Arctic Sea Ice : Forum

Cryosphere => Arctic sea ice => Topic started by: crandles on March 28, 2018, 05:31:41 PM

Title: First year PIOMAS volume below 1000km^3 poll 2018
Post by: crandles on March 28, 2018, 05:31:41 PM
This poll was first posted 10 Dec 2014. Over 3 years seemed suitable delay before trying again and after lots of comments on the 'Ice free arctic' thread https://forum.arctic-sea-ice.net/index.php/topic,1886.0.html also seemed suitable.

The original post had

Since 2013 and 2014 minimums were so high, I thought it might be an idea to have another poll to see how much later if at all people think ice free conditions will occur.

Other long term outlooks are welcome. Feel free to describe what you think will happen. If you wish that can include downloading the attachment and drawing what you think is more plausible.

To explain the attached graph:

Blue data is April Average PIOMAS volume
Yellow data is September average PIOMAS volume

Red and green are 4 parameter gompertz fits.

The straight blue line is intended to show acceleration as MYI over 2m thick collapsed due to less area, less age and thinner MYI mainly as the MYI stopped making it around the Beaufort Gyre. Once there was little MYI over 2m thick this accelerated phase dies out so that the thinning was only at a rate consistent with just FYI thinning.

The purple line descends more quickly than the blue line again aiming to be consistent with past. If there is less ice at the start of the season then albedo will be lower allowing more open water to form and more energy to be absorbed so that more ice melts. I have the difference between the two straight lines increasing from 17.8 K Km^3 in 2014 to 18.8 K Km^3 when we reach ice free.

This purple line first goes below 1000 km^3 in 2028.

Also note that the difference between 2012 and 2014 minimum volumes is nearly 3200 Km^3. Therefore while the purple line only gets down to 1000 Km^3 by 2028, it could occur any time after the purple line gets below 2600 km^3 which could be as early as 2022. I am therefore going to average 2022 and 2028 to arrive at 2025.

To this I am adding updated graphs for September and April PIOMAS volume with 4 parameter gompertz fits.

Votes should be changeable until the vote deadline. Also viewable after you have voted.

Anything else I should add? (I haven't put a link to the old poll, think I would prefer people to vote without looking to see how they compare. But open to arguments for doing so.)

Edit: in response to question, I have edited to make clear it is daily minimum per PIOMAS. Note that the graphs are of September average not daily and first year could well be ahead of any trend.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Tor Bejnar on March 28, 2018, 07:30:56 PM
The 2014 First Ice free day poll (volume) (https://forum.arctic-sea-ice.net/index.php?topic=1086.0) comments can be reviewed. Voting record below.


An Arctic sea ice free (extent) (https://forum.arctic-sea-ice.net/index.php/topic,80.0.html) poll was started in March 2013.  About half of us were wrong (so far). At least one or two of us will undoubtedly be right!  (I'm still in the running.  Boy my thinking changed between this 2013 extent poll and the 2014 volume poll!) This wasn't a volume poll, I know, but I think it is worth reviewing. Voting record below.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: oren on March 28, 2018, 08:16:00 PM
Crandles just to verify, your poll is about the daily minimum, correct? I am asking as the graphs you posted are for the Sept average.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Archimid on March 28, 2018, 10:29:09 PM
Attached is Volume Max with an extended linear trend.

Loss maximum, minimum and average are taken for the 2007-2017 period and drawn on the line

According to that a graph if a maximum loss happened last year volume below 1000km^3  would've been achieved then!

If the average loss remains constant, then the date would be somewhere around 2030.

However because gains are decreasing and temperatures rising I'm going with 2019-2021.

Edit: Replaced graph. Forgot to add 1 to the average
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Dharma Rupa on March 28, 2018, 11:03:00 PM
This is a crap shoot with real loaded dice.  Loaded dice have a shot of lead inside with something sticky, like wax.  Turn the dice to a particular pair of faces and smack them down hard against the table and now that pair of faces becomes the most likely roll next time.

I don't know which year will be first, but I'm pretty sure the next year will be the same.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: crandles on March 29, 2018, 01:26:41 AM
Crandles just to verify, your poll is about the daily minimum, correct? I am asking as the graphs you posted are for the Sept average.

Should have known I would miss something obvious. Have edited poll question to add daily and also put in some warning about this issue in the first post.

People should be able to change their vote if they wish.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: oren on March 29, 2018, 03:19:05 AM
Thanks for the clarification.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Dave C on March 30, 2018, 12:29:15 PM
My real answer is "not likely to be soon", but I guess I'll pick 29-33.

Obviously you have to be careful against cherry picking, but the fact is that there has been no volume decline for 7 years now. I don't believe an objective rate of yearly volume decline exists. The rate is entirely dependent on the starting year you pick.
I think the most likely theory is the slow decline one(but still faster than scientific models predicted in the past). It is becoming increasingly likely that the ice dynamics have changed after most of the multi-year ice was eliminated. There is no reason that a trend has to continue. It's quite possible that the usual trend lines referred to will be wrong because the negative feedbacks certain to occur are stronger than predicted.
At least 4 negative feedbacks are certain to occur with less ice. Lower temperatures in ice covered areas, less average insolation, less ice transport and greater chance for refreezing in winter. It's possible that less ice creates more protective cloud cover as well. In the long run the ice is doomed. But in the short run I think these negative feedbacks are likely to prevail.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: crandles on March 30, 2018, 02:46:31 PM

At least 4 negative feedbacks are certain to occur with less ice. Lower temperatures in ice covered areas, less average insolation, less ice transport and greater chance for refreezing in winter. It's possible that less ice creates more protective cloud cover as well. In the long run the ice is doomed. But in the short run I think these negative feedbacks are likely to prevail.

>"Lower temperatures in ice covered areas"
Why would there be lower temperatures? Surely there are warmer temperatures nearer than previously that can get blown to such positions more easily? Then there is GHG levels.

'Less average insolation' is assuming increased cloud cover? (Not sure there is data showing this or at least isn't very clear.) Then there is lower albedo meaning a higher proportion is absorbed.

'Less ice transport' ice is thinner but moves faster so not sure about less being transported out of arctic. It is possible as ice retreats to smaller area.

But maybe you are talking about, we have cleared ice from area where there is a net movement out of the areas where quick increase in ice free area occurs so readily creating albedo feedback, but when we try to clear area with net movement in the area doesn't clear quickly so the albedo feedback is much slower.

Certainly agree with winter regrowth feedback.

Then there are others like:

Bathymetry: We have cleared the shallow area where warm salty gulf stream water cannot sink.

Distance from land and rivers:
Land warms up fast warming the air and rivers provide fresh water warmed during its journey. As the ice retreats away from these areas it gets harder to melt the ice.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: oren on March 30, 2018, 03:55:12 PM
Dave C, the slow transition theory postulated a plateau in winter volume, due to fast refreeze of open water and thin ice, and with the freezing season remaining almost the same length, and thus it postulated a slow decline in summer. But instead we got a record low max volume last year, and a number two this year, so I think the theory is flawed, not taking into account very delayed refreeze. I therefore believe only luck prevented new lows in summer volume.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Tor Bejnar on March 30, 2018, 04:18:26 PM
Great reply, crandles!  (You wrote everything I was thinking while reading Dave C's post, plus an item or two.)

The Arctic conditions that most support the "slow transition theory", in my opinion, are the bathymetry and distance from coasts concerns.  (I don't think these are really "negative feedbacks" because 'nothing has changed'; years ago I posted, IICR, a concern that ice loss graphs used to predict an ice-free Arctic should use 'only' CAB data.  [I think my concern at the time was the limited 'length of summer' in the high Arctic {late May to mid-September.}  I've learned something along the way!])
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Daniel B. on March 30, 2018, 05:46:03 PM

At least 4 negative feedbacks are certain to occur with less ice. Lower temperatures in ice covered areas, less average insolation, less ice transport and greater chance for refreezing in winter. It's possible that less ice creates more protective cloud cover as well. In the long run the ice is doomed. But in the short run I think these negative feedbacks are likely to prevail.

>"Lower temperatures in ice covered areas"
Why would there be lower temperatures? Surely there are warmer temperatures nearer than previously that can get blown to such positions more easily? Then there is GHG levels.

'Less average insolation' is assuming increased cloud cover? (Not sure there is data showing this or at least isn't very clear.) Then there is lower albedo meaning a higher proportion is absorbed.

'Less ice transport' ice is thinner but moves faster so not sure about less being transported out of arctic. It is possible as ice retreats to smaller area.

But maybe you are talking about, we have cleared ice from area where there is a net movement out of the areas where quick increase in ice free area occurs so readily creating albedo feedback, but when we try to clear area with net movement in the area doesn't clear quickly so the albedo feedback is much slower.

Certainly agree with winter regrowth feedback.

Then there are others like:

Bathymetry: We have cleared the shallow area where warm salty gulf stream water cannot sink.

Distance from land and rivers:
Land warms up fast warming the air and rivers provide fresh water warmed during its journey. As the ice retreats away from these areas it gets harder to melt the ice.

Dave may not be that far off.  Considers his 4 feedbacks the remaining ice-covered areas. 

1.  Even if the average temperature of the Arctic increases, it will still be substantially colder than the water.  The open water will lose more heat than the ice-covered areas.  This could result in a short-term temperature decrease (at least until most of the ice is lost). 

2.  Less ice transport is most likely to occur, as most of the ice loss occurs in the open ocean where it is much more susceptible to transport, whereas the remaining ice will be tied to land areas.

3.  Yes, the is definitely greater opportunity for refreezing.  This has already occurred during the winters following low summer minima.  This ice is then more likely to melt the following summer.  Not sure that this is a feedback at all.

4.  The ice will not create more cloud cover.  Open water may.  The effect of clouds are two-fold; warmer winters, due to heat retention, and cooler summers, due to solar blockage.  This would be a negative feedback on summer ice loss, but a positive for winter gains.  Overall, clouds tend to reduce temperature extremes; cooling the warmest areas and warming the coldest.  With the Arctic being among the coldest, I would expect a general warming with more cloudiness, even though summer temperatures may decrease slightly.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: litesong on March 30, 2018, 06:07:44 PM
cherry picking.... has been no volume decline for 7 years..... rate is entirely dependent on the starting year you pick.....most likely theory is the slow decline one..... in the short run I think these negative feedbacks are likely to prevail.
AGW deniers depend on the temporary decrease in solar TSI which has been languid for half a century & low for 11+ years(including a 3+ year period setting a 100 year record low). AGW deniers lock on to anomalous low ice records like 2012(which  decreased greatly in part due to fortuitously directed winds driving much ice out of the arctic). AGW deniers don't mention that present Arctic sea ice ranges from 8000 to 12,000 cubic kilometers LESS than the average of the 1980's, this despite the already mentioned low solar TSI.  AGW deniers are cherry pickers & blame AGW advocates as cherry pickers. 
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Daniel B. on March 30, 2018, 06:37:17 PM
cherry picking.... has been no volume decline for 7 years..... rate is entirely dependent on the starting year you pick.....most likely theory is the slow decline one..... in the short run I think these negative feedbacks are likely to prevail.
AGW deniers depend on the temporary decrease in solar TSI which has been languid for half a century & low for 11+ years(including a 3+ year period setting a 100 year record low). AGW deniers lock on to anomalous low ice records like 2012(which  decreased greatly in part due to fortuitously directed winds driving much ice out of the arctic). AGW deniers don't mention that present Arctic sea ice ranges from 8000 to 12,000 cubic kilometers LESS than the average of the 1980's, this despite the already mentioned low solar TSI.  AGW deniers are cherry pickers & blame AGW advocates as cherry pickers.

I would caution against automatically calling it cherry picking.  Only 40 years of data exists, so the analysis is somewhat strained initially.  Overall, the trend over the first and last decades show a slow decline as stated by Dave.  The middle two decades show a large decline.  While the long term decline is definitely apparent, it is difficult to say which trend will continue in the short term.  Obviously you and Dave disagree on which will prevail in the short run.  This does not make either of you cherry pickers.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Dharma Rupa on March 30, 2018, 10:08:19 PM
cherry picking.... has been no volume decline for 7 years..... rate is entirely dependent on the starting year you pick.....most likely theory is the slow decline one..... in the short run I think these negative feedbacks are likely to prevail.
AGW deniers depend on the temporary decrease in solar TSI which has been languid for half a century & low for 11+ years(including a 3+ year period setting a 100 year record low). AGW deniers lock on to anomalous low ice records like 2012(which  decreased greatly in part due to fortuitously directed winds driving much ice out of the arctic). AGW deniers don't mention that present Arctic sea ice ranges from 8000 to 12,000 cubic kilometers LESS than the average of the 1980's, this despite the already mentioned low solar TSI.  AGW deniers are cherry pickers & blame AGW advocates as cherry pickers.

I would caution against automatically calling it cherry picking.  Only 40 years of data exists, so the analysis is somewhat strained initially.  Overall, the trend over the first and last decades show a slow decline as stated by Dave.  The middle two decades show a large decline.  While the long term decline is definitely apparent, it is difficult to say which trend will continue in the short term.  Obviously you and Dave disagree on which will prevail in the short run.  This does not make either of you cherry pickers.

Why are you talking decades when the only interesting inflection point is the beginning of the Industrial Age?

We ain't seen nothing yet, and I don't know when the first year will be, but the next year (and many more) will be ice free too.

Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: litesong on March 30, 2018, 10:16:20 PM
cherry picking.... has been no volume decline for 7 years..... rate is entirely dependent on the starting year you pick.....most likely theory is the slow decline one..... in the short run I think these negative feedbacks are likely to prevail.
AGW deniers depend on the temporary decrease in solar TSI which has been languid for half a century & low for 11+ years(including a 3+ year period setting a 100 year record low). AGW deniers lock on to anomalous low ice records like 2012(which  decreased greatly in part due to fortuitously directed winds driving much ice out of the arctic). AGW deniers don't mention that present Arctic sea ice ranges from 8000 to 12,000 cubic kilometers LESS than the average of the 1980's, this despite the already mentioned low solar TSI.  AGW deniers are cherry pickers & blame AGW advocates as cherry pickers.
.... cherry picking.  Only 40 years of data exists, so the analysis is somewhat strained initially......last decades show a slow decline as stated by Dave.....Obviously you and Dave disagree
Quoting Dave & giving him cred, while saying its a difference between him & me, tells us where you land.  Stating that there is only 40 years of AGW effects, while AGW denier data is neglected or nil, then landing in the AGW denier nest, also tells us what you are hatching.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Daniel B. on March 30, 2018, 10:29:46 PM
cherry picking.... has been no volume decline for 7 years..... rate is entirely dependent on the starting year you pick.....most likely theory is the slow decline one..... in the short run I think these negative feedbacks are likely to prevail.
AGW deniers depend on the temporary decrease in solar TSI which has been languid for half a century & low for 11+ years(including a 3+ year period setting a 100 year record low). AGW deniers lock on to anomalous low ice records like 2012(which  decreased greatly in part due to fortuitously directed winds driving much ice out of the arctic). AGW deniers don't mention that present Arctic sea ice ranges from 8000 to 12,000 cubic kilometers LESS than the average of the 1980's, this despite the already mentioned low solar TSI.  AGW deniers are cherry pickers & blame AGW advocates as cherry pickers.

I would caution against automatically calling it cherry picking.  Only 40 years of data exists, so the analysis is somewhat strained initially.  Overall, the trend over the first and last decades show a slow decline as stated by Dave.  The middle two decades show a large decline.  While the long term decline is definitely apparent, it is difficult to say which trend will continue in the short term.  Obviously you and Dave disagree on which will prevail in the short run.  This does not make either of you cherry pickers.

Why are you talking decades when the only interesting inflection point is the beginning of the Industrial Age?

We ain't seen nothing yet, and I don't know when the first year will be, but the next year (and many more) will be ice free too.

Quite simple.  The satellite data starts in 1979.  There is no good measure of ice volume to that, so anything else is speculation.  Can you state with any certainty the volume of ice in the Arctic at the beginning of the industrial era?  or at any time prior?  I do not know when the first ice-free year will occur either.   However, that does not guarantee that next will be similar. 
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: litesong on March 30, 2018, 11:31:24 PM
The satellite data starts in 1979.  There is no good measure of ice volume to that, so anything else is speculation.
Much submarine data is available. AGW deniers love to hoot that submarines were surfacing at the North Pole in the 1950's, intimating that 1950's Arctic sea ice was thin. But submarine logs indicate 1950's sea ice was much thicker than today. It took weeks for submarines to find sea ice thin enough, through which submarines could surface. & in weeks previous to that, submarines could not enter the Arctic Ocean from the Bering Strait easily or safely, due to sea ice that was as much as 60 feet thick.
Article about submarine data on sea ice in the 50's & 60's:
http://news.bbc.co.uk/2/hi/science/nature/523065.stm
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: litesong on March 31, 2018, 12:03:39 AM
I don't know when the first year(of month or a few weeks of ice-free) will be, but the next year (and many more) will be ice free too.
The real problem will be 4 or 5 months of ice-free Arctic Ocean waters. An ice free September has the sun low & even below the horizon & ocean waters will not collect much solar energy. But when Arctic Ocean waters are ice-free in May, June, July, & August, with the sun at its highest elevation in the sky, much solar energy will absorbed & will warm Arctic waters. Also, wherever solar energy is absorbed on waters that are on downwellings, much solar energy(previously unavailable) will be transported to continental shelves & even to ocean depths for deep sea storage.
Already, tho NOT ice-free, present Arctic waters have as much as 2 million square kilometers less sea ice as that of the 1980's. & as above, these present clear ice waters ARE gathering solar energy during April, May, June, July & August, that wasn't available before sea ice reductions. 
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Archimid on March 31, 2018, 12:53:28 AM
Daniel B.'s lies are delicious because by finding what the lie is, you find enlightenment. They are getting very easy to spot though. As climate change advances the evilness of his lies will be evident.

