Arctic Sea Ice : Forum

Cryosphere => Arctic sea ice => Topic started by: Tetra on May 28, 2017, 05:34:47 PM

Title: How soon could we go ice free?
Post by: Tetra on May 28, 2017, 05:34:47 PM
Based on the current weather forceast and low ice volume (I've been very depressed over this since April) could we be ice free by the end of June?
Title: Re: How soon could we go ice free?
Post by: Jim Pettit on May 28, 2017, 06:59:51 PM
Based on the current weather forceast and low ice volume (I've been very depressed over this since April) could we be ice free by the end of June?

Suggestion: read many of the many awesome past threads here discussing this very thing, and you are guaranteed to learn much. At any rate, ice-free by June? The answer depends in part on how one defines the term "ice free", but as it's normally understood, there is a 0% chance of this happening this year. The same answer goes for July and August and--at this point--September.
Title: Re: How soon could we go ice free?
Post by: Tetra on May 28, 2017, 07:14:14 PM
Based on the current weather forceast and low ice volume (I've been very depressed over this since April) could we be ice free by the end of June?

Suggestion: read many of the many awesome past threads here discussing this very thing, and you are guaranteed to learn much. At any rate, ice-free by June? The answer depends in part on how one defines the term "ice free", but as it's normally understood, there is a 0% chance of this happening this year. The same answer goes for July and August and--at this point--September.

I mean in terms of "blue ocean event" levels likely to cause a hike up in world temps and other unpleasant things.
Title: Re: How soon could we go ice free?
Post by: Pmt111500 on May 28, 2017, 08:49:19 PM
Nah, the blue ocean event would be the starting signal for the worse things to happen, will likely take a decade or two afterwards to have those all over globe. Of course it's pretty impossible to stop it once it starts. So i'd say 2040s-50s earliest decapita... No. Hopefully denialists will do it themselves.

Why not concentrate on the happier aspects of cc. Even now, you could grow elephants in southern europe if you had enough land... Oops. Troubling times ahead, i'd say, no way around it. There are some other more positive opinions on this. Maybe some descendants in the far future find a copy of H.G.Wells' "time machine" and start to think him as nostradamus or prophet.
Title: Re: How soon could we go ice free?
Post by: Robert Greer on May 28, 2017, 09:00:03 PM
Based on the current weather forceast and low ice volume (I've been very depressed over this since April) could we be ice free by the end of June?

Suggestion: read many of the many awesome past threads here discussing this very thing, and you are guaranteed to learn much. At any rate, ice-free by June? The answer depends in part on how one defines the term "ice free", but as it's normally understood, there is a 0% chance of this happening this year. The same answer goes for July and August and--at this point--September.

How can we have a 0% chance of an ice-free Arctic in September, when we're already in uncharted territory for low May volume? Especially given that the regions that looked relatively okay this year -- Beaufort and Chukchi -- are disintegrating much more quickly than expected?
Title: Re: How soon could we go ice free?
Post by: Neven on May 28, 2017, 09:25:01 PM
Based on the current weather forceast and low ice volume (I've been very depressed over this since April) could we be ice free by the end of June?

Like Jim Pettit says, you need to inform yourself more before getting scared/depressed.
Title: Re: How soon could we go ice free?
Post by: magnamentis on May 28, 2017, 11:06:35 PM
Based on the current weather forceast and low ice volume (I've been very depressed over this since April) could we be ice free by the end of June?

Suggestion: read many of the many awesome past threads here discussing this very thing, and you are guaranteed to learn much. At any rate, ice-free by June? The answer depends in part on how one defines the term "ice free", but as it's normally understood, there is a 0% chance of this happening this year. The same answer goes for July and August and--at this point--September.

How can we have a 0% chance of an ice-free Arctic in September, when we're already in uncharted territory for low May volume? Especially given that the regions that looked relatively okay this year -- Beaufort and Chukchi -- are disintegrating much more quickly than expected?

zero chance is as much a number i'd never use as is 100% chance (gererally, not topic related) but it's as close to zero as one can imagine, you'll see, there will still be A LOT of ice left at the end of this season, while once we cross the 1'000'000km2 line some will claim ice-free which IMO, can only repeat over and over, is more to get the headline than it would have anything to do with ICE-FREE.

since we're still far away from even that number the topic is a bit neglect but as soon as we get down to the million this will become a hot topic because i'm sure i'm not the only one who is not happy with that 1 million mark. no clue where it even comes from, the wine cask will be empty when the last drop has gone but earliest once one cannot fill a wine glass anymore and 1 MIO km2 is a real lot of ice especially should it consist of ice that is perhaps a bit thicker than just a few cm.

those who like to stick to that 1MIO number so that the event will happen earlier, should at least come up with corresponding thickness = volume numbers.

further it's never good to try to fool the public to get an effect. once people start to claim ice-free arctic while satellite images who everyone can see still show significant ice cover <1'000'000km2 but still, people will say: you see, it's a fake, they try to fool us.

hence the satellites will better show no significant ice-cover once the news will be fed with the "ice-free" term.

Title: Re: How soon could we go ice free?
Post by: Archimid on May 28, 2017, 11:11:07 PM
I disagree that the chance for ice free September or even August is 0. The chance is certainly low and decreasing but it is not 0. A melt similar to 2012 will be enough to puts us in "virtuallly ice free"  territory. The chance for that is low but is there.

I think everyone should be at least aware of the possible danger and planning and preparation for the worst are very much in order with the caveat that it is a low probability event.

Title: Re: How soon could we go ice free?
Post by: slow wing on May 29, 2017, 01:06:40 AM
... the 1'000'000km2 line some will claim ice-free which IMO, can only repeat over and over, is more to get the headline than it would have anything to do with ICE-FREE.

since we're still far away from even that number the topic is a bit neglect but as soon as we get down to the million this will become a hot topic because i'm sure i'm not the only one who is not happy with that 1 million mark. no clue where it even comes from, the wine cask will be empty when the last drop has gone but earliest once one cannot fill a wine glass anymore and 1 MIO km2 is a real lot of ice especially should it consist of ice that is perhaps a bit thicker than just a few cm.

those who like to stick to that 1MIO number so that the event will happen earlier, should at least come up with corresponding thickness = volume numbers.

further it's never good to try to fool the public to get an effect. once people start to claim ice-free arctic while satellite images who everyone can see still show significant ice cover <1'000'000km2 but still, people will say: you see, it's a fake, they try to fool us.

hence the satellites will better show no significant ice-cover once the news will be fed with the "ice-free" term.
One million square kilometres is an established operational definition of ice-free.

In my view it is a good definition.

 In practice there has to be some sort of non-zero threshold chosen. Otherwise the Arctic cannot be ice-free until, for example, the Greenland ice sheet has almost completely melted out to the extent where there are no more icebergs calving off it into the Arctic Ocean.

  The chosen value of one million square kilometres is sensible in my view as it is a round number that is small compared to the area of the Arctic basin (~7-8 million kilometres?). The satellite photos will look very blue when we reach that level.

 The almost-blue status of the Arctic Ocean means that reaching that threshold will act much like 'ice-free' in terms of changes in the weather relative to today, so the definition also makes sense in terms of consequences.


  The beef I have with politicization of the science is somewhat to the contrary: I'm actually not too thrilled at the recent change (was it around a year ago?) in the IPCC that the Arctic reaching the one million threshold in one year now doesn't count - the Arctic now needs to cross the threshold five years in a row before it has officially reached the status of 'ice-free in Summer'. To me, that artificially delays the announcement and it smells of political interference.
Title: Re: How soon could we go ice free?
Post by: jdallen on May 29, 2017, 03:06:06 AM
I disagree that the chance for ice free September or even August is 0. The chance is certainly low and decreasing but it is not 0. A melt similar to 2012 will be enough to puts us in "virtuallly ice free"  territory. The chance for that is low but is there.

I think everyone should be at least aware of the possible danger and planning and preparation for the worst are very much in order with the caveat that it is a low probability event.
I hesitate to put a number on it and simply call it doubtful for the pure reason that the outcome is entirely dependent on weather; which at this juncture is entirely too unpredictable for us to make any rational, skillfull prediction.

In short, making any quantitative statement is rolling the dice and hoping your guessed outcome is close to how things turn out.  I don't think we're in any position to do that yet.

Conditions certainly are very dangerous for exactly the reason that there *exists a risk*  we could lose the ice.  That in and by itself is sufficient justification for alarm, even without the actual event taking place. We should never have gotten here.

So, it is a matter of random probability; in this pass through of the seasons just exactly how will our multi-armed pendulum swing?
Title: Re: How soon could we go ice free?
Post by: FredBear on May 29, 2017, 09:23:34 AM
... the 1'000'000km2 line some will claim ice-free which IMO, can only repeat over and over, is more to get the headline than it would have anything to do with ICE-FREE.

i'm sure i'm not the only one who is not happy with that 1 million mark. no clue where it even comes from.

One million square kilometres is an established operational definition of ice-free.

In my view it is a good definition.

 In practice there has to be some sort of non-zero threshold chosen. Otherwise the Arctic cannot be ice-free until, for example, the Greenland ice sheet has almost completely melted out to the extent where there are no more icebergs calving off it into the Arctic Ocean.

  The chosen value of one million square kilometres is sensible in my view as it is a round number that is small compared to the area of the Arctic basin (~7-8 million kilometres?). The satellite photos will look very blue when we reach that level.

 The almost-blue status of the Arctic Ocean means that reaching that threshold will act much like 'ice-free' in terms of changes in the weather relative to today, so the definition also makes sense in terms of consequences.


