly data, sometimes especially for the 2000's average, and sometimes all years. The variation is greatest for small seas as summer comes and melt is fast.

These wobbles also show in the Greenland and Barents, which I guess is due to large changes in ice pushed in and out that perhaps are a melange of varying thickness.

Meanwhile - back to When will the Arctic go ice-free?
I attach 4 graphs about the "High Arctic" - the 7 central seas as defined by Tealight.
- Area,
- Volume,
- Thickness,
and
- Open water as a percentage of the total area of these seas.

My guess is that even a 2012 event won't do a BOE - yet. The baseline of area, volume and thickness needs to drop some more so such an event as 2012 will get to the magic marker.

On the other hand, the only way is down.
Title: Re: When will the Arctic Go Ice Free?
Post by: jdallen on June 21, 2019, 11:49:28 PM
@gerontocrat

Concur, even with the current hideous torching going on, we're not going to see a BoE this year.

If it keeps up, we might beat 2012, but most likely, we'd end up somewhere between 2012 and 2016.
Title: Re: When will the Arctic Go Ice Free?
Post by: Stephan on July 08, 2019, 08:05:04 PM
It is time for the monthly update of my extrapolation when the extent [Extent], volume [Volumen] and thickness [Dicke] will reach zero. The extrapolation occured linearly and by a logarithmic function; the latter one almost constantly resulting in earlier times (valid for volume and thickness, not for extent). June value now includes 2019.
Extent value, volume and thickness for June 2019 lie at the long-term linear trend lines. As these anomalies are quite small, the "BOE numbers" haven't changed significantly compared to last year.

Please note that this is not a forecast but a trend!
See attached table.
Title: Re: When will the Arctic Go Ice Free?
Post by: gerontocrat on July 09, 2019, 03:49:00 PM
Thought I would have another look at thickness at minimum and maximum.
Graphs of volume, area & thickness at min and max attached.

Just says to me two things
- it will be volume loss wot does it,
- back in the early years average thickness at maximum was less than at minimum by about 1 metre. That's a lot. This gradually declined until reversed in 2010, i.e. average thickness at maximum more than at minimum (by about 0.1 to 0.2 metres). Pourquoi ? All to do with the amount and location of area and volume loss, methinks, but it made me blink.

Still say BOE sometime in the 2020's, but imagine (using the 1 million km2 rule)..
Scenario 1:-
About 900 km3 of volume, all squashed in together in the Greenland triangle.
Average thickness 1 metre spread over an extent of 1 million km2.
BOE !! No problem.

Scenario 1:-
About 500 km3 of volume, dispersed all over the place. Average thickness only 0.5 metres, spread over a measured extent of nearly 2 million km2.
is this  a BOE ??

05   REM Scientific discussion ensues...
10   "Oh yes it is,"
20   "On no it isn't",
30    GOTO 10
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on July 09, 2019, 05:10:33 PM
Thought I would have another look at thickness at minimum and maximum.
Graphs of volume, area & thickness at min and max attached.

Just says to me two things
- it will be volume loss wot does it,
- back in the early years average thickness at maximum was less than at minimum by about 1 metre. That's a lot. This gradually declined until reversed in 2010, i.e. average thickness at maximum more than at minimum (by about 0.1 to 0.2 metres). Pourquoi ? All to do with the amount and location of area and volume loss, methinks, but it made me blink.

Still say BOE sometime in the 2020's, but imagine (using the 1 million km2 rule)..


They will all go simultaneously - one cannot occur without the other.  That said, the linear trend line does not appear to mimic the actual data - especially over the last decade.  Hence, I do not foresee a BOE event before 2030.
Title: Re: When will the Arctic Go Ice Free?
Post by: vox_mundi on July 09, 2019, 05:39:17 PM
Paris Agreement Does Not Rule Out Ice-Free Arctic
https://phys.org/news/2019-07-paris-agreement-ice-free-arctic.html

Research published in this week's issue of Nature Communications reveals a considerable chance for an ice-free Arctic Ocean at global warming limits stipulated in the Paris Agreement. Scientists from South Korea, Australia and the U.S. used results from climate models and a new statistical approach to calculate the likelihood for Arctic sea ice to disappear at different warming levels.

Using 31 different climate models, which exhibit considerable inter-dependence, the authors find that there is at least a 6% probability that summer sea ice in the Arctic Ocean will disappear at 1.5 °C warming above preindustrial levels—a lower limit recommended by the Paris Agreement of the United Nations Framework Convention on Climate Change. For a 2°C warming, the probability for losing the ice rises to at least 28%. Most likely we will see a sea ice-free summer Arctic Ocean for the first time at 2 to 2.5°C warming.

Open Access: R. Olson, S.-I. An, Y. Fan, W. Chang, J. P. Evans. A novel method to test non-exclusive hypotheses applied to Arctic ice projections from dependent models (https://www.nature.com/articles/s41467-019-10561-x). Nature Communications, 2019
Title: Re: When will the Arctic Go Ice Free?
Post by: Sebastian Jones on July 10, 2019, 07:15:24 AM
Paris Agreement Does Not Rule Out Ice-Free Arctic
https://phys.org/news/2019-07-paris-agreement-ice-free-arctic.html

Research published in this week's issue of Nature Communications reveals a considerable chance for an ice-free Arctic Ocean at global warming limits stipulated in the Paris Agreement. Scientists from South Korea, Australia and the U.S. used results from climate models and a new statistical approach to calculate the likelihood for Arctic sea ice to disappear at different warming levels.

Using 31 different climate models, which exhibit considerable inter-dependence, the authors find that there is at least a 6% probability that summer sea ice in the Arctic Ocean will disappear at 1.5 °C warming above preindustrial levels—a lower limit recommended by the Paris Agreement of the United Nations Framework Convention on Climate Change. For a 2°C warming, the probability for losing the ice rises to at least 28%. Most likely we will see a sea ice-free summer Arctic Ocean for the first time at 2 to 2.5°C warming.

Open Access: R. Olson, S.-I. An, Y. Fan, W. Chang, J. P. Evans. A novel method to test non-exclusive hypotheses applied to Arctic ice projections from dependent models (https://www.nature.com/articles/s41467-019-10561-x). Nature Communications, 2019

I don't think many regulars on this forum think there is much chance for a BOE to wait until global temps have risen over 2C. Personally, I expect it to happen before we reach 1.5C.
Title: Re: When will the Arctic Go Ice Free?
Post by: RikW on July 10, 2019, 10:04:40 AM
Well, it all depends on how fast temperature keeps rising;

What I learnt from reading this forum and other online sources last years blue arctic ocean is almost inevitable. Even if we stop all CO2 emissions today
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on July 10, 2019, 03:32:48 PM
I don't think many regulars on this forum think there is much chance for a BOE to wait until global temps have risen over 2C. Personally, I expect it to happen before we reach 1.5C.

That is because many of the regulars are pessimists.  Just look at the polls.  In the 2017 poll, half of the respondents predicted a new JAXA minimum.  That was down from the 2016 poll, in which 60% predicted a new minimum.  Last year was rather subdued, with only 16% predicting a new minimum. 
Title: Re: When will the Arctic Go Ice Free?
Post by: be cause on July 10, 2019, 04:03:52 PM
many of the regulars are realists . Also .. as a wake-up call a BOE would be better sooner than later . I still consider this year a candidate . However I prefer area as the measure .. extent could be nearly all water . b.c.
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on July 10, 2019, 04:24:40 PM
I can get that up to 84.5% for 2017:

https://forum.arctic-sea-ice.net/index.php/topic,2031.0.html

When will be break PIOMAS 2012 September record?
2017 (In General) 60 (51.7%)
2018-2019 7 (6%)
2020-2023 5 (4.3%)
2022-2025 2 (1.7%)
2024-2027  70 (0%)
2026-2029 0 (0%)
2028-2030 0 (0%)
After 2030 1 (0.9%)
Never 3 (2.6%)
2017 by month: July 1 (0.9%)
2017 by month: August 16 (13.8%)
2017 by month: September 21 (18.1%)

So just 15.5% thought it wouldn't be 2017, but to be fair the volume was at a clear record low for the time of year and had been for some time when the poll closed 30 May 2017.

Agree there is some self selection bias: alarmists more likely to be active on this forum, therefore no surprise if the poll results tend towards alarmism. OTOH with 2017 data available at the time, perhaps it is not too surprising if high proportion of people were predicting new minimums to occur.

>Last year was rather subdued
Perhaps people are learning from their errors? Maybe I posted my infamous 4 parameter gompertz fit graphs frequently enough.  ;)
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on July 10, 2019, 05:10:33 PM
I can get that up to 84.5% for 2017:

https://forum.arctic-sea-ice.net/index.php/topic,2031.0.html

When will be break PIOMAS 2012 September record?
2017 (In General) 60 (51.7%)
2018-2019 7 (6%)
2020-2023 5 (4.3%)
2022-2025 2 (1.7%)
2024-2027  70 (0%)
2026-2029 0 (0%)
2028-2030 0 (0%)
After 2030 1 (0.9%)
Never 3 (2.6%)
2017 by month: July 1 (0.9%)
2017 by month: August 16 (13.8%)
2017 by month: September 21 (18.1%)

So just 15.5% thought it wouldn't be 2017, but to be fair the volume was at a clear record low for the time of year and had been for some time when the poll closed 30 May 2017.

Agree there is some self selection bias: alarmists more likely to be active on this forum, therefore no surprise if the poll results tend towards alarmism. OTOH with 2017 data available at the time, perhaps it is not too surprising if high proportion of people were predicting new minimums to occur.

>Last year was rather subdued
Perhaps people are learning from their errors? Maybe I posted my infamous 4 parameter gompertz fit graphs frequently enough.  ;)

For the record, I particularly like for gompertz plot, as it poses a much better match than a simple linear fit.
Title: Re: When will the Arctic Go Ice Free?
Post by: El Cid on July 10, 2019, 05:14:19 PM
many of the regulars are realists . Also .. as a wake-up call a BOE would be better sooner than later .

Sorry bro, no such luck. Noone will give a s**t about BOE even when it happens especially that by definition (the 1 M sq km threshold) it will still include some remnants of the arctic ice. There's going to be no wake up call, no more than 2007 or 2012. Extreme, previously unimaginable (and unforeseen by models) things happened in 07 and 12 and yet no one gave a s**t either.

A BOE could happen even this year but it might not come until the 30s. BOE is not the wake up call. Global crop-failures or millions (in developed countries) losing their homes would be. I hope (and think) that these will not happen in my lifetime. If they do, then MAYBE, just maybe, humanity will try to change
Title: Re: When will the Arctic Go Ice Free?
Post by: be cause on July 10, 2019, 05:20:24 PM
I reckon a lot of children will give a shit .. even open seas at the pole will stir the next generation .. b.c.
Title: Re: When will the Arctic Go Ice Free?
Post by: magnamentis on July 10, 2019, 07:15:23 PM
many of the regulars are realists . Also .. as a wake-up call a BOE would be better sooner than later .

Sorry bro, no such luck. Noone will give a s**t about BOE even when it happens especially that by definition (the 1 M sq km threshold) it will still include some remnants of the arctic ice. There's going to be no wake up call, no more than 2007 or 2012. Extreme, previously unimaginable (and unforeseen by models) things happened in 07 and 12 and yet no one gave a s**t either.

A BOE could happen even this year but it might not come until the 30s. BOE is not the wake up call. Global crop-failures or millions (in developed countries) losing their homes would be. I hope (and think) that these will not happen in my lifetime. If they do, then MAYBE, just maybe, humanity will try to change

sorry but i disagree here, i dunno where you live but in europe the movements for sustainability is getting stronger by the month and i'm totally convinced that an extreme event would again increase the percentage of awareness and once the critical mass is reached we could even end in an environmental dictatorship. i mean kind of widely spread prohibition that will not solve the problem because it's too late but destroy what still working.

i do not expect any followership on such thoughts. only thing i say is that: study how communism evolved and played out and who knows whether it could repeat in the green spectrum after the red spectrum didn't succeed. too complicated and OT to take it further here.
Title: Re: When will the Arctic Go Ice Free?
Post by: D-Penguin on July 10, 2019, 11:45:49 PM
many of the regulars are realists . Also .. as a wake-up call a BOE would be better sooner than later .

Sorry bro, no such luck. Noone will give a s**t about BOE even when it happens especially that by definition (the 1 M sq km threshold) it will still include some remnants of the arctic ice. There's going to be no wake up call, no more than 2007 or 2012. Extreme, previously unimaginable (and unforeseen by models) things happened in 07 and 12 and yet no one gave a s**t either.

A BOE could happen even this year but it might not come until the 30s. BOE is not the wake up call. Global crop-failures or millions (in developed countries) losing their homes would be. I hope (and think) that these will not happen in my lifetime. If they do, then MAYBE, just maybe, humanity will try to change

sorry but i disagree here, i dunno where you live but in europe the movements for sustainability is getting stronger by the month and i'm totally convinced that an extreme event would again increase the percentage of awareness and once the critical mass is reached we could even end in an environmental dictatorship. i mean kind of widely spread prohibition that will not solve the problem because it's too late but destroy what still working.

i do not expect any followership on such thoughts. only thing i say is that: study how communism evolved and played out and who knows whether it could repeat in the green spectrum after the red spectrum didn't succeed. too complicated and OT to take it further here.

I agree with Magnamentis. A BOE would DEFINITELY motivate and give greater momentum to the younger generation. The present teenage generation are more knowledgeable about Critical Climate Change (CCC) than most of their parents and grandparents. Many of these young people will be voting at the next General Election in the UK and other European elections and the weight of their votes will determine the next government. To get the 'young vote' it will be necessary to present  the most credible policies to tackle CCC.

Also, note the success of the Green Party in the recent EU elections, essentially a 'young persons' political movement.

Yes, a BOE and sooner the better to create a critical mass of public opinion with the young in the vanguard of public reaction and demands for action.
Title: Re: When will the Arctic Go Ice Free?
Post by: El Cid on July 11, 2019, 12:10:32 AM
Yes, you and magnamentis may be right but I think that it is just wishful thinking on your part. What happened to the hippie generation? The same thing will happen to these young green voters...unfortunately for all of us. But we will most likely see which of us is right soon enough
Title: Re: When will the Arctic Go Ice Free?
Post by: Ardeus on July 11, 2019, 12:34:51 AM
A Disney film about a polar bear cub that lost its mother while the ice was melting and was adopted by a beluga whale will have more impact than a BOE.

Unless there are serious immediate consequences in the lives of several millions of people, the BOE will be just an extra degree in the boiling pan with frog at the bottom.

The BOE is a psychological milestone mostly for people that follow the arctic. Even for people that are concerned with climate change, it's just another piece of terrible news, that are becoming more and more common.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 11, 2019, 01:02:18 AM
After a BOE there won't be debates about climate change, it will be quite clear. What happens in the Arctic does not stay in the Arctic.

After a BOE, anthropogenic climate change won't even matter anymore. Human emissions will drop significantly  the year after the first BOE. Plastic pollution will pretty much stop a few years after. About the only impact humans will have on the planet at that point will be that of war, and it won't be for long, we'll be fighting with stones and sticks after a while.
Title: Re: When will the Arctic Go Ice Free?
Post by: magnamentis on July 11, 2019, 01:10:27 AM
A Disney film about a polar bear cub that lost its mother while the ice was melting and was adopted by a beluga whale will have more impact than a BOE.

Unless there are serious immediate consequences in the lives of several millions of people, the BOE will be just an extra degree in the boiling pan with frog at the bottom.

The BOE is a psychological milestone mostly for people that follow the arctic. Even for people that are concerned with climate change, it's just another piece of terrible news, that are becoming more and more common.

if you follow this forum thoroughly and read what others have to say you will find that there is a certain probability that the arctic ocean will see up water temps between 5-15C depending and if that probability becomes true, you can assume that exactly that will happen, such a shift in temperatures over such a vast area, and the difference will not be restricted to summers, only the highs, cannot go unnoticed by the system (climate) as w whole and i'd guess that we shall see an abrupt SLR by something between 30-100cm, extreme storms and other effects that, jointly with the news what happened up north (don't forget down south) will cause some panic sales, panic moves, panic all over the sea-level-dwellers.

but then i'm just asking myself whether it's worth to post this, now that all was said in one or another way and some will never see it coming until it's too late.

seen from that perspective, people who can't or don't want to see the huge impact of such game-changers are exactly those responsible that it will happen.
Title: Re: When will the Arctic Go Ice Free?
Post by: dnem on July 11, 2019, 02:14:40 AM
After a BOE there won't be debates about climate change, it will be quite clear. What happens in the Arctic does not stay in the Arctic.

After a BOE, anthropogenic climate change won't even matter anymore. Human emissions will drop significantly  the year after the first BOE. Plastic pollution will pretty much stop a few years after. About the only impact humans will have on the planet at that point will be that of war, and it won't be for long, we'll be fighting with stones and sticks after a while.

This is hyperbole.  If extent slips below 1,000,000 km2 for a day and then heads into a relatively normal (for these abnormal times) freeze season, it will not result in chaos and collapse.  It will be a just another ratchet step down that road.  When we have a few summers in a row with no ice, then you might be right.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on July 11, 2019, 03:07:28 AM
After a BOE there won't be debates about climate change, it will be quite clear. What happens in the Arctic does not stay in the Arctic.

After a BOE, anthropogenic climate change won't even matter anymore. Human emissions will drop significantly  the year after the first BOE. Plastic pollution will pretty much stop a few years after. About the only impact humans will have on the planet at that point will be that of war, and it won't be for long, we'll be fighting with stones and sticks after a while.

This is hyperbole.  If extent slips below 1,000,000 km2 for a day and then heads into a relatively normal (for these abnormal times) freeze season, it will not result in chaos and collapse.  It will be a just another ratchet step down that road.  When we have a few summers in a row with no ice, then you might be right.

Agreed.  There is nothing magical about a BOE.  Just like their is nothing magical about 1.5 or 2.0 degrees temperature rise.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 11, 2019, 11:25:49 AM
The abrupt changes in planetary climate that a BOE will bring are not magic. They are simple physics. The Earth has had a planetary refrigerator for likely millions of years. After a BOE that refrigerator fails and the NH will know true climate change. There won't be any denying because we'll be busy surviving.

I'm not arguing against logic here. It is frustrating to see how intelligent people who are aware of the role of arctic sea ice on atmospheric and oceanic patterns can't see the destruction that will ensue as the arctic disappears. The destruction has already started and the Arctic has barely begun to change.

But I may be wrong, so let's get to the science. Find me a paper that describes what happens after the first BOE, that doesn't ignore the ASI teleconections to the rest of the world and predicts a BOE much sooner than 2070.

Good luck with it. 
Title: Re: When will the Arctic Go Ice Free?
Post by: pietkuip on July 11, 2019, 12:20:26 PM
Find me a paper that describes what happens after the first BOE...
That seems to be very uncertain. The IPCC states "with high confidence" that there will be no hysteresis (but that is because they excluded feedback from all of their models) and that the Arctic will just refreeze like normal. I doubt that, because there should be more mixing caused by stronger wave action due to the longer wind fetch.

As to linkages and the effects on temperate weather patterns, effects are uncertain. Some results indicate that weather will remain variable. Jennifer Francis etc do not agree.

What seems obvious is that there will be a lot more evaporation from the open ocean in the autumn. But the relative increase of humidity and latent heat in the atmosphere won't be large, not in Western Europe.

I fear that things might get bad but we will see soon enough. Sooner than reliable calculations and predictions.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 11, 2019, 12:43:46 PM
Quote
The IPCC states "with high confidence" that there will be no hysteresis (because they excluded feedback from all of their models) and that the Arctic will just refreeze like normal.

I'm convinced that after the first BOE the Arctic will refreeze like normal, if by normal you mean later than ever and by the end of the freezing season there is a record low amount of first year ice. No instant hysteresis. Hysteresis happens in the years after the BOE as consecutive BOE's happen at earlier dates.

Quote
As to linkages and the effects on temperate weather patterns, effects are uncertain. Some results indicate that weather will remain variable. Jennifer Francis etc do not agree.

IMHO the effects are visible and evident but scientist haven't figured out how to correctly account for it. As the Arctic shrinks and the climate extremes get worse data will come in and scientist will get a better quantitative understanding of the new climate regime. Hopefully, not too late.

Quote
What seems obvious is that there will be a lot more evaporation from the open ocean in the autumn. But the relative increase of humidity and latent heat in the atmosphere won't be large, not in Western Europe.


To me the biggie is going to be the change in atmospheric pressure as arctic temperatures depart normal Pleistocene temperatures in a geological instant ( a few decades).

In the past, when fast warming like this happened it was stopped by glaciers melting quick and cooling the ocean. Where there used to be glaciers during Pleistocene warming there is now permafrost. I don't know if Greenland alone is capable of that.
Title: Re: When will the Arctic Go Ice Free?
Post by: El Cid on July 11, 2019, 02:29:49 PM
The abrupt changes in planetary climate that a BOE will bring are not magic. They are simple physics. The Earth has had a planetary refrigerator for likely millions of years.


That is likely not true. Many studies had been posted on other threads about historical BOE events. We probably had no or little Arctice ice 120 000 yrs ago and we may not have had ice  8000 yrs ago. Look up the studies, as I said they had been quoted on other threads before - and not just once.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 11, 2019, 03:01:28 PM
And in all those threads I’ve made clear the existence of  massive ice sheets that offset the warming. Ice sheets that do not exist today except for Greenland. I also made clear that the time frame of these events of the past happen over centuries and millennia, not decades. 

It’s all right there in the same literature you now allude to. You just don’t want to see it.
Title: Re: When will the Arctic Go Ice Free?
Post by: pietkuip on July 11, 2019, 03:18:55 PM
Quote
The IPCC states "with high confidence" that there will be no hysteresis (because they excluded feedback from all of their models) and that the Arctic will just refreeze like normal.

I'm convinced that after the first BOE the Arctic will refreeze like normal, if by normal you mean later than ever and by the end of the freezing season there is a record low amount of first year ice. No instant hysteresis. Hysteresis happens in the years after the BOE as consecutive BOE's happen at earlier dates.

Yes, it would refreeze later than usual, and the ice would be thinner next year with very little multi-year ice. Which would give a much higher probability of another BOE. Probably earlier in the melting season. But this is what the IPCC wrote:

Quote from: IPCC  Special Report on the impacts of global warming of 1.5°C Executive summary B.4.1
With 1.5°C of global warming, one sea ice-free Arctic summer is projected per century.

This likelihood is increased to at least one per decade with 2°C global warming.

Effects of a temperature overshoot are reversible for Arctic sea ice cover on decadal time scales (high confidence).

That confidence is just silly. But it is very difficult to predict with any kind of certainty what the effects would be. I expect consequences all over the Northern Hemisphere. And any fast change is very likely to be bad.
Title: Re: When will the Arctic Go Ice Free?
Post by: RikW on July 11, 2019, 03:41:20 PM
Yeah, I don't expect massive climate change (except those we have now) when we hit BOE, because that will likely happen at the end of august/beginning of september thus fast refreeze. But unless there are some nice feedback mechanisms after going blue, I'd guess BOE will happen in year BOE+1 a couple of days/weeks earlier, so much more heating of the arctic ocean, refreeze will hapen weeks/months later and in BOE+2 I'd imagine having BOE for mid july-november. And that will be too long without our arctic refrigerator and I won't be suprised if the following happens

BOE-year: "aaaah, blue ocean" "oh, nothing happens, it just refreezes"
BOE-year+1: "oh, again blue ocean" and we will have some weird weather, but those are just 'incidents'
BOE-year+2: "that's weird, 3rd BOE in a row and too early" and weather patterns become unpredictable in northern hemisphere with lots of extreme weather and reality finally sinks in
Title: Re: When will the Arctic Go Ice Free?
Post by: El Cid on July 11, 2019, 03:46:49 PM
And in all those threads I’ve made clear the existence of  massive ice sheets that offset the warming. Ice sheets that do not exist today except for Greenland. I also made clear that the time frame of these events of the past happen over centuries and millennia, not decades. 

It’s all right there in the same literature you now allude to. You just don’t want to see it.

Yes, you made clear that YOU THINK that BOE will bring disaster and pretty much and end of all life. You never supported your claims with any literature and disregarded any literature I cited (many times!) even from pretty reliable journals, eg. Nature. These show that the changes in the past happened in decades not centuries or millenia and the changes were huge and widespread (Greenland temp change at the end of the last ice age of 8-15 C in a mere decades or years!). All you do is extreme, baseless scaremongering, never supported by any research - and completely disregarding any research cited to you.
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on July 11, 2019, 04:22:47 PM

Yes, it would refreeze later than usual, and the ice would be thinner next year with very little multi-year ice. Which would give a much higher probability of another BOE. Probably earlier in the melting season.