This is one of the best write ups I've seen on Arctic sea ice history. I highly recommended.

https://www.carbonbrief.org/guest-post-piecing-together-arctic-sea-ice-history-1850

This image is from the article.

(https://www.carbonbrief.org/wp-content/uploads/2016/08/Walsh-et-al.-2016-Fig8.png)


Daniel B. is right in that the satellite record is very small. Where he is wrong is that when the rest of the evidence is compiled there is reason for alarm.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Daniel B. on March 31, 2018, 01:10:41 AM
Daniel B.'s lies are delicious because by finding what the lie is, you find enlightenment. They are getting very easy to spot though. As climate change advances the evilness of his lies will be evident.

This is one of the best write ups I've seen on Arctic sea ice history. I highly recommended.

https://www.carbonbrief.org/guest-post-piecing-together-arctic-sea-ice-history-1850

This image is from the article.

(https://www.carbonbrief.org/wp-content/uploads/2016/08/Walsh-et-al.-2016-Fig8.png)


Daniel B. is right in that the satellite record is very small. Where he is wrong is that when the rest of the evidence is compiled there is reason for alarm.

Please leave your false accusations out of this discussion please.  If you wish to present evidence against my claim, at least try to present relative evidence.  We are discussing PIOMAS volume, and you present evidence on extent.  This is similar to the thread on which we were discussing extent, and your refuting evidence was volume.  When you post negative comments about another poster it reflects more on you than the person whom you are attacking.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Archimid on March 31, 2018, 04:29:02 AM
Quote
Please leave your false accusations out of this discussion please.


Calling you a liar is an accurate description, not an accusation.

Quote
If you wish to present evidence against my claim, at least try to present relative evidence

There was twice as much extent for the last 150+years, plenty of anecdotal evidence that it was much thicker and much colder temperatures. The historical data doesn't have the precision and accuracy of the satellite record but it is equally scientific and consistent.
 
Quote
We are discussing PIOMAS volume, and you present evidence on extent.

If you are talking about the ice-free thread, this is what I said in regard to extent vs volume

Quote
If we were talking about albedo, extent would be a good metric, but we are not talking about albedo. We are talking about when the Arctic will be ice free for the first time. For that the best measure is volume for two good reasons. One, extent has no information about ice content, volume does. The second one is that volume hits 0 first. 0 volume = 0 extent.


But you ignored it and kept using extent without justification for it's use.
 
Quote
When you post negative comments about another poster it reflects more on you than the person whom you are attacking.

Yeah, and as climate change gets worse that reflection will improve as the nature of your lies become evident. For now, I'll bite the reputation bullet and treat you like a liar you are, hiding the risks of climate change from others.  Sure my words are rough, and I'm sure nice people everywhere despise me for it but what you are doing is despicable and if no one denounce you, then I will, when I have the strength.

 I'm sorry to the nice people that must read these strong words, but given the nature of the argument and it's consequences I believe it must be done.


To close in a more scientific note:

Quote
Can you state with any certainty the volume of ice in the Arctic at the beginning of the industrial era? 

Yes. Given the large extent of the past, lower temperatures of the past and recorded descriptions of the Arctic of the past, as long as the physics are the same as today, the ice was much thicker and the volume much higher to a high degree of certainty. To a very high degree certainty.

However there is always uncertainty. Daniel B. lies uses that fact of life to throw unnecessary uncertainty on the fact that there was much more volume of ice in the past.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Daniel B. on March 31, 2018, 06:30:03 AM
Rather odd that you have been arguing on another thread that volume can be less, even though extent is higher.  You seem to be changing your argument to fit your opinion.  I am truly sorry that you think honesty is despicable, and prefer exaggeration to accuracy.  We have argued this previously.  I understand that you are passionate, but your repeated attacks are reflecting poorly on yourself.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: jdallen on March 31, 2018, 07:34:27 AM
People, please chill.  Please don't turn this into a flame war. :o
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: 2phil4u on March 31, 2018, 01:45:53 PM
I read about the negative feedbacks.
This is what i thought about.
We saw better years after low minimums in general and not the opposit, thus winter outperformed the summer because of more heat loss to space.
I only wasnt sure about water temperature in deeper depth, so it could be that even if we have better ice grow after low minimas this is only true for the upper lawyer of the water, but deeper water store energy.
I was not sure, if this is possible or  not.
On the other hand with open water all around the pole there is a small cold surface surrounded by a large area with way above average temperature in summer due to no ice.
So im not sure if there is at least if we dont go up with world temperatures tremendous an area that is absolute safe or not.
But i will vote for last possible options, there is no never ?
 ;D
o.k. that is unlikely to that never before our sun system collapse the global average is high enouph like it was in the past.
So the negative feedbacks but the tremendous amount of warm air in summer if there is only a little core left, hm.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Archimid on March 31, 2018, 02:38:52 PM
Rather odd that you have been arguing on another thread that volume can be less, even though extent is higher.

Not only did you ignore my arguments about why volume was obviously higher, you twist my words to fit your lies. This is what I said about volume and extent in the past:

Quote
It also works in longer time frames. Volume has been free falling since the beginning of the satellite record but area remained mostly the same for much of it until the 2007 crash. In the colder past when the Arctic was 15m thick I’m sure volume grew yearly but area was limited by export and the Atlantic and Pacific interface.

I told you then, as I tell you now, volume was much higher in the past

Quote
You seem to be changing your argument to fit your opinion.


No, you are twisting my words to fit your lies.

Quote
I am truly sorry that you think honesty is despicable, and prefer exaggeration to accuracy.
 

Your exaggeration of the uncertainties is despicable. Your exaggerations are already costing lives and property. Your honesty is fake. Fake honesty is a very powerful tool.

Quote
I understand that you are passionate, but your repeated attacks are reflecting poorly on yourself.

 I'm telling the harsh truth and your telling comfortable lies. There is no way around it. Calling you a liar is harsh but accurate.

 I could take the Katherine Hayhoe approach, but by doing that I risk understating the risk. While her way is the most effective way of gaining acceptance of climate change (thank goodness for her), my way better depicts the risks we face.

Quote
Can you state with any certainty the volume of ice in the Arctic at the beginning of the industrial era?  or at any time prior?

The answer is yes, you can. There are all sorts of proxies confirming that the ice used to be much thicker than it is now.  Expeditions, temperatures, ship logs, sediments, anecdotes and human settlement distribution all point at a consistently thick sea ice sheet and a large extent.

On top of the evidence, the laws of physics ensure that with that much extent there will be more volume.

Your uncertainty argument is false.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Dave C on March 31, 2018, 07:33:21 PM
Dave C, the slow transition theory postulated a plateau in winter volume, due to fast refreeze of open water and thin ice, and with the freezing season remaining almost the same length, and thus it postulated a slow decline in summer. But instead we got a record low max volume last year, and a number two this year, so I think the theory is flawed, not taking into account very delayed refreeze. I therefore believe only luck prevented new lows in summer volume.

It seems to be more than luck that the minimum record wasn't broken last year. There is evidence that the arctic is countercyclical to a degree.

I don't know if winter volume has to plateau. It would be enough to slow melting if winter ice gain is increasing, which over the last decade it has on average. It's weird to refer to it as "slow transition theory" though. I am still predicting that the ice will melt way faster than the official IPCC consensus. I just don't think it's going to drop to 1 km^3 in the next decade.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Dave C on March 31, 2018, 07:35:34 PM

At least 4 negative feedbacks are certain to occur with less ice. Lower temperatures in ice covered areas, less average insolation, less ice transport and greater chance for refreezing in winter. It's possible that less ice creates more protective cloud cover as well. In the long run the ice is doomed. But in the short run I think these negative feedbacks are likely to prevail.

>"Lower temperatures in ice covered areas"
Why would there be lower temperatures? Surely there are warmer temperatures nearer than previously that can get blown to such positions more easily? Then there is GHG levels.

'Less average insolation' is assuming increased cloud cover? (Not sure there is data showing this or at least isn't very clear.) Then there is lower albedo meaning a higher proportion is absorbed.

'Less ice transport' ice is thinner but moves faster so not sure about less being transported out of arctic. It is possible as ice retreats to smaller area.

But maybe you are talking about, we have cleared ice from area where there is a net movement out of the areas where quick increase in ice free area occurs so readily creating albedo feedback, but when we try to clear area with net movement in the area doesn't clear quickly so the albedo feedback is much slower.

Certainly agree with winter regrowth feedback.

Then there are others like:

Bathymetry: We have cleared the shallow area where warm salty gulf stream water cannot sink.

Distance from land and rivers:
Land warms up fast warming the air and rivers provide fresh water warmed during its journey. As the ice retreats away from these areas it gets harder to melt the ice.

Temperatures would be lower because remaining ice will be further north and further out to sea. I don't think increased weather variability will outweigh that effect. In the long run increased GHG levels will melt the ice, but we are talking about what will happen in the next 20 years.

I'm not talking about cloud cover, but the basic fact that there is less annual insolation the further north you go.

Most ice transport is through the Fram strait. Transport declines significantly in the summer because there is less ice nearby. We can expect that feedback to increase as the ice extent decreases.

I wasn't talking about albedo. But speaking of that- If the albedo effect were important then you would expect increased melting in the second half of the summer due to warmer waters. But we see the opposite. Melt at the end of the summer is decreasing and the melt season is increasingly focused around the solstice. Of course the albedo effect still exists on some level, but at least in the short run it appears that the albedo effect is being dominated by the negative feedbacks I have listed.

As for bathymetry, I am skeptical. The ocean map doesn't line up well with this theory. On the Atlantic side it fits well. But on the Alaska/Russian side bathymetry seems like a poor fit for the typical melt shape. See image below.

I agree that distance from land is also likely to be a negative feedback.

http://s16.photobucket.com/user/iciclespike/media/common%20ice%20shape.jpg.html?sort=3&o=0



Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: litesong on March 31, 2018, 08:20:08 PM
People, please chill.  Please don't turn this into a flame war.
Addressing the obvious, conscious & determined errors(lies) of a poster is no flame war. If such is NOT opposed from the beginning, THEN more lies will propagate.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Red on March 31, 2018, 08:31:21 PM
This may well be of base by many kilometres but the multi-year ice is the most important part of this equation. If the multi-year ice is losing out year on year than volume will be the Arctic Ocean area times the thickness of one winters freeze. One winters freeze tends to turn to water the following season except in the very far north but with the intrusion of the open water on both sides the chances of multi-year ice build up is seemingly impaired by transport out of the arctic. The multi-year ice is the catalyst that was keeping things together, I think. Winter refreeze is the all important variable that seems to be compromised. Remember that the night time lows globally are rising faster than the daytime highs. Well the polar night is the longest night on the planet so it goes to follow that the polar night might just have the time available to creep into heights that not too long ago were unimaginable. Oooh look, I think it just happened in the last couple of years. A few more nights like the last couple and we may well have something here.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Daniel B. on March 31, 2018, 08:35:59 PM
People, please chill.  Please don't turn this into a flame war.
Addressing the obvious, conscious & determined errors(lies) of a poster is no flame war. If such is NOT opposed from the beginning, THEN more lies will propagate.

I think that is a given, and often posters will point out glaring errors.  I believe he was referring to actual ad hominem attacks and name calling, instead of countering scientifically.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: jdallen on March 31, 2018, 11:30:08 PM
People, please chill.  Please don't turn this into a flame war.
Addressing the obvious, conscious & determined errors(lies) of a poster is no flame war. If such is NOT opposed from the beginning, THEN more lies will propagate.

I think that is a given, and often posters will point out glaring errors.  I believe he was referring to actual ad hominem attacks and name calling, instead of countering scientifically.
Precisely.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: icefisher on April 01, 2018, 01:28:44 AM
I chose 2017 as my first year with area less than 1MM.  After 2007 and 2012, 2017 seemed as likely as not.  Negative reinforcements may delay melting for a few more years or we may have another perfect melting season.  Either way we are already dealing with the effects of global warming.  The future looks unknowable.  Unlike Darth Vader we have already altered it further.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Archimid on April 01, 2018, 10:20:29 PM
Quote
Ad hominem (Latin for "to the man" or "to the person"[1]), short for argumentum ad hominem, is a fallacious argumentative strategy whereby genuine discussion of the topic at hand is avoided by instead attacking the character, motive, or other attribute of the person making the argument, or persons associated with the argument, rather than attacking the substance of the argument itself
I addressed the discussion at hand and provided evidence. Since his point was false, that would make his statement a lie, making him a liar. Without any context, I didn't perform an ad hominem, however, the rough nature of the words I use make it look like I did. With the context of the climate change debate what I did was way too nice, given the cost in lives and property, present and future.

However I acknowledge that my words have unintended consequences for the good flow of information in a public forum. Thus I pledge to hold strong language back in favor of more  calmed and objective language, even if it understates the nature of these falsehoods.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: crandles on April 02, 2018, 12:48:58 PM

Temperatures would be lower because remaining ice will be further north and further out to sea. I don't think increased weather variability will outweigh that effect. In the long run increased GHG levels will melt the ice, but we are talking about what will happen in the next 20 years.

I'm not talking about cloud cover, but the basic fact that there is less annual insolation the further north you go.

Most ice transport is through the Fram strait. Transport declines significantly in the summer because there is less ice nearby. We can expect that feedback to increase as the ice extent decreases.

I wasn't talking about albedo. But speaking of that- If the albedo effect were important then you would expect increased melting in the second half of the summer due to warmer waters. But we see the opposite. Melt at the end of the summer is decreasing and the melt season is increasingly focused around the solstice. Of course the albedo effect still exists on some level, but at least in the short run it appears that the albedo effect is being dominated by the negative feedbacks I have listed.

As for bathymetry, I am skeptical. The ocean map doesn't line up well with this theory. On the Atlantic side it fits well. But on the Alaska/Russian side bathymetry seems like a poor fit for the typical melt shape. See image below.

I agree that distance from land is also likely to be a negative feedback.

http://s16.photobucket.com/user/iciclespike/media/common%20ice%20shape.jpg.html?sort=3&o=0

Further north - less insolation.
OK.

I am a little more sceptical of colder temperatures though. In summer temps pegged closely to melting point/freezing point. In winter there is very little insolation and I would expect distance to relatively warm water to be a much more important factor.

Also not sure about your 'further out to sea'. The sea is warm. Secondly i expect wind and currents to keep the last of the ice to hug Greenland and Canadian islands. So for the last of the ice the retreat will be southward not northward. Does that make your insolation effect a positive feedback at the end?

Transport, yes I agree that seems highly probable.

How can the albedo effect not be important? Maybe heat absorbed by ocean doesn't travel far. I would expect winds to pick up this heat but even leaving that out, thin ice has lower albedo and surely that has to be important. But as you say "Melt at the end of the summer is decreasing and the melt season is increasingly focused around the solstice."

How can this be? I suggest it points toward 'distance from land', 'bathymetry' and 'we have done the easy areas where there is net movement of ice out of the area so the albedo effect is artificially enhanced' being important feedbacks.


Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: litesong on April 02, 2018, 06:24:59 PM
People, please chill.  Please don't turn this into a flame war.
Addressing the obvious, conscious & determined errors(lies) of a poster is no flame war. If such is NOT opposed from the beginning, THEN more lies will propagate.
I believe he was referring to actual ad hominem attacks and name calling, instead of countering scientifically.
Daniel tries to side-slip away, pretending the following earlier set of posts didn't occur:
///////
Daniel B. wrote: The satellite data starts in 1979.  There is no good measure of ice volume to that, so anything else is speculation.
litesong wrote:
Much submarine data is available. AGW deniers love to hoot that submarines were surfacing at the North Pole in the 1950's, intimating that 1950's Arctic sea ice was thin. But submarine logs indicate 1950's sea ice was much thicker than today. It took weeks for submarines to find sea ice thin enough, through which submarines could surface. & in weeks previous to that, submarines could not enter the Arctic Ocean from the Bering Strait easily or safely, due to sea ice that was as much as 60 feet thick.
Article about submarine data on sea ice in the 50's & 60's:
http://news.bbc.co.uk/2/hi/science/nature/523065.stm 
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Juan C. García on April 02, 2018, 09:00:32 PM
Last week, I voted for 2029-2033 and today I try to change it to 2034-2039 or even the 2040-49 range, but there is no option to remove my vote [help Neven or DungeonMaster].

Would that make me a denier?  :o  :-[

No way!  8)

I believe that we are sub estimating the impact that the melting ice on Greenland will have on the process of having an ice-free Arctic. Also, the impact that permafrost melting could have on delaying the ASI melting.