  The beef I have with politicization of the science is somewhat to the contrary: I'm actually not too thrilled at the recent change (was it around a year ago?) in the IPCC that the Arctic reaching the one million threshold in one year now doesn't count - the Arctic now needs to cross the threshold five years in a row before it has officially reached the status of 'ice-free in Summer'. To me, that artificially delays the announcement and it smells of political interference.

Thanks for your thoughts on "Ice-Free", I fear that fighting over how much ice shows in satellite images fudges the issue of fundamental changes in the Arctic. The battle magnamentis is foreseeing does not need to be fought now - I am sure someone will try to raise it later but if 1M km2 is generally accepted as "ice-free" that will be a good foundation.

I can see magnamentis's view but things like that will be used to justify the sorts of changes the IPCC are trying to make, and I hope that the original definition will continue to be accepted.
Title: Re: How soon could we go ice free?
Post by: FredBear on May 29, 2017, 10:04:10 AM
P.S.    .    .     As I have just caught a flea on my nether regions maybe I should just go nit-picking with the dog???
Title: Re: How soon could we go ice free?
Post by: Michael J on May 29, 2017, 10:21:55 AM
I think that an ice-free minimum is possible but it would take a perfect storm of weather events. I think the slow start this year probably means that it wont be that extreme but possible next year
Title: Re: How soon could we go ice free?
Post by: RikW on May 29, 2017, 12:11:23 PM
Based on the current weather forceast and low ice volume (I've been very depressed over this since April) could we be ice free by the end of June?

Suggestion: read many of the many awesome past threads here discussing this very thing, and you are guaranteed to learn much. At any rate, ice-free by June? The answer depends in part on how one defines the term "ice free", but as it's normally understood, there is a 0% chance of this happening this year. The same answer goes for July and August and--at this point--September.

I don't agree with the September part that there is 0% chance. The long-term trend get's closer to zero each year, april and may aren't very good predictors, but the ice does look bad. If we get a 'perfect' melting season, the arctic could be ice free i guess.

I still think we will break a lot of records this year, but ice free is unlikely, but not impossible yet
Title: Re: How soon could we go ice free?
Post by: magnamentis on May 29, 2017, 05:37:18 PM
Based on the current weather forceast and low ice volume (I've been very depressed over this since April) could we be ice free by the end of June?

Suggestion: read many of the many awesome past threads here discussing this very thing, and you are guaranteed to learn much. At any rate, ice-free by June? The answer depends in part on how one defines the term "ice free", but as it's normally understood, there is a 0% chance of this happening this year. The same answer goes for July and August and--at this point--September.

I don't agree with the September part that there is 0% chance. The long-term trend get's closer to zero each year, april and may aren't very good predictors, but the ice does look bad. If we get a 'perfect' melting season, the arctic could be ice free i guess.

I still think we will break a lot of records this year, but ice free is unlikely, but not impossible yet

one would have to put the volume in to account which more or less tells how much energy will be needed to get rid of it all and volume numbers, albeit decreasing, are simply too high to make a melt-out probable. i mean just calculate the energy to melt the now given amount of ice withing the remaining time and i believe that chances, even though never "zero" are as close to zero as one can assume.

after all the laws of physics remain in effect at all times, hence it's a very matter of fact amount of energy needed to melt the current ice volume.
Title: Re: How soon could we go ice free?
Post by: Jim Pettit on May 29, 2017, 05:44:48 PM
How can we have a 0% chance of an ice-free Arctic in September, when we're already in uncharted territory for low May volume? Especially given that the regions that looked relatively okay this year -- Beaufort and Chukchi -- are disintegrating much more quickly than expected?

I was simplifying for and placating a new reader who seemed to be overworried, so apologies for any confusion. Yes, there's theoretically a non-zero chance of reaching an ice-free state in the Arctic this year, of course. But there's also a non-zero chance of me winning next week's Powerball, or a non-zero chance of Earth being violently ejected from the Solar System by a passing star. But I'll stake my entire life savings* on the belief that none of the three will happen this year. :)

* - Not that that's a lot of money.
Title: Re: How soon could we go ice free?
Post by: Archimid on May 29, 2017, 05:47:35 PM
one would have to put the volume in to account which more or less tells how much energy will be needed to get rid of it all and volume numbers, albeit decreasing, are simply too high to make a melt-out probable. i mean just calculate the energy to melt the now given amount of ice withing the remaining time and i believe that chances, even though never "zero" are as close to zero as one can assume.

after all the laws of physics remain in effect at all times, hence it's a very matter of fact amount of energy needed to melt the current ice volume.


I don't think the probability is almost 0 anymore. I think it may be as high as double digits. Read Neven's update on the latest PIOMAS

http://neven1.typepad.com/blog/2017/05/piomas-may-2017.html#more (http://neven1.typepad.com/blog/2017/05/piomas-may-2017.html#more)

Quote
If this year's melt is equal to the average of the last 10 years, there will be around 2500 km3 left in September (mind you, the 2012 record low minimum is 3673 km3). If there's as much melt as in 2010 or 2012, this year's minimum will barely go above 1000 km3. I don't want to know what the Arctic looks like if that should happen.
Title: Re: How soon could we go ice free?
Post by: magnamentis on May 29, 2017, 06:33:47 PM
one would have to put the volume in to account which more or less tells how much energy will be needed to get rid of it all and volume numbers, albeit decreasing, are simply too high to make a melt-out probable. i mean just calculate the energy to melt the now given amount of ice withing the remaining time and i believe that chances, even though never "zero" are as close to zero as one can assume.

after all the laws of physics remain in effect at all times, hence it's a very matter of fact amount of energy needed to melt the current ice volume.

I don't think the probability is almost 0 anymore. I think it may be as high as double digits. Read Neven's update on the latest PIOMAS

http://neven1.typepad.com/blog/2017/05/piomas-may-2017.html#more (http://neven1.typepad.com/blog/2017/05/piomas-may-2017.html#more)

Quote
If this year's melt is equal to the average of the last 10 years, there will be around 2500 km3 left in September (mind you, the 2012 record low minimum is 3673 km3). If there's as much melt as in 2010 or 2012, this year's minimum will barely go above 1000 km3. I don't want to know what the Arctic looks like if that should happen.

you're free to think whatever you like of course ;) just read the post above yours and the term "close to zero would have to be defined first before continuing any discussion. as you may have recognized i'm not a friend of the 1'000'000km2 threshold as a definition and depending where one would accept the term zero to apply, it's closer or less close to "close to zero" chance LOL.

however, like JP i'd bet close to everything on a non-event, we shall see

enjoy further
Title: Re: How soon could we go ice free?
Post by: Archimid on May 29, 2017, 06:38:14 PM
Yeah I would have to agree with that. The chance for literally ice free arctic this year is as close to 0 as you describe.  Only by defining ice free with some arbitrary non zero number  do we get significant probabilities. Thanks for the clarification.
Title: Re: How soon could we go ice free?
Post by: pauldry600 on May 29, 2017, 08:27:43 PM
I think the chance of zero is zero

The chance of 1m is 5

The chance of 2m is 10

The chance of 3m  is 30

The chance of 3.7m is 100per cent  :)
Title: Re: How soon could we go ice free?
Post by: Jim Williams on May 29, 2017, 08:35:19 PM
Based on the current weather forceast and low ice volume (I've been very depressed over this since April) could we be ice free by the end of June?

Suggestion: read many of the many awesome past threads here discussing this very thing, and you are guaranteed to learn much. At any rate, ice-free by June? The answer depends in part on how one defines the term "ice free", but as it's normally understood, there is a 0% chance of this happening this year. The same answer goes for July and August and--at this point--September.

I don't agree with the September part that there is 0% chance. The long-term trend get's closer to zero each year, april and may aren't very good predictors, but the ice does look bad. If we get a 'perfect' melting season, the arctic could be ice free i guess.

I still think we will break a lot of records this year, but ice free is unlikely, but not impossible yet

one would have to put the volume in to account which more or less tells how much energy will be needed to get rid of it all and volume numbers, albeit decreasing, are simply too high to make a melt-out probable. i mean just calculate the energy to melt the now given amount of ice withing the remaining time and i believe that chances, even though never "zero" are as close to zero as one can assume.

after all the laws of physics remain in effect at all times, hence it's a very matter of fact amount of energy needed to melt the current ice volume.

There is all the energy you could possibly need just a few meters away from that ice.  The big known unknown is just how many meters.

I say that at some point there is enough overturning that all the sea ice melts out rather quickly and the Arctic Ocean can no longer pin the air temperature to near 0c.  I don't know when it will happen, but when it does it will be sudden -- leaving behind bergy bits and maybe some stuff flushed from the land.
Title: Re: How soon could we go ice free?
Post by: Tetra on May 30, 2017, 06:50:00 AM
The reason I started this thread is because I am very depressed over this.

I've been losing sleep and having trouble not worrying my loved ones about the arctic sea ice.

I don't expect to be catered to or comforted. But I truly expect not to live another year if the arctic goes ice free this year, heck definitely not two years.