The research like Tietsche et al and Schroeder and Connolley
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2007GL030253

suggests that the lack of ice from BOE means little snow can be supported by ice during time when there are reasonable amounts of snow. The ice gets thicker than usual (not thinner) during the freeze season due to lack of insulating snow. After two years it gets back to pretty near normal. This research is covering situation where unusual weather causes a BOE when the climate is not really ready for a BOE yet.

If the climate is ready for a BOE then I would still suggest little snow supported so thicker ice than usual but perhaps this still melts out because more ice but little snow means reduced albedo so perhaps the extra ice still melts out in this situation. However, alternating years of BOE and not is perhaps a possibility.

I think we are a long way from the climate being ready to support BOE occurring frequently.

I think arguing that one BOE causes next year to have longer BOE is like arguing that a record low ice volume means the next year will definitely beat that record. It might seem logical but it just isn't true for record low ice volume and while predicting future is more difficult, it probably isn't true for a BOE either.
Title: Re: When will the Arctic Go Ice Free?
Post by: gerontocrat on July 11, 2019, 04:31:51 PM
One thing we do know, and that is the potential for increased energy capture by ice-free Arctic Seas and progress towards that, courtesy of Tealight. (https://cryospherecomputing.tk/NRTawp)

And it is early melt that contributes the most to achieving that potential. Does that suggest that while a BOE is a natural consequence of AGW in the Arctic, climatic impacts may depend more on ever-increasing energy capture in the years before - like now.
_______________________________________________________________
ps: What will the IPCC 2021 report in 20121 have to say about it (- as we watch the horse that has already bolted several kilometers down the road and the stable door is still open) ?
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 11, 2019, 04:41:27 PM
Quote
Yes, you made clear that YOU THINK that BOE will bring disaster and pretty much and end of all life.

 A BOE will most certainly not cause the end of all life on earth, not by a long shot. Only the end of modern civilization and, overtime, a huge chunk of the human population. Most of nature will be just fine after a few hundred years of climate stability. A scientist 50k years from now will

Quote
You never supported your claims with any literature and disregarded any literature I cited (many times!) even from pretty reliable journals,

Quite the opposite, I have used your links to prove my point. Abrupt climate change happens, and the type of abrupt climate change we are inducing will end our civilization, just like minor changes in Holocene climate ended local human civilizations.

Quote
These show that the changes in the past happened in decades not centuries or millenia and the changes were huge and widespread (Greenland temp change at the end of the last ice age of 8-15 C in a mere decades or years!).

Indeed. I’m not challenging that fact. It is just that you are overlooking the changes that took place at the time. The climate changed, the flora changed, the water cycle changed. If humans of the time had settled at the time, their settlements would have failed.
Title: Re: When will the Arctic Go Ice Free?
Post by: b_lumenkraft on July 11, 2019, 04:45:24 PM
What happened to the hippie generation?

o/
Title: Re: When will the Arctic Go Ice Free?
Post by: Shared Humanity on July 11, 2019, 05:45:53 PM
The abrupt changes in planetary climate that a BOE will bring are not magic. They are simple physics. The Earth has had a planetary refrigerator for likely millions of years. After a BOE that refrigerator fails and the NH will know true climate change. There won't be any denying because we'll be busy surviving.

I'm not arguing against logic here. It is frustrating to see how intelligent people who are aware of the role of arctic sea ice on atmospheric and oceanic patterns can't see the destruction that will ensue as the arctic disappears. The destruction has already started and the Arctic has barely begun to change.

But I may be wrong, so let's get to the science. Find me a paper that describes what happens after the first BOE, that doesn't ignore the ASI teleconections to the rest of the world and predicts a BOE much sooner than 2070.

Good luck with it.

The impacts of a BOE is simply a continuum of what we are already seeing. The very low SIE and SIA we are reaching now are already impacting the weather across the NH. While we define a BOE as less than 1 million square kilometers, NH weather will see no real diffirence between 1.4 and 0.8 million square kilometers.
Title: Re: When will the Arctic Go Ice Free?
Post by: b_lumenkraft on July 11, 2019, 05:54:20 PM
The impacts of a BOE is simply a continuum of what we are already seeing

So much this!

The weather is already weird. I think flooding, droughts, bad harvests, water problems, etc will impact people massively before we even see the real effects of a first BOE.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on July 11, 2019, 06:01:09 PM
The abrupt changes in planetary climate that a BOE will bring are not magic. They are simple physics. The Earth has had a planetary refrigerator for likely millions of years. After a BOE that refrigerator fails and the NH will know true climate change. There won't be any denying because we'll be busy surviving.

I'm not arguing against logic here. It is frustrating to see how intelligent people who are aware of the role of arctic sea ice on atmospheric and oceanic patterns can't see the destruction that will ensue as the arctic disappears. The destruction has already started and the Arctic has barely begun to change.

But I may be wrong, so let's get to the science. Find me a paper that describes what happens after the first BOE, that doesn't ignore the ASI teleconections to the rest of the world and predicts a BOE much sooner than 2070.

Good luck with it.

The impacts of a BOE is simply a continuum of what we are already seeing. The very low SIE and SIA we are reaching now are already impacting the weather across the NH. While we define a BOE as less than 1 million square kilometers, NH weather will see no real diffirence between 1.4 and 0.8 million square kilometers.

Agreed.  It will impact the weather, but as far as a collapse of civilization as we know it, hardly.  Mankind (and nature) is more resilient than many people think.
Title: Re: When will the Arctic Go Ice Free?
Post by: b_lumenkraft on July 11, 2019, 06:17:43 PM
Mankind (and nature) is more resilient than many people think.

Always the optimist, eh?  ;)

Die Hoffnung stirbt zuletzt! (Hope is the last to die)

Title: Re: When will the Arctic Go Ice Free?
Post by: gerontocrat on July 11, 2019, 06:30:37 PM
The abrupt changes in planetary climate that a BOE will bring are not magic. They are simple physics. The Earth has had a planetary refrigerator for likely millions of years. After a BOE that refrigerator fails and the NH will know true climate change. There won't be any denying because we'll be busy surviving.

I'm not arguing against logic here. It is frustrating to see how intelligent people who are aware of the role of arctic sea ice on atmospheric and oceanic patterns can't see the destruction that will ensue as the arctic disappears. The destruction has already started and the Arctic has barely begun to change.

But I may be wrong, so let's get to the science. Find me a paper that describes what happens after the first BOE, that doesn't ignore the ASI teleconections to the rest of the world and predicts a BOE much sooner than 2070.

Good luck with it.

The impacts of a BOE is simply a continuum of what we are already seeing. The very low SIE and SIA we are reaching now are already impacting the weather across the NH. While we define a BOE as less than 1 million square kilometers, NH weather will see no real diffirence between 1.4 and 0.8 million square kilometers.

Agreed.  It will impact the weather, but as far as a collapse of civilization as we know it, hardly.  Mankind (and nature) is more resilient than many people think.
Look at what is happening in Central America, Mexico and the US / Mexico border.
A situation born of Government mismanagement, compounded by AGW.
Now multiply the number of people on the move to the North by 2, 5, 10 ?
You think US border guards can cope? Not going so well at the moment, is it.

How many refugees will drown this summer in the Mediterranean?
Now multiply the number of people on the move by 2, 5, 10 ?

Of course, many humans will survive, but it won't be pretty.
Call that civilisation?
Title: Re: When will the Arctic Go Ice Free?
Post by: nanning on July 11, 2019, 06:38:04 PM
Re:BOE
If the arctic ocean and peripheral seas warm up, the NH weathersystems will change a lot I think.

@gerontocrat
I totally agree with that view.
Title: Re: When will the Arctic Go Ice Free?
Post by: ArcticMelt2 on July 11, 2019, 06:39:25 PM
Mankind (and nature) is more resilient than many people think.

I agree. Even if our planet becomes uninhabited, we can create shelters in space.
Title: Re: When will the Arctic Go Ice Free?
Post by: nanning on July 11, 2019, 06:40:21 PM
Yes, you and magnamentis may be right but I think that it is just wishful thinking on your part. What happened to the hippie generation? The same thing will happen to these young green voters...unfortunately for all of us. But we will most likely see which of us is right soon enough

The hippies didn't have the scientific community and UN behind them.
Title: Re: When will the Arctic Go Ice Free?
Post by: El Cid on July 11, 2019, 06:52:49 PM
I know it is OT (sry) but I attach this chart for gerontocrat regarding drowning in the Mediterranean and the number of migrants.

Truth is migrants arrive mostly (exception: Syrian war refugees) looking for a job and once they are not welcome anymore, they get the message and don't come anymore

Title: Re: When will the Arctic Go Ice Free?
Post by: kassy on July 11, 2019, 07:47:01 PM
I think the BOE timing is also important.

If we hit BOE on the last day of the season we will have a gloomy party but things go on as they go.

If we get a lot of open sea early in those central arctic seas and huge storms there this could mix up lots of heat from the deep. And mix waters. Not sure how much you need to wreck the halocline but the less salty water is from rivers or ice so that might make interesting refreeze patterns in the middle?

Title: Re: When will the Arctic Go Ice Free?
Post by: gerontocrat on July 11, 2019, 07:51:36 PM
I know it is OT (sry) but I attach this chart for gerontocrat regarding drowning in the Mediterranean and the number of migrants.

Truth is migrants arrive mostly (exception: Syrian war refugees) looking for a job and once they are not welcome anymore, they get the message and don't come anymore
The OT continues.

So we create Fortress Europe - just like Trump in the USA.
How civilised.

Does this stop climate / political / economic refugees increasing?
No. They get trapped in appalling conditions in Libya etc etc.
Out of sight, out of mind.
How civilised.
Title: Re: When will the Arctic Go Ice Free?
Post by: aslan on July 11, 2019, 08:01:08 PM
Sorry to quote myself but the end of the thinking woul have been too much off topic I think :

To add to the discussion about the begining of the end, June 2019 was the warmest month of June regarding SST in Bering sea and Bering strait according to reanalysis.
Aans as an illustration, Kotzebue is near or above record Tn and Td since 4 days : http://ogimet.com/cgi-bin/gsynres?ind=70133&ano=2019&mes=7&day=11&hora=12&min=0&ndays=30

The transport is strong this year trough the strait, and so the SST are more asymetric than usual, but despite this all the Bering sea and Chuckchi sea are at or above record level, and strong currents are burring this heat to great depth. The chart from the DMI is now saturated with red, after reaching a "low" the 4th. An incredible amount of heat is building into Arctic Ocean, and is now wanting to ease.

In 2009 Eisenman published a paper : https://www.pnas.org/content/106/1/28.short which was later criticized : https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2011GL048739 or https://journals.ametsoc.org/doi/full/10.1175/JCLI-D-14-00654.1 but not fully rejected : https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2011JD015653

In the same time, with lower sea ice cover, there is an increase in cloud cover in Autumn and Winter, acting as a positive feedback insulating the open ocean below.

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2010JD013900

I think we are nearer and nearer to the point where open ocean, increase poleward oceanic heat flux, and increase SST, will make the system unstable. As a warm, sunny, open Arctic in Spring and Summer will build up a lot of energy. In Autumn and Winter, warm ocean, help by poleward heat transport, will moisten the atmospheric column, with an increase in low clouds, insulating the Ocean and allowing the heat build up in Summer to be lost slowly. As the next Summer comes, even though the weather is the friend of ice, as there is no more ice, heat can build up again in the system -and it is quite unlikely to see low cloud cover increased in Summer as in Winter- and bringing the all Arctic to a state change.
Title: Re: When will the Arctic Go Ice Free?
Post by: Glen Koehler on July 11, 2019, 08:18:52 PM
BOE-year: "aaaah, blue ocean" "oh, nothing happens, it just refreezes"
BOE-year+1: "oh, again blue ocean" and we will have some weird weather, but those are just 'incidents'
BOE-year+2: "that's weird, 3rd BOE in a row and too early" and weather patterns become unpredictable in northern hemisphere with lots of extreme weather and reality finally sinks in

 :) Yup, human adaptability is huge with both good and bad consequences.

    Wipneus monthly volume chart ...
 https://14adebb0-a-62cb3a1a-s-sites.googlegroups.com/site/arctischepinguin/home/piomas/grf/piomas-trnd2.png?attachauth=ANoY7crjDWOoXxuYh--3XZJMMEyECWySrgq9Q6TOUN13dC9ljMI_ZkqhIWoNNcgTFYxBjLxvMe3STZLbt3k6bd0GwBpqzGkzohemPAA3GvfzG6SssxfZyFH-g31mVYUi2ry5mVuUDXgqskqLyP-DxntNev3GJXMUYPhCqQkciQp6wMWdg2ZwozcLhLTUP5cobWGW4oqexYFgcc5c_0LIY1S59DGxmZW-Fjn61fUNUVGaZPJ2bmTzGpCSJLsnGmLbSmB9feyuhBT_&attredirects=0 (https://14adebb0-a-62cb3a1a-s-sites.googlegroups.com/site/arctischepinguin/home/piomas/grf/piomas-trnd2.png?attachauth=ANoY7crjDWOoXxuYh--3XZJMMEyECWySrgq9Q6TOUN13dC9ljMI_ZkqhIWoNNcgTFYxBjLxvMe3STZLbt3k6bd0GwBpqzGkzohemPAA3GvfzG6SssxfZyFH-g31mVYUi2ry5mVuUDXgqskqLyP-DxntNev3GJXMUYPhCqQkciQp6wMWdg2ZwozcLhLTUP5cobWGW4oqexYFgcc5c_0LIY1S59DGxmZW-Fjn61fUNUVGaZPJ2bmTzGpCSJLsnGmLbSmB9feyuhBT_&attredirects=0)

    ... shows that August (and October) only trail September by about 2 years.  Since September is pretty flat on the volume curve, it doesn't seem like it would take too many years for a BOE day in September to lead to a full month September BOE.  Then, with the usual annual variations adding a few years of noise, we might have a BOE for much of August.  And that would create some serious albedo change and create a new "melting momentum" that might not be polite enough to stop by the time we notice. 

     In recent interview Peter Wadhams threw out a concept I hadn't heard before.  With continued loss of ASI there could be a tipping point where polar jet stream doesn't just weaken and wobble, but just goes away completely.  I don't know if that is at all realistic, but if it did happen it would seem to be like Jennifer Francis thesis on steroids, with potential drastic changes in weather patterns, or just weather chaos until new patterns emerged.  I guess there's always a pattern, but if there was a complete loss of polar jet stream steering of weather systems that just seems like crazy town.
Title: Re: When will the Arctic Go Ice Free?
Post by: pietkuip on July 11, 2019, 09:16:56 PM
In recent interview Peter Wadhams threw out a concept I hadn't heard before.  With continued loss of ASI there could be a tipping point where polar jet stream doesn't just weaken and wobble, but just goes away completely.
I suppose that would be the single large Hadley cell extending from equator to pole? As in hothouse paleoclimates.
Title: Re: When will the Arctic Go Ice Free?
Post by: HapHazard on July 11, 2019, 09:21:07 PM
Yep, it's the atmospheric effects that concern me most, going forward. (jet streams, hadley cell)
Title: Re: When will the Arctic Go Ice Free?
Post by: jdallen on July 11, 2019, 09:35:52 PM
Find me a paper that describes what happens after the first BOE...
That seems to be very uncertain. The IPCC states "with high confidence" that there will be no hysteresis ...
<snippage>
I think we're already seeing hysteresis with changes in feedback and increased uptake of heat, not to mention the extermination of ice more than 4 years old.  It would take generations of pre-1980's weather to restore the pack to the state it was in before 2010, much less earlier.
Title: Re: When will the Arctic Go Ice Free?
Post by: Tom_Mazanec on July 12, 2019, 02:29:31 AM
 A BOE will most certainly not cause the end of all life on earth, not by a long shot. Only the end of modern civilization and, overtime, a huge chunk of the human population. Most of nature will be just fine after a few hundred years of climate stability. A scientist 50k years from now will


Archimid, your prediction cut off in mid-sentence. What was it?
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 12, 2019, 03:45:15 AM

The research like Tietsche et al and Schroeder and Connolley
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2007GL030253

I asked for a resource with a BOE before 2070 for a good reason. If the model that you use says the arctic will have ice in the summer 50 years from now, that model is missing something huge, a BOE will happen much sooner than that. Thus a model that has the ice going by 2070 is very likely to assume the ice will return, because it is already underestimating the changes happening in the Arctic.

The paper you posted uses HadCM3. From a quick search HadCM3 predicts ice free during summer somewhere around 2080. That ain't happening. Please try a newer source, with a model that makes a prediction for the first BOE that more closely matches the observations.

Quote
suggests that the lack of ice from BOE means little snow can be supported by ice during time when there are reasonable amounts of snow. The ice gets thicker than usual (not thinner) during the freeze season due to lack of insulating snow.

I don't understand. Can you explain to me how can there be conditions for sea ice formation but no condition for snow? It seems the opposite will happen. There will be more snow than ever before. By your own argument that should result in warming. The data clearly indicates that snow fall during fall is increasing.

Quote
  After two years it gets back to pretty near normal. This research is covering situation where unusual weather causes a BOE when the climate is not really ready for a BOE yet.

Actually, this research is covering an imaginary situation where the first BOE happens close to 2080.

Quote
I think arguing that one BOE causes next year to have longer BOE is like arguing that a record low ice volume means the next year will definitely beat that record.

All things being equal, a record low volume increases the chances of a lower volume next year for the mere fact of having a lower starting point. But the argument of  why the first BOE highly increases the chances of a BOE the year after is much more nuanced than that and with better fundamentals.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 12, 2019, 04:09:06 AM
The impacts of a BOE is simply a continuum of what we are already seeing. The very low SIE and SIA we are reaching now are already impacting the weather across the NH. While we define a BOE as less than 1 million square kilometers, NH weather will see no real diffirence between 1.4 and 0.8 million square kilometers.

I agree that it is a continuum. It has already started. From now on things only get worse as more open Arctic is warmed and the atmospheric currents start running amok. Things get progressively worse as ASI shrinks during summer and the Arctic winter keeps its meteoric temperature increase. By the time a BOE is here ( excluding sudden BOE) we'll be in enough trouble. But a BOE makes things worse, much worse. The year after the first BOE, by definition there will only be first year ice.  It will lead to another BOE , but earlier, and with more heat to dissipate before freezing begins. This will warm the Arctic faster than it is warming now, with global consequences to match.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 12, 2019, 04:16:56 AM
A BOE will most certainly not cause the end of all life on earth, not by a long shot. Only the end of modern civilization and, overtime, a huge chunk of the human population. Most of nature will be just fine after a few hundred years of climate stability. A scientist 50k years from now will


Archimid, your prediction cut off in mid-sentence. What was it?

My apologies, I thought I deleted that. I was trying to make a point that a scientist long into the future will not know about our abrupt climate change problem because they will be surrounded by green, just like we are today. They might assume that because it is green and there is life around them humanity's climate change problem never happened.
Title: Re: When will the Arctic Go Ice Free?
Post by: nanning on July 12, 2019, 05:53:21 AM
<snippage>
     In recent interview Peter Wadhams threw out a concept I hadn't heard before.  With continued loss of ASI there could be a tipping point where polar jet stream doesn't just weaken and wobble, but just goes away completely.  I don't know if that is at all realistic, but if it did happen it would seem to be like Jennifer Francis thesis on steroids, with potential drastic changes in weather patterns, or just weather chaos until new patterns emerged.  I guess there's always a pattern, but if there was a complete loss of polar jet stream steering of weather systems that just seems like crazy town.
Hi Glen, I'd like to read/listen to this interview. Do you perhaps have a link?
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on July 12, 2019, 12:43:46 PM


I asked for a resource with a BOE before 2070 for a good reason. If the model that you use says the arctic will have ice in the summer 50 years from now, that model is missing something huge, a BOE will happen much sooner than that. Thus a model that has the ice going by 2070 is very likely to assume the ice will return, because it is already underestimating the changes happening in the Arctic.

The paper you posted uses HadCM3. From a quick search HadCM3 predicts ice free during summer somewhere around 2080. That ain't happening. Please try a newer source, with a model that makes a prediction for the first BOE that more closely matches the observations.

You might want a newer source and better model, but basically tough: If it doesn't exist, then you are not going to get it. If there are two papers saying the same thing, then another paper is unlikely to be published unless it is saying something markedly different.

Quote
Quote
suggests that the lack of ice from BOE means little snow can be supported by ice during time when there are reasonable amounts of snow. The ice gets thicker than usual (not thinner) during the freeze season due to lack of insulating snow.

I don't understand. Can you explain to me how can there be conditions for sea ice formation but no condition for snow? It seems the opposite will happen. There will be more snow than ever before. By your own argument that should result in warming. The data clearly indicates that snow fall during fall is increasing.

I agree there will be more snow fall, but if this falls on open water because the ice hasn't formed yet then the snow is not supported by ice and melts in ocean rather than persisting. I do find the conclusion slightly odd in that I expect the snow season to be extended until surrounding area is mostly ice covered. So perhaps the effect is that the minimum of the season becomes broad and flatish but with the freeze over happening later then it happens faster. This leaves a shorter period when the ice is able to support snow and there is reasonable amounts of snow falling.

Not sure of my mechanism described above, but the models seem to predict it and they are much more likely to include lots of things we are unlikely to be able to accurately describe.


Quote
Quote
  After two years it gets back to pretty near normal. This research is covering situation where unusual weather causes a BOE when the climate is not really ready for a BOE yet.

Actually, this research is covering an imaginary situation where the first BOE happens close to 2080.

The models are far from perfect and 2080 does seem late. But they are better than nothing, you have to work with the tools you have got not the ones you would like, and the models show the same thing for 2020 2040 and 2060. If you think it is happening faster, why is there anything much wrong with treating 2060 as if it is just an incorrect label and that is more representative of maybe 2025?

Quote
Quote
I think arguing that one BOE causes next year to have longer BOE is like arguing that a record low ice volume means the next year will definitely beat that record.

All things being equal, a record low volume increases the chances of a lower volume next year for the mere fact of having a lower starting point. But the argument of  why the first BOE highly increases the chances of a BOE the year after is much more nuanced than that and with better fundamentals.

We didn't get new record in year following 2012, 2007, ... Better fundamentals, yes in direction I am arguing IMO, but you just choose to question/dismiss.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 12, 2019, 01:00:29 PM
Quote
But they are better than nothing, you have to work with the tools you have got not the ones you would like, and the models show the same thing for 2020 2040 and 2060.

Let me be very clear about this. In the model that predicts a BOE by 2080, if you instantly remove the ice in 2020, 2040, or 2060 the ice immediately comes back. Well of course it does. The model is underestimating melt and/or overestimating freeze.

A wrong model is worse than nothing, if you make decisions according to the wrong model.

However, as the arctic keeps changing and showing scientist new secrets, I'm sure that better models will emerge.

Quote
You might want a newer source and better model, but basically tough: If it doesn't exist, then you are not going to get it. If there are two papers saying the same thing, then another paper is unlikely to be published unless it is saying something markedly different.

You don't think missing the first BOE by 4 decades (possibly more) is something markedly different?
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on July 12, 2019, 01:44:13 PM
Just because a model is wrong or very poor on one topic doesn't mean the model is useless at everything.

The models are all over the place on when we get a BOE. So you would be crazy to trust them on that.

OTOH if several models are showing at several different attempts that there is no hyteresis and reliably show they are more likely to bounce back the following period after an unusual disturbance, what then should you conclude?

Should you cautiously trust them on such matters or throw the baby out with the bathwater leaving yourself nothing to rely on?

If you choose the latter, there doesn't seem much more to say.

We don't trust long term weather forecasts but climate models are useful. This is nothing more than working out when and when not to trust such models.

Quote
You don't think missing the first BOE by 4 decades (possibly more) is something markedly different?

If the paper is on the topic of when the first BOE will be, the models are all over the place so one new model saying something different doesn't seem particularly new or important.

If the paper is on the topic of what happens after instantaneous removal of sea ice then what happens after instantaneous removal has to be markedly different to make it markedly different.




Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on July 12, 2019, 01:55:51 PM
The abrupt changes in planetary climate that a BOE will bring are not magic. They are simple physics. The Earth has had a planetary refrigerator for likely millions of years. After a BOE that refrigerator fails and the NH will know true climate change. There won't be any denying because we'll be busy surviving.