So, we could think that it is good news that the ASI will melt slower than forecasted by some of us, but that will not be true. The problem with AGW is that there are some things going on, that we are not able to see or to measure properly. That is the case of [Oh, my God] “Oceans melting Greenland” (OMG).

https://omg.jpl.nasa.gov/portal/ (https://omg.jpl.nasa.gov/portal/)

OMG?...really?
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Daniel B. on April 02, 2018, 09:46:05 PM
People, please chill.  Please don't turn this into a flame war.
Addressing the obvious, conscious & determined errors(lies) of a poster is no flame war. If such is NOT opposed from the beginning, THEN more lies will propagate.
I believe he was referring to actual ad hominem attacks and name calling, instead of countering scientifically.
Daniel tries to side-slip away, pretending the following earlier set of posts didn't occur:
///////
Daniel B. wrote: The satellite data starts in 1979.  There is no good measure of ice volume to that, so anything else is speculation.
litesong wrote:
Much submarine data is available. AGW deniers love to hoot that submarines were surfacing at the North Pole in the 1950's, intimating that 1950's Arctic sea ice was thin. But submarine logs indicate 1950's sea ice was much thicker than today. It took weeks for submarines to find sea ice thin enough, through which submarines could surface. & in weeks previous to that, submarines could not enter the Arctic Ocean from the Bering Strait easily or safely, due to sea ice that was as much as 60 feet thick.
Article about submarine data on sea ice in the 50's & 60's:
http://news.bbc.co.uk/2/hi/science/nature/523065.stm

I have seen several papers, whereby the scientists try to piece together sea ice extent from various sources.  I have yet to see one detailing volume.  Please post any references.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Archimid on April 02, 2018, 10:18:13 PM
Quote
I have seen several papers, whereby the scientists try to piece together sea ice extent from various sources.  I have yet to see one detailing volume.  Please post any references.

We know the thickness since the 50's to the 80's was extremely thick, relative to today. We have good proxies for extent that go back centuries that confirm the extent was much higher than now.  We have proxy temperatures that confirm that it was much colder than now that extends for thousands of years.

There is absolutely no indication that the Arctic or the world were as warm as they are today.

You can start here : https://skepticalscience.com/past-Arctic-sea-ice-extent.htm

Evidence was provided that proves Daniel B. statements false. Evidence provided by Daniel B. to justify his uncertainty about volume in the past 0.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Daniel B. on April 02, 2018, 11:53:39 PM
Quote
I have seen several papers, whereby the scientists try to piece together sea ice extent from various sources.  I have yet to see one detailing volume.  Please post any references.

We know the thickness since the 50's to the 80's was extremely thick, relative to today. We have good proxies for extent that goes back centuries that confirm the extent was much higher than now.  We have proxy temperatures that confirm that it was much colder for than now that extends for thousands of years.

There is absolutely no indication that the Arctic or the world was were as warm as they are today.

You can start here : https://skepticalscience.com/past-Arctic-sea-ice-extent.htm

Evidence was provided that proves Daniel B. statements false. Evidence provided by Daniel B. to justify his uncertainty about volume in the past 0.

Sorry, but inferences do not constitute proof.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Archimid on April 03, 2018, 12:12:51 AM
Quote
Sorry, but inferences do not constitute proof.

How do you figure the earth is round without making inferences?
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Daniel B. on April 03, 2018, 12:45:21 AM
Quote
Sorry, but inferences do not constitute proof.

How do you figure the earth is round without making inferences?

We have visual from space for one.

Let's put your inferences to the test.  The rate of average ice loss, in volume, from 1990 to 2010 was about 4000 cubic km per decade.  Let us assume that your inference (based on proxy data) shows that the rate of ice loss prior to the satellite era (1979) was similar to that measured during those two decades.  If we extend that rate back to 1850, that would equate to a volume of ice loss covering the entire Arctic ocean to a depth of 30 meters!  You can infer all you like, but at some point, logic has to step in. 
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: slow wing on April 03, 2018, 12:58:42 AM
Picked 2019-21.

Main contender for me was 2022-2024.

In my humble opinion we are already at the stage where an extreme year could do it.

Superimposed on that is the expectation that the situation is getting progressively worse. But it's problematic to quantify that for Arctic sea ice - the physics is far too complicated & poorly understood, & the constraining observations and measurements are far too few &/or too poor.

I think the year-to-year fluctuations are so big as to be more important than the progressive trend in choosing the first year below 1000 km^3.

It could possibly be this year. But it would take a very bad melt season. The 2018 bin is only 1 year wide so I think it less likely than the 3 year bin afterwards that I did choose.

Competing against the progressive trend, the bins 2022-24 and later are disadvantaged by the possibility that, even if the volume does fall below 1000 km^3, it might have already happened in a prior melt season. That's why I chose 2019-21.

This poll runs for a long time - was it for two months? People voting near the start have less information than those voting later on. Can the close date be made earlier? Also, my preference would be to change the poll settings so we can change our vote.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Archimid on April 03, 2018, 02:26:13 AM

How do you figure the earth is round without making inferences?

We have visual from space for one.

There is a staggering amount of inferences that go into placing an object in orbit.

Quote
Let's put your inferences to the test.  The rate of average ice loss, in volume, from 1990 to 2010 was about 4000 cubic km per decade.  Let us assume that your inference (based on proxy data) shows that the rate of ice loss prior to the satellite era (1979) was similar to that measured during those two decades.  If we extend that rate back to 1850, that would equate to a volume of ice loss covering the entire Arctic ocean to a depth of 30 meters!  You can infer all you like, but at some point, logic has to step in.

There are inferences and there are false inferences.  For example by assuming continuous volume loss you arrive at a nonsensical result. However a quick look at Arctic temperatures tells you that the losses experienced in the late 20th didn't occur before. Assuming a permanent state of volume loss is a false assumption that leads to nonsensical results.

(https://skepticalscience.com/pics/Kaufmannetal.2009.png)
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: litesong on April 03, 2018, 03:17:31 AM
Let's put your inferences to the test.
Daniel B. put its own IN-ability to infer properly to the test.... & failed its own test.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Daniel B. on April 03, 2018, 04:17:17 AM

How do you figure the earth is round without making inferences?

We have visual from space for one.

There is a staggering amount of inferences that go into placing an object in orbit.

Quote
Let's put your inferences to the test.  The rate of average ice loss, in volume, from 1990 to 2010 was about 4000 cubic km per decade.  Let us assume that your inference (based on proxy data) shows that the rate of ice loss prior to the satellite era (1979) was similar to that measured during those two decades.  If we extend that rate back to 1850, that would equate to a volume of ice loss covering the entire Arctic ocean to a depth of 30 meters!  You can infer all you like, but at some point, logic has to step in.

There are inferences and there are false inferences.  For example by assuming continuous volume loss you arrive at a nonsensical result. However a quick look at Arctic temperatures tells you that the losses experienced in the late 20th didn't occur before. Assuming a permanent state of volume loss is a false assumption that leads to nonsensical results.

(https://skepticalscience.com/pics/Kaufmannetal.2009.png)

Since you just acknowledged that your previous inference was false, are you now saying that there was no volume loss prior to 1979?  If your new premise is based on rising temperatures resulting in volume loss, how do you explain the volume gains in recent years?  Or are you backtracking now, and supporting my previous contention.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Iceismylife on April 03, 2018, 04:17:38 AM
...
 You can infer all you like, but at some point, logic has to step in.
Did you really read what you wrote?

Let us try some logic.

Max volume is dropping.

How long can this be kept up?

really?

Run some numbers.



Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: oren on April 03, 2018, 04:20:49 AM
Quite simple.  The satellite data starts in 1979.  There is no good measure of ice volume to that, so anything else is speculation.  Can you state with any certainty the volume of ice in the Arctic at the beginning of the industrial era?  or at any time prior?  I do not know when the first ice-free year will occur either.   However, that does not guarantee that next will be similar.
The classic "argument from ignorance" logical fallacy. There is no good measure of prior ice volume indeed, but it doesn't mean that anything else is speculation. A quick read about Captain Cook's voyage to the Chukchi Sea in mid-August 1778, will reveal that uncertainty is not a good proxy for unknown. The captain's journal describes "ice which was as compact as a wall and seemed to be ten or twelve feet high at least". Compare that to the current ice edge and thickness in mid-August. So yes, anybody can state with certainty that sea ice volume 200 years ago in summer was much higher than today, even though no one can say what the actual volume was.
(https://www.adn.com/resizer/PWRFaKsRgJD3esW8So7kH52etY0=/992x0/s3.amazonaws.com/arc-wordpress-client-uploads/arctic/wp-content/uploads/2016/11/17152300/20161117_COOK-1.jpg)
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Daniel B. on April 03, 2018, 04:45:52 AM
Of course the ice volume was higher than today.  No one is arguing that.  However, the claim that the volume from past centuries is known, and the recent volume decreases are similar to past is unsupported.  I have been arguing against this “argument from ignorance,” yet others seem to be supportive of it.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Neven on April 03, 2018, 06:54:12 AM
Lets not stray too far off-topic, please.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Alexander555 on April 03, 2018, 05:07:45 PM
What would be the impact on the Greenland ice, the moment the Arctic becomes ice-free in summer ?
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: jdallen on April 03, 2018, 07:52:37 PM
What would be the impact on the Greenland ice, the moment the Arctic becomes ice-free in summer ?
Mass loss would accelerate. It might be buffered by more snowfall, but the flow of ice itself will accelerate as well.

What *I* think ahead to when considering a summer ice free Arctic, is the storms, like as have not been seen in millions of years.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: gerontocrat on April 05, 2018, 03:54:42 PM
Gompertz curves, 4 parameter curves, and sound and fury. A couple of years of large decreases and it's "The ice is gone - we are doomed!" and then a couple of large increases and it's " The ice is coming back - the New Ice Age is upon us !"

Me, I am sticking with the Polar Science Center stuff, and I quote :- "March 2018 ice volume sits right on the long term trend line". The trend line is linear, for March -3.1 km3 '000 per decade.

For September, the linear trend is -3.2 km3 '000 per decade, with 4,000 km3 to go to get to 1,000 km3. As was pointed out, the poll is for the daily minimum. Taking that into account, and possible high variation when such a small volume is left, I think I voted for 2028 (biased by wishing to be still extant when it happens).



Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Daniel B. on April 05, 2018, 04:30:54 PM
Yes, high potential variations at low volume will make for difficult predictive capabilities.  A strict linear trend will take the minimum ice below 1000 km3 in 2040.  One or two years of large decrease will accelerate that prediction.  A more Gompertz-like curve could extent its life by decades.  I opted for the 2050s time frame, due to an expected difficulty in melting the ice protected by land.  I seriously doubt that I will be extant at that time.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: crandles on April 05, 2018, 08:43:03 PM
due to an expected difficulty in melting the ice protected by land.

I expect the ice will be pretty thin by the time it gets down to 1000 cubic km, much thinner than 1m average so much more area than million km^2. How much area do you expect to be 'protected by land'? Quite a bit of land warms much faster than ocean so helps melt. Ice covered land probably doesn't warm faster until the ice is gone so perhaps its a bit complicated. Shade from sunlight might help protect, but even with low sun angles, the area isn't very much unless there are huge cliffs. There isn't a million km of coastline.

I could easily be wrong about some aspects but quoted reasoning seems to me to attach too much area and importance to 'ice protected by land'.

Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Alexander555 on April 05, 2018, 09:09:59 PM
2028 Gerontocrat ? Don't put to much money on that one. Your own grap shows that it's accelerating. In 1996 there was more volume than in 1982. It's only after 1996 that it started to drop fast. And the thinner it gets, the more vulnerable it will become.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: crandles on April 05, 2018, 10:24:37 PM
2028 Gerontocrat ? Don't put to much money on that one. Your own grap shows that it's accelerating. In 1996 there was more volume than in 1982. It's only after 1996 that it started to drop fast. And the thinner it gets, the more vulnerable it will become.

Time to go back to beginning of thread?
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Daniel B. on April 05, 2018, 10:37:50 PM
due to an expected difficulty in melting the ice protected by land.

I expect the ice will be pretty thin by the time it gets down to 1000 cubic km, much thinner than 1m average so much more area than million km^2. How much area do you expect to be 'protected by land'? Quite a bit of land warms much faster than ocean so helps melt. Ice covered land probably doesn't warm faster until the ice is gone so perhaps its a bit complicated. Shade from sunlight might help protect, but even with low sun angles, the area isn't very much unless there are huge cliffs. There isn't a million km of coastline.

I could easily be wrong about some aspects but quoted reasoning seems to me to attach too much area and importance to 'ice protected by land'.

Yes, the land is ice-covered.  The glaciers in Greenland and the Canadian archipelago will not just cool their surroundings, but provide additional glacial ice.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: gerontocrat on April 05, 2018, 10:49:03 PM
Yes, high potential variations at low volume will make for difficult predictive capabilities.  A strict linear trend will take the minimum ice below 1000 km3 in 2040.  One or two years of large decrease will accelerate that prediction.  A more Gompertz-like curve could extent its life by decades.  I opted for the 2050s time frame, due to an expected difficulty in melting the ice protected by land.  I seriously doubt that I will be extant at that time.
Earlier this year A-team did a post to say there is no land fast ice in the Arctic. It is just ice that has been shoved against the land as in north of greenland and the caa.
Lo and behold in February that so-called  land fast ice is shoved north and there is open ocean north of greenland. If that can happen in the dead of winter then in late summer all arctic ice is at the mercy of the vagaries of the weather?
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Daniel B. on April 06, 2018, 05:41:30 PM
Yes, high potential variations at low volume will make for difficult predictive capabilities.  A strict linear trend will take the minimum ice below 1000 km3 in 2040.  One or two years of large decrease will accelerate that prediction.  A more Gompertz-like curve could extent its life by decades.  I opted for the 2050s time frame, due to an expected difficulty in melting the ice protected by land.  I seriously doubt that I will be extant at that time.
Earlier this year A-team did a post to say there is no land fast ice in the Arctic. It is just ice that has been shoved against the land as in north of greenland and the caa.
Lo and behold in February that so-called  land fast ice is shoved north and there is open ocean north of greenland. If that can happen in the dead of winter then in late summer all arctic ice is at the mercy of the vagaries of the weather?

I cannot say that I agree with his assessment, and am attaching some recent publications on the landfast ice.

https://www.the-cryosphere.net/10/1463/2016/tc-10-1463-2016.pdf (https://www.the-cryosphere.net/10/1463/2016/tc-10-1463-2016.pdf)

https://www.the-cryosphere.net/10/1463/2016/tc-10-1463-2016.pdf (https://www.the-cryosphere.net/10/1463/2016/tc-10-1463-2016.pdf)

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2014JC010353 (https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2014JC010353)
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: jdallen on April 06, 2018, 06:34:10 PM
If your definition of land fast ice is nonmobile ice anchored to land right now, you may be correct. However if you deine land fast ice as it was, multi year, more than 3M thick, A-Team's assessment is the more accurate one.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Daniel B. on April 06, 2018, 06:39:14 PM
If your definition of land fast ice is nonmobile ice anchored to land right now, you may be correct. However if you deine land fast ice as it was, multi year, more than 3M thick, A-Team's assessment is the more accurate one.

Since most of the ice is ~2m thickness, we may be using different metrics.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: jdallen on April 06, 2018, 07:05:50 PM
If your definition of land fast ice is nonmobile ice anchored to land right now, you may be correct. However if you deine land fast ice as it was, multi year, more than 3M thick, A-Team's assessment is the more accurate one.

Since most of the ice is ~2m thickness, we may be using different metrics.
... which speaks exactly to my point, as it is the older, in some cases thousands of years old land fast ice in places like the Lincoln sea and along the CAA which i think of when I say land fast ice.  It no longer exists.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Sebastian Jones on April 06, 2018, 09:24:01 PM
If your definition of land fast ice is nonmobile ice anchored to land right now, you may be correct. However if you deine land fast ice as it was, multi year, more than 3M thick, A-Team's assessment is the more accurate one.

Since most of the ice is ~2m thickness, we may be using different metrics.
... which speaks exactly to my point, as it is the older, in some cases thousands of years old land fast ice in places like the Lincoln sea and along the CAA which i think of when I say land fast ice.  It no longer exists.
Perhaps the confusion arises from terminology: The ice SHELVES of the arctic are indeed gone, land fast ice forms every year, and usually melts out each summer.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Tor Bejnar on April 06, 2018, 09:31:15 PM
Not quite:
https://en.wikipedia.org/wiki/Ice_shelf#Canadian_ice_shelves
Quote
All Canadian ice shelves are attached to Ellesmere Island and lie north of 82°N. Ice shelves that are still in existence are the
  • Alfred Ernest Ice Shelf
  • Milne Ice Shelf
  • Ward Hunt Ice Shelf and
  • Smith Ice Shelf.
The M'Clintock Ice Shelf broke up from 1963 to 1966; the Ayles Ice Shelf broke up in 2005; and the Markham Ice Shelf broke up in 2008.
[formatting altered]
But yes, gone (apparently) from Russia:
Quote
The Matusevich Ice Shelf was a 222 km² ice shelf located in Severnaya Zemlya being fed by some of the largest ice caps on October Revolution Island, the Karpinsky Ice Cap to the south and the Rusanov Ice Cap to the north.[9] In 2012 it ceased to exist.[10]
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Sebastian Jones on April 06, 2018, 09:47:24 PM
Not quite:
https://en.wikipedia.org/wiki/Ice_shelf#Canadian_ice_shelves
Quote
All Canadian ice shelves are attached to Ellesmere Island and lie north of 82°N. Ice shelves that are still in existence are the
  • Alfred Ernest Ice Shelf
  • Milne Ice Shelf
  • Ward Hunt Ice Shelf and
  • Smith Ice Shelf.
The M'Clintock Ice Shelf broke up from 1963 to 1966; the Ayles Ice Shelf broke up in 2005; and the Markham Ice Shelf broke up in 2008.
[formatting altered]
But yes, gone (apparently) from Russia:
Quote
The Matusevich Ice Shelf was a 222 km² ice shelf located in Severnaya Zemlya being fed by some of the largest ice caps on October Revolution Island, the Karpinsky Ice Cap to the south and the Rusanov Ice Cap to the north.[9] In 2012 it ceased to exist.[10]
Thanks for the correction. I was under the impression that they had disintegrated, e.g.:
Quote
The Ward Hunt ice sheet began breaking up approximately 100 years ago, but was believed to have stabilized by the early 1980s. However, in April 2000, satellite images revealed that a large crack in the ice had begun to form, and in 2003, it was announced that the ice sheet had split completely in two in 2002, releasing a huge pool of fresh water from the largest epishelf lake in the Northern Hemisphere, located in Disraeli Fjord.[3] In April 2008, it was discovered that the shelf was fractured into dozens of deep, multi-faceted cracks.[4] In late July 2008, it was announced that nearly 8 square miles (21 km2) broke away from the shelf.[1] In August 2010, another 50 km² (19 sq mi) calved off from the northeast quarter of the ice shelf.[5]
https://en.wikipedia.org/wiki/Ward_Hunt_Ice_Shelf (https://en.wikipedia.org/wiki/Ward_Hunt_Ice_Shelf)
All of which, upon closer read, indicates the shelves remain, albeit much reduced. Which explains why Jill Heinurth is heading there this summer to dive in the ice shelf ice caves. :-[
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: gerontocrat on April 06, 2018, 10:17:04 PM
Would I be right in thinking that the ice shelf remnants that remain amount to less than 1,000 km3. I ask as there is a view that ice protected by land could delay volume getting below the poll figure.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: jdallen on April 06, 2018, 10:45:30 PM
Would I be rig3ht in thinking that the ice shelf remnants that remain amount to less than 1,000 km3. I ask as there is a view that ice protected by land could delay volume getting below the poll figure.
The volume of those shelf remnants is 10s of KM3, certainly not thousands, and their total area trivial compared to total Arctic ice extent and area.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: binntho on April 07, 2018, 07:47:32 AM
Earlier this year A-team did a post to say there is no land fast ice in the Arctic. It is just ice that has been shoved against the land as in north of greenland and the caa. ...