Is there still a chance we could stay above 2000km3 with a decent chance of having another year of a stable climate?
Title: Re: How soon could we go ice free?
Post by: oren on May 30, 2017, 07:18:49 AM
Tetra I wish you wouldn't be so depressed over the sea ice. Many who realize the long-term trend of humanity, of the climate, of the ice, whatever, are somewhat depressed. But it's a long-term, slow-moving monster. The arctic is a symptom and a part of a system. A virtually ice-free arctic won't kill you within a year or two. It won't. (Even though climate change coupled with other trends might kill hundreds of millions within 30 years... but that's still far off, and some even claim it can still be changed).
So I wish you could relax a bit and not lose sleep. Better focus on the good things in life and on your loved ones. Everything will come in good time, and not sleeping for decades will not make it better. We are all mortal anyway, it's bad psychology to focus on the end instead of on the journey.
Title: Re: How soon could we go ice free?
Post by: Tor Bejnar on May 30, 2017, 02:54:51 PM
I second oren's wish. 
(Arctic ice may be healthy for us, but so is peace [or something like that].)
Title: Re: How soon could we go ice free?
Post by: jai mitchell on May 30, 2017, 03:29:59 PM
The ice will be gone soon and we will see rapid changes that were not included in the IPCC feedback.  This is a train wreck in slow motion and it is very normal to be depressed about this.  In the process of mourning we move through difficult phases that vary from denial to anger to sadness and, finally, acceptance.

This is what needs to happen and we need to be 'all-hands on deck' to prevent further destabilization as we enter into the anthropocene and leave the stable, gentle Holocene behind.

I wake up every day and hear this song in my mind as we are rapidly (I believe this year) moving into a state of climate beyond anything humans have experienced.  I then get up and go out and think about ways to make it better and talk with people who care about these things too.  I find outlets that assist me in gaining confidence that, once we all collectively wake up to these realities that we will marshal the extraordinary efforts needed to protect future generations and restore a stable climate.

https://www.youtube.com/watch?v=OomaNxkY-KY (https://www.youtube.com/watch?v=OomaNxkY-KY)
Title: Re: How soon could we go ice free?
Post by: Tetra on May 30, 2017, 03:36:45 PM
The ice will be gone soon and we will see rapid changes that were not included in the IPCC feedback.  This is a train wreck in slow motion and it is very normal to be depressed about this.  In the process of mourning we move through difficult phases that vary from denial to anger to sadness and, finally, acceptance.

This is what needs to happen and we need to be 'all-hands on deck' to prevent further destabilization as we enter into the anthropocene and leave the stable, gentle Holocene behind.

I wake up every day and hear this song in my mind as we are rapidly (I believe this year) moving into a state of climate beyond anything humans have experienced.  I then get up and go out and think about ways to make it better and talk with people who care about these things too.  I find outlets that assist me in gaining confidence that, once we all collectively wake up to these realities that we will marshal the extraordinary efforts needed to protect future generations and restore a stable climate.

https://www.youtube.com/watch?v=OomaNxkY-KY (https://www.youtube.com/watch?v=OomaNxkY-KY)

Is there a slim chance it could just be avoided this year? With buildup of ice and enough cloudy weather in July-August to be above 1.5kmcubed and enter the colder September with minimal damage for winter 2018. As in we scrape by with enough ice to avoid catastrophic warming for a few more months. I understand that in terms of stability, it's in months not years. At least in terms of having a stable civilisation until the end of 2017, until April-may 2018.

And will a blue ocean event have the highest chance of happening in September, and not earlier?

Plus will the fact we probably won't have an El Niño this year help matters much?
Title: Re: How soon could we go ice free?
Post by: gerontocrat on May 30, 2017, 04:15:19 PM
Hullo Tetra,

A blue ocean event simply means (for the moment) near-as-dammit no Arctic Sea Ice for a brief period in late summer. It's importance is very much symbolic, as for many years the world has been in denial that such a thing could happen. Symbols such as these are vital to grab public interest and change public policy.

As that period of an ice-free arctic ocean gets longer in the coming years, there will be significant changes in climate and weather systems in addition to those changes that have already happened. It is expected that those changes will make survival more difficult for life on earth for nearly, but not all, living things. (Peregrine falcons love New York). How quickly all this will happen is a matter of fierce debate on this forum and elsewhere.

However, it is as well to remember that humans are very adaptable. I have lived and worked in some of the poorest and war-torn societies in the world. Even there humans manage to not just survive but be civilised. I can assure you that we humans are very difficult to wipe out. This is good for us and in most cases unfortunate for other life forms.
 
Nil desperandum.
Title: Re: How soon could we go ice free?
Post by: magnamentis on May 30, 2017, 04:16:31 PM
The ice will be gone soon and we will see rapid changes that were not included in the IPCC feedback.  This is a train wreck in slow motion and it is very normal to be depressed about this.  In the process of mourning we move through difficult phases that vary from denial to anger to sadness and, finally, acceptance.

This is what needs to happen and we need to be 'all-hands on deck' to prevent further destabilization as we enter into the anthropocene and leave the stable, gentle Holocene behind.

I wake up every day and hear this song in my mind as we are rapidly (I believe this year) moving into a state of climate beyond anything humans have experienced.  I then get up and go out and think about ways to make it better and talk with people who care about these things too.  I find outlets that assist me in gaining confidence that, once we all collectively wake up to these realities that we will marshal the extraordinary efforts needed to protect future generations and restore a stable climate.

https://www.youtube.com/watch?v=OomaNxkY-KY (https://www.youtube.com/watch?v=OomaNxkY-KY)

Is there a slim chance it could just be avoided this year? With buildup of ice and enough cloudy weather in July-August to be above 1.5kmcubed and enter the colder September with minimal damage for winter 2018. As in we scrape by with enough ice to avoid catastrophic warming for a few more months. I understand that in terms of stability, it's in months not years. At least in terms of having a stable civilisation until the end of 2017, until April-may 2018.

And will a blue ocean event have the highest chance of happening in September, and not earlier?

Plus will the fact we probably won't have an El Niño this year help matters much?

there is not a slim chance that it can be avoided, on the contrary, there is only a very slim chance that it will happen (this year).

i'm not quite sure what, but something's not right with this conversation but soon we shall know, especially whether it's intentional or not ;) i'm not pulling the word for my suspicion out of my inventory yet.
Title: Re: How soon could we go ice free?
Post by: Archimid on May 30, 2017, 04:22:22 PM
Quote
Is there a slim chance it could just be avoided this year?

The most likely outcome is that we avoid the worst this year. Furthermore, if 2016 was a peak warm year, there is a pretty good chance that the Earth enters another warming slowdown that could last a decade or two at the most.  Maybe that buys the Arctic some time.

However the likelihood that we do get a BOE is too high, even when it is unlikely. 10 years ago it would have been impossible. 5 years ago it would have been so unlikely it might as well be impossible, today it is merely unlikely, but well within the realm of the possible. That is too high a likelihood.

Quote
Plus will the fact we probably won't have an El Niño this year help matters much?

I think it does.


For your depression problem, first know that it is inevitable in climate change research. However there are things that you can do to make it better. The logical solution is to take action. Prepare, talk to others, lower your carbon footprints and share your solutions. Anything would do, but do something. You will not only feel better, you will be making a difference and perhaps improving the outcome.

The other thing you can do is to stop researching climate change all together. Stick to WUWT, Fox News and other "republican" news sources. They have built a propaganda machine that it will cure you of all climate change related depression in no time. 
Title: Re: How soon could we go ice free?
Post by: TerryM on May 30, 2017, 05:21:00 PM

there is not a slim chance that it can be avoided, on the contrary, there is only a very slim chance that it will happen (this year).

i'm not quite sure what, but something's not right with this conversation but soon we shall know, especially whether it's intentional or not ;) i'm not pulling the word for my suspicion out of my inventory yet.
Ramen


Something's rotten in Tetra
What it is I'm not entirely sure.
But the blue water blues
Lacks conviction, and skews
Understandings, misrepresents our views


If proven wrong, I'll sincerely apologize
Terry





Title: Re: How soon could we go ice free?
Post by: Tetra on May 30, 2017, 05:51:33 PM

there is not a slim chance that it can be avoided, on the contrary, there is only a very slim chance that it will happen (this year).

i'm not quite sure what, but something's not right with this conversation but soon we shall know, especially whether it's intentional or not ;) i'm not pulling the word for my suspicion out of my inventory yet.

I'm so sorry for my behaviour. I've just been very stressed lately that a BOE might cause clathrate destabilization in the short term and cause the warming of the oceans to speed up enough to kill farming and crops.

If it doesn't happen this year, it must happen next. And there doesn't seem to be any tech to stop rapid warming. This planet was never able to support 7 billion people. I have the idea that my life and society as a whole hinges on a BOE not happening until next year to give it a few more months.

I've just discovered Guy Mcpherson and the positive feedbacks scare me that they will accelerate fast enough with a BOE and kill us all within a year.




Something's rotten in Tetra
What it is I'm not entirely sure.
But the blue water blues
Lacks conviction, and skews
Understandings, misrepresents our views


If proven wrong, I'll sincerely apologize
Terry
Title: Re: How soon could we go ice free?
Post by: Neven on May 30, 2017, 07:00:23 PM
Quote
I've just discovered Guy Mcpherson and the positive feedbacks scare me that they will accelerate fast enough with a BOE and kill us all within a year.

Don't take what McPherson says at face value. He's more or less on the other extreme side of the spectrum that climate risk deniers are on. The latter believe there is 0% chance of anything bad happening because of AGW, McPherson and his followers believe that there is a 100% chance of catastrophe (and real soon too).

At least, that was my interpretation when I read/watched some of McPherson's stuff a couple of years ago. Data is skewed towards the absolute extreme and beyond.