I'm not arguing against logic here. It is frustrating to see how intelligent people who are aware of the role of arctic sea ice on atmospheric and oceanic patterns can't see the destruction that will ensue as the arctic disappears. The destruction has already started and the Arctic has barely begun to change.

But I may be wrong, so let's get to the science. Find me a paper that describes what happens after the first BOE, that doesn't ignore the ASI teleconections to the rest of the world and predicts a BOE much sooner than 2070.

Good luck with it.

The impacts of a BOE is simply a continuum of what we are already seeing. The very low SIE and SIA we are reaching now are already impacting the weather across the NH. While we define a BOE as less than 1 million square kilometers, NH weather will see no real diffirence between 1.4 and 0.8 million square kilometers.

I found this analysis of a BOE event to be rather informative.

https://climatetippingpoints.info/2019/04/02/fact-check-will-an-ice-free-arctic-trigger-a-climate-catastrophe/
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on July 12, 2019, 05:57:13 PM
I found this analysis of a BOE event to be rather informative.

https://climatetippingpoints.info/2019/04/02/fact-check-will-an-ice-free-arctic-trigger-a-climate-catastrophe/

Nice but surprisingly little about negative winter ice thickness/insulation negative feedback.
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on July 12, 2019, 06:17:09 PM
Global warming of 1.5C IPCC draft report, sorry if this has been quoted and discussed before. Probably not supposed to quote it yet but at this level and if it is available....

Quote
11 3.3.8 Sea ice
12
13 Summer sea ice in the Arctic has been retreating rapidly in recent decades. During the period 1997 to 2014
14 for example, the monthly mean sea-ice extent during September decreased on average by 130,000 km² per
15 year (Serreze and Stroeve, 2015). This is about four times as fast as the September sea-ice loss during the
16 period 1979 to 1996. Also sea-ice thickness has decreased substantially, with an estimated decrease in ice
17 thickness of more than 50% in the central Arctic (Lindsay and Schweiger, 2015). Sea-ice coverage and
18 thickness also decrease in CMIP5-model simulations of the recent past, and are projected to decrease in the
19 future (Collins et al., 2013). However, the modeled sea-ice loss in most CMIP5 models is much weaker
20 than observed. Compared to observations, the simulations are weak in terms of their sensitivity to both
21 global mean temperature rise (Rosenblum and Eisenman, 2017) and to anthropogenic CO2 emissions (Notz
22 and Stroeve, 2016). This mismatch between the observed and modeled sensitivity of Arctic sea ice implies
23 that the multi-model-mean response of future sea-ice evolution probably underestimates the sea-ice loss for
24 a given amount of global warming. To address this issue, studies estimating the future evolution of Arctic
25 sea ice tend to bias correct the model simulations based on the observed evolution of Arctic sea ice in
26 response to global warming. Often based on such bias correction, pre-AR5 and post-AR5 studies agree that
27 for 1.5 °C global warming relative to pre-industrial levels, the Arctic Ocean will maintain a sea-ice cover
28 throughout summer for most years (Collins et al., 2013; Notz and Stroeve, 2016; Screen and Williamson,
29 2017; Jahn, 2018; Niederdrenk and Notz, 2018; Sigmond et al., 2018). For 2°C global warming relative to
30 pre-industrial levels, chances of an ice-free Arctic during summer are substantially higher (Screen and
31 Williamson, 2017; Jahn, 2018; Niederdrenk and Notz, 2018; Screen et al., 2018; Sigmond et al., 2018). The
32 Arctic is very likely to have experienced at least one ice-free Arctic summer after about 10 years of
33 stabilized warming at 2°C compared to after about 100 years of stabilized warming at 1.5°C (Jahn, 2018;
34 Screen et al., 2018; Sigmond et al., 2018). For a specific given year under stabilized warming of 2°C,
35 studies based on large ensembles of simulations with a single model estimate the likelihood for ice-free
36 conditions as 35% without a bias correction of the underlying model (Sanderson et al., 2017; Jahn, 2018);
37 as between 10% and >99% depending on the observational record used to correct the sensitivity of sea ice
38 decline to global warming in the underlying model (Niederdrenk and Notz, 2018); and as 19% based on a
39 procedure to correct for biases in the climatological sea ice coverage in the underlying model (Sigmond et
40 al., 2018). The uncertainty of the first year of the occurrence of an ice-free Arctic Ocean arising from
41 internal variability is estimated to be about 20 years (Notz, 2015; Jahn et al., 2016).
42
43 The more recent estimates of the warming necessary to achieve an ice-free Arctic Ocean during summer are
44 lower than the ones given in AR5 (about 2.6C-3.1C relative to preindustrial or 1.6C-2.1C global
45 warming relative to the present day), which was similar to the estimate of 3C relative to preindustrial
46 levels (or 2C global warming relative to the present day) by Mahlstein and Knutti (2012) based on bias47 corrected CMIP3 models. Rosenblum and Eisenman (2016) explain why the sensitivity estimated by


1 Mahlstein and Knutti (2012) might be too low, estimating instead that September sea ice in the Arctic
2 disappears for 2°C relative to preindustrial (or about 1°C global warming relative to the present day), in line
3 with the other recent estimates. Notz and Stroeve (2016) use the observed correlation between September
4 sea-ice extent and cumulative CO2 emissions to estimate that the Arctic Ocean would become nearly sea5 ice-free during September with a further 1000 Gt of emissions, which also implies a sea-ice loss at about
6 2°C global warming. Some of the uncertainty in these numbers derives from the possible impact of aerosols
7 (Gagne et al., 2017) and of volcanic forcing (Rosenblum and Eisenman, 2016). During winter, little Arctic
8 sea ice is projected to be lost for either 1.5°C or 2ºC global warming (Niederdrenk and Notz, 2018).
9
10 Regarding the behavior of Arctic sea ice under decreasing temperatures following a possible overshoot of a
11 long-term temperature target, a substantial number of pre-AR5 studies have found that there is no indication
12 of hysteresis behavior of Arctic sea ice (Holland et al., 2006; Schroeder and Connolley, 2007; Armour et
13 al., 2011; Sedláček et al., 2011; Tietsche et al., 2011; Boucher et al., 2012; Ridley et al., 2012). In
14 particular, the relationship between Arctic sea-ice coverage and GMST is found to be indistinguishable
15 between a warming scenario and a cooling scenario. These results have been confirmed by post-AR5
16 studies (Li et al., 2013; Jahn, 2018), which implies high confidence that an intermediate temperature
17 overshoot has no long-term consequences for Arctic sea-ice coverage.

While more on the consequences of loss of sea ice, the discussion is as follows:

Quote
33 Loss of sea ice
34 Sea ice has been a persistent feature of the planet’s polar regions (Polyak et al., 2010) and is central to
35 marine ecosystems, people (e.g. food, culture and livelihoods) and industries (e.g. fishing, tourism, oil and
36 gas, and shipping). Summer sea ice in these regions (e.g. Arctic, Antarctic and Southern Ocean), however,
37 has been retreating rapidly in recent decades (Section 3.3.8) with an assessment of the literature revealing
38 that a fundamental transformation is occurring in polar organisms and ecosystems driven by climate change
39 (high agreement, robust evidence) (Larsen et al., 2014). These changes are strongly affecting people in the
40 Arctic who have close relationships with sea ice and associated ecosystems, and are facing major adaptation
41 challenges as a result of sea level rise, coastal erosion, the accelerated thawing of permafrost, changing
42 ecosystems and resources, and many other issues (Ford, 2012; Ford et al., 2015).
43
44 There is considerable and compelling evidence that a further increase of 0.5°C from today in average global
45 surface temperature will lead to multiple levels of impact on a variety of organisms - from phytoplankton to
46 marine mammals some of the most dramatic changes occurring in the Arctic Ocean and Western Antarctic
47 Peninsula (Turner et al., 2014, 2017b; Steinberg et al., 2015; Piñones and Fedorov, 2016).

1
2 The impacts of climate change on sea ice is part of the focus of the IPCC Special Report on the Ocean and
3 Cryosphere in a Changing Climate (SROCC), due to be released in 2019. Therefore, without intending to be
4 comprehensive, there are a range of responses to the loss of sea ice that are occurring and are likely to
5 increase at 1.5°C and 2°C of global warming. Photosynthetic communities such macroalgae, phytoplankton,
6 and microalgae dwelling on the underside of floating sea ice are changing due to increased temperatures,
7 light, and nutrient levels. As sea ice retreats, mixing of the water column increases, and phototrophs have
8 increased access to seasonally high levels of solar radiation (Dalpadado et al., 2014; W.N. Meier et al., 2014)
9 (medium agreement, medium evidence). These changes are very likely to stimulate fisheries productivity in
10 high latitude regions by mid-century (Cheung et al., 2009, 2010, 2016b; Lam et al., 2014), with evidence of
11 this is already happening for several fisheries species in high latitude regions in the northern hemisphere
12 such as the Bering Sea, although these ‘positive’ impacts may be relatively short-lived (Hollowed and
13 Sundby, 2014; Sundby et al., 2016). In addition to the impact of climate change on fisheries via impacts on
14 NPP, there are also direct effects of temperature on fish, which may have a range of impacts (Pörtner et al.,
15 2014). Sea ice in Antarctica is undergoing changes that exceed those seen in the Arctic (Maksym et al.,
16 2011; Reid et al., 2015) with increases in sea ice coverage in the western Ross Sea being accompanied by
17 strong decreases in the Bellingshausen and Amundsen seas (Hobbs et al., 2016). While Antarctica is not
18 permanently populated, the ramifications of changes to the productivity of vaste regions such as the Southern
19 Ocean has substantial implications as far as ocean foodwebs and fisheries are concerned.
Title: Re: When will the Arctic Go Ice Free?
Post by: gerontocrat on July 12, 2019, 06:30:08 PM
Global warming of 1.5C IPCC draft report, sorry if this has been quoted and discussed before. Probably not supposed to quote it yet but at this level and if it is available....

Quote
In particular, the relationship between Arctic sea-ice coverage and GMST is found to be indistinguishable  between a warming scenario and a cooling scenario. These results have been confirmed by post-AR5 studies (Li et al., 2013; Jahn, 2018), which implies high confidence that an intermediate temperature overshoot has no long-term consequences for Arctic sea-ice coverage.
In other words, it seems likely that IPCC will accept that a temperature overshoot will occur, but no matter, "We have the technology, we can rebuild the climate". A bit of BECCS here, a bit of Direct Carbon Capture there, and everything will be fixed.

Oh well, one can dream.



Title: Re: When will the Arctic Go Ice Free?
Post by: pietkuip on July 12, 2019, 07:48:18 PM
Global warming of 1.5C IPCC draft report, sorry if this has been quoted and discussed before. Probably not supposed to quote it yet but at this level and if it is available....
Quote
Often based on such bias correction, pre-AR5 and post-AR5 studies agree that for 1.5 °C global warming relative to pre-industrial levels, the Arctic Ocean will maintain a sea-ice cover throughout summer for most years.
And we are not at global 1.5 °C global warming now.  Is it truthful to say that the Arctic Ocean is "maintaining a sea ice cover"?
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on July 12, 2019, 11:37:02 PM
And we are not at global 1.5 °C global warming now.  Is it truthful to say that the Arctic Ocean is "maintaining a sea ice cover"?

Hmm. I am thinking you have a point and the language needs to be tightened up: Does Arctic Ocean include the surrounding seas?

Also is "will maintain a sea-ice cover throughout summer for most years" being used as just the opposite of "an ice-free Arctic during summer" and hence former includes partial coverage during summer or is partial coverage a separate category that isn't discussed and hence excluded from 'maintaining cover throughout summer for most years' category?

If a 3 category interpretation, then what is written seems wrong, or if seas are excluded, highly likely to be wrong before 1.5C is reached.
Title: Re: When will the Arctic Go Ice Free?
Post by: Pragma on July 13, 2019, 12:27:06 AM
Hmm. I am thinking you have a point and the language needs to be tightened up: Does Arctic Ocean include the surrounding seas?

Also is "will maintain a sea-ice cover throughout summer for most years" being used as just the opposite of "an ice-free Arctic during summer" and hence former includes partial coverage during summer or is partial coverage a separate category that isn't discussed and hence excluded from 'maintaining cover throughout summer for most years' category?

If a 3 category interpretation, then what is written seems wrong, or if seas are excluded, highly likely to be wrong before 1.5C is reached.

Just like caveats about the limitations of various measurement methods, we need to remind ourselves of the fact that IPPC documents are essentially political statements.

After the scientists have had their say, the politicians, bureaucrats and diplomats take over and nothing gets put into the final report unless there is consensus.

When you couple this with the fact that most reports are at least five years old, they are out of touch with reality, and I would say for some, intentionally so.

The result is an anodyne word salad that should be taken with a large grain of salt.

It will be, however, a good document for whatever generations come after us, about how we said a great deal and accomplished little.
Title: Re: When will the Arctic Go Ice Free?
Post by: Ardeus on July 13, 2019, 01:54:58 AM
<snippage>
     In recent interview Peter Wadhams threw out a concept I hadn't heard before.  With continued loss of ASI there could be a tipping point where polar jet stream doesn't just weaken and wobble, but just goes away completely.  I don't know if that is at all realistic, but if it did happen it would seem to be like Jennifer Francis thesis on steroids, with potential drastic changes in weather patterns, or just weather chaos until new patterns emerged.  I guess there's always a pattern, but if there was a complete loss of polar jet stream steering of weather systems that just seems like crazy town.
Hi Glen, I'd like to read/listen to this interview. Do you perhaps have a link?

I am not sure if Glen was referring to this interview I did, but he did consider the possibility of the jetstream going away. I used a few minutes of this interview in a doc about Lake Tanganyika.

https://youtu.be/fPEUfc965i8
Title: Re: When will the Arctic Go Ice Free?
Post by: nanning on July 13, 2019, 07:07:24 AM
Thanks Ardeus.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on July 13, 2019, 02:45:13 PM
Hmm. I am thinking you have a point and the language needs to be tightened up: Does Arctic Ocean include the surrounding seas?

Also is "will maintain a sea-ice cover throughout summer for most years" being used as just the opposite of "an ice-free Arctic during summer" and hence former includes partial coverage during summer or is partial coverage a separate category that isn't discussed and hence excluded from 'maintaining cover throughout summer for most years' category?

If a 3 category interpretation, then what is written seems wrong, or if seas are excluded, highly likely to be wrong before 1.5C is reached.

Just like caveats about the limitations of various measurement methods, we need to remind ourselves of the fact that IPPC documents are essentially political statements.

After the scientists have had their say, the politicians, bureaucrats and diplomats take over and nothing gets put into the final report unless there is consensus.

When you couple this with the fact that most reports are at least five years old, they are out of touch with reality, and I would say for some, intentionally so.

The result is an anodyne word salad that should be taken with a large grain of salt.

It will be, however, a good document for whatever generations come after us, about how we said a great deal and accomplished little.

Wow!  I thought I was the only one that felt that way.
Title: Re: When will the Arctic Go Ice Free?
Post by: Glen Koehler on July 13, 2019, 03:54:47 PM
Thanks Ardeus.  Yes that is the one.  The jet stream part starts aroud 12:00.
(And thanks for doing the interview.)

 "Just Have A Think" also did a 4-part interview with Wadhams.  In part 1 he briefly discusses jet stream impact (starting at about 8:30).  https://www.youtube.com/watch?v=q8-dTG3H434 (https://www.youtube.com/watch?v=q8-dTG3H434)
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 14, 2019, 10:48:25 AM
Thanks Crandles. My response, quotes edited for legibility.

Quote
However, the modeled sea-ice loss in most CMIP5 models is much weaker than observed. Compared to observations, the simulations are weak in terms of their sensitivity to both global mean temperature rise (Rosenblum and Eisenman, 2017) and to anthropogenic CO2 emissions (Notz and Stroeve, 2016).

That makes perfect sense. Arctic sea ice is decreasing faster than the models predict because influence from positive feedbacks like albedo warming, intrusions of hot air and winter cloudiness are overtaking both the global warming signature and the CO2 signature.

Quote
This mismatch between the observed and modeled sensitivity of Arctic sea ice implies that the multi-model-mean response of future sea-ice evolution probably underestimates the sea-ice loss for a given amount of global warming.

The first mistake is to associate Arctic Sea Ice with global temperatures. If Antarctica cooled 10C and the Arctic warmed 10C the Arctic would melt with zero degrees of global warming.

Quote
To address this issue, studies estimating the future evolution of Arctic Sea Ice tend to bias correct the model simulations based on the observed evolution of Arctic sea ice in response to global warming.

Bias correct... I honestly don't know exactly what that means, but that never stopped me from speculating before, so here we go.

I assume bias correction involves tinkering with parameters and functions until the model produces a better match for the observations. Then the future results are expected to produce better result. If that's the case, I understand the scientific validity and necessity of bias correction. It is a process of perpetual improvement.

Quote
Often based on such bias correction, pre-AR5 and post-AR5 studies agree that for 1.5 °C global warming relative to pre-industrial levels, the Arctic Ocean will maintain a sea-ice cover throughout summer for most years

Bias correcting a model that has the wrong shape (strait line vs exponential) will still produce the wrong result. How do we know if the model has the wrong shape?  We don't, unless a model with a different shape shows better skill.

But what if a different shape can only be resolved adding so many variable that the model can't be computed? Or what if assumptions taken as invariable because of hundreds of years of climate data are no longer valid when the climate changes? Unknown unknowns.

Quote
In particular, the relationship between Arctic sea-ice coverage and GMST is found to be indistinguishable between a warming scenario and a cooling scenario. These results have been confirmed by post-AR5 studies (Li et al., 2013; Jahn, 2018), which implies high confidence that an intermediate temperature overshoot has no long-term consequences for Arctic sea-ice coverage.

So I went looking for the confirmation studies and found what I believe to be Jahn, 2018. This is part of the abstract:

Quote
For warming above 2 °C, frequent ice-free conditions can be expected, potentially for several months per year. Although sea-ice loss is generally reversible for decreasing temperatures, sea ice will only recover to current conditions if atmospheric CO2 is reduced below present-day concentrations.

https://www.nature.com/articles/s41558-018-0127-8


This paper says that the ice will be gone 2 months during summer,  so from mid July to mid September, but there will be no hysteresis. That is quite simply unbelievable and it doesn't even pass a sanity check.

Even more unbelievable is "sea ice will only recover to current conditions if atmospheric CO2 is reduced below present-day concentrations."

The sea ice disappearance might have started because of CO2, but the acceleration of sea ice loss is not because of CO2, as the failure of the models prove. The loss of sea ice is now mostly do to albedo feedback, jetstream destabilization and local Arctic GHG, not CO2. Reducing CO2 back to historic levels will eventually restore the ice, but that will take decades or centuries.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 14, 2019, 11:13:41 AM
On the consequences of a BOE according to Crandles post:

Quote
These changes are very likely to stimulate fisheries productivity in high latitude regions by mid-century

Absolute madness. I totally believe that fish population may increase in the arctic because of warmer water and better light. However that is almost an irrelevant fact, relative with the myriad of changes that are happening as the Arctic melts.

This mentions nothing about changes in atmospheric currents that are already beginning, nor oceanic currents, nor acceleration of Greenland melt, nor forest fires, nor methane release...

Really, this part of the document is a work of fiction. It mentions possible positive feedbacks but it ignores possible negative impacts. This document misleads the proper risk assessment of the Arctic.
Title: Re: When will the Arctic Go Ice Free?
Post by: gerontocrat on July 14, 2019, 12:19:53 PM
On the consequences of a BOE according to Crandles post:

Quote
These changes are very likely to stimulate fisheries productivity in high latitude regions by mid-century

Absolute madness. I totally believe that fish population may increase in the arctic because of warmer water and better light. However that is almost an irrelevant fact, relative with the myriad of changes that are happening as the Arctic melts.

This mentions nothing about changes in atmospheric currents that are already beginning, nor oceanic currents, nor acceleration of Greenland melt, nor forest fires, nor methane release...

Really, this part of the document is a work of fiction. It mentions possible positive feedbacks but it ignores possible negative impacts. This document misleads the proper risk assessment of the Arctic.
"I totally believe that fish population may increase in the arctic because of warmer water and better light."

I think even that is totally optimistic. Ice covered sea does not cover a life-free ocean.

Concerning the Antarctic:-
Quote
Krill are a key part of the delicate Antarctic food chain. They feed on marine algae and are a key source of food for whales, penguins and seals. ... ...the ice that is home to the algae and plankton on which krill feed is retreating

I guess the algae and plankton in the Arctic form the base of a food-web that will be severely impacted by retreat of ice. The guy who wrote this stuff for the IPCC probably has not even 1.01 knowledge of the Arctic food-web.

It is an unfortunate fact that some scientists who are justifiably renowned experts in a specialised field sometimes feel the need to make pronouncements on other fields in which their expertise is - zilch
_______________________________________________________________
one google hit later.... Thin ice promotes phytoplankton, then zero ice reduces phytoplankton ?

https://www.newscientist.com/article/dn21893-plankton-under-sea-ice-may-disrupt-arctic-food-chain/
Plankton under sea ice may disrupt Arctic food chain
EARTH 7 June 2012

Quote
The water beneath a snow-covered expanse of ice 1 metre thick hardly seems like a good home for light-loving creatures. But microscopic phytoplankton, which rely on the sun for their nutrients and form the base of Arctic food webs, have managed to thrive under ice sheets that are thinning as the poles become warmer.

The buried “bloom” of phytoplankton – the largest ever found underneath an ice shelf – was four times more concentrated than blooms found in the open ocean. Some say its discovery could mark the first major change in the Arctic ecosystem as a result of climate change.

“We had no clue [they existed],” says Kevin Arrigo of Stanford University in Stanford, California, although he says researchers had found hints of blooms under the ice in the past.

Remote sensing technology, which monitors ocean life from space, cannot detect blooms through the ice. Arrigo and other researchers came across the bloom by accident on a cruise in Alaska’s Chukchi Sea. Their icebreaker was cutting through ice that was only 1 metre thick – compared to the 3-metre thickness in the past – and was pockmarked with pools of melted ice, which allow light through.

What is most amazing, Arrigo says, is that the column of phytoplankton extended downwards for 70 metres and was extremely dense. “It was like pea soup,” he says, “and not a lot of light gets through pea soup.”

Although rarely seen, under-ice blooms such as this one are almost certainly widespread. Arrigo says that most of the Arctic has the right conditions of shallow waters and nutrients. But finding out just how prevalent they are and when they bloom may prove difficult. “A ship is a needle in the haystack,” says Jean-Éric Tremblay of Université Laval in Quebec, Canada. He suggests that researchers might need to use multiple methods, such as sampling buoys, to detect them in the future.

It’s important we try, though. Although no one knows for sure how often blooms occurred under ice sheets in the past, they will probably bloom earlier in the year as the ice sheet thins and completes its summer cycle earlier and earlier, Arrigo says.

This could throw off the timing of the entire Arctic food web. When the ice sheet melts in the spring, zooplankton move into areas of open water to feed on phytoplankton, and in turn become food for fish. If they follow the seasons rather than the phytoplankton blooms, they may arrive too late.

Larger animals that feed directly on phytoplankton might be even more affected. “A whale in Baja California has no way of knowing the bloom will happen a month earlier this year and can’t get there any faster,” says Arrigo.

“These blooms could perhaps be one of the first major responses we can see with climate change,” says C.J. Mundy of the University of Manitoba in Winnipeg, Canada.
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on July 14, 2019, 12:42:36 PM

The first mistake is to associate Arctic Sea Ice with global temperatures. If Antarctica cooled 10C and the Arctic warmed 10C the Arctic would melt with zero degrees of global warming.

1. Yes, certainly true if there is a redistribution of temperatures, but is this likely?

2. Given the report is tasked with reporting on a 1.5C warmer world (and perhaps whether much different from a 2C warmer world), they didn't really have much choice.

3. Is it a mistake? If they think it is a long way off (which unlikely with less than 1.5C warming implies), is it better to link it to some measure of global change rather than some specific years? Not sure on this, there is not much scope for 1.5C to arrive at noticeably different years but perhaps there is scope for 2C to arrive at different years depending what happens with future emissions.

Perhaps the stronger argument against this linkage to global temperatures is: does it depend whether aerosols decline rapidly as coal mining ends or not.

Quote

Bias correct... I honestly don't know exactly what that means, but that never stopped me from speculating before, so here we go.