I cannot say that I agree with his assessment, and am attaching some recent publications on the landfast ice.

https://www.the-cryosphere.net/10/1463/2016/tc-10-1463-2016.pdf (https://www.the-cryosphere.net/10/1463/2016/tc-10-1463-2016.pdf)

https://www.the-cryosphere.net/10/1463/2016/tc-10-1463-2016.pdf (https://www.the-cryosphere.net/10/1463/2016/tc-10-1463-2016.pdf)

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2014JC010353 (https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2014JC010353)
One of the least instructive and constructive postings I've seen for a long time. Links to two publications (not three) that have nothing to do with what A-Team said! No attempt to justify your position, no data, no insights. Obfuscationism in its purest form.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Alexander555 on April 07, 2018, 08:44:00 AM
Maybe that's because there is much at risk. The lives of hundreds of millions of people can be fliped over in a very short periode, trillions of real-estate at risk, stockmarkets at risk, the entire global economy is at risk. And it is hard to calculate effects of everything. But what we do know for sure is that arctic winter volume is something like 20 000 km3 of ice ,and summer volume in 1980 was something like 16500 km3 of ice. The winter maximum we have today is only a little bit higher than the summer minimum from less than 40 years ago. And that is the result  from only a small change (for some) in temperature.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Daniel B. on April 07, 2018, 01:52:22 PM
Earlier this year A-team did a post to say there is no land fast ice in the Arctic. It is just ice that has been shoved against the land as in north of greenland and the caa. ...

I cannot say that I agree with his assessment, and am attaching some recent publications on the landfast ice.

https://www.the-cryosphere.net/10/1463/2016/tc-10-1463-2016.pdf (https://www.the-cryosphere.net/10/1463/2016/tc-10-1463-2016.pdf)

https://www.the-cryosphere.net/10/1463/2016/tc-10-1463-2016.pdf (https://www.the-cryosphere.net/10/1463/2016/tc-10-1463-2016.pdf)

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2014JC010353 (https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2014JC010353)
One of the least instructive and constructive postings I've seen for a long time. Links to two publications (not three) that have nothing to do with what A-Team said! No attempt to justify your position, no data, no insights. Obfuscationism in its purest form.

That was because when I went to post, I was kicked off.  Going back, I must’ve inadvertently copied one link twice.  However to call it obfuscation when they are conducting research on something a previous claims does not exist, seems rather odd.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: binntho on April 09, 2018, 08:23:39 AM
Earlier this year A-team did a post to say there is no land fast ice in the Arctic. It is just ice that has been shoved against the land as in north of greenland and the caa. ...

I cannot say that I agree with his assessment, and am attaching some recent publications on the landfast ice.

https://www.the-cryosphere.net/10/1463/2016/tc-10-1463-2016.pdf (https://www.the-cryosphere.net/10/1463/2016/tc-10-1463-2016.pdf)

https://www.the-cryosphere.net/10/1463/2016/tc-10-1463-2016.pdf (https://www.the-cryosphere.net/10/1463/2016/tc-10-1463-2016.pdf)

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2014JC010353 (https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2014JC010353)
One of the least instructive and constructive postings I've seen for a long time. Links to two publications (not three) that have nothing to do with what A-Team said! No attempt to justify your position, no data, no insights. Obfuscationism in its purest form.

That was because when I went to post, I was kicked off.  Going back, I must’ve inadvertently copied one link twice.  However to call it obfuscation when they are conducting research on something a previous claims does not exist, seems rather odd.
I wonder if you are aware of what A-Team's "assessment" was to begin with. He never claimed that land-fast ice (as described in your links) did not exist. It obviously does, as everyone can see. But the point he made (as I understand it) was that when the CAB ice goes below e.g. 1 million square kilometers, this "land-fast" ice would not exist any more, i.e. it would simply float away.

This applies in particular to the thick land-fast ice along the coast of northern Greenland and the Arctic Archipelago - it is not grounded or made "fast" to the land in any sense, but held in place by the push of ice movement in the CAB. As we saw this winter, the land-fast ice along the northern Greenland coast wasn't - in accordance with what A-Team said - and simply floated away.

This is an important point to make when a future with much less ice is considered. Will the remaining 1 million km2 (presumably the oldest and thickest ice) stay where it is or float away into warmer waters? We may well see, when sea ice falls below a certain threshold in some future summer's melting, that the entire pack starts breaking up and floating freely, speeding the melt of the remaining bits and pieces.

So back to my critique: Your post showed that you did not know what the "assessment" was that you were objecting to, nor how your two randomly found papers that mentioned "arctic land-fast ice" could have any bearing on the discussion. With no input what so ever from yourself, I am still inclined to view this as obfuscation.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Daniel B. on April 10, 2018, 05:05:44 PM
Earlier this year A-team did a post to say there is no land fast ice in the Arctic. It is just ice that has been shoved against the land as in north of greenland and the caa. ...

I cannot say that I agree with his assessment, and am attaching some recent publications on the landfast ice.

https://www.the-cryosphere.net/10/1463/2016/tc-10-1463-2016.pdf (https://www.the-cryosphere.net/10/1463/2016/tc-10-1463-2016.pdf)

https://www.the-cryosphere.net/10/1463/2016/tc-10-1463-2016.pdf (https://www.the-cryosphere.net/10/1463/2016/tc-10-1463-2016.pdf)

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2014JC010353 (https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2014JC010353)
One of the least instructive and constructive postings I've seen for a long time. Links to two publications (not three) that have nothing to do with what A-Team said! No attempt to justify your position, no data, no insights. Obfuscationism in its purest form.

That was because when I went to post, I was kicked off.  Going back, I must’ve inadvertently copied one link twice.  However to call it obfuscation when they are conducting research on something a previous claims does not exist, seems rather odd.
I wonder if you are aware of what A-Team's "assessment" was to begin with. He never claimed that land-fast ice (as described in your links) did not exist. It obviously does, as everyone can see. But the point he made (as I understand it) was that when the CAB ice goes below e.g. 1 million square kilometers, this "land-fast" ice would not exist any more, i.e. it would simply float away.

This applies in particular to the thick land-fast ice along the coast of northern Greenland and the Arctic Archipelago - it is not grounded or made "fast" to the land in any sense, but held in place by the push of ice movement in the CAB. As we saw this winter, the land-fast ice along the northern Greenland coast wasn't - in accordance with what A-Team said - and simply floated away.

This is an important point to make when a future with much less ice is considered. Will the remaining 1 million km2 (presumably the oldest and thickest ice) stay where it is or float away into warmer waters? We may well see, when sea ice falls below a certain threshold in some future summer's melting, that the entire pack starts breaking up and floating freely, speeding the melt of the remaining bits and pieces.

So back to my critique: Your post showed that you did not know what the "assessment" was that you were objecting to, nor how your two randomly found papers that mentioned "arctic land-fast ice" could have any bearing on the discussion. With no input what so ever from yourself, I am still inclined to view this as obfuscation.

The third (non-random) link, which was omitted due to the previously mentioned kick off, describes the stability of the landfast ice in the CA.

http://www.mdpi.com/2072-4292/10/1/37 (http://www.mdpi.com/2072-4292/10/1/37)

The MYI landfast ice (which does not simply float away) has a median thickness of 2.7m, which is below the criteria A-team selectively chose for his definition.  This ice maintains a higher depth of snow cover during the winter, and forms fewer melt ponds during the summer.  Their study emphasizes the differences between the FYI and MYI, and that the landfast MYI is not simply "ice that has been shoved against the land."
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: gerontocrat on April 10, 2018, 05:12:09 PM
Any data on extent and or km3 on how much of this genuinely landfast myi is still extant? If > 1000km3 then a significant parameter in guessing when the poll date happens.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Daniel B. on April 10, 2018, 05:31:57 PM
Any data on extent and or km3 on how much of this genuinely landfast myi is still extant? If > 1000km3 then a significant parameter in guessing when the poll date happens.

I have not seen any data on this.  Possibly because of the difficulty in distinguishing between landfast and floating ice.  The landfast ice is thicker, so less area is necessary to reach 1000km3.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2F4.bp.blogspot.com%2F-Cz0j9XGj1Tc%2FUGHzN-1ra-I%2FAAAAAAAAAmg%2FA71mfgQiueo%2Fs1600%2FArctic%2BSea%2BIce%2BMinimum%2B2012.jpg&hash=9dc4e3e3133712750db8e2ec7f7738b4)
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: oren on April 11, 2018, 04:21:49 AM
Quote
2.1. Study Area
... collected in Victoria Strait region of the CAA during April and June 2015. Victoria Strait is part of the Northwest Passage in the CAA, which typically contains a mixture of FYI and MYI. The sea ice in the CAA is not strongly affected by wind driven movement because the ice is landfast for six to eight months of the year. Furthermore, wind driven movement of sea ice is restricted by the narrow channels that dominate the CAA [22]. During the melt season, MYI drifts into and subsequently through the CAA from the central Arctic during late summer and early fall and becomes locked in place by FYI that forms in the fall and early winter [23]. This makes for an ideal study area for understanding the evolution of sea ice from winter to summer conditions, without the need for tracking mobile ice.
DB you are confusing (again?) between actual landfast ice - ice that sticks to land during the summer, and therefore could be protected from melt-out and not be exported even in a bad year - and wintertime landfast ice, a transient phenomenon that has no bearing on the first year PIOMAS volume goes below 1000 km3.
Actual landfast ice used to exist in quantity off the coast of Ellesmere. Currently there is such ice (almost) only adjacent to Greenland, and even there it barely manages to stick around, as we see every melting season.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: binntho on April 11, 2018, 08:29:02 AM
Daniel, you seem to confuse resilience with "fastness" - all the ice under discussion here floats, as can be seen quite easily on satellite images. It floats back and forth, it moves away from the shore and back again.

It's a bit tricky finding clear weather in the images from last summer but the "fast" ice north of Ellesmere Island can be seen in this image from September 15th 2017. The strait between Ellesmere and Axel Heiberg is appr. 30 km wide.

Although not really visible on this image, the above mentioned strait has a static plug of 50 km, below which are floes drifting south. The area between Meighen Island and Ellef + Amund is mostly freefloating ice, but there is landfast ice between Meighen and Axel Heiberg. Other than that there is landfast ice in the inlets and fjords.

The supposedly "landfast" ice north of Ellesmere and Greenland moves quite freely every summer (and even, as recently seen, during the middle of the winter) in total accordance with A-Teams assertion that this "landfast" ice will drift wherever it will when the area to the north is ice-free at some point in the future.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Daniel B. on April 11, 2018, 02:17:23 PM
Of course all the ice floats, that is a physical property of the ice.  The contention that it disconnects from the shore, floats out and back again, is unsupported.  Granted I could be wrong about this.  However, I have seen no evidence of this occurring with the MYI, as opposed to FYI.  Many supposed images of these occurrences, are simply melt ponds, which give the appearance of ice separation.  The landfast ice is quite thick (even that which is less than the 3m criteria for A Team's contentions), such that it will not release and reattach so easily.  Yes, from time to time, some of the ice plug break off due to compelling forces, giving the appearance of less fastness.  These are stress releases, which are completely normal, albeit more frequent as the Arctic warms.  Don't get me wrong.  I am not saying that the landfast ice is not in decline.  Rather, it will take much longer to melt this ice, than the floating FYI, in contrast to those claiming that it will disintegrate as the FYI declines.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: sedziobs on April 11, 2018, 04:54:59 PM
The contention that it disconnects from the shore, floats out and back again, is unsupported.  Granted I could be wrong about this.  However, I have seen no evidence of this occurring with the MYI, as opposed to FYI.  Many supposed images of these occurrences, are simply melt ponds, which give the appearance of ice separation.
Other than the small proper ice shelves occupying fjords and inlets, all of the sea ice disconnects from shore.  See uniquorn's recent gif for evidence of that.  In Dec 2017 the ice north of the CAA detached, so certainly not melt ponds then.

Edit: I should note that the below image is older (probably 20th century). Most of the shelves are now gone, with the exception of Ward Hunt and Milne.

(https://www.canadiangeographic.ca/sites/cgcorp/files/images/web_articles/magazine/oct08/radar1.jpg)
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Daniel B. on April 11, 2018, 08:13:32 PM
That does merit a re-evaluation of my conclusions.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: binntho on April 12, 2018, 08:22:17 AM
I thought the satellite image in my last post showed this clearly, but for a newcomer this might not bee as apparent, what with clouds and everything. Individual meltponds cannot normally be seen in satellite images, but when they are present they give a light blue sheen to the whiteness of the ice.

Open water appears as very dark blue, and the cracks visible in my last posting have a width in the order of kilometers (each pixel is several hundred meters wide, so for a crack to be visible as a hairline it has to be at least that wide).

Perhaps a nice animation will help you understand this better. It has half the resolution of my last posting, but covers 15 days at the end of spring last year. Ellesmere is on the lower right.

Also take a look at Worldview, very useful if you want to follow the discussions here. (https://worldview.earthdata.nasa.gov/)

PS - gif may need a click to animate.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: binntho on April 12, 2018, 08:29:54 AM
If I remember correctly, what triggered A-Teams original musings on landfast ice were the predictions of an ice-free arctic that assumed that some one million square kilometers would still be left as landfast ice hugging the shores of the Arcic Archipelago. This is where ice is normally thickest, with lots of MYI, so it would be reasonable to assume that this would be the last to go.

But A-Team's point (as I understood it) was that if there was only one million km2 of ice left, the "landfast" ice would break up into floes and drift away from the shore into open waters where it would melt quite quickly. Accordingly one could assume that if ice cover went below a certain minimum for at least a few weeks, it would simply all melt out quite quickly, including the thick, hitherto resilient, "landfast" ice along the Arctic Archipelago.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: binntho on April 12, 2018, 08:30:13 AM
So am I a citizen yet?  8)
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: gerontocrat on April 12, 2018, 10:13:25 AM
In the end, I still stick with my plumping for a day in 2028 when volume is less than 1000km3 , caused by ice volume loss for a few years more or less in line with the PIOMAS linear projection and a sort of collapse as volume gets close to 1,000? 1,500? 2,000? km3.

If there are any remnants of ice-shelves and genuinely land-fast ice left, I also assume the amount will not be enough to signify for this poll.

Now, all I've got to do is wait for n years, where n is, as yet, unknown.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Daniel B. on April 12, 2018, 01:59:00 PM
Based on a linear rate of volume loss, 2028 will still require accelerated ice loss.  I still believe that the deceleration over the past decade is real and not a random artifact in the data, and largely due to the previous ice being overly exposed to the warmer waters.  Therefore, I am sticking with my original prognosis of 30+ years. 
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: binntho on April 12, 2018, 06:03:30 PM
Based on a linear rate of volume loss, 2028 will still require accelerated ice loss.  I still believe that the deceleration over the past decade is real and not a random artifact in the data, and largely due to the previous ice being overly exposed to the warmer waters.  Therefore, I am sticking with my original prognosis of 30+ years.
Using Excel's linear trend line and extending it downwards in Paint I got the following graph. Following the trend, 0 volume would be reached in 2032 and 1 million km3 in 2029. So 2028 is perhaps stretching it a bit ... but given the above discussion, perhaps we should be seeing a sudden acceleration at some point, so if the decline were to follow the linear trend more or less, one summer (perhaps 2018?) we would see a collapse of the volume, to way below 1 million km3.

The "deceleration" in the last decade looks like an artifact created by the three very low years 2010, 2011 and 2012 - and 10 data points out of 38 is far too few to tell if there has been a statistically valid change in trend. Using just the ten last years and extrapolating the trend line results in zero volume in 2047.

I've never before seen anybody state that the ice before 2007 was "overly exposed to warm waters" ... do you have any data to support this novel claim?

Personally I would guess that volume loss might accelerate at some point in the near future but I might be totally wrong.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Daniel B. on April 12, 2018, 07:35:58 PM
I have been using the minimum volume, but I suspect that is not much difference from the September average.  In either case, it comes down to whether you feel that the higher volume loss in the first decade of this century or the slower volume loss since will predominate. 