Most of the members of the ASIF community take AGW seriously, but not to the point where they think everything is going to end the day after tomorrow. Some think it will happen later, others think/hope the worst may still be averted. I (choose to) belong to that latter group.
Title: Re: How soon could we go ice free?
Post by: Tetra on May 30, 2017, 07:20:53 PM
Quote
I've just discovered Guy Mcpherson and the positive feedbacks scare me that they will accelerate fast enough with a BOE and kill us all within a year.

Don't take what McPherson says at face value. He's more or less on the other extreme side of the spectrum that climate risk deniers are on. The latter believe there is 0% chance of anything bad happening because of AGW, McPherson and his followers believe that there is a 100% chance of catastrophe (and real soon too).

At least, that was my interpretation when I read/watched some of McPherson's stuff a couple of years ago. Data is skewed towards the absolute extreme and beyond.

Most of the members of the ASIF community take AGW seriously, but not to the point where they think everything is going to end the day after tomorrow. Some think it will happen later, others think/hope the worst may still be averted. I (choose to) belong to that latter group.

I'm really sorry for my posting. It's just that im terrified a  BOE could really destabilise the planet. That and climate change seems to be here already and speeding things up.

I really don't think we have a year left due to abrupt warming and some runaway effects stacking up.
Title: Re: How soon could we go ice free?
Post by: oren on May 30, 2017, 07:41:56 PM
Tetra, somebody messed with your head. Large systems don't collapse so quickly. "We have only a year", nobody can know that. A BOE may come and go several times before the effects are extreme. And even extreme effects don't kill civilisation overnight. It's a process of decades, certainly not months. I'm very much not an optimist,
I feel it's unstoppable, but it's also quite slow on a human lifetime scale (though not slow enough, sadly). So please, take a deep breath and chill a bit.
Title: Re: How soon could we go ice free?
Post by: jai mitchell on May 30, 2017, 07:49:35 PM
Quote
I've just discovered Guy Mcpherson and the positive feedbacks scare me that they will accelerate fast enough with a BOE and kill us all within a year.

Don't take what McPherson says at face value. He's more or less on the other extreme side of the spectrum that climate risk deniers are on. The latter believe there is 0% chance of anything bad happening because of AGW, McPherson and his followers believe that there is a 100% chance of catastrophe (and real soon too).

At least, that was my interpretation when I read/watched some of McPherson's stuff a couple of years ago. Data is skewed towards the absolute extreme and beyond.

Most of the members of the ASIF community take AGW seriously, but not to the point where they think everything is going to end the day after tomorrow. Some think it will happen later, others think/hope the worst may still be averted. I (choose to) belong to that latter group.

+1 

I never fully discount another's perspective and assertion, however, McPherson falls into pseudoscience and hyperbole with incorrect assessments about things like permafrost pingos and subsea methane explosions. . . predicting the extinction of humanity in 10 years is not only foolish and dangerous it is, well, kinda dumb.
Title: Re: How soon could we go ice free?
Post by: josh-j on May 30, 2017, 07:55:46 PM
I'm really sorry for my posting. It's just that im terrified a  BOE could really destabilise the planet. That and climate change seems to be here already and speeding things up.

I really don't think we have a year left due to abrupt warming and some runaway effects stacking up.

I'm no expert but I don't think its inevitable that we will have a BOE this year, far from it - let alone that having one would immediately end our civilisation. Who knows, maybe there is a chance of all that happening in one year... but surely a low chance. The BOE itself could happen if we are unlucky, judging by ice volumes, but nothing is certain.

Try to change our world for the better; don't wallow in despair to the point of paralysis.

The only certainty is that if all of humanity had your level of concern, we'd already be well on our way to fixing the problem.
Title: Re: How soon could we go ice free?
Post by: Cook on May 30, 2017, 09:58:28 PM

I'm really sorry for my posting. It's just that im terrified a  BOE could really destabilise the planet. That and climate change seems to be here already and speeding things up.

I really don't think we have a year left due to abrupt warming and some runaway effects stacking up.

Please, don't be sorry, and don't be terrified. Since you are posting here I assume you have some great things like an education, a computer, food and shelter. Don't take these things for granted. Be thankful for them every day.

Change for the better or worse is inevitable, but we are short changing ourselves if we let that degrade our life in the now.

Let me suggest something like meditation. It can bring things into perspective.

The way I see it, we live in a thrilling time. A time of learning for human beings. We will learn a great deal about ourselves and our planet in the coming decades, and as usual there will be joy and suffering.

Isn't it amazing that we can monitor what is happening in real time and discuss it among ourselves?
Title: Re: How soon could we go ice free?
Post by: Jim Williams on May 30, 2017, 10:24:08 PM
(Peregrine falcons love New York)

So did the doves (pigeons) before those damn predators showed up.
Title: Re: How soon could we go ice free?
Post by: Jim Williams on May 30, 2017, 10:34:20 PM
Quote
I've just discovered Guy Mcpherson and the positive feedbacks scare me that they will accelerate fast enough with a BOE and kill us all within a year.

Don't take what McPherson says at face value. He's more or less on the other extreme side of the spectrum that climate risk deniers are on. The latter believe there is 0% chance of anything bad happening because of AGW, McPherson and his followers believe that there is a 100% chance of catastrophe (and real soon too).

At least, that was my interpretation when I read/watched some of McPherson's stuff a couple of years ago. Data is skewed towards the absolute extreme and beyond.

Most of the members of the ASIF community take AGW seriously, but not to the point where they think everything is going to end the day after tomorrow. Some think it will happen later, others think/hope the worst may still be averted. I (choose to) belong to that latter group.

I'm really sorry for my posting. It's just that im terrified a  BOE could really destabilise the planet. That and climate change seems to be here already and speeding things up.

I really don't think we have a year left due to abrupt warming and some runaway effects stacking up.

I bought a house on the hill overlooking Boston 30 years ago expecting to have valuable oceanfront property, and while I still expect that to happen I despair of it doing so in my lifetime.

The sea level might start rising a foot a year within the next few years, but only poor people will notice.
Title: Re: How soon could we go ice free?
Post by: Archimid on May 30, 2017, 11:06:00 PM
+1 Neven, with caveats

Guy McPherson is wrong in several fronts. Particularly the Methane clathrates bomb and human extinction.  Methane clathrates could become a significant player, but it won't be significant enough compared to other feedback loops. As for human extinction, it is highly unlikely. Even in a worst case scenario there are plenty of isolated communities and underground bunkers that will  keep H. sapiens going. I think extinction can be safely ruled out.

However in the grand scheme of things I think McPherson's position is closer to the real thing than the current consensus position. Something like a BOE will be enough to throw the global weather into a frenzy that will collapse economies and communities all over the world.  This will lead to wars and instability that will make matters worse, but even then it is very likely that a large percentage of humanity survives and adapt. You just have to make sure that you are ready to be part of that bunch.
Title: Re: How soon could we go ice free?
Post by: Cid_Yama on May 30, 2017, 11:29:21 PM
What you fail to take into account is that warm-blooded creatures are now at the upper end of their ability to lose metabolic heat.  Yes, man has the ability to now build enclosed environments that, with inputs from the outside, and the ability to dump wastes outside, several thousand could survive, using environmental suits to allow work outside.

But that technology, with such a small population, would be lost in short order.

And CO2 in the atmosphere is forever, with regards to human time scales.

http://www.independent.co.uk/environment/climate-change/greenhouse-gases-will-heat-up-planet-for-ever-1041642.html (http://www.independent.co.uk/environment/climate-change/greenhouse-gases-will-heat-up-planet-for-ever-1041642.html)

http://geosci.uchicago.edu/~archer/reprints/archer.2009.ann_rev_tail.pdf (http://geosci.uchicago.edu/~archer/reprints/archer.2009.ann_rev_tail.pdf)

Who would want to live in that world?

It would be like trying to colonize an inhospitable planet.  With no hope for further assistance from outside. 


Title: Re: How soon could we go ice free?
Post by: magnamentis on May 31, 2017, 12:12:55 AM
What you fail to take into account is that warm-blooded creatures are now at the upper end of their ability to lose metabolic heat.  Yes, man has the ability to now build enclosed environments that, with inputs from the outside, and the ability to dump wastes outside, several thousand could survive, using environmental suits to allow work outside.

But that technology, with such a small population, would be lost in short order.

And CO2 in the atmosphere is forever, with regards to human time scales.

http://www.independent.co.uk/environment/climate-change/greenhouse-gases-will-heat-up-planet-for-ever-1041642.html (http://www.independent.co.uk/environment/climate-change/greenhouse-gases-will-heat-up-planet-for-ever-1041642.html)

http://geosci.uchicago.edu/~archer/reprints/archer.2009.ann_rev_tail.pdf (http://geosci.uchicago.edu/~archer/reprints/archer.2009.ann_rev_tail.pdf)

Who would want to live in that world?

It would be like trying to colonize an inhospitable planet.  With no hope for further assistance from outside.

counting all of asia, india and africa plus the arabian peninsula he vast majority of global population are living in way above average temperature environment, hence i don't think that air temperatures and their effect on livability are a huge issue by themselves. of course hi temps come with a lot of side effects but then i understood that you refer to the sheer capability of a warmblooded body to absorb heat (more heat) no problem IMO
Title: Re: How soon could we go ice free?
Post by: Cid_Yama on May 31, 2017, 12:27:04 AM
The Limits of Human Adaptability
Quote
It seems to be widely assumed that humans can adapt to any amount of warming, on the basis that humans live in such a wide variety of climates now. We show that when examined in terms of the peak value of the wet-bulb temperature (Tw), which ultimately governs the possibility of transfer of metabolic heat to the environment, the worlds present-day climates are far less variable than one might think based on mean temperature. A warming of only a few degrees will cause large parts of the globe to experience peak Tw values that never occur today; 7C would begin to create zones of uninhabitability due to unsurvivable peak heat stresses (periods when the shedding of metabolic heat is thermodynamically impossible); and 10C would expand such zones far enough to encompass a majority of today's population. It is unknown how much of our present 7- 10C cushion we can live without before experiencing significant problems, making it difficult to draw conclusions about more modest climate changes, but the limits themselves rest squarely on basic thermodynamics.