I assume bias correction involves tinkering with parameters and functions until the model produces a better match for the observations. Then the future results are expected to produce better result. If that's the case, I understand the scientific validity and necessity of bias correction. It is a process of perpetual improvement.

Perpetual improvement goes on but I don't think this is what is being referred to here. I don't think the models are rerun just the output adjusted.

more like taking these models
(https://sites.google.com/site/arcticseaicegraphs/_/rsrc/1452976336289/longterm/Obs%20vs%20models%20September%20SIE%202015.jpg?height=281&width=400)

and adjusting the output to look more like shown below (not the completely flat bit at the end)

Quote


Bias correcting a model that has the wrong shape (strait line vs exponential) will still produce the wrong result. How do we know if the model has the wrong shape?  We don't, unless a model with a different shape shows better skill.

Fair point but what if essentially all the models show the same shape? Do you still think that is co-incidence or do you start to ponder if this shape is a reliable result from the models

Quote

This paper says that the ice will be gone 2 months during summer,  so from mid July to mid September, but there will be no hysteresis. That is quite simply unbelievable and it doesn't even pass a sanity check.

Even more unbelievable is "sea ice will only recover to current conditions if atmospheric CO2 is reduced below present-day concentrations."

The sea ice disappearance might have started because of CO2, but the acceleration of sea ice loss is not because of CO2, as the failure of the models prove. The loss of sea ice is now mostly do to albedo feedback, jetstream destabilization and local Arctic GHG, not CO2. Reducing CO2 back to historic levels will eventually restore the ice, but that will take decades or centuries.

What is this? Seems like you are trusting your gut instead of the result of modelling.
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on July 14, 2019, 01:06:08 PM
it ignores possible negative impacts.

Those positive benefits did seems to stand out. However

Quote
a fundamental transformation is occurring in polar organisms and ecosystems driven by climate change (high agreement, robust evidence) (Larsen et al., 2014). These changes are strongly affecting people in the Arctic who have close relationships with sea ice and associated ecosystems, and are facing major adaptation challenges as a result of sea level rise, coastal erosion, the accelerated thawing of permafrost, changing ecosystems and resources, and many other issues (Ford, 2012; Ford et al., 2015).

There is considerable and compelling evidence that a further increase ....

is hardly ignoring negative impacts. However, I would agree that it does seem rather limited in scope and I would have expected some mention of some possible effects on mid latitude weather patterns and therefore on people outside the arctic region. Maybe this is elsewhere in the document.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 14, 2019, 01:32:05 PM
Quote
1. Yes, certainly true if there is a redistribution of temperatures, but is this likely?

There IS a redistribution of temperatures and it is mostly caused by Arctic sea ice loss.

https://www.nature.com/articles/s41467-018-07954-9

Abstract:
Quote
Warming in the Arctic has been much faster than the rest of the world in both observations and model simulations, a phenomenon known as the Arctic amplification (AA) whose cause is still under debate. By analyzing data and model simulations, here we show that large AA occurs only from October to April and only over areas with significant sea-ice loss. AA largely disappears when Arctic sea ice is fixed or melts away. Periods with larger AA are associated with larger sea-ice loss, and models with bigger sea-ice loss produce larger AA. Increased outgoing longwave radiation and heat fluxes from the newly opened waters cause AA, whereas all other processes can only indirectly contribute to AA by melting sea-ice. We conclude that sea-ice loss is necessary for the existence of large AA and that models need to simulate Arctic sea ice realistically in order to correctly simulate Arctic warming under increasing CO2.

From the paper:

Quote
We found that large AA occurs only from October to April and only over areas with significant sea-ice loss in both observations and model simulations. AA largely disappears when Arctic sea ice melts away or is held fixed for calculating surface fluxes. Periods with large AA are associated with large sea-ice loss in model simulations, and models with bigger sea-ice loss produce larger AA. Increased LW radiation and latent and sensible heat fluxes from the newly exposed Arctic waters enhance surface and low-tropospheric warming and cause AA, whereas water vapor feedback, increased downward LW radiation, and other processes can only modulate the AA induced by sea-ice loss or indirectly contribute to AA by melting sea ice. Our results highlight the essential role of sea-ice loss in producing AA under GHG-induced global warming.


Quote
2. Given the report is tasked with reporting on a 1.5C warmer world (and perhaps whether much different from a 2C warmer world), they didn't really have much choice.

I know they didn't have much choice. If they use the proper language to describe what the science tells, they will be considered mad alarmists and their words never published.

Quote
3. Is it a mistake? If they think it is a long way off (which unlikely with less than 1.5C warming implies), is it better to link it to some measure of global change rather than some specific years? Not sure on this, there is not much scope for 1.5C to arrive at noticeably different years but perhaps there is scope for 2C to arrive at different years depending what happens with future emissions.

It is a huge mistake. A BOE will happen because of the natural feedback that already started, evident by Arctic Amplification, not because of CO2 or global temperatures.

Quote
Perpetual improvement goes on but I don't think this is what is being referred to here. I don't think the models are rerun just the output adjusted.

To think the leader of the world will be making decisions based on this is terrifying.


Quote
Fair point but what if essentially all the models show the same shape? Do you still think that is co-incidence or do you start to ponder if this shape is a reliable result from the models

Most models are the same shape because:

1. They are based on the same set of assumption, which is the climate of the 20th century for high resolution and the climate of the past with low resolution. As the climate changes, the models will fail and then improve.
2. The models don't have enough local scale resolution.
3. Results of exponential shape are scary.

Quote
What is this? Seems like you are trusting your gut instead of the result of modelling.

I'm trusting what my eyes see, and when I search the literature I get confirmation. See article linked above.
 
Title: Re: When will the Arctic Go Ice Free?
Post by: gerontocrat on July 14, 2019, 01:39:48 PM

Seems like you are trusting your gut instead of the result of modelling.
Should I put my trust in a projection based on a 4 parameter Gompertz equation?
Any more than I should put my trust in the attached?
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on July 14, 2019, 01:56:04 PM
Quote
1. Yes, certainly true if there is a redistribution of temperatures, but is this likely?
There IS a redistribution of temperatures and it is mostly caused by Arctic sea ice loss.

Yes you are right there is redistribution of temperature.

I was reacting to
Quote
If Antarctica cooled 10C and the Arctic warmed 10C the Arctic would melt with zero degrees of global warming.
which is somewhat extreme and I fell into giving extreme response to this extreme.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 14, 2019, 02:03:43 PM
10 and -10 nicely average to 0 and 10C guarantees an arctic sea ice melt down. I thought they were useful numbers to illustrate my point.
Title: Re: When will the Arctic Go Ice Free?
Post by: pietkuip on July 14, 2019, 03:27:55 PM
10 and -10 nicely average to 0 and 10C guarantees an arctic sea ice melt down. I thought they were useful numbers to illustrate my point.
Sure. But (if a serious reaction is allowed), the areas beyond to polar circle are much smaller than the rest of the world.

The extra energy in the Arctic comes from all directions, the South is everywhere.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on July 14, 2019, 03:43:14 PM

Seems like you are trusting your gut instead of the result of modelling.
Should I put my trust in a projection based on a 4 parameter Gompertz equation?
Any more than I should put my trust in the attached?

Probably not.  However the Gompertz does a better job of fitting the observation data.  Is that just coincidence?  On the other hand, is there any reason to suspect a straight line decline?  In any case, the largest rate of decline occurred over a roughly 10-year period, from 1998 - 2007.  The decades both before and after have shown much less melt.  Perhaps we are trying to apply a mathematical fit, where none exists.  I think the ice will continue to decline, but in method between the two fits; less than the straight line, but more than the Gompertz.  However, I could be just as wrong as the many others before who tried to predict the Arctic sea ice.
Title: Re: When will the Arctic Go Ice Free?
Post by: Tor Bejnar on July 14, 2019, 03:50:04 PM
The discussion above about thinner ice creates more bio-activity sounded positive, but the comment that a 'no ice' Arctic decreased bio-activity seems to be based on the recent evidence of migrating mammals (whales) dying of starvation after spending 'bulking up' time in the Arctic with, apparently, inadequate food, so no actual 'bulking up' (as reported in other threads on the ASIF).
Title: Re: When will the Arctic Go Ice Free?
Post by: gerontocrat on July 14, 2019, 04:01:25 PM
Quote
1. Yes, certainly true if there is a redistribution of temperatures, but is this likely?

There IS a redistribution of temperatures
NASA seem to think so
Title: Re: When will the Arctic Go Ice Free?
Post by: grixm on July 14, 2019, 04:36:31 PM

Seems like you are trusting your gut instead of the result of modelling.
Should I put my trust in a projection based on a 4 parameter Gompertz equation?
Any more than I should put my trust in the attached?

Probably not.  However the Gompertz does a better job of fitting the observation data.  Is that just coincidence?  On the other hand, is there any reason to suspect a straight line decline?  In any case, the largest rate of decline occurred over a roughly 10-year period, from 1998 - 2007.  The decades both before and after have shown much less melt.  Perhaps we are trying to apply a mathematical fit, where none exists.  I think the ice will continue to decline, but in method between the two fits; less than the straight line, but more than the Gompertz.  However, I could be just as wrong as the many others before who tried to predict the Arctic sea ice.

A 4 parameter gompertz is a far more complicated equation than the 2 parameter straight line. When allowed complexity rises the pool of possible functions that fit the observed data also rises, but the chance of such a fit being genuine and not a coincidence also falls, because of overfitting. Thus, when several equations fit the observed data reasonably, the least complex of them is more likely to be more correct, that's Occam's razor.
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on July 14, 2019, 05:18:53 PM

A 4 parameter gompertz is a far more complicated equation than the 2 parameter straight line. When allowed complexity rises the pool of possible functions that fit the observed data also rises, but the chance of such a fit being genuine and not a coincidence also falls, because of overfitting. Thus, when several equations fit the observed data reasonably, the least complex of them is more likely to be more correct, that's Occam's razor.

Yes, this is certainly a very reasonable criticism of 4 parameter gompertz. I don't agree with the completely flat extrapolation and 2 or 3 parameters would certainly be preferable to 4 but I don't know any curve equation that has some curves in the ways needed to fit the data. Could go down to 2 parameter straight line but as I suspect curve is flattening out (backed by both data and models) then the straight line predicts too soon and I want some way to show this then I need to use something. 3 parameter gompertz may well be better for some uses.

>more likely to be more correct
All models are wrong but some are useful. So I don't think 'correct' is the right word to use but I do agree with the sentiment if you change that word to 'more accurate for future projections' or useful or something like that.
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on July 14, 2019, 05:34:39 PM
I think the responses to the IPCC draft report is interesting.

Do some of the responses have the feel of:

I am convinced a BOE is going to be fairly catastophic, and I am sure I am right about this. Given this, how little the IPCC report says feels very weird.

But it is IPCC, so top experts used so can't easily attack expertise.
Clearly has reviewed and summarised lots of scientific papers so can't attack limited scope.

Which sort of leaves attacking scientists reticence & toning down language. This may not really make sense as adequate explanation for large divergence in views on severity of a BOE, but if it is all that is left, someone confident in their beliefs may end up believing it adequately explains the large divergence to protect their own world views.

Does this strike others as happening on the thread above?

Or maybe it is just me seeing this because I want to believe it as reinforcing my beliefs?

It isn't all that, of course. There is some genuine discussion of the report as well.
Title: Re: When will the Arctic Go Ice Free?
Post by: oren on July 14, 2019, 05:59:35 PM
To a certainty, the IPCC process is conservative, reticent and toned down by politics. Very understandable.
This doesn't mean that a BOE (1M km2 in mid September) will be a step-change catastrophic.
Title: Re: When will the Arctic Go Ice Free?
Post by: gerontocrat on July 14, 2019, 06:17:08 PM
My difficulty with the IPCC report(s) comes from a different place. I cannot challenge the science and methodologies the scientists use. So on what basis can I criticise.

Simply put, because so far in each cycle they have been wrong, and each new IPCC cycle has built into it an unrealistic view of what the world is doing and will do.

Why,
- because the action taken by the world has not reduced CO2 emissions. They have increased.
- because the majority of new papers with new and improved data say things are worse.
- because the IPCC mandate is to look towards 2100.
- because ......

The proof is that the UN felt it necessary to issue the report to say to the world - you've got 12 years left or you/we are well are truly done for. And look at the reality, CO2 emissions are rising, carbon sinks are being degraded. We don't have 12 years. 2019 is not just a year wasted, it is a year that stole 2 years from that 12 years (if it exists at all).

So when will the Arctic go ice free? Sooner than when the IPCC says.
When will the Arctic return to its previous state? Probably never.

And that is all I am going to say about that.
Back to looking at data.
Title: Re: When will the Arctic Go Ice Free?
Post by: Pragma on July 14, 2019, 06:22:15 PM
With no disrespect intended toward any scientists involved, I think the IPCC is flawed and intentionally so. As I have said before, it is primarily a political document, constrained by consensus. I'm not sure we can exclude limited scope as a possibility. They continue to ignore reality, i.e. empiricism, because reality has yet to be peer reviewed.

Also, as I understand it, they specifically have not mentioned feedbacks in their reports. The rationale, such as it is, is that the feedbacks can not be adequately characterized, so they are eliminated. One can debate the merits of that approach, but a large gap exists, nonetheless.

This thread contains a wide variety of views, some scientific, some emotional, but deviating from the IPCC is far from blasphemy IMHO. 

Title: Re: When will the Arctic Go Ice Free?
Post by: Sam on July 14, 2019, 08:05:25 PM
The IPCC does one hugely good thing - confirm with an extraordinarily high consensus that climate disruption is real, that it is entirely caused by man and that it will devastate the environment, civilization, humanity and more.

The IPCC though also does a hugely bad thing. It repeatedly and systematically understates the severity of the problem, the severity of the consequences, the incredible speed at which the changes are occurring, the impossibly great difficulties that we will encounter in trying to keep the change to less than 2 degrees C, the incredibly great difficulty we will have in limiting the change to 3 C, the unimaginably horrible impacts a 3 C increase will have, and more. It is vital to note that the errors the IPCC makes in these regards are caused by politicians and financial interests aided by those who refuse to believe that man could possibly cause such impacts, or worse that the local personal impacts that change would have are more important than the devestation of the earth. It is also vital to note that these errors are intentional and that they all go in the same direction - understating both the severity of the problem, and the incredible speed at which the change is actually occurring.

All of that is shameful and disgusting. The iPCC’s failure as great as the failure of our leaders doom everyone and most species on the earth.

Before there can be any possibility of a meaningful response to climate disruption, we must first be honest about the effects. Only then can we be honest about what is needed to do anything about it, and to assess realistically how much we can do. But doing that means admitting massive failure and the future premature death and suffering of billions of people - and that is if we do succeed. That answer is too horrible for the leaders to even entertain. Failing to take those actions assures those harms and much worse. Somehow though they seem to wrongly believe that if they stick their heads in the ground like the proverbial ostrich, that either the problems won’t come to pass, or that they won’t personally be blamed.

And that leads to my last point. The scientists are particularly to blame for couching the outcome as risks. They seem not to understand or not to want to understand that the people they are reporting to utterly and completely fail to understand that these are certainties of massive destruction, and only uncertainties in how fast that will occur. Risks in this context are not gambles as to whether certain outcomes will occur, but rather how horribly severe they will be or how fast they will arrive.

The outcome is certain catastrophe on an unprecedented scale. And that will happen if we mobilize every capability we have, as fast as we physically can, AND destroy civilization as we know it in the process. Should we fail to do that the outcomes are vastly worse.

Sam
Title: Re: When will the Arctic Go Ice Free?
Post by: petm on July 14, 2019, 08:15:18 PM
The outcome is certain catastrophe on an unprecedented scale.

hear! hear!
Title: Re: When will the Arctic Go Ice Free?
Post by: Glen Koehler on July 14, 2019, 11:18:11 PM
    IPCC is made of humans.  From what I understand the scientists (mostly unpaid for the extra work) give their best effort at corralling and summarizing vast amounts of information, then the politicians get to edit the language used to communicate it.  The IPCC reports are essential and immensely useful, imagine if we did NOT have them.  But they are imperfect. 

     Short report well worth reading --
"What Lies Beneath: The scientific understatement of climate risks"
   excerpt: 
    "What were lower-probability, higher-impact events are now becoming more likely. This is a particular concern with potential climatic “tipping points” — passing critical thresholds which result in step changes in the system — such as the polar ice sheets (and hence sea levels), and permafrost and other carbon stores, where the impacts of global warming are non-linear and difficult to model at present. Under-reporting on these issues contributes to the “failure of imagination” that is occurring today in our understanding of, and response to, climate change. If climate policymaking is to be soundly based, a reframing of scientific research within an existential risk-management framework is now urgently required. "

https://www.researchgate.net/profile/David_Spratt3/publication/324528571_What_Lies_Beneath_The_scientific_understatement_of_climate_risks/links/5ad2e4120f7e9b2859343e58/What-Lies-Beneath-The-scientific-understatement-of-climate-risks.pdf (https://www.researchgate.net/profile/David_Spratt3/publication/324528571_What_Lies_Beneath_The_scientific_understatement_of_climate_risks/links/5ad2e4120f7e9b2859343e58/What-Lies-Beneath-The-scientific-understatement-of-climate-risks.pdf)
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 15, 2019, 12:10:13 PM
Quote
Or maybe it is just me seeing this because I want to believe it as reinforcing my beliefs?

That is a brave question. So far it hasn't been answered. In fact it has been avoided. Too bad I can't answer it because I have the exact same question and I may be the one seeking to reinforce beliefs.
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on July 15, 2019, 02:28:32 PM
My difficulty with the IPCC report(s) comes from a different place. I cannot challenge the science and methodologies the scientists use. So on what basis can I criticise.

Simply put, because so far in each cycle they have been wrong, and each new IPCC cycle has built into it an unrealistic view of what the world is doing and will do.

Why,
- because the action taken by the world has not reduced CO2 emissions. They have increased.
- because the majority of new papers with new and improved data say things are worse.
- because the IPCC mandate is to look towards 2100.
- because ......

The proof is that the UN felt it necessary to issue the report to say to the world - you've got 12 years left or you/we are well are truly done for. And look at the reality, CO2 emissions are rising, carbon sinks are being degraded. We don't have 12 years. 2019 is not just a year wasted, it is a year that stole 2 years from that 12 years (if it exists at all).

So when will the Arctic go ice free? Sooner than when the IPCC says.

It is certainly reasonable to have some divergence of views from what the IPCC reports: The IPCC only reports on what the science says. There can be quite considerable number of thinks that are suspected and reasonably feared but don't get into the science because both 1) the science isn't yet good enough to show these effects occur and 2) observations are not clear enough to demonstrate them.

In addition there are political considerations and scientific language toning things down.

So yes logical and sensible to believe the IPCC understates matters.

But how much of a gap?
On political interference, is it reasonable to think the scientists allow the politicians to completely rewrite to clearly distort fundamental meanings or is it just a little tinkering about the edges?

On the science, if the observations are not clear enough on an effect then there may still be an effect and it will almost certainly get worse with a +1.5C world rather than a +1C world. But if it is barely measurable is it really going to grow to be anywhere near of the order of civilisation collapsing effects?

.

'It is worse than we thought' headlines. Yes I believe this is true in many cases even if other times it is mere clickbait exaggeration. However, on the subject of arctic sea ice

https://14adebb0-a-62cb3a1a-s-sites.googlegroups.com/site/arctischepinguin/home/piomas/grf/piomas-trnd6-1.png?attachauth=ANoY7cqZn7MvUtOPSwAcG0HCDb0_QidUTkM1iUgm9Lmbvbi4Skbmj0H0SgbjaO5MYzgSYYwnDBpf6H10QTZgJHf8fpb7ljiaCjwNRSUj0mDjSqxr_wLTcXh1biD7cvh8acBIZHailxdtF6rBDslzGBqyf4SUOSZS6K8uIo06xXevpF5vocB192bUHAIa0EOqLPyKVVSG1_LBrMzPIIrHg2egUGSdaQeF4Rw_CS4cg9hNdhhIgtf946frtyhtCwabcZzi4UYSXsoF&attredirects=0

the conclusion seems to repeatedly be that it isn't as bad as we feared.
Title: Re: When will the Arctic Go Ice Free?
Post by: Peter Ellis on July 15, 2019, 02:42:53 PM
BZZT - ambiguous pronoun referents detected!

"It is worse than we thought" = the "we" refers to the climate science community.

"It isn't as bad as we feared" = the "we" refers to members of this board.

Both statements are thus true, because this board is much more alarmist that the community in general.
Title: Re: When will the Arctic Go Ice Free?
Post by: Sam on July 15, 2019, 02:54:47 PM
Peter,

I disagree on several counts.

The “we” in both cases is a generic we of unassigned humanity looking at the problem.

More than that I reject flatly your assertion that members of this community are “more alarmist”.

“More alarmed” is correct. “Alarmist” as used in English today is a derogatory valuation of the state of alarm. Far from being alarmist, the vast majority of those participating in this forum are stark realists. Alarm in the context you use it is generally a statement about something the writer takes as being a wrong headed and unjustified emotional reaction.

Clearly many of us are having emotional reactions to the terrifying changes we are seeing and to the most likely consequences of those observed changes and trends. That does not make them “alarmist” statements in the pejorative sense that you seem to intend.

I find it more concerning that this sort of language use has become the stock and trade of political and financial interests hell bent on maintaining their rapacious ways without regard to the consequences.

And there’s is in my opinion no place for that in the discussion.

Sam
Title: Re: When will the Arctic Go Ice Free?
Post by: gerontocrat on July 15, 2019, 03:16:25 PM
23rd August 2027.
End of debate.
Title: Re: When will the Arctic Go Ice Free?
Post by: Simon on July 15, 2019, 03:24:04 PM
When the Arctic goes very low early September looks as though it depends upon the volume at maximum. It seems that if the max volume is below 18 000km3 then there is a good chance of a BOE occurring. Then in any given season, the rate of ice loss would depend upon weather, insolation etc. So, perhaps a September virtually ice free arctic may depend on poor autumn winter recovery. Does this make sense?
Title: Re: When will the Arctic Go Ice Free?
Post by: Shared Humanity on July 15, 2019, 03:33:02 PM
On the science, if the observations are not clear enough on an effect then there may still be an effect and it will almost certainly get worse with a +1.5C world rather than a +1C world. But if it is barely measurable is it really going to grow to be anywhere near of the order of civilisation collapsing effects?


I agree with most of what you have said but why would you choose to draw a distinction between 1C and 1.5C. We are going to blow past 1.5C as BAU is still the rule of the day. Would be shocked if we do not find ourselves in a 3C warmer world, minimum, by the end of this century.

I think that some of our most pessimistic commenters here on this forum have this as the context from which they make their comments. Having said this, I think we are probably 2 decades from having perennial BOE's.
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on July 15, 2019, 03:58:43 PM

I agree with most of what you have said but why would you choose to draw a distinction between 1C and 1.5C. We are going to blow past 1.5C as BAU is still the rule of the day. Would be shocked if we do not find ourselves in a 3C warmer world, minimum, by the end of this century.

I think that some of our most pessimistic commenters here on this forum have this as the context from which they make their comments. Having said this, I think we are probably 2 decades from having perennial BOE's.

The 1C was about where we are now. The 1.5C was what the IPCC report was aimed at.

I agree we are likely to blow past 1.5C: Almost certainly .5C of committed warming as ocean thermal inertia takes some time to catch up with atmosphere. We haven't stopped emissions yet and that will take some time so avoiding 2C is likely to need substantial carbon drawdown tech. If that is not possible or not adequately funded we are likely to go past 2C. If renewables take off as I expect with them being cheaper only recently we may manage some slow down in the rate of rise at between +2C  and +3C. Further out than that it is hard to know what we will develop. Resilience may increase more from wealth than the increasing problems of more adverse weather.
Title: Re: When will the Arctic Go Ice Free?
Post by: Glen Koehler on July 15, 2019, 06:20:00 PM
the conclusion seems to repeatedly be that it isn't as bad as we feared.

Whichever "we" said that, they would be wrong.  Measurements and projections of both the ASI loss trajectory and impacts have shown increase over time more often than decrease.  (This also applies to climate disruption in general.)

Check out the 16 minute "A World Without Ice" author interview Neven posted the other day at the ASIB.
https://www.youtube.com/watch?v=uiV-46FUOeI (https://www.youtube.com/watch?v=uiV-46FUOeI)

Title: Re: When will the Arctic Go Ice Free?
Post by: gerontocrat on July 15, 2019, 06:34:18 PM
Someone posted on this thread, and totally correctly, that there has been only one year where extent was less than 4 million km2, and that was 2012. Not only that, but 2012 extent minimum was, at 3.2 million km2, more than 800,000 km2 less than 2nd place 2016 (JAXA data).