(https://upload.wikimedia.org/wikipedia/commons/5/51/Plot_arctic_sea_ice_volume.svg)
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: jdallen on April 12, 2018, 08:02:55 PM
I have been using the minimum volume, but I suspect that is not much difference from the September average.  In either case, it comes down to whether you feel that the higher volume loss in the first decade of this century or the slower volume loss since will predominate. 

(https://upload.wikimedia.org/wikipedia/commons/5/51/Plot_arctic_sea_ice_volume.svg)
We are at low enough volume that the volatility matters.  Even with an anemic melt this season volume will likely dip under 5000KM3 again.  A more serious melt could take us under 3000, which will border on catastrophic, as it would suggest all but a very limited extent along the CAA  and isolated bergs will be gone. This would have very dramatic consequences for northern hemisphere weather.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: crandles on April 12, 2018, 08:46:46 PM

The "deceleration" in the last decade looks like an artifact created by the three very low years 2010, 2011 and 2012 - and 10 data points out of 38 is far too few to tell if there has been a statistically valid change in trend. Using just the ten last years and extrapolating the trend line results in zero volume in 2047.

The gompertz fit puts the point of inflection between 2005 and 2006 whether using April or September volume data. There are 11 years data after 2006.

Statistically valid change in trend? Well I would trust Tamino on this. For extent
see for example https://tamino.wordpress.com/2017/11/01/arctic-sea-ice-4/

I think the pattern shows up more clearly in the volume data than in extent.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: binntho on April 12, 2018, 09:13:22 PM

The "deceleration" in the last decade looks like an artifact created by the three very low years 2010, 2011 and 2012 - and 10 data points out of 38 is far too few to tell if there has been a statistically valid change in trend. Using just the ten last years and extrapolating the trend line results in zero volume in 2047.

The gompertz fit puts the point of inflection between 2005 and 2006 whether using April or September volume data. There are 11 years data after 2006.

Statistically valid change in trend? Well I would trust Tamino on this. For extent
see for example https://tamino.wordpress.com/2017/11/01/arctic-sea-ice-4/

I think the pattern shows up more clearly in the volume data than in extent.
Well Tamino is the guy, and I made a donation at his site earlier today hoping he would somehow divine my wish that he would work this out. So Tamino, if you are reading this, pretty please ...

But as for your link, there is a very large problem with it: It is about extent, not volume. Another minor problem: Tamino does not directly address whether the change in the smoothed trendline is statistically significant or not. I myself am not qualified to tell whether a "Gompertz inflection point" is statistically significant or not, but given the paucity of data in my earlier graph, and the magnitude of noise, I'd be extremely surprised if there were any statistically significant changes in the trend.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Urbanus Simpliticus on April 12, 2018, 09:50:19 PM
Well, I've been lurking on the periphery way too long so I'm a gonna wade in on this with bare feet.
My interpretation of the single ice cube 10 Km high limit is that given the dynamic equilibrium between land fast ice and open ocean ice, the endpoint of absolute zero floating Ice is unachievable.
(As long as there are still conditions that have most of glacier ice intact )
And I'm not going to fact check myself or revisit definitions at this point.
Therefore an amount of ice that is 1 meter thick and has an area of a million kilometers has to be the arbitrary endpoint of floating ice, since it's physical origin is irrelevant, within the narrow focus of what matters. What matters is that is the crashing of the Arctic is definable when there is an insignificant amount of floating ice versus open water.
And "insignificant" has to be some arbitrary value that is not zero, because that is the physical reality of approaching the limit from the direction of "ice is still present". And freshwater melt and calving and other contribution from land and natural processes of the cycle.
If it were that sea ice was an isolated system, than "zero" could be zero. 
As it is, a tenth of normal coverage or a Fourteenth of total available area are a fair threshold for a "no ice" definition. 
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: binntho on April 13, 2018, 08:27:36 AM
I'm not sure what you mean by "dynamic equilibrium" between landfast ice and open ocean ice. The landfast ice under discussion here is floating in the open ocean - it is sea ice that abuts land.

There are other areas of landfast ice in the arctic that are not in the open ocean - all the inlets and fjords, the straits and sounds in the Canadian Arctic Archipelago contain a fair bit of landfast ice, but a very large proportion of this melts out each summer, leaving some 0,1 million km2 (a significant part of which are free-floating floes in the various straits).

The only source of arctic sea ice is frozen ocean water. There may be tiny bits of calved glacier floes to the north of Greenland, but nothing that makes any difference. So all the ice has the same origin, i.e. the ocean surface freezes in winter.

Last summer, the Arctic Ocean was still more than 50% covered in ice at minimum, even 2012 barely reached 60% open ocean in a short dip, recovering quickly. Open ocean  soaks solar energy while the sun shines, and wind driven waves stir up the warmer underlying waters. The more open ocean there is (and for longer periods) the more heat will be absorbed from the sun, more and bigger waves will batter the ice and bring up warmer waters, and the tendrils of warm surface waters from the Atlantic may well seek to go further north (as they have apparently been doing as the ice retreats).

But the remaining 4 million km2 or so make their own barrier of size - the warm seas can't reach them, waves batter the periphery and any warm air intrusions quickly cool down. And being also the thickest part of the ice, solar melt does not suffice to melt it out.

So if there is a "dynamic balance" it is one between extent on the one hand and waves and weather on the other. And as extent diminishes, the weather seems to be getting worse, with more warm air intrusions, bigger waves and, of course, more heat absorbed from the sun. A smaller extent will have proportionally more ice facing the open ocean, and weather systems will have an easier time of bringing warm air across.

So I see no reason what there should be any sort of natural barrier to the trend - at some point almost all the ice will disappear, and the end will probably be quick.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Daniel B. on April 13, 2018, 04:54:11 PM
Many posters have discussed whether volume or extent is the best measure of the sea ice.  In reality, there both are, as long as one recognizing their connection.  As stated previously, a liner fit for both would have volume reaching zero much before extent, which is an impossibility.  Others have pushed for a gompertz fit to the volumetric data.  This would nearly correspond to a linear decrease in extent, particularly going forward.

Individual data points appear to support this, as in 2007, extent fell below 70%, while volume plunged below 50%, and extent fell below 50% briefly in 2012, as volume fell below 25%.  A gompertz fit for volume and linear fit for extent would be the best current match for the observed data.  Indeed mathematics and physics suggests that extent would be the better measure, as the ice melts 2-dimensionally (mostly).  The third dimension (thickness) is six orders of magnitude less than either of the other two, reducing its effect on the total.  The ice melts mostly from above (solar) and below (water), with minimal side effects.  The third dimension has influenced the melt in the past through wave action (namely the infamous 2012 summer storm), but this effect has been the anomaly, not the norm.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Archimid on April 13, 2018, 11:28:43 PM
  As stated previously, a liner fit for both would have volume reaching zero much before extent, which is an impossibility. 

Why do you say it is an impossibility? If volume goes to zero while extent is still relatively large it will look like a poof from a satellite perspective.

(https://forum.arctic-sea-ice.net/index.php?action=dlattach;topic=1493.0;attach=77852;image)

This gif from the 2016 Melting Season thread illustrate how that last poof might look like. During September of the melting season most volume loss is in the from of bottom melt. If a state like the one in the image is reached in early to mid August then the ice will keep melting from below until it all the summer energy is spent or the ice is gone. That will probably look like a series of poofs.

Quote
  Indeed mathematics and physics suggests that extent would be the better measure, as the ice melts 2-dimensionally (mostly).
 

Sea ice does not melt in 2 dimensions at all. Ice melting or freezing is a function of mass, volume and temperature.

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The third dimension (thickness) is six orders of magnitude less than either of the other two, reducing its effect on the total.

Volume is not just the third dimension. Volume contains all the information of area plus the information for a third dimension.

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The ice melts mostly from above (solar) and below (water), with minimal side effects.

And both the melt and freezing, both from above and below have to interact with the entire thickness of the ice to produce melt or freeze from above or below.

Quote
The third dimension has influenced the melt in the past through wave action (namely the infamous 2012 summer storm), but this effect has been the anomaly, not the norm.

Ice grows mostly from below, that means that heat must flow through the entire thickness of the ice to form ice. The thicker the ice is, the slower it melt or freezes. The thinner it is the faster it melts or freezes.

Volume contains all the information area has plus all the information for thickness.

Ice is literally some volume of water at freezing temperature.

Thickness plays a vital role in ice formation.

Area and extent have very important uses, and without them volume wouldn't have meaning but to determine the future of ice in the Arctic volume is a much better metric.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: CameraMan on April 14, 2018, 12:37:21 AM
Ah, the hazy crystal ball.   Following trends, I'd guess late 20s to mid 30s, but temps have been rising, and broken up ice is easier to melt, so I'm going with 22-24.  Of course a couple seasons of unusual weather could toss that in either direction.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: binntho on April 14, 2018, 07:17:53 AM
There is no mathematical impossibility in volume decreasing faster than extent. But of course it would be impossible for there to be extent without volume. Whatever metric reaches zero first pulls the other down with it.

Extent or volume - which is more important? Well, extent is what we see directly, it's extent that affects the weather and the flow of heat from the ocean. But a decrease in volume is the hidden danger lurking underneath the surface. Volume has been decreasing faster than extent which means that the ice is getting thinner. And as Archimid points out, once the ice is thin enough, normal summer melt will easily destroy it.

So volume is the key to an eventual ice-free summer. Winter freezing will continue to cover the entire Arctic Ocean with ice, and peripheral areas that always melt out may well see more ice as cold air is repeatedly pushed out of the Arctic as has been happening this winter.

But the thickness of the ice will be less, mainly due to warmer winter air over the Arctic and warmer underlying waters. And once summer melt gets going, the thin ice may well disappear with a "poof" over a few weeks given the right weather.

And such a precipitous meltout may alter the Arctic permanently - a sudden vast increase in open ocean, with wind, waves and other turbulence, may well delay refreeze significantly, leading to almost inevitable meltout the following summer.

But that's just my guess - let's wait and see, I don't think we will have to wait for that many years to find out - but then again I may be totally wrong!
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Daniel B. on April 14, 2018, 02:44:18 PM
No, it is not an impossibility for volume to decrease faster than extent.  Rather it is a mathematical certainty, unless thickness somehow remains unchanged.  They both cannot decrease linearly.  Hence, a linear loss in extent (or area) will result in much faster volumetric losses, which taper to zero to coincide with the two dimensional losses.  Volume will not hit zero first, and “pull” extent down with it.  This is not physically possible.  Since melt is mainly two dimensional, extent seems to be the logical metric.  With the exception of MYI, the thickness has much less relevance that you claim.  The second cm is no easier to melt than the first, and so on.  The only exception is when the ice becomes so thin, that the smallest forces break the connection.  But that is just a change of a day or so. 

The sea ice is not an ice cube in water, where melting occurs from all sides, as someone falsely referenced earlier.  It is a long sheet, more or less, which melts from above and below.  Mathematically, either extent losses accelerate to catch up with volume, or volumetric losses must decelerate to match extent.  Physics points to volumetric deceleration.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: binntho on April 14, 2018, 04:04:14 PM
Daniel, you seem to be confusing some things. At the moment, both volume and extent may well be decreasing linearly and at different rates - nothing wrong with that. The thickness of the ice is changing which is saying the same thing in a different way.

Of course, both metrics will have to reach zero at the same time (since you can't have one without the other), so if e.g. volume decreases linearly and at a faster rate than extent, and continues to do so until it reaches zero, then at some point extent will have to decrease faster and thus deviate from any earlier linear trend. Because both have to reach zero at the same time.

Other scenarios are of course possible - volume decrease may flatten out to match extent, or both may change their trends. But one thing is absolutely certain: If one metric reaches zero, the other will by necessity reach zero at the same time.

As you have pointed our repeatedly, melting is primarily from above and below. Once melt starts, 1 meter thick ice will lose volume at the same rate as 2 m thick ice.

Each winter, ice in the Arctic reaches very similar extent, constrained by geography - the Arctic Ocean simply freezes over, with small exceptions. So each melting season starts with similar extent, but since volume is going down, the average thickness is less each year.

Average thickness at maximum has been going down from some 2.6 meters in the 80's to around 1.7 meters the last few years (from eyeballing the graphs - not a scientific number!), a drop of some 35%.  Extent at max has gone down from some 15.5 million km2 in the 80's to just under 14 now, a drop of 10%. So thickness at max is going down some three times faster than extent at max.

Each year the thickness drops some 0.9 meters between max and min, and this has not really changed during the last 40 years. If we take this to mean that a given thickness of ice loses 0.9 meters during melt season, any ice thicker than that should survive the summer, the rest melts out (again the 0.9 figure is from eyeballing the graph - some years, e.g. 2017 lost only 0.7 meters, admittedly from a very low start, while 2012 lost 0.9 meters in a record-breaking year).

So thickness at max (and hence volume at max) seems to be the important variable here - extent is more or less the same each winter, and the rate of loss of thickness is the same as well. So extent at minimum is perhaps driven mostly by thickness at maximum?

It's interesting to note that the decline in extent at minimum is 45% (from 7.2 in the 80's to some 4 million km2 now) which seems to coincide surprisingly well between a 10% fall en extent at max + 35% fall in thickness at max.

But this is only playing around with numbers. My gut feeling is the same as has been expressed by others here - as thickness keeps going down, a rapid melt year could simply make it all more or less vanish. So both metrics at minimum, volume and extent, will deviate sharply downwards form any linear trend, getting damn close to zero (and well below 1million km2 or 1000 km3 in one big leap). But given a linear trend in thickness decline, it may well take another 20 years before thickness is below 1 meter on average at max.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Archimid on April 14, 2018, 06:31:50 PM
Volume will not hit zero first, and “pull” extent down with it.  This is not physically possible.

Why not? That makes no sense. If top and bottom melt makes up most of the melt, then the ice will poof out of existence when it is thin enough, regardless of how large the area is. In fact the physics clearly indicate that if the ice get's too thin, too early, area will be reduced almost instantly.

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Since melt is mainly two dimensional, extent seems to be the logical metric.
 

Melt is not mainly 2 dimensional. Melt is not at all 2 dimensional. Melt is literally 3 dimensional. Area reduction of sea ice is called melt because it is a good indicator of melt from the periphery, but it doesn't represent the physical process of melt at all.

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With the exception of MYI, the thickness has much less relevance that you claim.  The second cm is no easier to melt than the first, and so on.


The thinner the ice the faster it melts.

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Mathematically, either extent losses accelerate to catch up with volume, or volumetric losses must decelerate to match extent.  Physics points to volumetric deceleration.

Mathematically, that is nonsense. In terms of physics, as the ice approaches the north pole it  receives less insolation, making it harder to melt. That leads to slowdown in melt apparent volume lost because most of the easy ice has already melted. This may be confusing you into thinking that volume loses will stop increasing. However there is no physical reason for volume losses to stop increasing. You are using the same fallacy as "no warming since 1998".
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Tor Bejnar on April 14, 2018, 06:35:32 PM
Quote
As you have pointed our repeatedly, melting is primarily from above and below. Once melt starts, 1 meter thick ice will lose volume at the same rate as 2 m thick ice.
I don't think this is exactly true.  I'm no expert, but I recall reading on these threads that sunlight penetrating the ice helps with bottom melt.  I expect this bottom-melt assist increases with decreased ice thickness.  In addition, ice temperature is a significant factor in ice melt, and thinner ice will probably, during the melt season, be warmer on average than thicker ice.  (If melt is occurring at top and bottom, then the coldest ice will be in the middle, and if there is less 'middle' ...)

I appreciate folks posting statistics about Arctic ice thickness/volume/extent/area and drawing projections from them.  I'd much rather see statistics about the CAB.  I do not believe the ice-loss experience (rate of loss) of marginal seas will replicate in the CAB: shorter summer (CAB ice thickens into late May or early June, I understand) and more protected from boundary issues (marginal seas melt edge [waves, warmed water] long predate most CAB melt edges).
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Daniel B. on April 14, 2018, 06:36:16 PM
Binntho, no there is no confusion.  The declines at minimum and maximum cannot be directly comparable precisely due to the geographic constraint you mentioned.  The only areas of potential expansion (contraction) are the Bering Sea and North Atlantic.  Hence, maximum extent has decreased only 10% since 1979.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fneven1.typepad.com%2F.a%2F6a0133f03a1e37970b01b7c8e1e415970b-pi&hash=40f2e6629047f4b7855dad2b65774e07)

The ice maximum appears to have decreased more in the past few years, presumably tied to recent winter warmth.  The minimum has decreased less, possibly tied to summer cooling.  The summer minimum does not appear to be that closely tied to extent or thickness at maximum.  The lowest minimum occurred in 2012, but the previous and subsequent maxima were relatively high.  Similarly, the last two maxima have been the lowest, but the intervening minimum was relatively high (only 8th lowest, and 4th highest since the 2007 record loss). 

I think we agree that one metric cannot reach zero before the other.  If volume were to continue a liner decrease, extent losses must accelerate to keep up, resulting in an ice-free Arctic ~2030.  However, if extent continues to decline linearly, then volume will continue on its current deceleration, resulting in an ice-free Arctic around 2050.  The thickness is an average across the entire Arctic.  In many areas, thickness goes to zero in the summer, resulting in open water.  Other areas are much thicker, retaining ice year-round.  Only that ice which is very thin will experience large melt each year, the rest will not.  This non-uniformity will extend the timeframe until an ice-free Arctic much longer than expressed by others here.  But I admit, that this is just my opinion also, and the Arctic will do whatever it does, regardless of what we say it will.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: oren on April 14, 2018, 07:15:08 PM
There is a lot of micro-level data from mass balance buoys that can shed light on the discussion. Where to find it and how to analyse it?
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Archimid on April 14, 2018, 07:17:53 PM

I appreciate folks posting statistics about Arctic ice thickness/volume/extent/area and drawing projections from them.  I'd much rather see statistics about the CAB.