These inferences stand in contradiction to damage functions currently used in economic cost-benefit calculations. In these, climate damages increase with global mean temperature according to a polynomial form, and remain moderate (typically <30% of GDP) even for 10C or more despite the implication that most of the surface would become uninhabitable by humans and most livestock during the warm season. We suggest that more attention should be paid to the behavior of damage functions at large departures from the present climate, and that damage functions should perhaps be based on a model of interpolation from adaptability limits rather than extrapolation from calculated impacts of small changes.
http://web.science.unsw.edu.au/~stevensherwood/PNAS-2010-Sherwood-0913352107.pdf (http://web.science.unsw.edu.au/~stevensherwood/PNAS-2010-Sherwood-0913352107.pdf)
Title: Re: How soon could we go ice free?
Post by: Archimid on May 31, 2017, 03:19:31 AM
Even at the unlikely case of 8C by 2100 there will be habitable places for at least part of the year. The world is simply too large. Not that many places will remain habitable for humans and probably even the habitable places become uninhabitable for part of the year but  I'm sure that using technology whatever humans are left can adapt.

Honestly I'm not worried about that. It is way beyond my lifespan. I'm worried about the changes in weather patterns that will continue to get worse as the arctic disappears. I think the usual  patterns will continue to change until the Arctic is ice free. Then they will change even more, specially on the years after the first BOE.

 Those year were there is ice in the Arctic during the winter years but no ice  in the summer will be the worst, at least as far as the Arctic is concerned. After the Arctic has warmed up enough to make winter insignificant I believe the rate of climate change will slow and the weather will become more settled. I have not yet ruled out that after the first BOE the Earth instead of warming snowballs. That could be even worse.



Title: Re: How soon could we go ice free?
Post by: rboyd on May 31, 2017, 03:39:47 AM
After the first BOE it would be logical for there to be a period of severely chaotic changes as the climate finds its way to a new equilibrium. All the models that predict that places like Canada and Northern Russia may benefit most from climate change may be proven very wrong if the Northern Hemisphere climate cells undergo a major transformation, after a period of chaotic behaviour.

The resulting temperature and rainfall patterns may be very different to those that are in place currently, or assumed by climate models.
Title: Re: How soon could we go ice free?
Post by: LRC1962 on May 31, 2017, 04:28:20 AM
I very interesting read on climate change. Loss, Mourning, and Climate Change (http://cmsw.mit.edu/loss-mourning-climate-change/)
Quote
“I sat on the makeshift step of what would be my refurbished porch and envisioned a yard with wildflowers. Anxious for some permanency, I guess I needed to be reminded how temporal permanency is.”

Extreme changes in weather and climate can augur great loss, because loss itself is socially and culturally constructed, and that loss can include both human and non-human life. The act of mourning these losses publicly is at once a responsibility that we have to engage with the bereaved and an effort to reconstruct meaning around it afterward. At the core, mourning is a recognition of impermanence and mortality – of the forms of life around us and of our own.
I think our biggest problem will not be the loss of the ice, I do not mean to minimize what that loss will mean to our environment. Our biggest problem will be that we will need to change how we do things and trying to use the BAU approach will only result in failure.

As for answering the main question, it is up to weather and that is the biggest known unknown.
Title: Re: How soon could we go ice free?
Post by: wili on May 31, 2017, 04:36:06 AM
I'm not sure that people are getting just what kinds of uncharted territory we are walking into here.

mag, I suggest you look into the facts about wet bulb temperatures. We are increasing not only temperatures, but also humidity levels (which increase by about 6% per degree C). When you reach 95 degrees F wet bulb temperature (that is, 95F = 35C plus 100% humidity, or its equivalent...higher temps but lower than 100% humidity...) everyone simply dies. Period.

Even if you are completely at rest in the shade in a strong breeze, under those conditions, you die within mere hours. It is simply a fact of human physiology. And the strongest and most able are as likely to die as are the weak, if not more so. The processes that under normal circumstance keep you cool (sweating and evaporation) just make you cook in your own skin that much faster.

We don't have to wait for 7 degrees C global temperature for this to start happening. We have come close at various locations around the globe already, and not just in the tropics. Parts of western Wisconsin, just a few miles from where I live, came close in the heat wave of '95.

In a context of the general societal collapse that will likely occur as more and more places approach and exceed that level, electricity and all the technology based on it will more and more frequently fail. So even those privileged to have AC will not make it under most circumstance.

We have pushed the earth out of the zone in which humans have evolved. The mechanisms that have most helped us adapt to the conditions of the last few million years will not help us, and will mostly work against us in these conditions.

Arch, when you say: "Honestly I'm not worried about that. It is way beyond my lifespan." Well, I guess I can thank you for being honest. But isn't that short-term thinking exactly part of what has gotten us into this mess. If nothing else, doesn't our present set of predicaments challenge us to question these individualistic and short term kinds of attitudes?

And I'm not sure how useful 'habitable places at least part of the year' are going to be. But at any rate, such place will not be where most people now live.

But back more specifically to the titular topic of the thread, do we have any good new science about what is predicted to happen with a Blue Ocean Event (or anything close to it)? When this first was something that some of us, at least started thinking seriously about, some ten years ago, I looked around and found precious little good science on the subject...it had been frankly outside of what most scientists had expected to happen. I admit that I have not been diligent since to keep up with the latest, but maybe someone here has? If so, please share what you've found. We are mostly just waving our hands around without some grounded modeling of these consequences, both in terms of atmospheric and oceanic circulation, not to mention carbon cycle issues.

Title: Re: How soon could we go ice free?
Post by: FishOutofWater on May 31, 2017, 04:41:33 AM
I think the focus on a few weeks of 90% blue ocean in September is misplaced. Changes in the weather have been already happening for the past decade as the European Arctic seas become more like the north Atlantic. Ocean convection, mid-deep water formation, is increasing in the European Arctic.

Convection in the Arctic ocean will be the big game changer because it will release heat in fall and winter but so far it is increasing gradually. Being "ice free" for a few weeks will not suddenly change the stability of the ocean.

And for what it's worth it has happened in the geologic past and life did just fine.

There are other things in the geologic past that I won't talk about now that weren't fine but they weren't caused by a "blue ocean event".

There is much to worry about in these times where American leadership has collapsed but worrying doesn't make it better. I'm just glad to see the French and German government getting along well together. There is some good news.
Title: Re: How soon could we go ice free?
Post by: Neven on May 31, 2017, 07:24:09 AM
I think the focus on a few weeks of 90% blue ocean in September is misplaced. Changes in the weather have been already happening for the past decade as the European Arctic seas become more like the north Atlantic. Ocean convection, mid-deep water formation, is increasing in the European Arctic.

I fully agree. The focus on an ice-free Arctic or blue ocean event is understandable from a PR point of view, as that image will hit hard and burn itself into the collective consciousness. But it's not a starting shot after which the consequences will suddenly start to make themselves felt. They already are, and if there is some tipping point, it doesn't suddenly start as soon as there is less than 1 million km2 of sea ice.

I hope I'm not further depressing you. Just saying.  ;)
Title: Re: How soon could we go ice free?
Post by: Tetra on May 31, 2017, 09:39:45 AM
I think the focus on a few weeks of 90% blue ocean in September is misplaced. Changes in the weather have been already happening for the past decade as the European Arctic seas become more like the north Atlantic. Ocean convection, mid-deep water formation, is increasing in the European Arctic.

I fully agree. The focus on an ice-free Arctic or blue ocean event is understandable from a PR point of view, as that image will hit hard and burn itself into the collective consciousness. But it's not a starting shot after which the consequences will suddenly start to make themselves felt. They already are, and if there is some tipping point, it doesn't suddenly start as soon as there is less than 1 million km2 of sea ice.

I hope I'm not further depressing you. Just saying.  ;)

So we've already passed the tipping point?

I guess what I'm really afraid of is just one big melt out in June and July, making us ice free earlier than many of us thought. (Especially with the open water in Alaska and the upcoming stage 5 heat vortex) and doing real damage that could really destabilise the world climate past the point of no return in short order.

Although, If we get a September BOE, the world will not fall apart within a year thanks to the refreezing season, at least until we get a proper one next June/July, but modern humanity will be tested.

Thank you for everything, both for running this excellent forum and the blog. I have been enlightened somewhat. I'll try to make more contributing posts in future. Let's see what the rest of this rather frightening and exciting melting season has for us.
Title: Re: How soon could we go ice free?
Post by: Cid_Yama on May 31, 2017, 02:33:10 PM
magnamentis, that's the ability for warm-blooded creatures (including us) to lose metabolic heat.  If we cannot lose the heat generated by our own metabolic processes, we experience cell death both apoptotic and necrotic, leading to death.  Any place that experiences temperatures that make it thermodynamically impossible to lose metabolic heat, even for a few hours, becomes uninhabitable.