That triggered my memory of a post I think by Tealight, in which he mentioned how when looking at area, we are much closer to a BOE. Time to have a look.

2012 NSIDC Area minimum was 2.25 million km2.

Not only that, 2016 area minimum was not 800,000 km2 greater than that, it was just 200,000 km2 greater at 2.45 million km2.

Not only that, if 2019 remaining area loss is average, minimum will come in at or a bit below the 2016 figure.

Suddenly, the 2012 minimum does not look such an outlier. The reason for the difference between extent and area comparisons? Dispersion. In 2016 the not so much greater area was spread out over a far larger extent.

My (joke?) prediction for the BOE on 23rd August 2027 suddenly looks more possible, or even conservative.


Title: Re: When will the Arctic Go Ice Free?
Post by: petm on July 15, 2019, 06:51:38 PM
Suddenly, the 2012 minimum does not look such an outlier.

Right and volume too. 2010-2012 were volume outliers for the time, but not anymore. 2016-2019 are at roughly the same level.

https://14adebb0-a-62cb3a1a-s-sites.googlegroups.com/site/arctischepinguin/home/piomas/grf/piomas-trnd2.png
Title: Re: When will the Arctic Go Ice Free?
Post by: Ken Feldman on July 15, 2019, 06:55:53 PM
Quote
But they are better than nothing, you have to work with the tools you have got not the ones you would like, and the models show the same thing for 2020 2040 and 2060.

Let me be very clear about this. In the model that predicts a BOE by 2080, if you instantly remove the ice in 2020, 2040, or 2060 the ice immediately comes back. Well of course it does. The model is underestimating melt and/or overestimating freeze.

A wrong model is worse than nothing, if you make decisions according to the wrong model.

However, as the arctic keeps changing and showing scientist new secrets, I'm sure that better models will emerge.

Quote
You might want a newer source and better model, but basically tough: If it doesn't exist, then you are not going to get it. If there are two papers saying the same thing, then another paper is unlikely to be published unless it is saying something markedly different.

You don't think missing the first BOE by 4 decades (possibly more) is something markedly different?

Those model results are based on actual physics and include things often missing from the simplistic arguments about a BOE.  For example, the negative feedbacks, the depth of the central Arctic Ocean, and the fact that the gradual build up of the heat in the atmosphere mostly goes into the deep ocean, not the atmosphere or the ice.

Here's a good explanation of why there isn't expected to be a "tipping point" in the event of a BOE from a 2018 paper by Julienne Stroeve and Dirk Notz.

https://iopscience.iop.org/article/10.1088/1748-9326/aade56/meta (https://iopscience.iop.org/article/10.1088/1748-9326/aade56/meta)

Quote
Changing state of Arctic sea ice across all seasons
Julienne Stroeve and Dirk Notz 2018 Environ. Res. Lett. 13 103001

Abstract
 

The decline in the floating sea ice cover in the Arctic is one of the most striking manifestations of climate change. In this review, we examine this ongoing loss of Arctic sea ice across all seasons. Our analysis is based on satellite retrievals, atmospheric reanalysis, climate-model simulations and a literature review. We find that relative to the 1981–2010 reference period, recent anomalies in spring and winter sea ice coverage have been more significant than any observed drop in summer sea ice extent (SIE) throughout the satellite period. For example, the SIE in May and November 2016 was almost four standard deviations below the reference SIE in these months. Decadal ice loss during winter months has accelerated from −2.4 %/decade from 1979 to 1999 to −3.4%/decade from 2000 onwards. We also examine regional ice loss and find that for any given region, the seasonal ice loss is larger the closer that region is to the seasonal outer edge of the ice cover. Finally, across all months, we identify a robust linear relationship between pan-Arctic SIE and total anthropogenic CO2 emissions. The annual cycle of Arctic sea ice loss per ton of CO2 emissions ranges from slightly above 1 m2 throughout winter to more than 3 m2 throughout summer. Based on a linear extrapolation of these trends, we find the Arctic Ocean will become sea-ice free throughout August and September for an additional 800 ± 300 Gt of CO2 emissions, while it becomes ice free from July to October for an additional 1400 ± 300 Gt of CO2 emissions.

Quote
4.2. Stability of the ice cover


In addition to changes in the external forcing and internal variability, a self-amplification of the ongoing ice-loss could in principle have contributed to the rapid ice loss in recent years. Such self-amplification is usually discussed in the context of so-called tipping points or nonlinear threshold, which are often defined as processes in the climate system that show substantial hysteresis in response to changed forcing.

The best known example for such possible hysteresis behavior is related to the ice-albedo feedback mechanism: a reduced ice cover in a given summer will cause increased absorption of solar radiation by the ocean, contributing to further reductions in the ice cover. Such positive feedback loop can cause the irreversible loss of Arctic sea ice in idealized studies based for example on energy-balance models (see review by North 1984), and have hence been suggested to possibly be relevant also for the real world.

However, an analysis of the existing observational record and a substantial number of respective modeling studies with complex ESMs all agree that such a 'tipping point' does not exist for the loss of Arctic summer sea ice. For example, Notz and Marotzke (2012) found a negative auto-correlation of the year-to-year changes in observed September SIE. Hence, whenever SIE was substantially reduced in a given summer, the next summer usually showed some recovery of the ice cover. This was further supported by Serreze and Stroeve (2015). Such behavior suggests that the sea-ice cover is at least currently in a stable region of the phase space, as otherwise one would then expect that any year with a really low ice coverage should be followed by a year with an even lower ice coverage, driven by the ice-albedo feedback mechanism. As shown by Tietsche et al (2011), the contrasting behavior of the real ice cover can be explained by compensating negative feedbacks that stabilize the ice cover despite the amplifying ice-albedo feedback. The most important of these stabilizing feedbacks relates to the fact that during winter the ocean very effectively releases heat from those areas that became ice free during summer, thus over-compensating for any extreme ice loss in a preceding summer. Ice that is formed later in the season also carries a thinner snow cover and can hence grow more effectively during winter (e.g., Notz 2009). Stroeve et al (2018) suggest, however, that this stabilizing feedback mechanism is becoming weaker and weaker as Arctic winters become warmer and warmer. Increased winter cloud cover after summer sea ice loss as found by Liu et al 2012 also weakens the stabilizing feedback, as it reduces the loss of heat from the ocean surface.

The apparent mismatch of observations and complex model studies on the one hand, which both show no emergent tipping-point behavior of the ice loss, and studies with idealized models, which show tipping-point behavior, was resolved in a dedicated study by Wagner and Eisenman (2015). They were able to extend simplified models until their behavior agreed with more complex models. In doing so, they found that both spatial communication through meridional heat transport and the annual cycle in solar radiation are important for stabilizing the ice cover's response to changes in the external forcing.
Title: Re: When will the Arctic Go Ice Free?
Post by: Rich on July 15, 2019, 07:08:10 PM
Someone posted on this thread, and totally correctly, that there has been only one year where extent was less than 4 million km2, and that was 2012. Not only that, but 2012 extent minimum was, at 3.2 million km2, more than 800,000 km2 less than 2nd place 2016 (JAXA data).

That triggered my memory of a post I think by Tealight, in which he mentioned how when looking at area, we are much closer to a BOE. Time to have a look.

2012 NSIDC Area minimum was 2.25 million km2.

Not only that, 2016 area minimum was not 800,000 km2 greater than that, it was just 200,000 km2 greater at 2.45 million km2.

Not only that, if 2019 remaining area loss is average, minimum will come in at or a bit below the 2016 figure.

Suddenly, the 2012 minimum does not look such an outlier. The reason for the difference between extent and area comparisons? Dispersion. In 2016 the not so much greater area was spread out over a far larger extent.

My (joke?) prediction for the BOE on 23rd August 2027 suddenly looks more possible, or even conservative.

Thanks for sharing that Gerontocrat. I learned something there.

It's kinda bizarre that the extent : area ratio would vary so much.

What caused the great dispersion of 2016?
Title: Re: When will the Arctic Go Ice Free?
Post by: Tor Bejnar on July 16, 2019, 12:43:58 AM
Thanks, Ken, for the link and long quotes.  I was curious how they dealt with Bering Sea winter lack-of-freezing in recent years.  It seems this parallels other peripheral seas, helping create this one (or several) conclusions:
Quote
5.  Accelerated sea ice loss during all months of the year is additionally driven by a lengthening of the melt season. As assessed for the Arctic as a whole through April 2018, melt onset is occurring 3 days earlier per decade, and freeze-up is happening 7 days later per decade (figure 3). Over the 40 year long satellite record, this amounts to a 12 day earlier melt onset and a 28 day later freeze-up.
Not a conclusion, but the paper includes:
Quote
while the amount of ice exported through Fram Strait has increased over the satellite data, the increased ice export might instead be linked to the fact that that a thinner ice pack is more mobile (e.g. Rampal et al 2009, Olason and Notz 2014).
A graph suggests a BOE about 2050, based on the final conclusion:
Quote
7.  The primary cause of the ongoing changes in all months are anthropogenic CO2 emissions, with a clear linear relationship between sea ice loss and cumulative anthropogenic CO2 emissions in all months (figure 7). ...
Title: Re: When will the Arctic Go Ice Free?
Post by: jdallen on July 16, 2019, 03:07:44 AM
I've been ruminating on this a bit...

For all of a BoE marking some sort of milestone in the Arctic, the impact of reduced summer (and Winter...) ice coverage is already making itself felt.  In short, the difference between 2 million km2 extent and 1 million km2 extent won't be that significant from the standpoint of its effect on climate.

We're already seeing dire changes to the ecosystem and major impacts to year-round atmospheric circulation.  I'm not seeing that changing much with a BoE, except on ramp up, in the manner of degree.
Title: Re: When will the Arctic Go Ice Free?
Post by: binntho on July 16, 2019, 06:33:11 AM
Here's a good explanation of why there isn't expected to be a "tipping point" in the event of a BOE from a 2018 paper by Julienne Stroeve and Dirk Notz.

https://iopscience.iop.org/article/10.1088/1748-9326/aade56/meta (https://iopscience.iop.org/article/10.1088/1748-9326/aade56/meta)

Quote
Changing state of Arctic sea ice across all seasons
Julienne Stroeve and Dirk Notz 2018 Environ. Res. Lett. 13 103001

... The annual cycle of Arctic sea ice loss per ton of CO2 emissions ranges from slightly above 1 m2 throughout winter to more than 3 m2 throughout summer. Based on a linear extrapolation of these trends, we find the Arctic Ocean will become sea-ice free throughout August and September for an additional 800 ± 300 Gt of CO2 emissions, while it becomes ice free from July to October for an additional 1400 ± 300 Gt of CO2 emissions.

With current CO2 release, an additional 800 Gt takes 50 years (36 Gt annual release, 44% of which is retained in the atmosphere).

A good article though, and I would tend to agree with the conclusions.
Title: Re: When will the Arctic Go Ice Free?
Post by: Tony Mcleod on July 16, 2019, 07:08:14 AM
I've been ruminating on this a bit...

For all of a BoE marking some sort of milestone in the Arctic, the impact of reduced summer (and Winter...) ice coverage is already making itself felt.  In short, the difference between 2 million km2 extent and 1 million km2 extent won't be that significant from the standpoint of its effect on climate.

We're already seeing dire changes to the ecosystem and major impacts to year-round atmospheric circulation.  I'm not seeing that changing much with a BoE, except on ramp up, in the manner of degree.

You may be right, but there is another possibility and that is a flipping cold pole. Arctic-centred for now summer and winter, but starting to flicker to a Greenland centre in summer. That could be a whole lot flipping worse than a gradual ramp up.
Title: Re: When will the Arctic Go Ice Free?
Post by: jdallen on July 16, 2019, 07:09:15 PM
I've been ruminating on this a bit...

For all of a BoE marking some sort of milestone in the Arctic, the impact of reduced summer (and Winter...) ice coverage is already making itself felt.  In short, the difference between 2 million km2 extent and 1 million km2 extent won't be that significant from the standpoint of its effect on climate.

We're already seeing dire changes to the ecosystem and major impacts to year-round atmospheric circulation.  I'm not seeing that changing much with a BoE, except on ramp up, in the manner of degree.

You may be right, but there is another possibility and that is a flipping cold pole. Arctic-centred for now summer and winter, but starting to flicker to a Greenland centre in summer. That could be a whole lot flipping worse than a gradual ramp up.

I do not preclude wild cards showing which would make things even worse. In fact I kinda expect it...
Title: Re: When will the Arctic Go Ice Free?
Post by: gerontocrat on July 16, 2019, 08:32:49 PM
Here's a good explanation of why there isn't expected to be a "tipping point" in the event of a BOE from a 2018 paper by Julienne Stroeve and Dirk Notz.

https://iopscience.iop.org/article/10.1088/1748-9326/aade56/meta (https://iopscience.iop.org/article/10.1088/1748-9326/aade56/meta)

Quote
Changing state of Arctic sea ice across all seasons
Julienne Stroeve and Dirk Notz 2018 Environ. Res. Lett. 13 103001

... The annual cycle of Arctic sea ice loss per ton of CO2 emissions ranges from slightly above 1 m2 throughout winter to more than 3 m2 throughout summer. Based on a linear extrapolation of these trends, we find the Arctic Ocean will become sea-ice free throughout August and September for an additional 800 ± 300 Gt of CO2 emissions, while it becomes ice free from July to October for an additional 1400 ± 300 Gt of CO2 emissions.

With current CO2 release, an additional 800 Gt takes 50 years (36 Gt annual release, 44% of which is retained in the atmosphere).

A good article though, and I would tend to agree with the conclusions.
Why agree with that methodology and not agree with this methodology?

VOLUME
Since 1980 the amount of CO2 in the atmosphere has risen by about 600GT
Summer volume minimum has decreased from about 17,000 GT to about 5,000 GT.

Thus 1 GT additional CO2 in the atmosphere equates to summer volume loss of 20GT.

To get to minimum therefore needs 5000 divided by 20 additional GT of CO2 in the atmosphere,. i.e. 250 GT.

Current rates of emissions of 36 GT and 44 % retained in the atmosphere gives 16 GT more CO2 in the atmosphere per annum.

That gives zero ice in 16 years, 2035.

Assuming 1 million km2 of area = 1,000 km3 of ice volume.
A BOE then requires volume to go down by 4,000 GT, which takes 13 years, i.e. 2032

But if volume continues on its current trend, minimum this year could be about 3,500 km3. That brings a BOE into the 2020's.

Looking that far in the future is a mug's game.
So I think the methodology I used is junk, and so is the one by Stroeve / Notz. I am amazed they came up with that. Linear extrapolations to 2050? C'mon.
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on July 19, 2019, 05:13:18 PM

Looking that far in the future is a mug's game.
So I think the methodology I used is junk, and so is the one by Stroeve / Notz. I am amazed they came up with that. Linear extrapolations to 2050? C'mon.

I have to agree to some extent, but:

Shouldn't use such a linear trend for such a long way into future, unless it looks reliable?

Looks quite good for a longish period: 1953 to 2017. (Or have they used scale to minimise look of y axis variation?)

My issues with it are:

Last 10 years doesn't look as good and prior to that we were losing MYI which doesn't grow back each winter, from 2012ish onward or so the ice melted is largely growing back each winter. So could be much later than the relationship suggests.

OTOH if we stop coal mining rapidly, aerosol might decline while CO2 emissions keep rising changing previous relationship. Even without such a change, the aerosol effect is short term while CO2 cumulative emissions keep rising. This may cause more rapid drop than the relationship suggests.

Maybe these have cancelling effects and the linear relationship continues. More likely there are more such effects and they are unlikely to cancel so linear relationship does not continue, but if you believe that, why so linear over 1953 to 2017 period?
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on July 19, 2019, 05:49:35 PM
The abrupt changes in planetary climate that a BOE will bring are not magic. They are simple physics. The Earth has had a planetary refrigerator for likely millions of years. After a BOE that refrigerator fails and the NH will know true climate change. There won't be any denying because we'll be busy surviving.

I'm not arguing against logic here. It is frustrating to see how intelligent people who are aware of the role of arctic sea ice on atmospheric and oceanic patterns can't see the destruction that will ensue as the arctic disappears. The destruction has already started and the Arctic has barely begun to change.

But I may be wrong, so let's get to the science. Find me a paper that describes what happens after the first BOE, that doesn't ignore the ASI teleconections to the rest of the world and predicts a BOE much sooner than 2070.

Good luck with it.

Stroeve and Notz 2018
Changing state of Arctic sea ice across all seasons

Not sure it meets all your requirements or expectations though:

Quote
While it is understood that changes happening within the Arctic do not stay there, it is less certain whether current Arctic warming is already driving an increase in storm frequency and extreme weather events across the mid-latitudes, including extreme heat and rainfall events, and more severe winters. The possibility of a link has driven an increased number of studies to examine linkages in more detail. A host of mechanisms and processes have been proposed and some consensus has emerged; namely that amplified Arctic warming, regardless of its driver, has increased geopotential height thickness (Francis and Vavrus 2012, Cvijanovic et al 2017), which in turn has weakened the thermal wind (Francis and Vavrus 2012, Walsh 2014, Pedersen et al 2016). It is not clear, however, how much these atmospheric changes have influenced the jet stream (Barnes 2013) or the influence on storm tracks and occurrence of blocking events (Zhang et al 2012, Barnes et al 2014, Barnes and Screen 2015). It is entirely possible that such a link exists, yet its manifestation in the real world is likely only of minor importance given the substantial year-to-year variability arising from internal variability of the climate system.

Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on July 19, 2019, 06:24:12 PM

Looking that far in the future is a mug's game.
So I think the methodology I used is junk, and so is the one by Stroeve / Notz. I am amazed they came up with that. Linear extrapolations to 2050? C'mon.

I have to agree to some extent, but:

Shouldn't use such a linear trend for such a long way into future, unless it looks reliable?

Looks quite good for a longish period: 1953 to 2017. (Or have they used scale to minimise look of y axis variation?)

My issues with it are:

Last 10 years doesn't look as good and prior to that we were losing MYI which doesn't grow back each winter, from 2012ish onward or so the ice melted is largely growing back each winter. So could be much later than the relationship suggests.

OTOH if we stop coal mining rapidly, aerosol might decline while CO2 emissions keep rising changing previous relationship. Even without such a change, the aerosol effect is short term while CO2 cumulative emissions keep rising. This may cause more rapid drop than the relationship suggests.

Maybe these have cancelling effects and the linear relationship continues. More likely there are more such effects and they are unlikely to cancel so linear relationship does not continue, but if you believe that, why so linear over 1953 to 2017 period?

I do not think a linear trend extrapolated that far into the future is reliable.  The slope appears to have changed several times over the decades.  A Gompertz fit, as posted by others, appears to be a better fit, but it looks to flatten the curve too much. 
Title: Re: When will the Arctic Go Ice Free?
Post by: gerontocrat on July 19, 2019, 07:36:41 PM
I do not think a linear trend extrapolated that far into the future is reliable.  The slope appears to have changed several times over the decades.  A Gompertz fit, as posted by others, appears to be a better fit, but it looks to flatten the curve too much.
I was taught that the gompertz or S curve is used to represent the way an event happens. A classic example is expenditure on a construction project. Costs are low at the beginning, (design, approvals etc,) accelerate in the middle as main construction takes off and slows down with fiddly finishing work at the end. We used it in doing budgets for capital expenditure programmes.
 
The curve is also usual when looking at the annual melt of the Arctic Ocean as a whole.  The melt speeds up as temperatures rise and slows down when temperatures cool down. The second reason for the gompertz curve being appropriate as a representation is that when looking at an individual sea, no matter how early it melts out, when sea ice drops below a certain amount, the percentage of the remaining sea ice lost each day remains very much the same, and therefore the absolute decrease in daily sea ice declines, creating the classic gompertz end of graph shape. But there is no reason to suppose that to be the case with immediate future years ice loss in the Arctic.

At the moment, the increase in CO2 atmospheric concentrations is accelerating. This is likely to accelerate the increase in atmospheric temperatures.
If, as expected, pollution decreases due to public opinion and decreased use of coal, this is also likely to accelerate the increase in atmospheric temperatures,. albeit temporarily.

Summer Sea ice extent minimum is still at 50 % of the 1979 value.
Winter Sea ice extent maximum is still at nearly 90 % of the 1979 value.

We are nowhere near the tail end of the event being progress to an BOE. So why should future years annual losses in Arctic sea ice decline in line with the tail end of a Gompertz curve?

The only thing that makes any sense to me is to start with the idea of what is going to happen to AGW in general and AGW in the Arctic in particular in the immediate future, i.e. the next 5 to 10 years. And that looks pretty grim to me. How you stick that into a curve is beyond me. I don't have a few cray computers to help me out, either.
Title: Re: When will the Arctic Go Ice Free?
Post by: Threebellies on July 20, 2019, 06:06:40 AM
Gerontocrat said
Quote
Linear extrapolations to 2050? C'mon.

Every time I read many climate papers and projects I have this feeling. Concise and well said. This seems to be a very civil place bent on objective data.
Title: Re: When will the Arctic Go Ice Free?
Post by: gerontocrat on July 20, 2019, 12:46:14 PM
A lot of stuff on the thread about an article by Stroeve and Notz interpreted by people on the forum that the paper suggests an ice-free summer by around 2050.

Meanwhile, back in the day....

Arctic Sea Ice Extent Plummets in 2007 by BY J. STROEVE, M. SERREZE, S. DROBOT,
S. GEARHEARD, M. HOLLAND, J. MASLANIK, W. MEIER, AND T. SCAMBOS
Eos, Vol. 89, No. 2, 8 January 2008

Quote
While natural variability may instead stabilize the ice cover for the next few years, the long-term outlook is disturbing. All models evaluated in the Intergovernmental Panel on Climate Change Fourth Assessment Report show declining September sea ice from 1953 to 2006.

While these models point to a role of GHG forcing, as a group they significantly underrepresent the observed trend [Stroeve et al., 2007]. The reasons for this underrepresentation remain to be fully resolved, but overly thick ice in several of the models provides a partial explanation. Given these conservative model results, along with the remarkable events of 2007, our view is that a seasonally ice-free Arctic Ocean might be realized as early as 2030.

https://www.researchgate.net/profile/W_Meier/publication/248820158_Arctic_Sea_Ice_Extent_Plummets_in_2007/links/0deec535e81c7e2f09000000.pdf
Title: Re: When will the Arctic Go Ice Free?
Post by: gerontocrat on July 20, 2019, 01:12:54 PM
And from an earlier paper (2007)
Whither Arctic sea ice? A clear signal of decline regionally, seasonally and extending beyond the satellite record
Walter N. MEIER, Julienne STROEVE, Florence FETTERER
National Snow and Ice Data Center, University of Colorado, Boulder,

Highly edited extract follows:
________________________________________________________
Projections for ice-free conditions

Extrapolating the linear trend until the ice extent reaches zero is a naive method of projecting when ice-free conditions could occur (naive because it assumes that linear regression is always predictive, which it is not).

However, there is no reason to believe that the sea-ice trend is or will continue to be linear. Due to the sea-ice–albedo feedback, one would expect an accelerating trend, and in fact the recent acceleration in the downward trend is a tantalizing possible indication of this. Thus, two functions in addition to a linear fit have been used: a quadratic and an exponential (ex/3 was found to be a good fit).
Year range for fit       Function           First year ice-free
1953–2005               Linear               2106
                               Quadratic          2042
                               Exponential       2060

1979–2005               Linear               2101
                               Quadratic          2035
                               Exponential       2065
____________________________________________________
https://www.cambridge.org/core/services/aop-cambridge-core/content/view/A08934F159B0622754A63FEC6BDDCC2C/S026030550025444Xa.pdf/whither_arctic_sea_ice_a_clear_signal_of_decline_regionally_seasonally_and_extending_beyond_the_satellite_record.pdf
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on July 20, 2019, 02:09:42 PM
Yes, the trend up to 2007 (linear or otherwise) showed a dramatic decline.  This lead to many predictions of an imminent ice-free Arctic.  Many of these were knee-jerk reactions Trends over the past decade tell a different story.  All these predictions can really tell us is that the ice is changing.  Physically, the thin ice further south was much easier to melt.  Consequently, once the Arctic started warming, melt accelerated.  The remaining ice is much closer to the pole, and will melt with greater difficulty.  The decline in multi-year ice has affected the extent of the sea ice.
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on July 20, 2019, 02:26:09 PM
Quote
, our view is that a seasonally ice-free Arctic Ocean might be realized as early as 2030.