The other day I rediscovered Wipneus great regional PIOMAS spreadsheets. I've been playing with the CAB for a few days. I've been mulling the two attached graphs but I'm not quite sure what to make of them. Since you ask for them I'll take this opportunity to post them.

The first attachment is CAB Monthly Minimum as a percentage of the Total Monthly Minimum. In 1979 the CAB represented only 65% of the total ice in the Arctic at minimum. From 1979 to 2006  the CAB increased it's representation in the total minimum to 80%. After the big crash of 2007 the CAB now makes up about 95% of the total minimum.

The second attachment is the CAB monthly Maximum as a percentage of Total Maximum. This is a whole different story. Notice how regardless of the tremendous changes that happened in the Arctic over the last 30 years the CAB wants to be around 46% of the total maximum. I'm still trying to understand why this is.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: gerontocrat on April 14, 2018, 07:43:24 PM
"My theory, that belongs to me " (pace Monty Python) is that the linear decline of sea ice volume and the linear decline of sea ice extent will continue for a few years and then the remaining ice will fall apart, on 27th August 2018 WHOOPS!! 2028 (Thankyou Daniel B) at 3.15 pm (GMT).

And the data available is insufficient to say that this is nonsense. And that is the problem.

The more we find out what data we need to know the more we find out that the data is not there or inadequate. Sod's law says that we will get the data the day the ice is gone.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Daniel B. on April 14, 2018, 07:51:20 PM
"My theory, that belongs to me " (pace Monty Python) is that the linear decline of sea ice volume and the linear decline of sea ice extent will continue for a few years and then the remaining ice will fall apart, on 27th August 2018 at 3.15 pm (GMT).

And the data available is insufficient to say that this is nonsense. And that is the problem.

The more we find out what data we need to know the more we find out that the data is not there or inadequate. Sod's law says that we will get the data the day the ice is gone.

Based on the current data, your guess is as good as anyone's.  However, you may have made a typo in your year.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: gerontocrat on April 14, 2018, 07:57:14 PM
"My theory, that belongs to me " (pace Monty Python) is that the linear decline of sea ice volume and the linear decline of sea ice extent will continue for a few years and then the remaining ice will fall apart, on 27th August 2018 at 3.15 pm (GMT).

And the data available is insufficient to say that this is nonsense. And that is the problem.

The more we find out what data we need to know the more we find out that the data is not there or inadequate. Sod's law says that we will get the data the day the ice is gone.


Based on the current data, your guess is as good as anyone's.  However, you may have made a typo in your year.

You are correct, it is a typo - but what if it turns out to be correct?
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Daniel B. on April 14, 2018, 10:10:48 PM
That would be very scary.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Dharma Rupa on April 14, 2018, 11:20:25 PM
The thinner the ice the faster it melts.

I agree with this with one important qualification.  Below some threshold thermal conductivity takes hold and the thinner the ice the faster it melts.  Not sure but I believe it is just under 1 meter.

Once the ice is thin enough that ocean heat and insolation have merged effects the ice will melt faster in Summer and thicken faster in Winter.  (Not sure about that thickening faster in Winter, really.)

Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: binntho on April 15, 2018, 08:26:45 AM
The second attachment is the CAB monthly Maximum as a percentage of Total Maximum. This is a whole different story. Notice how regardless of the tremendous changes that happened in the Arctic over the last 30 years the CAB wants to be around 46% of the total maximum. I'm still trying to understand why this is.
Thanks for the graphs Archimid. But isn't the 46% figure the proportion of CAB area of the Arcic Ocean + some external areas, all of which freeze over almost completely (or to more or less the same extent) each winter?

The Central Arctic Basin is of course the most important, but as far as I am aware, the term Arctic Ocean is used to cover more or less all the open ocean constrained by Siberia, Alaska, Canada and Greenland. Which is significantly bigger than the CAB.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: binntho on April 15, 2018, 08:34:16 AM
The thinner the ice the faster it melts.
I agree with this with one important qualification.  Below some threshold thermal conductivity takes hold and the thinner the ice the faster it melts.  Not sure but I believe it is just under 1 meter.

I agree with you both, my original statement should perhaps have had a caveat. But I had an inkling of this so that's why I stated that 2m thick ice looses volume as fast as 1m thick ice - which I'm sure is not totally correct, but near enough for that discussion.

Thinner ice lets more sunlight through to be absorbed by the underlying ocean, that's pretty clear.

And thinner ice is also presumably warmer  - although I'm not sure why that would be - won't the ice have an internal temperature that is a gradient between the ocean underneath and the air above?
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: binntho on April 15, 2018, 09:57:43 AM
Binntho, no there is no confusion. 
I'm not so sure - I feel confused all the time ...

The summer minimum does not appear to be that closely tied to extent or thickness at maximum. 
I'm sure there is no year-on-year predictive value in looking at winter extent + winter thickness. Last year showed that very decisively. But I did find it intriguing that in the longer run, the decrease in winter extent (10%) + winter thickness (35%) = 45% which is the decrease in summer extent over the same period. But these are percentages of values eyeballed off some graphs, so I won't make any claims to them being particularly correct, valid or significant.

Having said that, I do think that winter thickness (which to all purposes is strongly linked to winter volume) is the most important metric when looking at what might happen if things continue as they are - which they might not, of course!

In my last post I talked as if all the ice melted at the same rate irregardless of thickness (which I think is close enough for our purposes) and location (which is obviously wrong). Ice further south melts faster, ice closer to warm waters melts faster, ice closer to the periphery melts faster. And no doubt there are other factors to consider as well. This is a very complex 4 dimensional system, no single metric is going to tell us what the future might hold.

Only that ice which is very thin will experience large melt each year, the rest will not.  This non-uniformity will extend the timeframe until an ice-free Arctic much longer than expressed by others here.

I'm not sure I follow your logic here. The "non-uniformity" you speak of has been there all the time, why should it change the projected outcome?

Thinner ice obviously has a higher chance of melting out than thicker. When has that not been true? But there is so much more thin ice than thick ice now, that is a change that has been ongoing for some time now. So shouldn't we conclude the time frame will be shortened rather than extended?

But all this talk of linearity and trends assumes a resilient system undergoing slow but steady change. And so far the Arctic has behaved like that, and the increasingly chaotic weather is, at least not yet, the decisive factor that it may become.

Personally I feel that the resilience is being chipped away, eventually to crumble into chaos. Using warlike metaphors fitting for this weekend, the ice is like a fortress that rebuilds its defenses each winter, only to suffer an increasing onslaught each summer. So far the ice has managed to retreat, and pulling its defenses along with it. But there is only so far it can go before the defenses crumble and the foes manage to destroy the rest. And this might happen quite suddenly.

The best defense of the sea ice is it's sheer size - even at minimum it's huge, maintaining a frigid atmosphere above and a cold-water lens below. Even as the ice becomes more fractured and mobile, the icepack maintains it's integrity, i.e. it is basically continuous at minimum, and landfast.

Going back to our original starting point of the landfast ice north of the Canadian Archipelago - this ice has so far mostly moved along the shore but can't very well move away from shore, mainly because of resistance from the ice further out. But as extent drops the whole area may break up and start drifting away from the shore. Two million km2 of ice that is drifting freely in the Arctic for a few weeks will really take a battering, the most serious consequence perhaps being that wave action and dispersion will break up the protecting underlying cold water lens.

We saw an example of how this might happen this winter, when a strong southerly wind managed to push the ice tens or even hundreds of kilometers away from the shore of Greenland, in an area of thick ice that does not melt out during summer (although it is pushed towards the Fram strait to eventual doom).

So my feeling is that irregardless of current linear trends, when we get closer to some threshold, all metrics may well plummet quite fast, as the normal resilience of the Arctic Sea Ice gives in to encroaching chaos. Logically one might then guess that the sea ice might vanish before the first of the linear trends reaches zero - but perhaps not. Perhaps we will see a period where e.g. volume flattens out while extent continues its linear decrease.

But then again, a minimum extent of 4 million km2, which is what we may expect at present, is already very fragile as the extreme melt of 2012 shows, when a combination of clear skies in early summer and very strong storms towards the end of summer caused extent to plummet by 2 million km2 in just over one month.

But I admit, that this is just my opinion also, and the Arctic will do whatever it does, regardless of what we say it will.

So true ...
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Archimid on April 15, 2018, 03:12:58 PM
Thanks for the graphs Archimid. But isn't the 46% figure the proportion of CAB area of the Arcic Ocean + some external areas, all of which freeze over almost completely (or to more or less the same extent) each winter?

I eliminated the Sea of Okhotsk, Hudson Bay and St Lawrence from the maximum and minimum. The justification is that all those area start their freezing from land, not from sea ice. Similarly, their melt has no bearing on any connected sea.

I then performed the same calculations for CAB volume as a percent of total volume. There is no discernible change in volume minimum as expected. Volume maximum now hovers at about 50% of the CAB. Like before it wants to remain at a constant amount of 50%.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: crandles on April 15, 2018, 09:53:53 PM
We have plotted volume against extent. The pattern looks like a straight line that does not intersect the origin. However, a more likely scenario, a curve through the origin can easily look like a straight line when well away from the place where it curves.

Now where was that old discussion? hmm. ???
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: crandles on April 16, 2018, 03:38:46 PM
Found this

Setting a power function to origin of zero, and fitting to scatter plot of CT Area as a function of PIOMAS minimum volume, gives a function:

CTArea = 1.287*PIOMASVol^0.5066.

Essentially a logarthimic curve.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: binntho on April 16, 2018, 04:57:19 PM
Found this

Setting a power function to origin of zero, and fitting to scatter plot of CT Area as a function of PIOMAS minimum volume, gives a function:

CTArea = 1.287*PIOMASVol^0.5066.

Essentially a logarthimic curve.
Might be fun to try! But what is meant by CT Area? Google isn't sure if it is Connecticut or something to to with Cthulhu (All hail!).
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Neven on April 16, 2018, 05:55:45 PM
CT, or Cryosphere Today, was one of the first website on the Internet offering all kinds of graphs, maps and daily data to the public.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: crandles on April 16, 2018, 06:20:34 PM
CT, or Cryosphere Today, was one of the first website on the Internet offering all kinds of graphs, maps and daily data to the public.

Well about arctic sea ice anyway.  ;) :P

also found

(https://forum.arctic-sea-ice.net/index.php?action=dlattach;topic=696.0;attach=7015;image)

Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: binntho on April 16, 2018, 06:56:23 PM
So "thickness" may well be a predictive metric ...
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: binntho on April 16, 2018, 06:57:19 PM
Found this

Setting a power function to origin of zero, and fitting to scatter plot of CT Area as a function of PIOMAS minimum volume, gives a function:

CTArea = 1.287*PIOMASVol^0.5066.

Essentially a logarthimic curve.
Should presumably have been "PIOMAS maximum volume"
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Steven on April 16, 2018, 08:46:00 PM
Found this

Setting a power function to origin of zero, and fitting to scatter plot of CT Area as a function of PIOMAS minimum volume, gives a function:

CTArea = 1.287*PIOMASVol^0.5066.

Here is an update of that formula.  The power function in the graph below is calculated from data for 1979-2017 (so there are 39 data points in total):

(https://i.imgur.com/WPINUr5.png)
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: gerontocrat on April 16, 2018, 10:15:57 PM

Here is an update of that formula.  The power function in the graph below is calculated from data for 1979-2017 (so there are 39 data points in total):

(https://i.imgur.com/WPINUr5.png)

Impressive R2.
It looks like a linear formula would also give a good fit?
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: jdallen on April 16, 2018, 11:21:07 PM

Here is an update of that formula.  The power function in the graph below is calculated from data for 1979-2017 (so there are 39 data points in total):

(https://i.imgur.com/WPINUr5.png)

Impressive R2.
It looks like a linear formula would also give a good fit?
I think the relationship is highly linear until we drop down to very small values of volume at which point thicker ice shed from Greenland's and other glaciers skew the thickness distribution.

Ice thickness has a lot of moderating feedbacks which have tended to keep it around a median value.  Increased heat in the system has slowly but steadily pushed that symmetry point down, such that in the last two decades it has become possible for normal seasonal variation in thickening and loss to threaten a blue Arctic Ocean event.

The recent winter warmings I think are far more crucial to the changes we are seeing, ant that if we look back, we may actually see th first hints of it starting to manifest 20 or more years ago. It is that more than the melt which I think has dropped our median volume.  My rationale here is, year over year insulation doesn't really vary that significantly, and it's influence is greatly dependent on other factors - albedo being most key.

However, increased heat import from the Atlantic and water vapor, along with increased cloudiness have steadily reduced the ability of the ice to recover in winter.

It is quite possible we could have a repeat of 2013 or 2014 with clouds and cool conditions. But even with that, the steady export of warm Atlantic and now Pacific water will reach the basin steadily increasing the total energy available to the system, effectively lowering the pendulum another few notches. 

Eventually, nothing more than natural variation will cause it to scrape bottom.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: kiwichick16 on April 17, 2018, 12:06:33 AM
if the gulf stream continues to weaken ......or shutdown ......won't that significantly reduce warm water transport to the arctic?
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: crandles on April 17, 2018, 12:07:40 AM

Here is an update of that formula.  The power function in the graph below is calculated from data for 1979-2017 (so there are 39 data points in total):

(https://i.imgur.com/WPINUr5.png)

Impressive R2.
It looks like a linear formula would also give a good fit?
I think the relationship is highly linear until we drop down to very small values of volume at which point thicker ice shed from Greenland's and other glaciers skew the thickness distribution.


I think that is unlikely. Consider lots of individual ice floes, a relationship where the bigger the area, the higher the thickness. Some melting occurs, and some small ones disappear and all become less in area and less in thickness. So after a bit of melting, all the pieces are smaller but are essentially similar in their ratio of area to volume.

Try such a exercise with linear relationship of area to volume and you run into problems: The ice suddenly goes poof as zero volume is approached, but why, shouldn't the smaller pieces disappear before the bigger pieces?
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: crandles on April 17, 2018, 12:10:43 AM
if the gulf stream continues to weaken ......or shutdown ......won't that significantly reduce warm water transport to the arctic?

Doesn't 'continue to weaken' imply that it already is slowing down and if it continues to weaken at the same pace, doesn't that mean this is already in the historical data which show sea ice declining?
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: jdallen on April 17, 2018, 12:55:13 AM
I think the relationship is highly linear until we drop down to very small values of volume at which point thicker ice shed from Greenland's and other glaciers skew the thickness distribution.


I think that is unlikely. Consider lots of individual ice floes, a relationship where the bigger the area, the higher the thickness. Some melting occurs, and some small ones disappear and all become less in area and less in thickness. So after a bit of melting, all the pieces are smaller but are essentially similar in their ratio of area to volume.

Try such a exercise with linear relationship of area to volume and you run into problems: The ice suddenly goes poof as zero volume is approached, but why, shouldn't the smaller pieces disappear before the bigger pieces?
I think our views are more similar than different.  I think to get "poofs" we will be at those low volume numbers to begin with - we will have to be.  I'm thinking sub 1000KM3 is where the relationship will start to break down.

Until then, sudden area losses will still I think have corresponding linear volume losses.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: kiwichick16 on April 17, 2018, 12:57:33 AM
@ crandles  # 124

https://cleantechnica.com/2018/04/15/its-the-gulf-stream-stupid-climate-scientists-warn-tipping-point-is-near/
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: jdallen on April 17, 2018, 02:28:32 AM
@ crandles  # 124

https://cleantechnica.com/2018/04/15/its-the-gulf-stream-stupid-climate-scientists-warn-tipping-point-is-near/
Sorry, not impressed. Fluffy article high in histronics and low on substance, which misinterpretes what is happening.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: kiwichick16 on April 17, 2018, 04:37:15 AM
"If we can keep temperature increase to well below 2 degrees....."

https://www.theguardian.com/environment/2018/apr/13/avoid-at-all-costs-gulf-streams-record-weakening-prompts-warnings-global-warming
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: binntho on April 17, 2018, 06:26:21 AM
I've seen a couple of people mentioning glacier ice from Greenland and other places as being a factor in Arctic Sea Ice. In my opinion this is extremely unlikely. The glaciers facing the Arctic Ocean can't be calving more than a few square kilometers each year, and this ice gets grabbed by currents and pushed out the Fram strait.

The huge icebergs typical of Greenland glacier calving float southwards, but has anybody ever seen any significant number of them in the Arctic? I don't think so.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Juan C. García on April 17, 2018, 09:16:55 AM
I've seen a couple of people mentioning glacier ice from Greenland and other places as being a factor in Arctic Sea Ice. In my opinion this is extremely unlikely. The glaciers facing the Arctic Ocean can't be calving more than a few square kilometers each year, and this ice gets grabbed by currents and pushed out the Fram strait.

The huge icebergs typical of Greenland glacier calving float southwards, but has anybody ever seen any significant number of them in the Arctic? I don't think so.

One of those people is me and I recognize that I don’t have a formal education in any science related to this topic. I had following the ASI for a decade and Neven’s Forum from the beginning (2013).