Parts of Iran, Pakistan and India have already come close. 
Title: Re: How soon could we go ice free?
Post by: Pi26 on May 31, 2017, 03:23:13 PM
magnamentis, that's the ability for warm-blooded creatures (including us) to lose metabolic heat.  If we cannot lose the heat generated by our own metabolic processes, we experience cell death both apoptotic and necrotic, leading to death.  Any place that experiences temperatures that make it thermodynamically impossible to lose metabolic heat, even for a few hours, becomes uninhabitable.

Parts of Iran, Pakistan and India have already come close.

...See also:

https://www.nytimes.com/2015/06/07/opinion/sunday/the-deadly-combination-of-heat-and-humidity.html?_r=0 (https://www.nytimes.com/2015/06/07/opinion/sunday/the-deadly-combination-of-heat-and-humidity.html?_r=0)


http://petergardner.info/2017/01/wet-bulb-temperatures-and-an-uninhabitable-earth/ (http://petergardner.info/2017/01/wet-bulb-temperatures-and-an-uninhabitable-earth/)
Title: Re: How soon could we go ice free?
Post by: binntho on May 31, 2017, 03:54:10 PM
This is I presume based on the wet-bulb temperature which takes into account both temperature and humidity.

I remember reading that in the heat wave in India last year the wet-bulb temperature was very close to the "fatal" zone of 35C, which can be reached by e.g. 46C temperature and 50% humidity (or 35C temperature and 100% humidity). Looking at Wikipedia, a heatwave in Iran and Iraq last year reached wet-bulb temperatures of 38,4C .

With increased warming, both temperature and humidity are set to rise, although not sure about relative humidity.
Title: Re: How soon could we go ice free?
Post by: Archimid on May 31, 2017, 07:35:18 PM
The human body is an engine. A machine that uses energy (food) to do work with the inevitable by product of heat. It has an optimal operating temperature as well as thermal limits both high and low. The average human operating temperature is 37C.

The human engine also has a cooling system whose principal components are skin, water and the surface area of the body. The human cooling system works by transferring heat from the body to the environment by means of perspiration, conduction and radiation. Like all other cooling systems a gradient must exist to transfer the heat. When the environment is hotter than the human engine radiation, conduction and convection work against the body. At that point excess heat is transferred to the environment by perspiration alone.

Water is a vital component of the cooling system both inside the human engine and in the environment. When the environmental temperature is higher than 37C the evaporation of water is the only way to cool the engine. Even at temperatures of  45C the human body can operate by evaporating heat away.  That's when water in the environment plays a role. The more water in the environment the more difficult to evaporate water excreted by the skin. 




Title: Re: How soon could we go ice free?
Post by: Jim Williams on May 31, 2017, 08:11:03 PM
I don't quite know how the conversation got here, but the usual solution warm blooded animals use for both extreme heat and extreme cold is to burrow underground where the temperatures tend to be much more consistent.

This has already been happening in several places, such as Montreal and Australia.
Title: Re: How soon could we go ice free?
Post by: crandles on May 31, 2017, 08:53:39 PM
8C in 83 years would be incredibly rapid warming. That is about 5 times faster than current fast rates of warming which would likely require somewhere near 5 times the forcing. Oceans have enormous thermal inertia and take an awful long time to warm up.

So 7C to create zone of habitability is not really in lifetime of anyone reading and understanding this unless you get a really strong clathrate gun runaway scenario which is not expected.

May as well worry about sun blowing up or a giant asteroid impacting Earth, they are highly unlikely events.

Long before we get to areas of uninhabitability, we perhaps should be concerned about weather patterns ruining harvests. Even with this while one crop in one country can take a hammering, it is rare for many countries to be hit similarly and if one crop does badly another crop may do well. So it would take extraordinary weather weirding to cut all crop production by 50%. And even with that, we waste about 50% of food and you can bet if crop yield fell dramatically that wasted food would suddenly be viewed as important and carefully managed and people would start planting more food crops in their gardens.

So civilisation/society may well be fairly resilient to dramatic weather weirding.
Title: Re: How soon could we go ice free?
Post by: Jim Williams on May 31, 2017, 09:15:23 PM
Long before we get to areas of uninhabitability...
While I basically agree with you I think I would say "general uninhabitability" here rather than "areas."  I think there are a few "hot spots" where we might see significant die-offs.
Title: Re: How soon could we go ice free?
Post by: gerontocrat on May 31, 2017, 09:24:51 PM
Is there not a thread about livability somewhere.
Title: Re: How soon could we go ice free?
Post by: wili on May 31, 2017, 09:39:30 PM
Arch wrote: "Even at temperatures of  45C the human body can operate by evaporating heat away."

Not at high humidity levels. Even at 35C, the human body can not evaporate heat away if the humidity is 100%. This is very well established science. If you have a different take, please go get it published in a major science journal. I'm sure many will be deeply impressed by your knowledge there.  ::)

Crandles, note that Cid's article was the first to come out about ten years ago. Since then, as I pointed out, many places have nearly hit the 35C wbt point, and more will inevitably follow. I believe follow up studies have concluded that we will not have to wait for a 7C global temp above pre-industrial levels to start seeing areas reaching and exceeding this figure, but don't have time right now to track them down.
Title: Re: How soon could we go ice free?
Post by: Archimid on May 31, 2017, 10:34:56 PM
Arch wrote: "Even at temperatures of  45C the human body can operate by evaporating heat away."

Not at high humidity levels. Even at 35C, the human body can not evaporate heat away if the humidity is 100%. This is very well established science.

Of course. I thought that was implied in the last sentence. "The more water in the environment the more difficult to evaporate water excreted by the skin." But you are correct. Thanks for the clarification.
Title: Re: How soon could we go ice free?
Post by: Neven on May 31, 2017, 10:36:31 PM
Hmmm, maybe I should change the thread title to 'How soon could we go sweat-free?'.  ;)
Title: Re: How soon could we go ice free?
Post by: Archimid on May 31, 2017, 11:34:37 PM
My apologies Neven. I could write more to bring it back on topic but the leap is too large. I would like to make points about heat conditioning of the human body, anomaly distribution by latitude and the danger of flash heat wave being greater than that of average temperature but that would get me only to global warming. To get back to how soon we go ice free  I would have to make some heavy contortions. Mod away.
Title: Re: How soon could we go ice free?
Post by: Pi26 on June 01, 2017, 12:40:22 AM
Hmmm, maybe I should change the thread title to 'How soon could we go sweat-free?'.  ;)


But not before year 3500?
Title: Re: How soon could we go ice free?
Post by: magnamentis on June 01, 2017, 02:57:03 AM
magnamentis, that's the ability for warm-blooded creatures (including us) to lose metabolic heat.  If we cannot lose the heat generated by our own metabolic processes, we experience cell death both apoptotic and necrotic, leading to death.  Any place that experiences temperatures that make it thermodynamically impossible to lose metabolic heat, even for a few hours, becomes uninhabitable.

Parts of Iran, Pakistan and India have already come close.

i think that's more or less what i said or at least wanted to point at, just that i don't think we are generally at the limit to do so which is why i mentioned that there are billions of humans living in hotter and more humid (humidity is a key factor beside heat) that's where we disagree, not the physical process itself i'm fully aware of that, basic knowledge IMO
Title: Re: How soon could we go ice free?
Post by: wili on June 01, 2017, 04:52:01 AM
mag, I'm afraid I am finding your prose incomprehensible. Specifically:

"..i don't think we are generally at the limit to do so which is why i mentioned that there are billions of humans living in hotter and more humid..."

you don't think we (which we) are at what limit to do what exactly?

Billions living in hotter more humid [conditions?] that what?

Are you intending to be 'not even wrong' here?

https://en.wikipedia.org/wiki/Not_even_wrong
Title: Re: How soon could we go ice free?
Post by: Tetra on June 01, 2017, 08:33:06 AM
Could we get a big melt out in June and be ice free by July?

Based on Nares being open, Chukchi and Beaufort melting early, and chances for high export of thick ice via Fram?

That and the fact many areas will be open water in high summer for the first time.

I'm so stressed over this...we could all be dead in months. Definitely don't have a year left.
Title: Re: How soon could we go ice free?
Post by: seaicesailor on June 01, 2017, 08:57:28 AM
Wasn't this the theme of the OP? Aw man not start again
Title: Re: How soon could we go ice free?
Post by: Andreas T on June 01, 2017, 09:32:11 AM
mag, I'm afraid I am finding your prose incomprehensible. Specifically:

"..i don't think we are generally at the limit to do so which is why i mentioned that there are billions of humans living in hotter and more humid..."

you don't think we (which we) are at what limit to do what exactly?

Billions living in hotter more humid [conditions?] that what?

Are you intending to be 'not even wrong' here?

https://en.wikipedia.org/wiki/Not_even_wrong
If you look at magnamentis' (is that latin for "grosskopfert"?) almost one thousand posts you will see he is never wrong  ;)
Title: Re: How soon could we go ice free?
Post by: be cause on June 01, 2017, 11:45:28 AM
Come on Tetra,pack it in ...
Title: Re: How soon could we go ice free?
Post by: oren on June 01, 2017, 12:02:49 PM
Could we get a big melt out in June and be ice free by July?

Based on Nares being open, Chukchi and Beaufort melting early, and chances for high export of thick ice via Fram?

That and the fact many areas will be open water in high summer for the first time.