New information causes new predictions to vary. What you are posting appear to show very little knee jerk reaction to new data and seems to me like a sign of good skill compared to wildly varying predictions on this forum. (Not sure if this is the message you are trying to convey.)
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on July 20, 2019, 02:56:43 PM
Quote
, our view is that a seasonally ice-free Arctic Ocean might be realized as early as 2030.

New information causes new predictions to vary. What you are posting appear to show very little knee jerk reaction to new data and seems to me like a sign of good skill compared to wildly varying predictions on this forum. (Not sure if this is the message you are trying to convey.)

The knee-jerk to which is am referring is those claiming that scientists say the Arctic will be ice-free in the 2030s, when they actually say might.  Additionally, some choose the date they prefer among the many given, as in the posted data.  Yes, new predictions today, based on new information, are significantly different than those made after 2012 - some of which were knee-jerk.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 20, 2019, 02:57:30 PM
Quote
Trends over the past decade tell a different story.


Yeah, things are much worse, specially when looking at volume and how the Arctic changes are feeding on themselves and spreading all over the world.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 20, 2019, 03:13:28 PM
The trends over the last decades???

Anyone browsing the forum knows that things in the Arctic are getting progressively worse. The data says so itself ( unless you hide your head deep in the sand of denial and cherry pick data).

As evidenced by the spectacle in denial using poor science the risk assessment of a BOE is completely wrong.

The data clearly points are worsening conditions in the Arctic yet the "consensus" science  is expecting stabilization of the ice for 30 MORE YEARS????? 

Absolute madness.

Quote
New information causes new predictions to vary. What you are posting appear to show very little knee jerk reaction to new data and seems to me like a sign of good skill compared to wildly varying predictions on this forum. (Not sure if this is the message you are trying to convey.)

A BOE by 2080, without local arctic warming and without world wide consequences is horrible skill. Forcing the models to hit 2050 by hacking the algorithms is horrible skill.

Out of the horrible skill of this algorithm comes horrible risk assessment, after which comes the wrong reaction by mankind and the end of our civilization.

All because KkK can't handle scary news and scientist are ashamed to deliver them. Damnit.
Title: Re: When will the Arctic Go Ice Free?
Post by: El Cid on July 20, 2019, 05:09:52 PM
The trends over the last decades???

Anyone browsing the forum knows that things in the Arctic are getting progressively worse. The data says so itself ( unless you hide your head deep in the sand of denial and cherry pick data).

I'll show you what anyone looking at what the data say can see.

I attach a chart which shows average volume (piomas) for the first 6 months of the given year. I use this because we already have this for 2019.
I also put in a polynomial forecast. I also attach (second chart) the 10 year rate of change which peaked 2007-12 and has been around the average of 1995-2005 in the past few years.
I also attach (third chart) the average volume for july-aug-sept-oct. As you can see, there has been really not much change since 2010.
Yes, volume is shrinking during winter. Yes, eventually we will lose all Arctic ice - no reason to argue with that. But looking at these pictures you could understand that the Center still holds and it is impossible to know how long it will, it might vanish in 2020 or hold out until 2050 - since summer volume hasn't changed for a decade, and there is a reason why: bathymetry. Our long-term models for forecasting ice clearly suck, so no surprise scientists also try to use various statistical projections (linear or any other they seem fit).
What we can see is that during the past 10 years winter volume and extent are shrinking and the surrounding oceans are warming, but still, the Center holds. Eventually the seas around the CAB will be strong(warm) enough to destroy it, but based on the data I believe it is impossible to say when it will happen.   
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 20, 2019, 11:22:53 PM
BZZT - ambiguous pronoun referents detected!

"It is worse than we thought" = the "we" refers to the climate science community.

"It isn't as bad as we feared" = the "we" refers to members of this board.

Both statements are thus true, because this board is much more alarmist that the community in general.

If you are not alarmed, you are in denial. The normal natural response of a person of science in the face of such monumental changes and uncertainty should be alarm.

If you are not alarmed you either don't really understand what is going on or fear psychology has taken over.

Members of this forum who peddle climate risk denial do not have the excuse of ignorance.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on July 20, 2019, 11:29:38 PM
Yes, there are those who refuse to acknowledge what the data states.  The summertime losses increased until the 2007-2012 maxima.  Since then losses have slowed dramatically.  Hence the graph showing a 2050 timeframe may even be too pessimistic.  Difficult to say though with any reliability.

Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 20, 2019, 11:40:06 PM
This. Again.

This is a more elaborate version of the "no warming since 1998" BS.

Anyone keeping track of the Arctic can see that conditions continue to deteriorate, and the data clearly shows it. You can look at any metric, extent, area, volume, thickness, air temperatures, ocean temperatures and tell that things continue to deteriorate.

Global cooling is not expected. Global warming with Arctic amplification is in the books for the foreseeable future. Things will get even worse.

You all denying risk, and worse scientists, publishing overly conservative, thoroughly incomplete models to decision makers will be wise to pay attention to this years minimum volume and refreeze behavior. It is likely that further confirmation of hysteresis will make itself available.

I partly say this with the hope that my bad luck is such that I'm wrong about a record minimum and slow refreeze that follows.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on July 21, 2019, 01:37:59 PM
BZZT - ambiguous pronoun referents detected!

"It is worse than we thought" = the "we" refers to the climate science community.

"It isn't as bad as we feared" = the "we" refers to members of this board.

Both statements are thus true, because this board is much more alarmist that the community in general.

If you are not alarmed, you are in denial. The normal natural response of a person of science in the face of such monumental changes and uncertainty should be alarm.

If you are not alarmed you either don't really understand what is going on or fear psychology has taken over.

Members of this forum who peddle climate risk denial do not have the excuse of ignorance.

I have little tolerance for either alarmists or deniers, as both seem to be arguing from emotion rather than objective science.  Both will cherrypick the data to show exactly what their psyche wants, instead of looking at the bigger view.  The real kicker is that both of these extremists think that only they know the answers, and everyone else is of the opposite extreme.  Some even think that most scientists support their views, and those that do not have been corrupted by politics or the like.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 21, 2019, 02:07:11 PM
Quote
I have little tolerance for either alarmists or deniers, as both seem to be arguing from emotion rather than objective science.  Both will cherrypick the data to show exactly what their psyche wants, instead of looking at the bigger view.  The real kicker is that both of these extremists think that only they know the answers, and everyone else is of the opposite extreme.

Pssst. You are a denier and you just perfectly described yourself. You are in denial even about your denial. How do I know?

We should be alarmed BECAUSE of the uncertainties. The uncertainty surrounding climate change is already enough to bring the world to a screeching halt. If it wasn't for deniers like you speaking deliciously convenient poison it would've happened already.

It doesn't matter tho. It is a simple matter of time that you will be scared about climate change. It will only get worse and hit closer and closer to home.

Monuments should be erected for people like you, so that when SHTF and people are looking for scapegoats they know who to blame.

Sadly, people like you will likely just change tune and pretend you've been warning us about the dangers of climate change for years. People like you will turn to the scientists quoted by crandles and blame them for not crying wolf with wolves right in their faces.

Tough to be a climate scientist these days.
Title: Re: When will the Arctic Go Ice Free?
Post by: dnem on July 21, 2019, 02:21:23 PM
Hey KK, you get my standard offer: Let's meet for lunch in 2030.  If you're not fully alarmed, lunch is on me.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on July 21, 2019, 02:22:36 PM
Hey KK, you get my standard offer: Let's meet for lunch in 2030.  If you're not fully alarmed, lunch is on me.

Deal.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on July 21, 2019, 02:28:24 PM
Quote
I have little tolerance for either alarmists or deniers, as both seem to be arguing from emotion rather than objective science.  Both will cherrypick the data to show exactly what their psyche wants, instead of looking at the bigger view.  The real kicker is that both of these extremists think that only they know the answers, and everyone else is of the opposite extreme.

Pssst. You are a denier and you just perfectly described yourself. You are in denial even about your denial. How do I know?

We should be alarmed BECAUSE of the uncertainties. The uncertainty surrounding climate change is already enough to bring the world to a screeching halt. If it wasn't for deniers like you speaking deliciously convenient poison it would've happened already.

It doesn't matter tho. It is a simple matter of time that you will be scared about climate change. It will only get worse and hit closer and closer to home.

Monuments should be erected for people like you, so that when SHTF and people are looking for scapegoats they know who to blame.

Sadly, people like you will likely just change tune and pretend you've been warning us about the dangers of climate change for years. People like you will turn to the scientists quoted by crandles and blame them for not crying wolf with wolves right in their faces.

Tough to be a climate scientist these days.

It is touch to be a climate scientists.  The deniers roast them for spreading false information, while the alarmists deride them for being soft on scaremongering.  Yes, there is much uncertainty.  But that is no reason to cower in fear.  Not everyone is a metathesiophobiac.
Title: Re: When will the Arctic Go Ice Free?
Post by: Rich on July 21, 2019, 02:41:43 PM
Climate change is deepening and the risks political leaders are taking is illogical from the perspective of the continuity of human civilization.

It's easy to demonstrate the deniers like Klondike are being disingenuous, but you have to choose the correct  issues.

The timing of an ice free Arctic could very well be deferred until the latter half of this century.

We can not extrapolate the experience of the shallow Arctic perimeter to the deep Central Basin.

If we treat the Central Basin as a separate entity as we should, there is no trend line supporting a likely BOE before 2030.

It may very well happen sooner than 2030, but it will be a function of weather variation.

The uncertainty that Archimid speaks to is indeed justification for rational fear. We would never get on a plane that had a 5% chance of crashing and killing us. There is no logic to support pushing the system to a point which has a meaningful possibility of causing global catastrophe.

We know enough to understand that the possibility of global catastrophe is real and too high.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on July 21, 2019, 02:47:43 PM
Archimid, will you calling Rich a denier also, as he thinks a BOE is unlikely by 2030 also?
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on July 21, 2019, 02:51:00 PM
Climate change is deepening and the risks political leaders are taking is illogical from the perspective of the continuity of human civilization.

It's easy to demonstrate the deniers like Klondike are being disingenuous, but you have to choose the correct  issues.

The timing of an ice free Arctic could very well be deferred until the latter half of this century.

We can not extrapolate the experience of the shallow Arctic perimeter to the deep Central Basin.

If we treat the Central Basin as a separate entity as we should, there is no trend line supporting a likely BOE before 2030.

It may very well happen sooner than 2030, but it will be a function of weather variation.

The uncertainty that Archimid speaks to is indeed justification for rational fear. We would never get on a plane that had a 5% chance of crashing and killing us. There is no logic to support pushing the system to a point which has a meaningful possibility of causing global catastrophe.

We know enough to understand that the possibility of global catastrophe is real and too high.

Disingenuous?  For posting facts, instead of rhetoric?  Or is it that I do not think the changes will bring about global catastrophe and mass extinction? 
Title: Re: When will the Arctic Go Ice Free?
Post by: Andre Koelewijn on July 21, 2019, 03:33:22 PM
The choice and arrangement of facts (or, alternatively, 'facts') are part of rhetoric, as the ancient Greek already knew.

Now, the terms 'global catastrophe' and 'mass extinction' are not really well defined terms and dependent on the context.
I've heard people argue that as long as this planet will continue to exist (at least as a dead piece of rock in space), you can't talk about a global catastrophe. On the other side of the spectrum, some disruptions in modern communication caused by e.g. sun flares could be classified as a global catastrophe.
Likewise, 'mass extinction' is a debatable term too. Of any species? Then it is a repititive process on this planet, of late rather frequent. Or is it only related to human beings? Then, does it refer only to (near-?)complete starvation of humans? Or a situation in which less than, say, 10% (of 7 billion) survives? Or a situation in which almost 10% dies? Or even "only" in a certain region?
In this forum, when it comes to 'mass extinction', I may have seen all these possibilities.

I do not want to start a discussion on definitions here, but please be a bit tolerant to what others might indicate by terms or words which you would use for quite a different situation.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 21, 2019, 04:10:39 PM
Quote
If we treat the Central Basin as a separate entity as we should, there is no trend line supporting a likely BOE before 2030.


Sorry dude, that's just what KkK loves to tells himself. The truth is different. If things continue as they have been, volume might set a new record, pulling the CAB BOE trend even earlier in time.
Title: Re: When will the Arctic Go Ice Free?
Post by: Shared Humanity on July 21, 2019, 04:16:05 PM
The trends over the last decades???

Anyone browsing the forum knows that things in the Arctic are getting progressively worse. The data says so itself ( unless you hide your head deep in the sand of denial and cherry pick data).

I'll show you what anyone looking at what the data say can see.

I attach a chart which shows average volume (piomas) for the first 6 months of the given year. I use this because we already have this for 2019.
I also put in a polynomial forecast. I also attach (second chart) the 10 year rate of change which peaked 2007-12 and has been around the average of 1995-2005 in the past few years.
I also attach (third chart) the average volume for july-aug-sept-oct. As you can see, there has been really not much change since 2010.
Yes, volume is shrinking during winter. Yes, eventually we will lose all Arctic ice - no reason to argue with that. But looking at these pictures you could understand that the Center still holds and it is impossible to know how long it will, it might vanish in 2020 or hold out until 2050 - since summer volume hasn't changed for a decade, and there is a reason why: bathymetry. Our long-term models for forecasting ice clearly suck, so no surprise scientists also try to use various statistical projections (linear or any other they seem fit).
What we can see is that during the past 10 years winter volume and extent are shrinking and the surrounding oceans are warming, but still, the Center holds. Eventually the seas around the CAB will be strong(warm) enough to destroy it, but based on the data I believe it is impossible to say when it will happen.

A worthy analysis...
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 21, 2019, 04:17:43 PM
It is touch to be a climate scientists.  The deniers roast them for spreading false information, while the alarmists deride them for being soft on scaremongering.  Yes, there is much uncertainty.  But that is no reason to cower in fear.  Not everyone is a metathesiophobiac.

 "But that is no reason to cower in fear."  Certainly. That's why I keep advising you to stop cowering in fear, face the risk of climate change and take firm action against it. Wake up.
Title: Re: When will the Arctic Go Ice Free?
Post by: El Cid on July 21, 2019, 04:28:18 PM
Ladies and gentlemen, welcome to the World Championship of Cherrypicking. Wonder why our good friend Archimid started his graph from 2000 and not 1979, the start of the data? Because that is the best fit for an intersection of the two lines before 2030. Whereas if you do this thing correctly, from the start of the data this is what you get (red: annual voulme loss in the CAB, blue: max volume in the CAB). Chart attached.

Title: Re: When will the Arctic Go Ice Free?
Post by: El Cid on July 21, 2019, 04:29:29 PM
Not that these linear extrapolations matter at all, because it is a nonlinear system, but anyway, if you claim to respects facts and data, you don't do things like this
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 21, 2019, 05:03:56 PM
Actually, the regional PIOMAS data that Wipneus posts starts on the year 2000. I merely used the whole data set. Where did you get regional PIOMAS from 1979?

When using all of PIOMAS from 1979 the date of the first BOE is also around 2030, pending the result of this melting season. Image attached.

You are right that this is a non linear system. It has already gone through several state changes.

This can be clearly seen in your graph. From 1979 to 2006 CAB melting was steady. Then in 2007 a state change occur where annual volume loses increased significantly. During this time multiyear ice was destroyed. Such volume loses peaked in 2012 and since then have been climbing steadily again, towards the next step change.

See second graph for the trends after the old ice was gone in 2012.

The risk deniers argument is that in the second graph  the losses will remain steadily around the average, or even drop.

This is supposed to happen even after world warms, and Arctic amplification amplifies and the jet streams collapse and the ice albedo feedback pick up speed.  I find their argument unbelievable.

I find it much more likely that the melt will keep increasing like the "linear trend"  from 2013-2018 suggest. It is not a linear system and the forces working on the system are pushing towards warming.
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on July 21, 2019, 07:58:46 PM
This can be clearly seen in your graph. From 1979 to 2006 CAB melting was steady. Then in 2007 a state change occur where annual volume loses increased significantly. During this time multiyear ice was destroyed. Such volume loses peaked in 2012 and since then have been climbing steadily again, towards the next step change.


You seem to be accepting this 'thick MYI destroyed' explanation which I have mentioned is in the scientific literature. But you don't seem to be thinking through the likely consequences.

> Such volume loses peaked in 2012 and since then have been climbing steadily again

What? Think about it! :

First the maximum volume line. So instead of one straight line we should have shallow decline, steep decline then shallow decline again. Fast rate being thick MYI disappearing and not coming back. Now this has gone there is more FYI which mainly reforms each winter so a shallower decline line for the maximum. This pushes the date of the intersection to later dates.

But this is not all, the shape of the maximum trend line also has consequences for the losses line. When there was a fast rate of max volume decline, this translates into more/faster open water formation and more albedo feedback so the losses increase at a faster rate. However, now that the fast rate of max volume decline has gone away, this effect also goes away and the rate of increase in losses should also be expected to be slower. (That isn't even considering whether losses decline as the ice shrinks to areas that are harder to melt)

Anyway shallower rate of decline for max volume and shallower rate of rise for the losses can give quite significantly longer times before regular ice free conditions are reached.


Title: Re: When will the Arctic Go Ice Free?
Post by: SteveMDFP on July 21, 2019, 08:08:11 PM


But this is not all, the shape of the maximum trend line also has consequences for the losses line. When there was a fast rate of max volume decline, this translates into more/faster open water formation and more albedo feedback so the losses increase at a faster rate. However, now that the fast rate of max volume decline has gone away, this effect also goes away and the rate of increase in losses should also be expected to be slower. (That isn't even considering whether losses decline as the ice shrinks to areas that are harder to melt)
 

I think the opposite is true.  Near record low minima, year after year, has meant more open water at the beginning of the arctic night, with vastly increased outgoing radiation to space in the arctic night.  Yet, the minimum has been trending down, despite this strong negative feedback.

By end of winter, there's still a (thinner) snow+ice cover over most of the traditionally ice-covered arctic, presenting a fairly typically low albedo for the spring high-insolation period.  And yet, losses have been trending to greater values, despite this negative feedback.

There's good reason to believe the observed trends will continue, as GHG levels continue to increase and sub-surface ocean warmth continues to increase.
Title: Re: When will the Arctic Go Ice Free?
Post by: HapHazard on July 21, 2019, 08:57:15 PM
The choice and arrangement of facts (or, alternatively, 'facts') are part of rhetoric, as the ancient Greek already knew.

Amen to that. Chosen & arranged in a certain manner, the same facts/data can be presented to mean 2 opposing things; in effect, they are all too often wielded as weapons.

I will once again throw out one of my favourite sayings:

Statistics are like bikinis. What they reveal is interesting, but what they hide is crucial.
Title: Re: When will the Arctic Go Ice Free?
Post by: Rich on July 21, 2019, 09:08:47 PM
Archimid, will you calling Rich a denier also, as he thinks a BOE is unlikely by 2030 also?

Please don't put words in my mouth KK.

I said that I see no trend line supporting a BOE by 2030. That is very different from opining that a BOE is likely or unlikely to happen by then.

The non-freeze of the Bering is just a 2 year trend at this point. Not enough to statistically demonstrate that it's a new normal, but a step change that dramatically increases the risk of BOE if it continues.

Only morons like yourself would advise waiting for confirmation of catastrophe outcomes before taking action to prevent them.
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on July 21, 2019, 09:16:12 PM

But this is not all, the shape of the maximum trend line also has consequences for the losses line.
....

I think the opposite is true.  Near record low minima, year after year, has meant more open water at the beginning of the arctic night, with vastly increased outgoing radiation to space in the arctic night.  Yet, the minimum has been trending down, despite this strong negative feedback.

By end of winter, there's still a (thinner) snow+ice cover over most of the traditionally ice-covered arctic, presenting a fairly typically low albedo for the spring high-insolation period.  And yet, losses have been trending to greater values, despite this negative feedback.

There's good reason to believe the observed trends will continue, as GHG levels continue to increase and sub-surface ocean warmth continues to increase.

I agree the minimum is and will continue trending down. A negative feedback like the winter ice thickness feedback does not stop any change. It reduces the effect, but there is still some effect left. (This is before discussing positive feedbacks in summer like albedo.)

But on the subject I was taking about, does the trend in max volume have an effect on trend in minimum volume?

Imagine 2 worlds where in one the maximum winter ice volume is holding steady and another where the maximum volume is trending downwards at quite a high rate. All else is the same including CO2 increases over time, water temperatures, wind temperatures etc.

As the fast declining max ice volume world gets less and less ice, the summer positive albedo feedback can get to work earlier and earlier and the ice volume loss increases more rapidly than in the max volume holding steady world. Does anyone really want to argue against this?
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 21, 2019, 09:23:23 PM

First the maximum volume line. So instead of one straight line we should have shallow decline, steep decline then shallow decline again. Fast rate being thick MYI disappearing and not coming back. Now this has gone there is more FYI which mainly reforms each winter so a shallower decline line for the maximum. This pushes the date of the intersection to later dates.


I try to capture what you are talking about dividing losses by maximum of each year. See first graph attached. I drew a 5 year average line through it that clearly shows the steps you mention.

 Before the early 2000's the ratio of loses to max grew very slowly. Around 2007 all hell broke lose and losses accelerated significantly while the maximum dropped more slowly. This continues until the record low year 2012. After 2012 the opposite happened. Maximum kept dropping but the losses stabilized relative to the high change years.

Until then the models were correct. 2013 and 2014 recovered. Then three hottest years on record happened.  2016 dropped to near record levels but there was no rebound. 2017 became the lowest max on record by a significant margin. Auto correlation be damned.

Then the obligatory low following  a max happened. El niño went away, the world cooled a bit. 2017 and 2018 recovered, but nothing like 2013 and 14.

Now 2019 with a weak el niño and favorable Atlantic temperatures for ice retention is showing us the true trend. Volume record seems likely to be broken, even when all that is left is "difficult" to melt ice and very low amount of it, according to your argument.

The next super el niño which will happen on top of the global warming and albedo feedback that will accumulate until then, is likely the end.


Quote
However, now that the fast rate of max volume decline has gone away

Have they gone away? 2017 just happenned and it was the lowest volume gain since the change of state in 2007.

Quote
this effect also goes away and the rate of increase in losses should also be expected to be slower. (That isn't even considering whether losses decline as the ice shrinks to areas that are harder to melt)

This would be more believable if the enthalpy of fusion wasn't a thing.

Title: Re: When will the Arctic Go Ice Free?
Post by: El Cid on July 21, 2019, 09:29:34 PM
Actually, the regional PIOMAS data that Wipneus posts starts on the year 2000. I merely used the whole data set. Where did you get regional PIOMAS from 1979?

It's on the piomas site, I just downloaded it
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on July 21, 2019, 09:35:22 PM
Actually, the regional PIOMAS data that Wipneus posts starts on the year 2000. I merely used the whole data set. Where did you get regional PIOMAS from 1979?

It's on the piomas site, I just downloaded it

Archmid's CAB excludes the peripheral seas. Your PIOMAS data includes them.
Title: Re: When will the Arctic Go Ice Free?
Post by: jdallen on July 21, 2019, 10:09:21 PM
Actually, the regional PIOMAS data that Wipneus posts starts on the year 2000. I merely used the whole data set. Where did you get regional PIOMAS from 1979?

It's on the piomas site, I just downloaded it

Archmid's CAB excludes the peripheral seas. Your PIOMAS data includes them.
For the sake of identifying trends, the peripheral seas very much need to be left out, as even before the current decline, they tended to melt out entirely over the melt season and buffer the numbers in ways that mask the actual shift in system behavior.

Archmid's arguments are very persuasive, and match my more anecdotal evaluation of what we are seeing.  I think the leveling off or even slight de-acceleration in the rate of volume decline is an "asymptotic" effect.  Namely, we are now approaching "hard" limits of the system, much like a descending pendulum starting to scrape a surface.  That suggests to me we've already made one non-reversible transition in system state.

The question now to be answered is how long it will stay in this current state before tipping into the next one - which would be where we see regular BoE's.

My own sense is that it will happen sometime in the next ten years, which I evaluate in terms of probabilities. 

This year I think is the 2nd (after 2016) where there was a non-zero probability of a BoE.  I don't think it will happen this year, but there is still good reason to believe 2019 will challenge 2012 for the low extent record.  I think we are seeing a cumulative increase in potential for it moving forward.  Pick your number - 1%, 2%, 5% (mine) or higher, I think that will stack up as enthalpy in the region and globe as a whole continues to stack up and pass key "non-tangible" thresholds which govern climate state. 