Making a summary: After 2012, some of us were waiting to have a collapse of the ASI in the following years. 2013 and 2014 were good years for increasing the ice, but 2015-2017 were the contrary. In 2016, the ASI extent was very low on the first semester, but at the end, nothing happened. Similarly, on 2017 the ASI volume was terrible, but at the end, nothing happened, for the second time. So, I started to think that there is a negative feedback that we were not contemplating. And I believe that this negative feedback is the ice bottom melting on Greenland.
As I said before, I could be wrong. I just believe that I am not wrong, but with not formal studies in this subject.

I made a topic covering this subject and answering your question, I believe the following answer:

Juan, check the currents around Greenland, they are all flowing southward, so Greenland melt is surely affecting the Atlantic ocean but I doubt it has much to do with low ASI melt in the Arctic.

In fact, all the Greenland currents are flowing southward, but then they clash with the Atlantic meridional overturning circulation (AMOC), maybe slowing the AMOC and turning northward.

The topic covering this ideas is:
"Ice melting (Antarctica, Greenland, etc.) as a short term ASI negative feedback"
https://forum.arctic-sea-ice.net/index.php/topic,2171.0.html (https://forum.arctic-sea-ice.net/index.php/topic,2171.0.html)
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: binntho on April 17, 2018, 09:44:31 AM
I've seen a couple of people mentioning glacier ice from Greenland and other places as being a factor in Arctic Sea Ice. In my opinion this is extremely unlikely. The glaciers facing the Arctic Ocean can't be calving more than a few square kilometers each year, and this ice gets grabbed by currents and pushed out the Fram strait.

The huge icebergs typical of Greenland glacier calving float southwards, but has anybody ever seen any significant number of them in the Arctic? I don't think so.

One of those persons is me and I recognize that I don’t have a formal education in any science related to this topic. I had following the ASI for a decade and Neven’s Forum from the beginning (2013).
You make a valid point, and I'm sure your scientific grounding is no worse than mine. But my point was on the actual floes themselves (the icebergs) constituting a significant proportion of Arctic Sea Ice - which I seriously doubt.

But it's true, we do tend to underestimate the resilience of the ASI - looking at the various metrics we get the feeling every year that it's all about to collapse, but then it doesn't. My feeling is that the biggest source of this resilience is the extent itself - the minimum 4 million or so km2 is still a huge area and it isn't reached until the end of the melting season, and for a very short time.

Weather is probably by far the biggest contributor to noise in the various metrics, so a year like 2012 (where an unlikely combination of weather effects caused a major melt out) becomes an outlier, but in the longer run the systems underlying the various metrics just chug along on their gentle downward slope.

Until perhaps one year, when the average minimum extent is considerably lower than now (between 2 and 3 million km2?) with another usual combination of weather events, and the whole thing might just collapse, with the contiguous ice breaking up and floating away from the Canadian Arctic Archipelago and melting rapidly in a totally new Arctic Ocean.

If my feeling is correct, and the resilience is somehow proportional to, or rather, dependent upon, extent staying above a certain threshold, then all bets are off and our metrics will all nosedive, and any trend lines become obsolete.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: oren on April 17, 2018, 11:09:26 AM
Making a summary: After 2012, some of us were waiting to have a collapse of the ASI in the following years. 2013 and 2014 were good years for increasing the ice, but 2015-2017 were the contrary. In 2016, the ASI extent was very low on the first semester, but at the end, nothing happened. Similarly, on 2017 the ASI volume was terrible, but at the end, nothing happened, for the second time.
Just to defend 2016's honor, although min extent wasn't that impressive (2nd but near 2011 and 2007) due to high dispersal, in terms of area it was quite far from all other years, and not very far from 2012. And it too had a GAC. 2016 had a terrible winter and spring, but then June/July were lucky, otherwise I believe the 2012 record would have been broken.

(https://sites.google.com/site/arctischepinguin/home/amsr2/grf/basin-area-multiprod.png)
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Steven on April 17, 2018, 11:25:43 AM
Impressive R2.
It looks like a linear formula would also give a good fit?

A linear fit would give basically the same R2 as the power function (about 0.92).  But the (extrapolated) linear fit doesn't pass through the origin (x=0, y=0).  In contract, the power function passes through the origin, expressing the fact that volume and area can only be zero simultaneously.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: gerontocrat on April 17, 2018, 12:17:12 PM
Impressive R2.
It looks like a linear formula would also give a good fit?

A linear fit would give basically the same R2 as the power function (about 0.92).  But the (extrapolated) linear fit doesn't pass through the origin (x=0, y=0).  In contract, the power function passes through the origin, expressing the fact that volume and area can only be zero simultaneously.

But is using the power function a better indication of what will happen? My speculation is, and always has been, that volume and extent/area will decline in a more or less orderly linear manner until volume/thickness becomes low enough for a 2012-type summer to cause a disorderly collapse of much of the remaining ice. i.e. both functions only work to a lower limit of n km3, where n is unknown but less than 4,000 and greater than 1,000.

What happens the following winter / summer? Not a clue. But this poll is about a one day low of < 1,000 km3. I am sticking with 2028.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Archimid on April 17, 2018, 01:05:50 PM
Quote
A linear fit would give basically the same R2 as the power function (about 0.92).  But the (extrapolated) linear fit doesn't pass through the origin (x=0, y=0).  In contract, the power function passes through the origin, expressing the fact that volume and area can only be zero simultaneously.

This implies that ice thickness will increase as the ice reaches 0? I don't see why. The CAB already makes up 95% of the volume at minimum. When volume reaches 0 extent will definitely be 0. However when volume is at 0+epsilon area will be relatively large. The only way to avoid that is by thickening the ice as extent disappears.  That makes no sense.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: crandles on April 17, 2018, 01:10:58 PM
Wonder if anyone wants to update this graph

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Ffarm9.staticflickr.com%2F8413%2F8750936961_a9c3f19ccb_z.jpg&hash=b3ae318fa7902db560033685485b023a)

Is there still a sweet spot somewhere that neither curves up nor down?

Note even if there is, there must be some good chance that melt from [31 May or whenever] will start curving one way or the other and we just haven't seen it yet.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: gerontocrat on April 17, 2018, 02:46:45 PM
I've seen a couple of people mentioning glacier ice from Greenland and other places as being a factor in Arctic Sea Ice. In my opinion this is extremely unlikely. The glaciers facing the Arctic Ocean can't be calving more than a few square kilometers each year, and this ice gets grabbed by currents and pushed out the Fram strait.

The huge icebergs typical of Greenland glacier calving float southwards, but has anybody ever seen any significant number of them in the Arctic? I don't think so.

One of those persons is me and I recognize that I don’t have a formal education in any science related to this topic. I had following the ASI for a decade and Neven’s Forum from the beginning (2013).
You make a valid point, and I'm sure your scientific grounding is no worse than mine. But my point was on the actual floes themselves (the icebergs) constituting a significant proportion of Arctic Sea Ice - which I seriously doubt.


GREENLAND MELT - EFFECT ON ARCTIC SEA ICE
I found this :-
https://link.springer.com/content/pdf/10.1007%2Fs40641-017-0070-1.pdf
Glacier Calving in Greenland

Extract follows:-
Quote
Contribution of Calving Glaciers to Greenland’s Mass Budget

Dynamic ice loss is a major factor in the mass balance of the Greenland Ice Sheet. In 2000, the total discharge from all of Greenland’s tidewater outlet glaciers was 462 ± 6 Gt [1].

Fifteen glaciers make up 50% of the total, and only five (Jakobshavns Isbrae, Kangerdlugssuaq, Koge Bugt, Ikertivaq South, and Helheim) account for > 30%. Total discharge rate increased by 18% to 546 ± 11 Gt/year between 2000 and 2012, but inter-annual variability is high, particularly in SE Greenland . Dynamic ice losses were roughly equal to surface melt and runoff in the period 2000–2008, but the share was somewhat less during the exceptionally high-surface melt years of 2009–2012.

Taken together, dynamic ice losses and runoff of surface meltwater exceed snow accumulation over the Greenland Ice Sheet, so the overall mass balance of the ice sheet is negative.
Analysis of surface elevation and mass changes from CryoSat-2 and GRACE satellite data indicates that the Greenland Ice Sheet had a net annual mass balance of − 269 ± 51 Gt/year from Jan 2011–Dec 2014.

Dynamic ice loss from marine outlet glaciers makes a large contribution to this deficit, particularly from Kangerdlugssuaq in the east, Jakobshavns Isbrae, Upernavik Isstrøm and Steenstrup
Glacier on the west coast, and Zachariæ Isstrøm in the north-east.

From this my best guess is:-
- As Greenland is drier and colder to the North and East, and much wetter and warmer to the South and West, surface melt (May to August) must be greatest into the Greenland Sea,
- most glaciers are melting into the Nares Strait, Baffin Bay and the Greenland Sea.

If Greenland mass balance loss continues to increase, the direct effect on Arctic ice must be minimal, but the effect on the AMOC could be significant - all that warmer, less dense freshwater.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Steven on April 17, 2018, 03:16:37 PM
This implies that ice thickness will increase as the ice reaches 0?

No, it doesn't.  Quite the contrary.  Note that the exponent in the power function is 0.5136, which is very close to 0.5.  So it's basically a square root function, i.e. area behaves like the square root of volume (multiplied by some unimportant constant).  This implies that volume goes to zero much faster than area.  For example, if area is halved, then only one fourth of the original volume remains.  So, based on that power function extrapolation, the average ice thickness would continue to decrease as the ice goes to zero.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: gerontocrat on April 17, 2018, 03:21:46 PM
And here is a map showing where Greenland is losing mass from this article :- http://www.pnas.org/content/109/49/19934
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: binntho on April 17, 2018, 03:42:27 PM
- As Greenland is drier and colder to the North and East, and much wetter and warmer to the South and West, surface melt (May to August) must be greatest into the Greenland Sea,
- most glaciers are melting into the Nares Strait, Baffin Bay and the Greenland Sea.

If Greenland mass balance loss continues to increase, the direct effect on Arctic ice must be minimal, but the effect on the AMOC could be significant - all that warmer, less dense freshwater.

I think you are quite right. Annual melt is in the region of 500 km3 and approximately half of which is due to calving, according to the extract. The vast majority of those calvings happen along the east and west coasts of Greenland and do not enter the Arctic Basin. But even those few calving that happen along the north coast eventually get swept away towards the Fram or Nares Straits.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Archimid on April 17, 2018, 04:53:11 PM
This implies that ice thickness will increase as the ice reaches 0?

No, it doesn't.  Quite the contrary.

I see it now. Thanks.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: DavidR on April 18, 2018, 10:59:21 AM
Wonder if anyone wants to update this graph
<snip>
Is there still a sweet spot somewhere that neither curves up nor down?

Note even if there is, there must be some good chance that melt from [31 May or whenever] will start curving one way or the other and we just haven't seen it yet.

This is not quite up to date but you get  the general impression. All trendlines are simply polynomials extrapolated out to 2025.

I have added the Max and total melt numbers to clarify the picture further. 
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: DavidR on April 18, 2018, 11:22:13 AM
An alternative view is to look at the gains and losses each year. This graph shows that although some years have greater gains than losses, on average the losses are larger than the gains by about 300 km^2 per year. This gap appears to be accelerating slightly probably as a consequence of Arctic waters warming up.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: crandles on April 18, 2018, 12:18:59 PM
Thank you very much.  :D

(31 May volume - 15) looks like it still works pretty well.

Maybe marginally curving up, but at some point I would expect it to curve downwards like the 30 June to Min curve.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: DavidR on April 19, 2018, 11:00:24 AM
Thank you very much.  :D

(31 May volume - 15) looks like it still works pretty well.

Maybe marginally curving up, but at some point I would expect it to curve downwards like the 30 June to Min curve.
The linear trend is an increase of  +15 km^3 (edited) per year and the polynomial trend is currently increasing. However if current trends hold we are only a few years away  from it being impossible to lose more than 15K after 31 May. The figures are only relevant until Sept volume reaches 0 which I and many others are suggesting will occur in about 5 years.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: litesong on April 19, 2018, 04:52:41 PM
I have been using the minimum volume, but I suspect that is not much difference from the September average.  In either case, it comes down to whether you feel that the higher volume loss in the first decade of this century or the slower volume loss since will predominate. 

(https://upload.wikimedia.org/wikipedia/commons/5/51/Plot_arctic_sea_ice_volume.svg)
Like you, I use Volume loss, thinking Volume is a better measure of conditions that are reducing Arctic sea ice. Recent studies on Antarctic sea ice with underwater drones indicate Southern Ocean warming currents are cutting large undersea "upside down canyons" in bottoms of Ice Shelves. Warming Arctic Ocean currents are helping cause Arctic Volume losses also. 
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: crandles on April 20, 2018, 04:06:27 PM
Thank you very much.  :D

(31 May volume - 15) looks like it still works pretty well.

Maybe marginally curving up, but at some point I would expect it to curve downwards like the 30 June to Min curve.
The linear trend is an increase of  +15 km^3 (edited) per year and the polynomial trend is currently increasing. However if current trends hold we are only a few years away  from it being impossible to lose more than 15K after 31 May. The figures are only relevant until Sept volume reaches 0 which I and many others are suggesting will occur in about 5 years.

Here are polynomial and 3 parameter gompertz fit to 31 May PIOMAS volume. These trendlines are going well below reality for last 5 years. Data doesn't justify 4 parameter gompertz (inflection point not til 2024). Maybe some other curve function is needed. Maybe the last 5 years values are oddly all above trend.

I think I should concede that the trend in May 31 volume isn't as leveling out as much as I expected and it may not be all that long before May 31 Volume reaches 15,000 km^3. (2020 - 2025 being plausible)

Even 31 July to minimum doesn't seem to be curving downwards much if at all. Obviously it has to curve downwards when there isn't that much left but it seems entirely possible that it could curve downwards before then but there is no evidence for that from what I have looked at.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: gerontocrat on April 20, 2018, 05:41:08 PM
"Linear Regression rule, OK?"
Sorry, non-scientific interjection
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Stephan on May 08, 2018, 10:02:58 PM
I have listed all extent and volume data monthly from 1979 to now. As extent and volume come from different sources, the calculated thickness may not be realistic or true. But, anyway, I have treated the data both with linear and logarithmic trends and calculated, when the September average will reach zero. It makes a huge difference whether you use extent, volume, or thickness. The kind of fit (linear or logarithmic) is much less important, nevertheless the log fit always gives an earlier year, when zero is reached. Here are the results:

Extent: zero (lin) 2076 --- zero (log) 2066
Volume: zero (lin) 2032 --- zero (log) 2025
Thickness: zero (lin) 2050 --- zero (log) 2045

From these data it is clear that the volume is the big issue when it comes to the first blue ocean event. Of course, the behaviour of an overall very small ice thickness in the CAB in some years, which probably leads to a faster melt-out if weather conditions are the right ones, cannot be included in the historical data.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: magnamentis on May 09, 2018, 12:03:28 AM
i vote for a sudden death event way before 2040, hence the example with reaching zero in the second half of the 2020ies is what i think is closest to how it will be. nevertheless something telles me that we're in for some kind of ugly surprise soon, not only is only little MYI left, that what's left is about 40% of the volume and that's a lot less energy needed to make that disappear entirely more sooner than later.

i know this is not scientific but science did not believe many later proven facts in the past. new things come from imagination and logical thinking not from established science/knowledge
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: jdallen on May 09, 2018, 12:11:37 AM
My impression is similar.  I figure it in probabilities... 1 in 10 up to about 2025, 1 in 6 through 2035, and 1 in 4 after that.

After it happens, I shift to thinking of the probability of a refreeze under 1 million KM2. That will take a few decades I think.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: DavidR on May 09, 2018, 04:11:28 AM
Found this

Setting a power function to origin of zero, and fitting to scatter plot of CT Area as a function of PIOMAS minimum volume, gives a function:

CTArea = 1.287*PIOMASVol^0.5066.

Here is an update of that formula.  The power function in the graph below is calculated from data for 1979-2017 (so there are 39 data points in total):

(https://i.imgur.com/WPINUr5.png)
Using the updated formula I've done some predictions of what  might happen. I have calculated volume based on the linear and polynomial trends since 1979. 

Starting with a 1988 volume of 14.2 which is close to  the figure of both trend lines, I have calculated the volume for subsequent years using the annual declines predicted by the trend lines.

I have then calculated the predicted area based on the formula provided. What is interesting is how quickly area drops away as volume approaches zero.

My 'theory which belongs to me' is that  the polynomial trend is accurate. This is because the Arctic is being warmed by a circular wave of heat approaching from all sides because of AGW. As that energy nears the centre it will spike very quickly and wipe out the remaining ice.

Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: miki on May 09, 2018, 06:52:48 AM
Feeling is that it will happen around 2020-2022.

I could not find the way to vote, though... am I missing it?
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: John_The_Elder on May 09, 2018, 04:35:03 PM
SUBMIT VOTE button visible in Chrome.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Dharma Rupa on May 09, 2018, 11:36:47 PM
SUBMIT VOTE button visible in Chrome.

I suspect he doesn't realize that the poll is the first message in the thread.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: miki on May 10, 2018, 03:06:49 AM
SUBMIT VOTE button visible in Chrome.

I suspect he doesn't realize that the poll is the first message in the thread.

Thanks, Dharma, John!

I had already voted, silly me. So no button or chance to change.
But I'll stick with my early vote: 2019-2021
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Neven on May 10, 2018, 01:24:54 PM
I've edited the poll, so people can change their vote if they want.