I'm so stressed over this...we could all be dead in months. Definitely don't have a year left.
Tetra seriously, enough with this shite. No we will not have ice free in July. And even if we do by some celestial intervention, no we will not all be dead within months. Stop it. I would stronly suggest that you follow the melting season thread for several months, at the end of which you will be much smarter, and meanwhile just lurk quietly.
If you wish to smarten up more quickly, go read the 2016 melting season thread from its beginning, read through every post, and imagine it's 2017 as you go along. You will get a very good feel for how it goes.
btw, Beaufort was worse in 2016, and Nares was worse in 2007. We are still alive.
Title: Re: How soon could we go ice free?
Post by: Tetra on June 01, 2017, 12:07:36 PM
Okay. I will do that.

Self imposed exile until I learn to get a grip on myself.

Title: Re: How soon could we go ice free?
Post by: magnamentis on June 01, 2017, 02:30:52 PM
mag, I'm afraid I am finding your prose incomprehensible. Specifically:

"..i don't think we are generally at the limit to do so which is why i mentioned that there are billions of humans living in hotter and more humid..."

you don't think we (which we) are at what limit to do what exactly?

Billions living in hotter more humid [conditions?] that what?

Are you intending to be 'not even wrong' here?

https://en.wikipedia.org/wiki/Not_even_wrong
If you look at magnamentis' (is that latin for "grosskopfert"?) almost one thousand posts you will see he is never wrong  ;)

a very bad translation and a false conclusion. we mostly learn through errors, mistakes and awareness of ignorance (of what we don't know), hence the opposite is the case because
great minds are only great in comparison to small narrow minds but still extremely ignorant and small when it comes to universally available knowledge, especially with a bit of imagination and phantasy.

further the correct translation of the latin term is not something i will apologize for, those who know me can assess whether it's true or "grosskopfert" and for all others only envy or the fear it might be true can hold as an explanation to make such poisoned statement. since that grosskopfert word is an austrian word it would probably suffice to provide some kind of a "Title" to satisfy some specific needs  for the "schmäh" LOL but this is not the place where i have to do that while of course it's there.

all my nicknames have not been invented by myself, there are more of that kind while this one provides the best energy and is less blunt. how i calculate that is another story LOL but normally those who can translate from latin have less problems with other fellow humans of their kind while exceptions exist for everything.
Title: Re: How soon could we go ice free?
Post by: Cid_Yama on June 01, 2017, 04:46:55 PM
Swell-headed?

Use of the archaic form of fantasy seems a bit pedantic.  Unless, of course, you just misspelled it.

Just yanking your chain.   ;D
Title: Re: How soon could we go ice free?
Post by: Ned W on June 14, 2018, 04:20:12 PM
I'm moving this discussion here, per Neven's observation that it was off-topic in the "2018 melt season" thread:

I think a large part of the issue here is that most scientists acknowledge that they cannot be sure how complex systems will respond to stresses in the future, and therefore they speak and write in terms of probability.  Thus Archimid states there is a chance, but only a very low chance that the Arctic would melt out this year, and that the probability increases in future years as the Earth (probably) warms up.  It really is the only sensible way to speak of the future.  If we toss ten pennies, it is unlikely that all ten will come up heads, but it is also possible, and we can assign a (low) numerical probability to that.

It is difficult to predict possible outcomes in the case of huge natural systems like the Arctic, but we can ascribe probabilities based upon trends, algorithms, computer models etc.  Then the experts argue about it all, gather more evidence and recalibrate their predictions, which is how it should be in science.  And we continue to be surprised, and often humbled, by how the planet and the Arctic responds.

Quote
No chance of an ice-free Arctic for at least 20 years.

That is false. There is a very low chance this year, increasing  every year that gets warmer and the weather more extreme. Saying there is no chance it will happen before 2037 is simply not true.
This year the uncertainties are the early opening of the Bering, a thin CAB, no ice North of Svalbard and the ever present warmer planet.
What if I said 15 years instead? Would that satisfy you?
There really is no chance of an ice-free Arctic for at least 15 years, but probably more like 20 years. The ice extent will continue to extend in winter, and will continue to bulge up and thicken against the CAA and Greenland. That the whole thing could be less than 15% in a few years is unlikely.
Much smaller ice-pack bunching up? Yes.
Zero ice-pack anywhere, and just some icebergs distantly floating around? No chance.

Here's one way to think about this.  First, here's the historical record of JAXA annual (daily) minima:

(https://i.imgur.com/kre7RWt.png)

The blue zigzag line are the actual observations, the green smooth line is a LOESS smoothing function with a 10-year timescale, the red smooth line is a 30-year LOESS function, and the blue dot with error bars is the current forecast for 2018.

That graph suggests a variety of possible future scenarios.  Here are four examples or "scenarios".  The first scenario is based on the idea that the 10-year LOESS model (green line above) shows a "stepwise" decrease, where extent drops sharply for a few years, then levels off for a few years, then drops again:

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

In that scenario, the ice could be around a lot longer than most of us expect -- potentially, there might not be an "ice-free" day (let alone month or summer) until 2080 or later.

If we focus instead on the red line (30-year LOESS) from the first graph, it tells a different story -- a slow decrease in the 1980s and 1990s, followed by a slightly faster decrease after 2000, with the apparent "flattening" over the past decade being just noise.  In my scenario 2 below, the post-2000 decrease continues unabated:

(https://i.imgur.com/E8lsNd5.png)

This scenario has an "ice-free" day sometime around 2035-2055.

A third scenario assumes that in 2020 we have another downward "bend" like in 2000, followed by a steeper loss of ice:

(https://i.imgur.com/s78EhnX.png)

That suggests an "ice-free" day somewhat earlier, between 2030-2040. 

Finally, a fourth scenario, that basically ignores the historical record and assumes that the ice suddenly collapses after 2020:

(https://i.imgur.com/PEOlnX2.png)

Personally, I think scenario 3 is most likely.  I would expect to see "ice-free" days in September routinely by the mid-2030s, with the first one perhaps occurring only 10-15 years from now given the apparent increase in interannual variability.

After that, I would rate scenario 2 as next-most likely, with scenarios 1 and 4 as potentially plausible but less likely.

FWIW ... I put "ice-free" in quotes throughout this post, because I personally dislike the standard definition of "ice-free" as under 1 million km2 of ice.  See this comment:

https://forum.arctic-sea-ice.net/index.php/topic,143.msg122338.html#msg122338

and this map (another simulation):

(https://i.imgur.com/t0I6clk.png)
Title: Re: How soon could we go ice free?
Post by: Ken Feldman on June 14, 2018, 06:29:33 PM
There are a variety of approaches to predicting when the arctic will go ice free.  (Since I'm going to be quoting from peer-reviewed science in this post, I'll use the standard definition of less than 1 million sq. km of ice remaining).

Global climate models use physics, tracking energy flows and predicting future forcings from elevated greenhouse gas levels.  In the past, they've missed the extreme melt seasons like 2012 and were overly conservative, general predicting that the Arctic wouldn't go ice free until late in the century.  For the IPCC AR5 report issued in 2013, they were updated and the paper linked to below evaluated the models for ability to reproduce the variability in observed melt seasons like 2012.  The models most able to reproduce that variability predict an ice free arctic in the 2050s under a high emissions scenario.  If emissions are significantly reduced, arctic sea ice minimums would level off around 1.7 million km2.

http://www.pnas.org/content/110/31/12571 (http://www.pnas.org/content/110/31/12571)

Quote
This paper addresses the specter of a September ice-free Arctic in the 21st century using newly available simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5). We find that large spread in the projected timing of the September ice-free Arctic in 30 CMIP5 models is associated at least as much with different atmospheric model components as with initial conditions. Here we reduce the spread in the timing of an ice-free state using two different approaches for the 30 CMIP5 models: (i) model selection based on the ability to reproduce the observed sea ice climatology and variability since 1979 and (ii) constrained estimation based on the strong and persistent relationship between present and future sea ice conditions. Results from the two approaches show good agreement. Under a high-emission scenario both approaches project that September ice extent will drop to ∼1.7 million km2 in the mid 2040s and reach the ice-free state (defined as 1 million km2) in 2054–2058. Under a medium-mitigation scenario, both approaches project a decrease to ∼1.7 million km2 in the early 2060s, followed by a leveling off in the ice extent.

Another paper looked at the observed trends and then used a variety of statistical methods to fit the data.  Depending on the method used, the arctic would have it's first ice free summer in the 2030s.

http://www.mdpi.com/2072-4292/10/2/230 (http://www.mdpi.com/2072-4292/10/2/230)

Quote
An ice-free Arctic summer would have pronounced impacts on global climate, coastal habitats, national security, and the shipping industry. Rapid and accelerated Arctic sea ice loss has placed the reality of an ice-free Arctic summer even closer to the present day. Accurate projection of the first Arctic ice-free summer year is extremely important for business planning and climate change mitigation, but the projection can be affected by many factors. Using an inter-calibrated satellite sea ice product, this article examines the sensitivity of decadal trends of Arctic sea ice extent and statistical projections of the first occurrence of an ice-free Arctic summer. The projection based on the linear trend of the last 20 years of data places the first Arctic ice-free summer year at 2036, 12 years earlier compared to that of the trend over the last 30 years. The results from a sensitivity analysis of six commonly used curve-fitting models show that the projected timings of the first Arctic ice-free summer year tend to be earlier for exponential, Gompertz, quadratic, and linear with lag fittings, and later for linear and log fittings. Projections of the first Arctic ice-free summer year by all six statistical models appear to converge to the 2037 ± 6 timeframe, with a spread of 17 years, and the earliest first ice-free Arctic summer year at 2031

That article is worth reading because it discusses the weakness of using varying curve fitting methods and how they're sensitive to the data inputs.  One of the methods, an exponential fit, shows the first year the arctic will be ice free as 2014!