When it comes, it will likely be sudden and still a surprise, even though we are looking for it.
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on July 21, 2019, 10:53:03 PM
Umm, I don't really believe this graph as the green and purple trend lines don't cross in future and with continues GHG emissions I believe they will. Also sorry about the trendlind being extended outside the range they are meant to apply to which makes graph horribly messy.


Anyway the issue I am trying to address is: If the green line is less steep than the yellow as implied by accepting MYI destroyed explanation, should the purple line also be less steep than the light blue line?

Can of course pick different change points and get different slopes. Not really enough data to do this reliably yet, but in principle, the purple line being less upward sloping than light blue seems an obvious conclusion to me.

Whether purple line should be positive or negatively sloped is a different argument about whether remaining ice is is harder to melt locations.

These need more data to verify, but so far the data suggests what?
Title: Re: When will the Arctic Go Ice Free?
Post by: jdallen on July 21, 2019, 11:09:25 PM
Umm, I don't really believe this graph as the green and purple trend lines don't cross in future and with continues GHG emissions I believe they will. Also sorry about the trendlind being extended outside the range they are meant to apply to which makes graph horribly messy.

<snippage>

These need more data to verify, but so far the data suggests what?
I think the problem lies in the fact we are trying to collapse probability in a 3 dimensional system over time down to 1 absolute scalar value.

I think what we need is something like the "probability of melt" map we've seen elsewhere on the forum, where we evaluate each section of the map in turn over time.

Then I'd say we can stack probabilities to something more sensible.
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on July 21, 2019, 11:28:01 PM
I try to capture what you are talking about

Doesn't seem to capture it very well, which probably means I explained badly. So I had another go.

Anyway, where are we up to?

Do you accept that my green line is less steep than a line through all the April data?
This pretty well necessarily follows from accepting a faster rate of decline while the MYI was destroyed?
And this suggest a longer time to ice free state?

If the max trendline changes the rate of decline to being less steep, do you accept this is likely to make the losses (April - Sept) trend line less positively sloped?
And this also suggests a longer time to ice free state?
Title: Re: When will the Arctic Go Ice Free?
Post by: icefisher on July 21, 2019, 11:56:46 PM
Volume is key to future ice health.  Expect continued year-over-year maximum volume losses unless a strong La Nina or major volcanic eruption occurs.  Without those interventions a 15-20% max volume loss compared to 2018 is possible by 2023.  Adding the effects of a major El Nino with lower maximum volumes after 2023 creates circumstances leading to a Low Volume Event and a potential BOE no later than 2030.  Another potential ice risk is a solar maximum.  When is the next solar maximum?  Is there a possibility that all of these risks will happen at the same time? ??? :-[
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 22, 2019, 12:56:28 AM
I think that starting the purple line in 2013 is a better choice than 2011, as in 2011 there were large amounts of thick ice left, same as 2012. 2013 better captures the beginning of a new state.  The minimum is undergoing a hiatus until the maximum is low enough and the arctic is hot enough to support bigger losses. This year is on trend to pull the purple line up and if the Chukchi and Bering behave like last year, the green line down.
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on July 22, 2019, 01:19:41 AM
I think that starting the purple line in 2013 is a better choice than 2011,

Probably more reasonable purple trendline even if I don't like gap between purple and blue lines at 2013. Also less data so more uncertainty about the trendline slope.

Previously missed the 2019 data point for April. Oops.
Title: Re: When will the Arctic Go Ice Free?
Post by: El Cid on July 22, 2019, 09:18:02 AM
Actually, the regional PIOMAS data that Wipneus posts starts on the year 2000. I merely used the whole data set. Where did you get regional PIOMAS from 1979?

It's on the piomas site, I just downloaded it

Archmid's CAB excludes the peripheral seas. Your PIOMAS data includes them.

No. I only used CAB volume (they have it on their site in the monthly file broken down by seas), and I think that is the right approach as the peripherial seas mostly melt out. The lines I drew are also (just like Archimid's) meaningless anyway as the system is nonlinear. The CAB might hold out for another 20-30 years even, ot go poof in the 2020s. Impossible to say. Nooone knows and what is more noone can know.
Title: Re: When will the Arctic Go Ice Free?
Post by: El Cid on July 22, 2019, 09:25:44 AM
I attach CAB volume (rolling 12 months, PIOMAS) since 1980. As you can all see, it has not gone anywhere since about 2010, meaning that the central pack has different characteristics than the periphery. This "hiatus" is probably caused by the fact that by the time the periphery melts out (aug-sept) it is too late to attack the CAB which is thicker anyway. How long this state lasts is impossible to say. Eventually the meltout in the periphery will happen earlier (maybe by July) and there will be time to "attack" the CAB which might or might not kill it completely. This "hiatus" is obviously (considering the ever warmer seas) will end some time. Noone knows when though and linear projections are useless, especially that there are obvious state-changes on the graph.
Title: Re: When will the Arctic Go Ice Free?
Post by: Rich on July 22, 2019, 11:07:08 AM
That's an A+ post El Cid. Explanation and chart tie it all together.
Title: Re: When will the Arctic Go Ice Free?
Post by: gerontocrat on July 22, 2019, 12:12:23 PM
The CAB has about 20% of the area of the Arctic Ocean and
- about 50% of the volume at maximum,
- about 90% of the volume at minimum.

and....

What story do you want ?
Choose your trend line and any future is yours.
Title: Re: When will the Arctic Go Ice Free?
Post by: Rich on July 22, 2019, 12:39:07 PM
The CAB has about 20% of the area of the Arctic Ocean and
- about 50% of the volume at maximum,
- about 90% of the volume at minimum.

and....

What story do you want ?
Choose your trend line and any future is yours.

Regardless of the conclusion, I prefer the story with the Central Basin as the main character in the plot.

The other characters are lacking in depth and becoming too predictable.
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on July 22, 2019, 12:41:54 PM

No. I only used CAB volume (they have it on their site in the monthly file broken down by seas),

My apologies.

(I still haven't found it.)
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 22, 2019, 01:46:11 PM
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How long this state lasts is impossible to say.

Given that you are risking all our lives, you better be damn sure. You are betting our lives that the hiatus will last more than 30 years. That you are saying this at the the same time it looks like the hiatus may be broken is a type of irony that I have grown used to in climate change debates.


This is an update on this year losses for the CAB.
Title: Re: When will the Arctic Go Ice Free?
Post by: binntho on July 22, 2019, 01:56:42 PM
Given that you are risking all our lives ...

What's with the hyberbole? Nobody on this forum is risking my life.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 22, 2019, 02:08:46 PM
Denying the risk of climate change, particularly, denying the risk to all our lives that A BOE presents is placing our lives at risk. This is not hyperbole, although it sounds like it. It is the simple fact.

The conclusions the IPCC reaches will determine our response to the threat. If you read Crandles post about the IPCC, the only conclusion a decision maker can reach is to wait and see.

What El Cid and Crandles are doing is a version of "no warming since 1998".  Their arguments are not a product of science or logic. Their arguments are a product of freezing fear that stops them from seeing evidence that confirms their fears.

If they are advocating no action against climate change and no alarm, they better have a damn good case, because the evidence is reason for great alarm.
Title: Re: When will the Arctic Go Ice Free?
Post by: Phil. on July 22, 2019, 02:11:04 PM
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How long this state lasts is impossible to say.
This is an update on this year losses for the CAB.

What are the units for the graph, loss in what terms cubic km?
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 22, 2019, 02:18:00 PM
1000 km3.
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on July 22, 2019, 02:24:12 PM
What El Cid and Crandles are doing is a version of "no warming since 1998".  Their arguments are not a product of science or logic. Their arguments are a product of freezing fear that stops them from seeing evidence that confirms their fears.

If they are advocating no action against climate change and no alarm, they better have a damn good case, because the evidence is reason for great alarm.

I am not advocating no action against climate change. I think we should be doing a lot more than we are doing.

In arguing for more action, I believe the case should be sound. There is plenty of good reason for more action without unduly hyping uncertainty and threats are are likely quite mild and/or highly unlikely.

Hyping uncertainty and/or threats and/or the possible timeline for things that are not really considered very serious, just gives conservatives reason to dismiss environmentalists as wide eyed, gullible, tree hugging, alarmist fools.
Title: Re: When will the Arctic Go Ice Free?
Post by: binntho on July 22, 2019, 02:24:44 PM
Denying the risk of climate change,
I'm not seeing anybody denying the risk of climate change?
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particularly, denying the risk to all our lives that A BOE presents
What risk does a BOE present to me above and beyond the general risk of continued AGW to my life? None in my opinion.
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is placing our lives at risk.
So I'm putting my (and your) life at risk by denying that BOE presents a risk above and beyond continued AGW?
Quote
This is not hyperbole, although it sounds like it.
Sounds like it, looks like it.
Quote
It is the simple fact.
When your hyberbolista starts claiming to know "the simple fact" about something then I think it's time to reach for the 'brellas.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 22, 2019, 02:46:34 PM
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I'm not seeing anybody denying the risk of climate change?

You can't see anyone denying risk of climate change? Here. Read your own words.

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What risk does a BOE present to me above and beyond the general risk of continued AGW to my life? None in my opinion.

I mean, you say that you don't see anyone denying risk in the same post that you deny the risk. If you can't see it when you deny it, how do you expect to see it when others deny it?  See, this is not science or logic. These types of contradictions are products of fear psychology.

Let's keep going

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So I'm putting my (and your) life at risk by denying that BOE presents a risk above and beyond continued AGW?

Correct. The harm that climate change will cause is a function of climate change but also of our response to it. If we ignore the threat that events like a BOE presents, then we will not prepare for them, making any negative effect orders of magnitude worse.

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Sounds like it, looks like it.

Yep. It is impossible to tell scary truths without sounding scary. That's a big disadvantage because people don't want to be scared about a not so distant event in the North pole. They have enough on their plate. If this was true they would be forced into action. That is too much to ask. It is easier to deny the risk. The chorus singing for risk denial makes it that much easier.

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When your hyberbolista starts claiming to know "the simple fact" about something then I think it's time to reach for the 'brellas.

An ice less Arctic ocean during summer is not hyperbole. It is so terrible that it sounds like hyperbole, but it is just simple physics.
Title: Re: When will the Arctic Go Ice Free?
Post by: Rich on July 22, 2019, 02:48:07 PM
Denying the risk of climate change, particularly, denying the risk to all our lives that A BOE presents is placing our lives at risk. This is not hyperbole, although it sounds like it. It is the simple fact.


I am with you in spirit Archimid, but not on this point.

I agree with you completely that society is not demonstrating appropriate risk management as it pertains to AGW.  The anecdotal data in support of potential looming catastrophe are overwhelming in their support of putting the brakes on GHG emissions.

Where I disagree with you is strictly regarding the focus on imminent BOE. The point that El Cid is making regarding the fundamental difference between CAB and rest of Arctic is salient. Focusing on CAB trends alone, we do not get a BOE by 2030 or 2040.

We could easily get a BOE before then as a result of state change (like Bering / Chuchki) or freak weather, but that:s not something we should expect the IPCC to forecast.

We give ammo to the deniers like KK by advancing claims such as BOE before 2030 which aren't empirically supported.

There are many better arguments in support of impending catastrophe than BOE.
Title: Re: When will the Arctic Go Ice Free?
Post by: binntho on July 22, 2019, 02:57:57 PM
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I'm not seeing anybody denying the risk of climate change?

You can't see anyone denying risk of climate change? Here. Read your own words.

Quote
What risk does a BOE present to me above and beyond the general risk of continued AGW to my life? None in my opinion.

I mean, you say that you don't see anyone denying risk in the same post that you deny the risk. If you can't see it when you deny it, how do you expect to see it when others deny it?  See, this is not science or logic. These types of contradictions are products of fear psychology.
I'm not sure if you are reading what I wrote? I do not think that BOE causes any risk to me or mankind above and beyond the general risk of continued AGW.

I've seen nothing that indicates that the huge risk involved in continued AGW is in any significant way increased (or decreased) by a BOE.

Does that mean that I deny that there is a risk involved in continued AGW? Of course not. Stop spouting nonsense my dear man!
Title: Re: When will the Arctic Go Ice Free?
Post by: FishOutofWater on July 22, 2019, 03:06:54 PM
What trends in the central Arctic. What we're seeing is a series of downward steps at irregular intervals. Those steps are related to the polewards advance of warm water and warm air in the north Atlantic and the intensification of El Niño with the heating of the planet. Surges of warm salty water into the Arctic from the north Atlantic have been irregular, but they involve large amounts of heat so they have a pan Arctic impact.

Forget about drawing lines and curves through irregular steps to make a forecast. We need to understand the steps better or we need to use a model that has stochastic elements.

Yes, the IPCC and governments have been doing abysmal risk management. There are huge weather and climate impacts of the polewards movement of ocean heat apart from the issue of an ice free Arctic in September. We are already seeing those impacts but they will get worse even if we do everything right to cut GHG emissions because of the earth's energy imbalance caused by thermal disequilibrium with the middle and deep oceans.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 22, 2019, 03:12:26 PM
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Where I disagree with you is strictly regarding the focus on imminent BOE.

Fine. As the arctic shrinks and the NH weather goes to shit then the scientist in you will agree with me. It might be too late then.

Quote
Where I disagree with you is strictly regarding the focus on imminent BOE. The point that El Cid is making regarding the fundamental difference between CAB and rest of Arctic is salient. Focusing on CAB trends alone, we do not get a BOE by 2030 or 2040.

Focusing on CAB trends alone is terrifying. Understanding the step changes the ice has gone through is reason for alarm. However, if displayed as conservatively as possible, if all context is ignores and a 30 years hiatus is assumed, the CAB reflects what you say.

Quote
We give ammo to the deniers like KK by advancing claims such as BOE before 2030 which aren't empirically supported.

It simply does not work like that. It does not matter what you say or how you say it, it will be taken out of context and misinterpreted to their hearts contempt. They question NASA's and NOAA dataset, they will question everything.

That's why it is better to tell the best truth, without worrying about what others will say and do.

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There are many better arguments in support of impending catastrophe than BOE.


Nope. The disappearance of the Arctic is the greatest threat of climate change. The only things that can potentially be worse are plastic contamination or maybe ocean anoxia.

No other single event presents a larger risk.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on July 22, 2019, 03:16:04 PM
Quote
I'm not seeing anybody denying the risk of climate change?

You can't see anyone denying risk of climate change? Here. Read your own words.

Quote
What risk does a BOE present to me above and beyond the general risk of continued AGW to my life? None in my opinion.

I mean, you say that you don't see anyone denying risk in the same post that you deny the risk. If you can't see it when you deny it, how do you expect to see it when others deny it?  See, this is not science or logic. These types of contradictions are products of fear psychology.
I'm not sure if you are reading what I wrote? I do not think that BOE causes any risk to me or mankind above and beyond the general risk of continued AGW.

I've seen nothing that indicates that the huge risk involved in continued AGW is in any significant way increased (or decreased) by a BOE.

Does that mean that I deny that there is a risk involved in continued AGW? Of course not. Stop spouting nonsense my dear man!

I believe that the problem is that there are several posters claiming knowledge of an imminent catastrophic event, without supporting evidence.  These same posters claim that anyone who does not believe their scenario is accurate, must be a denier.  As gerontocrat posted, one can obtain substantially different projections simple by varying the graphic fit chosen.  As El Cid posted, there appears to be state change after the periphery ice has melted, and the melting of the CAB may progress at an entire different rate.  While the overall trajectory points towards a BOE, the data gives little indications as to when. and certainly not imminently.  That does not mean that a sudden change could not occur in the very near future, which causes another substantial downturn in sea ice.

Knowledgeable people, here and elsewhere, have various speculations of the timing and overall consequences of a BOE.  As crandles stated, hyping timelines and threats only gives more ammunition to conservatives, wishing to dismiss environmentalists as alarmist.  How many claims of an ice-free Arctic have failed to materialize in the recent past.  I see no reason to add any more.  If that make me a denier Rich, then so be it.  I will take realism and accuracy in data over hyperbole any day of the week.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 22, 2019, 03:27:22 PM

I'm not sure if you are reading what I wrote? I do not think that BOE causes any risk to me or mankind above and beyond the general risk of continued AGW.

You are not reading what you wrote. A BOE presents a much greater risk than the generalized risk of AGW. you are denying it does, yet you think you are not.

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I've seen nothing that indicates that the huge risk involved in continued AGW is in any significant way increased (or decreased) by a BOE.

If you can't see yourself denying the risk, I doubt you can see the risk. There are countless thread of this forum that contain very good arguments, supported by good data that clearly outline the risks of a BOE. Accepting the risk a BOE presents is not for the faint of heart.

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Does that mean that I deny that there is a risk involved in continued AGW? Of course not. Stop spouting nonsense my dear man!

You are denying risk, vigorously and without evidence or logic, yet you think you are not denying risk. 

Let me help you out.

 You can make a list of all the threats climate change offers.

That list can be ordered in many ways, for severity and time. A BOE would be on top of that list, by a significant margin.

Divide and conquer. A time tested strategy applicable to everything from math problems to war.

Thus it is worth it to focus on the event that is likely to be the worse of a long list of horrible events.
Title: Re: When will the Arctic Go Ice Free?
Post by: binntho on July 22, 2019, 03:35:17 PM

I'm not sure if you are reading what I wrote? I do not think that BOE causes any risk to me or mankind above and beyond the general risk of continued AGW.

You are not reading what you wrote. A BOE presents a much greater risk than the generalized risk of AGW. you are denying it does, yet you think you are not.
What total nonsense.

A BOE is at most something  that gets in the news. AGW is already killing people and has the potential to totally wreck our civilization.

BOE bullocks!

And don't think that I think that losing Arctic Sea Ice is not a huge danger to us all. It has consequences that are already visible, and will only get worse.

The only denier here is you, Archimid, ignoring the very real and huge threat from ongoing AGW and focusing on a putative and spurious sometime-in-the-future BOE.

AGW is a huge risk and an ongoing catastrophe. Hammering on about a non-event that may or may not materialise within the next decade or six can perhaps be called hyperdenialism?

As in "nothing bad is happening now nor will it before we have my hyperbolically huge event that only I think is the real and only catastrophe that will wreck us all and where did I put my undies".
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 22, 2019, 03:43:52 PM
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What total nonsense.

Sigh. how does this:

Quote
A BOE is at most something  that gets in the news. AGW is already killing people and has the potential to totally wreck our civilization.

does not contradict this:

Quote
And don't think that I think that losing Arctic Sea Ice is not a huge danger to us all. It has consequences that are already visible, and will only get worse.

A BOE is a huge danger for us all but at most, it is something that gets in the news.

Please explain.
Title: Re: When will the Arctic Go Ice Free?
Post by: Rich on July 22, 2019, 03:47:19 PM
As it pertains to BOE, you are not a denier KK. I actually agree with you here.

The denier label speaks to your general contribution at ASIF.

If you check the polls taken here, the expectation of the voting members of ASIF is BOE in the near future. Much sooner than CAB trend lines would suggest.

In a sense, I think the ASIF community hands the deniers an easy win by engaging in so much speculation about imminent BOE. If I were a denier with an agenda of maintaining BAU, this is where I would want the conversation to be. This is where I would show up and amplify the denier message of uncertainty.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 22, 2019, 03:53:01 PM
Rich, there is thread for the consequences of a BOE, it is new and not as rich as other threads.  I invite you to read and participate in it and tell us why a BOE is not worth focusing on or it doesn't present life threatening consequences above and beyond AGW.

In the coming year it will become evident, but it also may become too late.
Title: Re: When will the Arctic Go Ice Free?
Post by: binntho on July 22, 2019, 04:06:56 PM
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What total nonsense.

Sigh. how does this:

Quote
A BOE is at most something  that gets in the news. AGW is already killing people and has the potential to totally wreck our civilization.

does not contradict this:

Quote
And don't think that I think that losing Arctic Sea Ice is not a huge danger to us all. It has consequences that are already visible, and will only get worse.

A BOE is a huge danger for us all but at most, it is something that gets in the news.

Please explain.
I did not say that a BOE is a huge danger. On the contrary, I think I made it abundantly clear that I think a BOE is a non-event.

The ongoing loss of Arctic Ice is not a BOE, and it is the ongoing and continuing loss of Arctic Ice that is already having dangerous effects and will only get worse as more ice is loss. Irregardless of an eventual BOE.

It seems you are confusing an event (which will be noteworthy but inconsequential) with an ongoing process (which is already causing danger and disruption and will continue to do so regardless of when BOE happens).

And this strange type of denialism, i.e. denying the real ongoing disruptions and real dangers in the near future and instead focusing on a hypothetical event after so and so many years as the point we have to avoid, is really a bit disturbing.

Are you, Archimid, denying that ongoing AGW is causing, and will cause, major disruptions and loss of life?
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on July 22, 2019, 04:14:44 PM
As it pertains to BOE, you are not a denier KK. I actually agree with you here.

The denier label speaks to your general contribution at ASIF.

If you check the polls taken here, the expectation of the voting members of ASIF is BOE in the near future. Much sooner than CAB trend lines would suggest.

In a sense, I think the ASIF community hands the deniers an easy win by engaging in so much speculation about imminent BOE. If I were a denier with an agenda of maintaining BAU, this is where I would want the conversation to be. This is where I would show up and amplify the denier message of uncertainty.

I agree with your post, until you mention uncertainty.  I disagree that the denier message is uncertainty.  Most denier talk uses no uncertain terms when they claim that AGW is a myth, farce, political agenda, etc.  Uncertainty is a scientific standard which should never be dismissed as political propaganda.  Yes, many voters here fall into the tail end of the uncertainty curve on just about every Arctic sea ice prediction.
Title: Re: When will the Arctic Go Ice Free?
Post by: dnem on July 22, 2019, 04:19:51 PM
Strongly disagree KK!! Sowing doubt is the key strategy of the denial movement.  At this point only kooks and fools push the "myth" line. 
Title: Re: When will the Arctic Go Ice Free?
Post by: TeaPotty on July 22, 2019, 04:37:26 PM
I generally consider it a waste of time to argue with deniers. The consequences of our climate crisis generally doesn't apply to them, and so the only risk they are concerned with is monetary, and not risk to human life.

More importantly, what is the greatest risk to human life as a consequence of climate change?
Changes in rainfall patterns, of course.

Humans need water for consumption, for food, for cleaning, etc.
We are already seeing drastic changes in our rainfall patterns, and you cannot pretend a BOE won't be a major factor, as the hastily melting Arctic Sea Ice already has.

We're already seeing how its effecting political stability in regions that have gone very dry, with migration gradually increasing. We're also seeing the consequences of too much rain in North America this year, with terrible consequences to farmers' growing season.
Title: Re: When will the Arctic Go Ice Free?
Post by: Tom_Mazanec on July 22, 2019, 05:11:59 PM
Don't forget, we just might go down to 3 Mm^2 this year, 2 Mm^2 in a couple years, and nearly no ice at all in the mid-Twenties, for longer and longer periods each year.
Then we could have catastrophic consequences at 1.3 Mm^2 in 2023 and very catastrophic ones at 0.6 Mm^2 in 2024. We may have the consequences before we hit 1 Mm^2, in other words.
There is nothing magical between almost a BOE and just slightly beyond a BOE.
Title: Re: When will the Arctic Go Ice Free?
Post by: Klondike Kat on July 22, 2019, 05:26:56 PM
I generally consider it a waste of time to argue with deniers. The consequences of our climate crisis generally doesn't apply to them, and so the only risk they are concerned with is monetary, and not risk to human life.

More importantly, what is the greatest risk to human life as a consequence of climate change?
Changes in rainfall patterns, of course.

Humans need water for consumption, for food, for cleaning, etc.
We are already seeing drastic changes in our rainfall patterns, and you cannot pretend a BOE won't be a major factor, as the hastily melting Arctic Sea Ice already has.

We're already seeing how its effecting political stability in regions that have gone very dry, with migration gradually increasing. We're also seeing the consequences of too much rain in North America this year, with terrible consequences to farmers' growing season.

I would agree with everything you just said.  How a BOE affects rainfall globally will be the major concern.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 22, 2019, 06:44:19 PM

Are you, Archimid, denying that ongoing AGW is causing, and will cause, major disruptions and loss of life?

The damage caused by AGW will pale in comparison with the damage caused by a BOE. Climate change will be much worse for not having ice over the Arctic during summer than for the increase in global temperatures.