Crandles, you opened the poll, let me know if you don't want that.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: kaixo on May 10, 2018, 08:28:34 PM
Hi all there,

For many years now i have been following the discussions on this forum. Very informative and to be honest also quite exciting to see what's happening up there in the north. I thought it fun to join the 1000 km3 vote, so here i go.
My prediction is 2019- 2021. This is primarily based on one of the volume grapghs by Jim Petitts. Unfortunately I don't know how to insert it here, hopefully it works with the attachment. The graph can be found at the ASIG site or at http://iwantsomeproof.com/extimg/siv_annual_max_loss_and_ice_remaining.png
Especially the strong and decade long declining trend in max volume, together with the moderate rise of seasonal melt makes the 1000km3 threshold within reach in the next few years i would say. Next best bet would certainly be 2022-2024




Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: oren on May 11, 2018, 03:12:16 AM
Welcome, kaixo! The first post is the hardest...
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Daniel B. on May 12, 2018, 09:01:47 PM
Hi all there,

For many years now i have been following the discussions on this forum. Very informative and to be honest also quite exciting to see what's happening up there in the north. I thought it fun to join the 1000 km3 vote, so here i go.
My prediction is 2019- 2021. This is primarily based on one of the volume grapghs by Jim Petitts. Unfortunately I don't know how to insert it here, hopefully it works with the attachment. The graph can be found at the ASIG site or at http://iwantsomeproof.com/extimg/siv_annual_max_loss_and_ice_remaining.png
Especially the strong and decade long declining trend in max volume, together with the moderate rise of seasonal melt makes the 1000km3 threshold within reach in the next few years i would say. Next best bet would certainly be 2022-2024

Using that graph and a simple linear fit, volume would break through the threshold in 2029.  Using a third-order polynomic would extend the time out further.  Based on the changes since 2007, that would be my bet.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: kaixo on May 12, 2018, 09:08:55 PM
Welcome, kaixo! The first post is the hardest...
Hi Oren, thank you. After so many years of just 'consuming' interesting thoughts and viewpoints, lets see if i can contribute something usefull as well now and then.  :)
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: kaixo on May 12, 2018, 09:36:41 PM
Hi all there,

For many years now i have been following the discussions on this forum. Very informative and to be honest also quite exciting to see what's happening up there in the north. I thought it fun to join the 1000 km3 vote, so here i go.
My prediction is 2019- 2021. This is primarily based on one of the volume grapghs by Jim Petitts. Unfortunately I don't know how to insert it here, hopefully it works with the attachment. The graph can be found at the ASIG site or at http://iwantsomeproof.com/extimg/siv_annual_max_loss_and_ice_remaining.png
Especially the strong and decade long declining trend in max volume, together with the moderate rise of seasonal melt makes the 1000km3 threshold within reach in the next few years i would say. Next best bet would certainly be 2022-2024

Using that graph and a simple linear fit, volume would break through the threshold in 2029.  Using a third-order polynomic would extend the time out further.  Based on the changes since 2007, that would be my bet.
Dan B, of course you are correct that by chosing another fit the year of breaking the 1000 km3 threshold changes considerably. However, a linear fit is not realistic i think. If you look at this graph below by Jim Petitt, you see that the average minimum volume per decade is decreasing rapidly.
So yes, maybe a third-order polynomic fit is the right thing, but only if strong negative feedbacks come into play. So far, the numbers don't suggest to me that this is the case. Rather the opposite. For now a second or even fourth polynomal fit seems best.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Dharma Rupa on May 12, 2018, 09:53:55 PM
So yes, maybe a third-order polynomic fit is the right thing, but only if strong negative feedbacks come into play. So far, the numbers don't suggest to me that this is the case. Rather the opposite. For now a second or even fourth polynomal fit seems best.

Interesting proposition, but can you explain to me how any sort of poly fit would make sense in a fitness surface with so many catastrophe folds laying about?  For starters, it used to be that the Arctic was completely ice covered all year, and now you have blue water at the continental edges every summer.  The entire climate must have changed suddenly with the first year that happened.  There are many more catastrophes waiting to happen...although I suspect that the falling of the Atlantic into the Arctic basin happened at the end of 2015 -- and that was the big one.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Alexander555 on May 12, 2018, 10:22:40 PM
This morning i was thinking about these negative feedbacks. And maybe the numbers are telling that's the case. If you look at that volume pic, since 2010 we stayed somewhere at that low volume. And the only year we had a significant winter temperature below average was 2013. And you had a little higher volume in 2014. But all the years the temperature in spring was at or below average for some time. And this spring we have'nt been below the average  so far. If the winter and spring become warmer in this little timespan. Than probably negative feedbacks are in play.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: jai mitchell on May 12, 2018, 10:52:17 PM
30% of sea ice volume loss between 1985 and 2012 has been preserved by artificial cooling provided by SO2 (air pollution).  The entire balance of remaining September sea ice volume is dependent on how much of this air pollution is emitted in the Northern Hemisphere.

https://forum.arctic-sea-ice.net/index.php/topic,1384.msg140828.html#msg140828
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: kaixo on May 12, 2018, 11:24:24 PM
Interesting proposition, but can you explain to me how any sort of poly fit would make sense in a fitness surface with so many catastrophe folds laying about?  For starters, it used to be that the Arctic was completely ice covered all year, and now you have blue water at the continental edges every summer.  The entire climate must have changed suddenly with the first year that happened.  There are many more catastrophes waiting to happen...although I suspect that the falling of the Atlantic into the Arctic basin happened at the end of 2015 -- and that was the big one.
[/quote]

Poly fits of course don't describe any physical process. They just show possible trends in the yearly final results, which are the outcome of many different (feedback) processes.  And there are many unknowns at play.
What i find interesting  is that in recent years the shape of the graph is slowly morphing, showing more and more a dent in september/october where the montly numbers used to be in a smooth, straight line in the 80's, 90's and even 00's.
This might suggest that some sort of regime change is taking place and certain effects are becoming more dominant than they used to be. Or new processes are getting started. Maybe that's because of the appearance of blue water at the continental edges as you mentioned.
Anyway, for now it seems to imply that volume in september could decline even more rapidly in years to come.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Dharma Rupa on May 13, 2018, 03:18:29 AM
Poly fits of course don't describe any physical process. They just show possible trends in the yearly final results, which are the outcome of many different (feedback) processes.  And there are many unknowns at play.
What i find interesting  is that in recent years the shape of the graph is slowly morphing, showing more and more a dent in september/october where the montly numbers used to be in a smooth, straight line in the 80's, 90's and even 00's.
I don't quite follow.  Please clarify.
This might suggest that some sort of regime change is taking place and certain effects are becoming more dominant than they used to be. Or new processes are getting started. Maybe that's because of the appearance of blue water at the continental edges as you mentioned.
Anyway, for now it seems to imply that volume in september could decline even more rapidly in years to come.
I'd be inclined to see it as a cascade of regime changes, and I am expecting at some point the ice will simply all melt without regard to time of year, but I haven't found a good hook for predicting when.  I always predict "this year" on the theory that I will eventually be right.

Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: jai mitchell on May 13, 2018, 06:31:08 AM
if China passes a clean air act similar to those enacted in the U.S. and Europe in the late 1970's we will see effective zero sea ice within 2 years.

https://www.carbonbrief.org/cuts-in-europes-air-pollution-have-boosted-arctic-warming

Cuts in Europe’s air pollution have boosted Arctic warming by 0.5C


Quote
Now a new study, published in Nature Geoscience, suggests that a reduction in air pollution over Europe has also been contributing to rapid Arctic warming in recent decades.

The study looks specifically at sulphur dioxide, which is emitted from power stations, vehicle exhausts and industrial processes, such as extracting metals from ore.

Sulphur dioxide reacts in the atmosphere to form tiny particles called sulphate aerosols. These have a cooling effect by scattering sunlight and stimulating clouds to form, preventing sunlight reaching the Earth’s surface.

Sulphur emissions in Europe peaked in the 1970s and have declined to around a quarter of that level as governments have tackled air pollution. This decline has meant a reduction of the aerosol cooling effect, the researchers say, magnifying Arctic warming by 0.5C since 1980.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: kaixo on May 13, 2018, 02:43:51 PM
Poly fits of course don't describe any physical process. They just show possible trends in the yearly final results, which are the outcome of many different (feedback) processes.  And there are many unknowns at play.
What i find interesting  is that in recent years the shape of the graph is slowly morphing, showing more and more a dent in september/october where the montly numbers used to be in a smooth, straight line in the 80's, 90's and even 00's.
I don't quite follow.  Please clarify.
This might suggest that some sort of regime change is taking place and certain effects are becoming more dominant than they used to be. Or new processes are getting started. Maybe that's because of the appearance of blue water at the continental edges as you mentioned.
Anyway, for now it seems to imply that volume in september could decline even more rapidly in years to come.

I'd be inclined to see it as a cascade of regime changes, and I am expecting at some point the ice will simply all melt without regard to time of year, but I haven't found a good hook for predicting when.  I always predict "this year" on the theory that I will eventually be right.

In the arctic death spiral graph below i marked the recent 'dented' trend line, compared to the decades before. In the good old days volume declined over the summer months at a certain pace and from october on it increased again. All very smooth. Although volume losses have been accelerating over the years for all months, in august and september this acceleration is even accelerating. To me this suggests that new dynamics are coming in to play. 

I agree with you that one year it will suddenly all melt out and this could be in 2018 as well. I only voted for 2019-2021 to enhance my chances a bit. ;)
I am very curious what would happen after that. With no ice in the arctic basin, would ice growth have to start from the coasts or the few reigons where there is still some ice left? But i am getting of topic here i guess.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Stephan on May 13, 2018, 10:23:45 PM
Interesting proposition, but can you explain to me how any sort of poly fit would make sense in a fitness surface with so many catastrophe folds laying about?  For starters, it used to be that the Arctic was completely ice covered all year, and now you have blue water at the continental edges every summer.  The entire climate must have changed suddenly with the first year that happened.  There are many more catastrophes waiting to happen...although I suspect that the falling of the Atlantic into the Arctic basin happened at the end of 2015 -- and that was the big one.
Poly fits of course don't describe any physical process. They just show possible trends in the yearly final results, which are the outcome of many different (feedback) processes.  And there are many unknowns at play.
What i find interesting  is that in recent years the shape of the graph is slowly morphing, showing more and more a dent in september/october where the montly numbers used to be in a smooth, straight line in the 80's, 90's and even 00's.
This might suggest that some sort of regime change is taking place and certain effects are becoming more dominant than they used to be. Or new processes are getting started. Maybe that's because of the appearance of blue water at the continental edges as you mentioned.
Anyway, for now it seems to imply that volume in september could decline even more rapidly in years to come.

When I treat all the monthly data from 1979 to present I also calculate the average extent, volume and thickness for every month of the year. Then I subtract the actual values from the "expected" (=averaged) values. The difference is then plotted from 1979 to present. From almost exactly 2007 on the negative deviation is very obvious in the months from August to December, whereas the months February to May show very little deviations from the expected values. It seems a kind of "delay" kicking in, a not very progressive start of melting in spring and a delayed re-freezing in late autumn, often combined with very high temp. anomalies (e.g. Oct-Dec 2016 with very high anomalies).

Explanation to the graph:
The thick blue curve is the sum of deviations (extent, volume and thickness) from the long-term average.
The thin blue line is the linear trend
The red line gives mean values for every five years of the deviations.
The y-axis is the normalized sum of the deviation.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Dharma Rupa on May 14, 2018, 12:07:24 AM
From almost exactly 2007 on the negative deviation is very obvious in the months from August to December, whereas the months February to May show very little deviations from the expected values. It seems a kind of "delay" kicking in, a not very progressive start of melting in spring and a delayed re-freezing in late autumn, often combined with very high temp. anomalies (e.g. Oct-Dec 2016 with very high anomalies).

I'm a bit unclear on your exact formulation, but I will agree that we have Warmer Winters but either unchanged or colder Summers -- or rather, that the climate in the Arctic is changing from Desert to Maritime.

I'm always expecting "this year" to be the end of the transition, but I won't know until it has actually already happened when it will do it.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Sebastian Jones on May 14, 2018, 07:15:55 AM
So, I know that this is pure blue sky speculation, but when I look at the death spiral graph upthread, it looks to me like a bubble about to burst....But also a bit like a blastocyst about to form a gut. Either way we are definitely seeing something new.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: uniquorn on May 14, 2018, 05:19:06 PM
snippage
When I treat all the monthly data from 1979 to present I also calculate the average extent, volume and thickness for every month of the year. Then I subtract the actual values from the "expected" (=averaged) values. The difference is then plotted from 1979 to present.
more snippage
Interesting chart. Why is it so flat in the middle? Is it something to do with the way you calculate your monthly average?
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Richard Rathbone on May 14, 2018, 06:30:55 PM
snippage
When I treat all the monthly data from 1979 to present I also calculate the average extent, volume and thickness for every month of the year. Then I subtract the actual values from the "expected" (=averaged) values. The difference is then plotted from 1979 to present.
more snippage
Interesting chart. Why is it so flat in the middle? Is it something to do with the way you calculate your monthly average?

It looks spiky upwards early then flat, then spiky downwards. Perhaps another piece of evidence for a 70 year cycle affecting the seasonal melt pattern.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Stephan on May 14, 2018, 08:48:16 PM
snippage
When I treat all the monthly data from 1979 to present I also calculate the average extent, volume and thickness for every month of the year. Then I subtract the actual values from the "expected" (=averaged) values. The difference is then plotted from 1979 to present.
more snippage
Interesting chart. Why is it so flat in the middle? Is it something to do with the way you calculate your monthly average?

The way this plot looks may come from the way I treated the data. I calculated the mean values of extent, volume and thickness (the latter one by division of volume and extent) over the whole period of now 39 years. Assuming the times around 2000-2005 represent quite the average of all these years the difference between the anomalies and the individual values are quite small. In the early years thickness and volume are much higher than average in summer/autumn - therefore the curve gives the positive bumps. In the last ten years the opposite is the case. As thickness plays a major role (both through volume and the thickness itself) the rapid decline of it, especially in late summer and autumn leads to the negative bumps in the curve. I think this shows the change that has reached arctic ice from 2007 on. Interestingly the shape of the curve has not changed since 2010, therefore I do not see an actual change of the behaviour of the arctic ice and - this is of course pure speculation - no reason for an abrupt decline in sea ice in the next years.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: Ned W on May 16, 2018, 01:42:36 AM
... artificial cooling provided by SO2 (air pollution)...
It's a bit more complicated than that.  Sulfate emissions reduce insolation and preserve the ice, but black carbon deposition reduces the albedo of the ice and has the opposite effect.  So to some extent the two forms of air pollution are working at cross purposes in the Arctic.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: jai mitchell on May 16, 2018, 07:46:56 AM
the effect of SO2 is 2-4C so I just say 3C of additional warming locked in.

the effect of black carbon is much much less than that.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: VaughnAn on May 16, 2018, 08:56:33 AM
I asked the following question on April 12 the April 2018 blog:

"How much do sulfates and aerosols affect temperature? I am thinking that incoming sunlight is reflected back into space by these substances before it reaches low altitudes thereby preventing some warming. Just how much effect they have is what I am not sure about."

A response from Al Roger on April 14:
"And mentioned up-thread, the SO2 emissions are very short-lived so drops in their negative forcing would quickly contribute a significant boost to AGW were they cut in a hurry. However, the cutting will not be immediate and so any significant boost could theoretically be mitigated by cuts in N2O or CH4 forcing as well as the more slowly falling CO2 forcing (when emissions are cut enough for that to begin)."

So it sounds a lot more complicated than "the effect of SO2 is 2-4C so I just say 3C of additional warming locked in."

So I am still trying to wrap my brain around this issue and understand it better.  Looking at worldwide air quality for the past several years http://aqicn.org/map/world/ (http://aqicn.org/map/world/) it appears China has significantly reduced air pollution and as a result has reduced aerosols and sulfur dioxide.  It is spring so China's air is cleaner than during the winter but air pollution levels are down significantly during all the seasons as best I can tell.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: jai mitchell on May 16, 2018, 05:04:39 PM
I asked the following question on April 12 the April 2018 blog:

"How much do sulfates and aerosols affect temperature? I am thinking that incoming sunlight is reflected back into space by these substances before it reaches low altitudes thereby preventing some warming. Just how much effect they have is what I am not sure about."

A response from Al Roger on April 14:
"And mentioned up-thread, the SO2 emissions are very short-lived so drops in their negative forcing would quickly contribute a significant boost to AGW were they cut in a hurry. However, the cutting will not be immediate and so any significant boost could theoretically be mitigated by cuts in N2O or CH4 forcing as well as the more slowly falling CO2 forcing (when emissions are cut enough for that to begin)."

So it sounds a lot more complicated than "the effect of SO2 is 2-4C so I just say 3C of additional warming locked in."

So I am still trying to wrap my brain around this issue and understand it better.  Looking at worldwide air quality for the past several years http://aqicn.org/map/world/ (http://aqicn.org/map/world/) it appears China has significantly reduced air pollution and as a result has reduced aerosols and sulfur dioxide.  It is spring so China's air is cleaner than during the winter but air pollution levels are down significantly during all the seasons as best I can tell.

Response in the appropriate thread here:  https://forum.arctic-sea-ice.net/index.php?board=25.0
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: litesong on May 17, 2018, 02:44:16 AM
I've edited the poll, so people can change their vote if they want.
Thank you.
Title: Re: First year PIOMAS volume below 1000km^3 poll 2018
Post by: litesong on May 18, 2018, 02:16:08 AM
I've edited the poll, so people can change their vote if they want.
Thank you.
Ah, haaaa....... Yeah, I changed my vote. But, someone else negated my vote, by jumping to another time period. Ain't it funny that democracy goes in directions ya just don' know 'bout. Others have been arranging the chairs on the sinking ship, also.