Orders of magnitude worse. Unimaginably worse. It is impossible to be hyperbolic about it. It is the end of the world as we know it.

You all assume I'm not considering a BOE a continuum. I am. I'm also assuming that the continuum already started and most of you will change your minds over the next several years because the change will be obvious and painful to most of us.
Title: Re: When will the Arctic Go Ice Free?
Post by: dnem on July 22, 2019, 07:05:57 PM
Got it Archimid.  You've said your piece.  If the arctic ice collapses and the climate breaks down over the next few years, you'll be on record.  I don't think there is any reason to keep saying it.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 22, 2019, 07:45:32 PM
Got it Archimid.  You've said your piece.


I hope that for as long as the evidence holds and I have the strength to keep saying it (and Neven lets me) I will keep saying it. I hope the evidence changes, if and when it does I will change my mind. Right now, given the knows, unknowns and observations, everyone should be alarmed.

Anyone not alarmed is either ignorant about the reality of climate change or a victim of fear psychology. This is alarming.

 
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If the arctic ice collapses and the climate breaks down over the next few years, you'll be on record.
 

The arctic is already collapsing and the climate is already breaking down, but because every tic takes 1/70th of your lifetime, some longer, you can't notice it. This breakdown was very slow, until about the middle of the 00's when it picked up speed. Now things are collapsing faster, forcing faster collapse of other things, all in ultra slow motion to us H. sapiens, but not for long.

"Luckily" as climate change happens more often and in larger scale it is easier for more people to observe it and more difficult to hide their heads in the sand. Sadly, there is a tipping point where  climate change is too noticeable to do anything about it.

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I don't think there is any reason to keep saying it.

The earlier people know, the more preparation will be done, the more people will survive. The more people understand the danger, the more solutions will emerge.

Right now, everyone is busy solving climate change for 2100, because "this is a problem for our children". It is not. This is a problem for us TODAY and NOW.  If we are solving for 2100 we are not solving for 2030, much less for today.

And we are solving for 2100 because the science is assuming a permanence of the world that really isn't there.  Abrupt climate change is real and it is already happening.

The research on this is basically non-existent because it is just too grim. If it was just the grimness it wouldn't be so bad, but then you have the chorus of people telling you to shut up because this is scary. They exert real pressure to shut up and not talk about it because it is scary.
 
This phenomenon happens everywhere from ASIF to the IPCC to the intelligence agencies of the world's greatest countries ( by their own measure).

It can't possibly be that bad... right? Wrong. It is that bad, and if it isn't, we should assume it is because it is going to be very damned bad.

Again I invite you to the effects of a BOE on the climate thread, over at /consequences. Bring evidence, bring studies, bring papers, bring your understanding of how things work. Go shut me up and bring me some peace.

Title: Re: When will the Arctic Go Ice Free?
Post by: TeaPotty on July 22, 2019, 08:08:16 PM
Got it Archimid.  You've said your piece.  If the arctic ice collapses and the climate breaks down over the next few years, you'll be on record.  I don't think there is any reason to keep saying it.

2019 is one of the worst arctic ice melt and climate breakdown years, in a thread meant for discussion about a BOE.

We are in the early stages of a trajectory that could very likely to lead to a collapse of civilization. Nearly every climate consequence is happening faster than we expected, and more interconnected with unknown feedbacks. That's a fact.

Claiming otherwise is factually wrong. Deal with it.
Title: Re: When will the Arctic Go Ice Free?
Post by: Sam on July 22, 2019, 09:02:58 PM
The blind are willfully blind and will not see. They are also unfortunately numerous - too numerous. And they doom us all in their willful ignorance.

A BOE of a day won’t severely disrupt climate. A BOE of a month might. A BOE of a season certainly will.

The great discontinuities that concern me the most are radical shifts in oceanic and atmospheric circulation. A prolonged BOE will wreck havoc on both, and each on the other. These won’t be linear changes. They will be something else.

To blithely hand waive them away shows stunning ignorance of the data and model projections.

Sigh. Alas. Such is our fate. We will get to see this play out. And we will all have seats on stage as the crescendo crashes, the scene shifts, and a whole new geologic epoch begins.

Sam
Title: Re: When will the Arctic Go Ice Free?
Post by: dnem on July 22, 2019, 10:10:51 PM
Hey, I'm TOTALLY alarmed.  I agree with Archimid, albeit with less certainty about the timing.  Obviously the arctic ice is collapsing and the climate is breaking down.  That is plain to see.  My point was a matter of etiquette on this site.  I realize I'm no one and have no authority to tell anyone how to behave here.  IMHO, it grows tiresome to keep repeating the same point.  The posters here are obviously paying attention and have their own strong opinions.  Take your passion to the streets.  Fighting back and forth on this site with someone with entrenched views is pointless. 

I have a 16 YO son.  If I knew then what is plain to see now, I never would have had kids.  I promise you, I'm plenty alarmed.

Peace.
Title: Re: When will the Arctic Go Ice Free?
Post by: Tor Bejnar on July 22, 2019, 10:21:31 PM
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It can't possibly be that bad... right? Wrong. It is that bad, and if it isn't, we should assume it is because it is going to be very damned bad.
Quote
A BOE of a day won’t severely disrupt climate. A BOE of a month might. A BOE of a season certainly will.
I agree that GW (which is all AGW) is bad and is getting worse, and deserves our shouting from the rooftops.  I'm not certain about what drives what (systems are interconnected and complicated), so a one-day BOE will, I believe, be associated with a noticeably more disrupted climate then we have now, and a month-long BOE will be associated with noticeably more disrupted climate than when we had the first one-day BOE.

I think we'll know more (by experience) what a BOE-associated climate is like this next decade.  But I don't really think a BOE will be the driving force that takes us places we do not want to go in a hand-basket; I believe CO2e is.  (In 2013 (https://neven1.typepad.com/blog/2012/10/naive-predictions-of-2013-sea-ice.html) I projected the first BOE would be "prior to 2019", so I've  tripled my opinion of our allotted time of wondering!)
Title: Re: When will the Arctic Go Ice Free?
Post by: Rich on July 22, 2019, 10:29:32 PM

I agree with your post, until you mention uncertainty.  I disagree that the denier message is uncertainty. 

Please don't be disingenuous. Denier fashion changes. .
Even Mitch McConnell is now public acknowledging that AGW is real. The favorite scientist in GOP circles has long been Judith Curry, purveyor of uncertainty.

A denier today is anyone who denies the urgent need to replace fossil fuels with renewables asap. 

The argument keeps changing, but the goal is the same....extract and sell as much petrol as possible for as long as possible.

The fundamental progression of AGW and it's consequences is no longer a winnable argument. The "pause" is over. Jennifer Francis is doing a great job of explaining the wacky weather changes. Heat records are being broken routinely. Hydrological extremes are obvious.

The trick for deniers today is to prey on alarmist arguments. Find someone(s) who overstates the case and try and make others believe that the alarmist message is the position of mainstream scientists.

Alarmist overreach is like dumpster food. You know it will attract rats. That's where deniers want to hang out.

If you want to share your perspective on managing the downside risk associated with GHG levels, the floor is yours. Here's your chance to prove that you're not a denier. Go for it.
Title: Re: When will the Arctic Go Ice Free?
Post by: jdallen on July 22, 2019, 10:35:15 PM
<various snippages>
I did not say that a BOE is a huge danger. On the contrary, I think I made it abundantly clear that I think a BOE is a non-event.

The ongoing loss of Arctic Ice is not a BOE, and it is the ongoing and continuing loss of Arctic Ice that is already having dangerous effects and will only get worse as more ice is loss. Irregardless of an eventual BOE.
On this, I have to say I'm in concord with binntho.  For all of our wrangling over what is an entirely symbolic metric threshold (1000km3 of ice), it is an effect, rather than a cause.

That cause - general heating of the Arctic climate - is already generating cascading failures in the biome and through teleconnections wreaking havoc all across the northern hemisphere.  One need go no further than news of massive animal die offs, massive floods, crushing heat waves, and images of half of Siberia under wood smoke to validate this.

This will no doubt scale with time, but reaching the specific above mentioned threshold will not mark nor prompt any abrupt transition that isn't already well underway, nor already having pronounced effects on the world.

The rest of it - the personal charges of denialism et. al. - are value judgements, and are really out of place here.

Gentle sentients, can we please return to the discussion of science rather than tearing at each other?
Title: Re: When will the Arctic Go Ice Free?
Post by: Shared Humanity on July 23, 2019, 12:58:32 AM
Thank you jdallen...
Title: Re: When will the Arctic Go Ice Free?
Post by: Rich on July 23, 2019, 03:11:26 AM
The Arctic ice will never be free. It is permanently enslaved in the Arctic for life.

Sometimes it makes a run for it, but it always gets caught and killed before getting out of Baffin Bay or the Greenland Sea.

It's touching that so many here are concerned with making the Arctic ice free, but maybe it's not a bad place to be stuck. There are loads of critters just dying to get to the Arctic because it's getting too damn hot in the Pacific and Atlantic.

I have more sympathy for the Antarctic ice. 30 million years in the same spot surrounded by the same ice. Imagine the boredom. I'd rather melt.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 23, 2019, 03:28:36 AM
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For all of our wrangling over what is an entirely symbolic metric threshold (1000km3 of ice), it is an effect, rather than a cause.


Sorry JD, but in this you are wrong. A BOE is not symbolic. It used to be just effect, but it is now both cause and effect.

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That cause - general heating of the Arctic climate - is already generating cascading failures in the biome and through teleconnections wreaking havoc all across the northern hemisphere.

CO2 alone is not causing this. Not anymore. The system is now feeding of itself.

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This will no doubt scale with time, but reaching the specific above mentioned threshold will not mark nor prompt any abrupt transition that isn't already well underway, nor already having pronounced effects on the world.

Abrupt changes are already under way. As the ice shrinks they will be greater and when the ice is gone during summer the transition accelerates to maximum.

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Gentle sentients, can we please return to the discussion of science rather than tearing at each other?

Sorry JD, but it is completely and absolutely wrong that a BOE will not be a significant event. I have no clue how you even arrive to that conclusion as it is nonsensical to me. If there is no ice to melt, then the Arctic will warm, significantly, the oceans will mix, humidity parameters will go out of whack.

I'm sorry that I have to resort to emotional appeals but you all are ridiculously wrong about this. It feels as If I'm debating flat earthers, not rational intelligent people.
Title: Re: When will the Arctic Go Ice Free?
Post by: jdallen on July 23, 2019, 05:57:31 AM
Sorry JD, but in this you are wrong. A BOE is not symbolic. It used to be just effect, but it is now both cause and effect.
I'm not arguing that a lack of ice won't change the Arctic.  Ice loss will and has been doing that.

What I (and I expect binntho) are suggesting is, (1) we don't think it will happen all at once. (2) the cumulative losses we have seen since around 2007 have contributed at least as much to upsetting the system as a BoE would and (3) a BoE will be proceeded by 1 to several years where the extent drops below 2012 levels, which in and of themselves cumulatively will have a greater impact overall on the Arctic than a single BoE event.

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CO2 alone is not causing this. Not anymore. The system is now feeding of itself.

Neither I nor binntho suggest otherwise and agree. Mostly I think we're saying that the harm currently being done, has been done, is greater than a single BoE event would be.  Our conclusion is, a BoE event won't be a trigger on its own.  It will be adding to momentum already in place.  In short, more a result, than a specific cause.

In argument to support that, you need go only as far as the current state of the northern hemisphere jet stream.  It will continue to degrade as the Ferrel, Hadley and Arctic cells collapse, as a direct result of heating already in place and continuing at high latitude.


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Sorry JD, but it is completely and absolutely wrong that a BOE will not be a significant event. I have no clue how you even arrive to that conclusion as it is nonsensical to me. If there is no ice to melt, then the Arctic will warm, significantly, the oceans will mix, humidity parameters will go out of whack.

I'm sorry that I have to resort to emotional appeals but you all are ridiculously wrong about this. It feels as If I'm debating flat earthers, not rational intelligent people.
<SMH> This, my friend, is hubris, flavored with a touch of conceit.

What I hear is, you are so caught up in your conclusion, you are failing to hear or understand the arguments being made contrary to it, and by extension making rather extreme assignations against people who've been fighting to save exactly this ecosystem for a very long time.

I recommend a dose of humility.  I got handed mine about 6 years ago when I first joined the forums.

That said, I *do* believe a BoE will have great symbolic meaning and will help accelerate change in climate, even if its direct effect is more contributory than system breaking as you suggest it will be.
Title: Re: When will the Arctic Go Ice Free?
Post by: binntho on July 23, 2019, 07:27:02 AM
Strange this hyperdenialism that seems to have gripped some people.

Global warming is already killing people and changing whole countries, being a significant factor in the ongoing war in Syria and the biggest risk to national security worldwide as has been comfirmed by, amongst others, the US Army.

The danger to global food production that global warming poses is huge, massive, scarily gigantic.

Denying this very real and present danger by clamoring about a purely hypothetical BOE Harmageddon is - denialism.
Title: Re: When will the Arctic Go Ice Free?
Post by: RikW on July 23, 2019, 09:45:23 AM
The problem is that we don't have good models to have reliable predictions when a BoE will happen and what the effect of a BoE will be.

Will there be feedback mechanism kicking in, 'restoring' the ice? Giving us a couple of extra years to act?
Will there be nothing special happening and will global warming just continue?
Will our 3-cell-atmospheric system collapse, possibly creating unstable/unpredictable weather and a fast changing climate?

We can only make educated guesses, because we don't know enough yet.

I personally think it all depends on how early in the season a BoE is happening. Currently the ice keeps the air temperature low, because most energy goes into melting the ice. When you check the temperature graphs, you can see there isn't a change in the summer temperature; If there is no ice/snow left, that limitation is gone; And the 3-cell system is there because of the temperature difference between the tropics and the arctic. When arctic temperature rises enough, i can imagine that system to collapse.
Title: Re: When will the Arctic Go Ice Free?
Post by: pleun on July 23, 2019, 10:56:02 AM
I think maybe Archimid has the mental image in his head of a kettle of water on the stove with a lump of ice in the middle. Not much will happen to the water untill the ice is gone.

I don't know how far you can extend this metafore to the arctic. Is the heat that's entering via the Chuckchi dissipating towards the cab ? Would the Chuckchi be 20 degrees allready if there were no ice in the cab ?
Title: Re: When will the Arctic Go Ice Free?
Post by: DrTskoul on July 23, 2019, 11:18:08 AM
I think maybe Archimid has the mental image in his head of a kettle of water on the stove with a lump of ice in the middle. Not much will happen to the water untill the ice is gone.

I don't know how far you can extend this metafore to the arctic. Is the heat that's entering via the Chuckchi dissipating towards the cab ? Would the Chuckchi be 20 degrees allready if there were no ice in the cab ?

Only if the kettle is well mixed ... otherwise there will be thermal gradients... the same with the Pacific intrusion... some flows depending on salinity might bypass ice edge...
Title: Re: When will the Arctic Go Ice Free?
Post by: philopek on July 23, 2019, 01:25:40 PM

I'm sorry that I have to resort to emotional appeals but you all are ridiculously wrong about this. It feels as If I'm debating flat earthers, not rational intelligent people.

First of all +1

Second, only major flaw in your post was the term "you all are....wrong"

I and others have clearly said the exact same thing, perhaps in slightly different terms.

So be happy, you're not alone and i like the example with "flat-earthers" while this is not the only example where I ask myself how certain conclusions can be reached.

However that may be, learning curve on this forum is very high and that means, mission accomplishment under way.

One point i missed and i'm not knowledgeable enough to talk details, is that the amount of energy to melt ice is huge and once there is no ice to melt all that energy will go into the ocean and distributed back to the air later in the season, including humidity that will isolate against heat loss further. I lack the terms and i lack the numbers but i know that is that way.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 23, 2019, 01:42:43 PM

What I (and I expect binntho) are suggesting is, (1) we don't think it will happen all at once.


I don't either. Thats just you all putting words in my mouth.

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(2) the cumulative losses we have seen since around 2007 have contributed at least as much to upsetting the system as a BoE would and

This can be easily quantified as not true. The losses from 2007 to today are just a small increase to the albedo feedback effect  and small changes to atmospheric patterns relative to no ice over the entire arctic.

 See tealight's wonderful regional albedo potentials to see where we are on that

https://cryospherecomputing.tk/awp-region.html


(3) a BoE will be proceeded by 1 to several years where the extent drops below 2012 levels, which in and of themselves cumulatively will have a greater impact overall on the Arctic than a single BoE event.

Again, see tealights graphs. The Albedo feedback effects increase until 0 ice is reached. Once 0 is reached the effect increases as 0 is reached earlier and earlier. At hat point  you must, on top of the albedo feedback and atmospheric considerations, account for the lack of ice as extra high temperature.

There will be changes from here to the first BOE, drastic painful changes and many will be tied directly to the loss of sea ice. But after the first BOE thing stake an entirely new form.


<SMH> This, my friend, is hubris, flavored with a touch of conceit.

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What I hear is, you are so caught up in your conclusion, you are failing to hear or understand the arguments being made contrary to it, and by extension making rather extreme assignations against people who've been fighting to save exactly this ecosystem for a very long time.

You are arguing that the climate conditions are bad, partly because the missing ice, but then you argue that if you remove all the ice it doesn't get worse. It doesn't even make sense.

Maybe what you are saying is that we  won't survive the transition to a BOE thus a BOE won't matter? That may be.
Title: Re: When will the Arctic Go Ice Free?
Post by: binntho on July 23, 2019, 01:47:18 PM
Perhaps it would help if Archimid laid out his reasoning, preferably supported by facts and figures and even (one hopes) a peer-reviwed paper or two.

Archimid, please explain: Why do you think that a BOE will be such a cataclysmic catastrophe?

Perhaps we could try and put numbers on them a bit like the Richter logarythmic scale for earthquakes. As in "Trump elected president" is a 2 but "Trump goes to war with Iran" is a 3 (effectively a 10 times bigger catastrophy, but mankind will adjust fairly quickly and the effects will mostly be local).

So "continued AGW" is in my optics at least a 6 or 7 and tending upwards, the real risk being that we will reach 8 or more (still thinking in earthquake terms - a 9 is "at or near total destruction").

Which brings to mind the flat-earther thing. How can anybody claim that a single event, albeit important, that does not really change anything can be a bigger catastrophe than what has been happening all the time leading up to that event?

A bit like claiming that we won't get tired from hiking until we've reached that peak in the distance that may be 1 or 10 km away.
Title: Re: When will the Arctic Go Ice Free?
Post by: TeaPotty on July 23, 2019, 01:54:55 PM
Strange this hyperdenialism that seems to have gripped some people.

Global warming is already killing people and changing whole countries, being a significant factor in the ongoing war in Syria and the biggest risk to national security worldwide as has been comfirmed by, amongst others, the US Army.

The danger to global food production that global warming poses is huge, massive, scarily gigantic.

Denying this very real and present danger by clamoring about a purely hypothetical BOE Harmageddon is - denialism.

This is obnoxious. The current gradual loss of Arctic Sea Ice is linked to the significant changes in weather and rainfall patterns. It is precisely one of the mechanisms by which Climate Change is effecting us soonest.

Looking at Arctic Sea Ice volume charts, we are not far off from a mostly ice-free Arctic. Not sure why you are so eager to argue semantics and technicalities. You have no argument if you're trying to say this isn't happening to the Arctic Sea Ice, or that the consequences won't get worse as we lose more ice.

Again more simply... A nearly ice-free Arctic is likely to make the current changes to rainfall patterns even worse, and our technical definition of a BOE may be overly-conservative a measure. This is going to destabilize entire countries, and bring much human suffering.
Title: Re: When will the Arctic Go Ice Free?
Post by: Rich on July 23, 2019, 02:03:00 PM

Perhaps we could try and put numbers on them a bit like the Richter logarythmic scale for earthquakes. As in "Trump elected president" is a 2 but "Trump goes to war with Iran" is a 3 (effectively a 10 times bigger catastrophy......

FYI - Each point of the Richter Scale is not a 10X increase. It is logarithmic, but 2 points on the scale is 1000x. One point on the scale is the square root of that or roughly 31 4x.

Weird scale.
Title: Re: When will the Arctic Go Ice Free?
Post by: binntho on July 23, 2019, 02:13:44 PM

Perhaps we could try and put numbers on them a bit like the Richter logarythmic scale for earthquakes. As in "Trump elected president" is a 2 but "Trump goes to war with Iran" is a 3 (effectively a 10 times bigger catastrophy......

FYI - Each point of the Richter Scale is not a 10X increase. It is logarithmic, but 2 points on the scale is 1000x. One point on the scale is the square root of that or roughly 31 4x.

Weird scale.
You are confusing the energy in each whole number (31.4x) and the wave amplitude (10x).
Title: Re: When will the Arctic Go Ice Free?
Post by: binntho on July 23, 2019, 02:14:51 PM
Strange this hyperdenialism that seems to have gripped some people.

Global warming is already killing people and changing whole countries, being a significant factor in the ongoing war in Syria and the biggest risk to national security worldwide as has been comfirmed by, amongst others, the US Army.

The danger to global food production that global warming poses is huge, massive, scarily gigantic.

Denying this very real and present danger by clamoring about a purely hypothetical BOE Harmageddon is - denialism.

This is obnoxious. The current gradual loss of Arctic Sea Ice is linked to the significant changes in weather and rainfall patterns. It is precisely one of the mechanisms by which Climate Change is effecting us soonest.

Looking at Arctic Sea Ice volume charts, we are not far off from a mostly ice-free Arctic. Not sure why you are so eager to argue semantics and technicalities. You have no argument if you're trying to say this isn't happening to the Arctic Sea Ice, or that the consequences won't get worse as we lose more ice.

Again more simply... A nearly ice-free Arctic is likely to make the current changes to rainfall patterns even worse, and our technical definition of a BOE may be overly-conservative a measure. This is going to destabilize entire countries, and bring much human suffering.
Exactly. We seem to be in total agreement. Strange that you find that obnoxious.
Title: Re: When will the Arctic Go Ice Free?
Post by: Archimid on July 23, 2019, 02:46:58 PM
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Perhaps it would help if Archimid laid out his reasoning, preferably supported by facts and figures and even (one hopes) a peer-reviewed paper or two.

Ok so who has the burden of proof? The one that's making an extraordinary claim.

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Archimid, please explain: Why do you think that a BOE will be such a cataclysmic catastrophe?

I promise I will, but first the burden of proof is on you to prove it won't be a cataclysm. It is an extraordinary claim that no ice on the Arctic does not lead to cataclysm. It is only the assumption of human permanence that gives you the impression that a cataclysm is not likely. The most basic physics dictate that cataclysm is the most likely outcome. What makes you think that such a large scale and sudden change in planetary heat distribution will not have huge impact?

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How can anybody claim that a single event, albeit important, that does not really change anything can be a bigger catastrophe than what has been happening all the time leading up to that event?

You think having no ice over the arctic in September does not really change anything?  How can I possibly take that seriously?

I'm sorry but I'm debating absurdities product of fear psychology, not logic or science.
Title: Re: When will the Arctic Go Ice Free?
Post by: crandles on July 23, 2019, 02:49:43 PM
Perhaps it would help if Archimid laid out his reasoning, preferably supported by facts and figures and even (one hopes) a peer-reviwed paper or two.

Archimid, please explain: Why do you think that a BOE will be such a cataclysmic catastrophe?

Agree that might be useful. (Haven't seen him do so, so far.)

You are arguing that the climate conditions are bad, partly because the missing ice, but then you argue that if you remove all the ice it doesn't get worse. It doesn't even make sense.

Interesting that you do include the word 'partly'. Would you care to explain how you apportion blame for perhaps rainfall changes (or some other measure), between:

1. Losses of sea ice so far
2. Losses of sea ice around point where we get a BOE for a week or so.
3. Heating of Arctic ocean after a BOE

Noting that Arctic is less than 10% of area of globe in a region where air is generally falling so very little responsibility for moisture in the atmosphere particularly in places where lots of people live and grow food.

4. Warming of the other 90% of world's atmosphere allowing more water to be held in the atmosphere, creating likelihood of heavier rainfall and more droughts.

If you are attributing more effects to 1 than to 4, perhaps you could explain why?
Title: Re: When will the Arctic Go Ice Free?
Post by: binntho on July 23, 2019, 03:01:36 PM
Ok so who has the burden of proof? The one that's making an extraordinary claim.
Yours is obviously the bigger claim.

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