Title: Re: How soon could we go ice free?
Post by: Dharma Rupa on June 14, 2018, 06:43:27 PM
The real answer is that we don't have a clue.

None of the models has been around long enough to have a valid skill metric assigned to them, and all the models have been way off in one way or another.  The "science" of Arctic Sea Ice is more like Alchemy than Chemistry.  We do not have an equivalent to the periodic table.  Everything that is said is based upon guesses about what is and has been going on.

(This is not to disparage the good work being done.  It is intended to reject the useless expectations people have about that work.)

Title: Re: How soon could we go ice free?
Post by: Ken Feldman on June 14, 2018, 07:02:47 PM
The real answer is that we don't have a clue.

None of the models has been around long enough to have a valid skill metric assigned to them, and all the models have been way off in one way or another.  The "science" of Arctic Sea Ice is more like Alchemy than Chemistry.  We do not have an equivalent to the periodic table.  Everything that is said is based upon guesses about what is and has been going on.

(This is not to disparage the good work being done.  It is intended to reject the useless expectations people have about that work.)

Wow, I take it you haven't been doing much research on climate change.  You may want to educate yourself by reading the most recent IPCC report.  Here's the link:

http://www.climatechange2013.org/report/ (http://www.climatechange2013.org/report/)

To just toss off decades of science done by hundreds (perhaps thousands) of dedicated, well-educated people smacks of denialism.
Title: Re: How soon could we go ice free?
Post by: Richard Rathbone on June 14, 2018, 07:44:08 PM
The real answer is that we don't have a clue.

None of the models has been around long enough to have a valid skill metric assigned to them, and all the models have been way off in one way or another.  The "science" of Arctic Sea Ice is more like Alchemy than Chemistry.  We do not have an equivalent to the periodic table.  Everything that is said is based upon guesses about what is and has been going on.

(This is not to disparage the good work being done.  It is intended to reject the useless expectations people have about that work.)

Wow, I take it you haven't been doing much research on climate change.  You may want to educate yourself by reading the most recent IPCC report.  Here's the link:

http://www.climatechange2013.org/report/ (http://www.climatechange2013.org/report/)

To just toss off decades of science done by hundreds (perhaps thousands) of dedicated, well-educated people smacks of denialism.

I think the state of the models as revealed in that IPCC report is pretty well summed up  in Dharma Rupa's comment.

I see some signs that it will be better next time around, but an informed reading of the 2013 report is not going to inspire any confidence in model predictions of future Arctic Sea Ice cover.
Title: Re: How soon could we go ice free?
Post by: jdallen on June 14, 2018, 08:02:26 PM
The real answer is that we don't have a clue.

None of the models has been around long enough to have a valid skill metric assigned to them, and all the models have been way off in one way or another.  The "science" of Arctic Sea Ice is more like Alchemy than Chemistry.  We do not have an equivalent to the periodic table.  Everything that is said is based upon guesses about what is and has been going on.

(This is not to disparage the good work being done.  It is intended to reject the useless expectations people have about that work.)

Wow, I take it you haven't been doing much research on climate change.  You may want to educate yourself by reading the most recent IPCC report.  Here's the link:

http://www.climatechange2013.org/report/ (http://www.climatechange2013.org/report/)

To just toss off decades of science done by hundreds (perhaps thousands) of dedicated, well-educated people smacks of denialism.
No insults please. Dharma Rupa is not a denialist, nor dismissing research.  I think he (And I now) are pointing out that we are attempting to derive system behavior from an *effect* rather than a cause, or at least, an rather incomplete one.

We have very incomplete data. For instance, we have only a vague sense of how total ocean enthalpy is increasing in the Arctic.  We dont know a lot about heat inflow from currents.  Atmospheric chemistry is changing.  Weather itself is a dynamic property that will completely turn our expectations on their heads.

We need much better data about heat, and weather will make a certain prediction impossible even with that.

What we are left with is probabilities and unanswered questions.
Title: Re: How soon could we go ice free?
Post by: Dharma Rupa on June 14, 2018, 09:40:43 PM
No insults please. Dharma Rupa is not a denialist, nor dismissing research.

Given the fact that I think we have completely underestimated the effects of the Industrial Revolution a couple hundred years ago, denial is a river in Egypt.

I just don't see any reason to accept the models as tablets from God.  They are people doing their best with the current understanding.  The people who bow down before those models, however, are idiots.

Title: Re: How soon could we go ice free?
Post by: magnamentis on June 14, 2018, 09:42:16 PM
Wow, I take it you haven't been doing much research on climate change.  You may want to educate yourself by reading the most recent IPCC report.  Here's the link:

To just toss off decades of science done by hundreds (perhaps thousands) of dedicated, well-educated people smacks of denialism.

there are a few problems:

a) he is right

b) you are asking a question while seeking confirmation for an already made up mind

c) you jump to false conclusion based on someone tells the truth

b + c are very modern and horrible attitudes IMO, beside other factors denying the truth brought the world very it currently stands and will bring either doom or at least more disaster to mankind.

further i find it interesting that someone who in the process of discarding facts blames others doing the same, interesting but not surprising because that too is human behaviour as long back as
the records are showing ;)

Title: Re: How soon could we go ice free?
Post by: Dharma Rupa on June 14, 2018, 10:16:43 PM
To make my position clear.  I think the evidence supporting Global Warming is overwhelming.  I also think the evidence supporting the models is basically NONE.
Title: Re: How soon could we go ice free?
Post by: jdallen on June 14, 2018, 10:48:19 PM
To make my position clear.  I think the evidence supporting Global Warming is overwhelming.  I also think the evidence supporting the models is basically NONE.
I'll temper what I said earlier.  I think models are useful to help discern the trend.  I don't think they have the skill yet to be narrowly predictive.  Multiple models processing the same data producing similar results are useful - very useful - as they can instruct us where to look next for better detail.

My own take is, that we hit an inflection point in 2007, and started on an irreversible change in system behavior.  We'll hit another I think when we drop below ~1 million KM2.

In between I figure that starting with 2007, we have a cumulative 1% chance of hitting that sub 1million KM2 mark.  Weather year over year is the wildcard.  Increasing system heat is the force raising potential for that melt-out.
Title: Re: How soon could we go ice free?
Post by: Daniel B. on June 15, 2018, 12:27:38 AM
To make my position clear.  I think the evidence supporting Global Warming is overwhelming.  I also think the evidence supporting the models is basically NONE.
I'll temper what I said earlier.  I think models are useful to help discern the trend.  I don't think they have the skill yet to be narrowly predictive.  Multiple models processing the same data producing similar results are useful - very useful - as they can instruct us where to look next for better detail.

My own take is, that we hit an inflection point in 2007, and started on an irreversible change in system behavior.  We'll hit another I think when we drop below ~1 million KM2.

In between I figure that starting with 2007, we have a cumulative 1% chance of hitting that sub 1million KM2 mark.  Weather year over year is the wildcard.  Increasing system heat is the force raising potential for that melt-out.

I tend to agree.  It will take another change to push the ice below the 1 million mark.  What that occurs is anyone’s guess, and the models are no help.
Title: Re: How soon could we go ice free?
Post by: Ken Feldman on June 15, 2018, 01:15:41 AM
Here's a summary of the updates in models made between the IPCC Fourth Assessment Report, AR4, (published in 2007) using the CMIP3 models and AR5 (published in 2013) using the CMIP5 models with respect to sea ice:

Quote
The CMIP5 simulations have recently become available (15). Relative to the CMIP3, a more diverse set of model types is included in the CMIP5 (i.e., climate/Earth system models with more interactive components such as atmospheric chemistry, aerosols, dynamic vegetation, ice sheets, and carbon cycle). Further, a number of improvements in physics, numerical algorithms, and configurations are implemented in the CMIP5 models. For example, some CMIP5 models include more realistic sea ice thermodynamics and dynamics in sea ice components, displaced pole to eliminate the singularity in sea ice and ocean components, better treatments of subgrid parameterizations in all of the components, and higher resolution in all of the components. Finally, a new set of scenarios called representative concentration pathways (RCPs) are used in the CMIP5 simulations (16).

And here's a 2017 paper that evaluates the results of the models that have been better at simulating observed conditions:

https://link.springer.com/article/10.1007/s13131-017-1029-8 (https://link.springer.com/article/10.1007/s13131-017-1029-8)

Quote
This paper is focused on the seasonality change of Arctic sea ice extent (SIE) from 1979 to 2100 using newly available simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5). A new approach to compare the simulation metric of Arctic SIE between observation and 31 CMIP5 models was established. The approach is based on four factors including the climatological average, linear trend of SIE, span of melting season and annual range of SIE. It is more objective and can be popularized to other comparison of models. Six good models (GFDL-CM3, CESM1-BGC, MPI-ESM-LR, ACCESS-1.0, HadGEM2-CC, and HadGEM2-AO in turn) are found which meet the criterion closely based on above approach. Based on ensemble mean of the six models, we found that the Arctic sea ice will continue declining in each season and firstly drop below 1 million km2 (defined as the ice-free state) in September 2065 under RCP4.5 scenario and in September 2053 under RCP8.5 scenario. We also study the seasonal cycle of the Arctic SIE and find out the duration of Arctic summer (melting season) will increase by about 100 days under RCP4.5 scenario and about 200 days under RCP8.5 scenario relative to current circumstance by the end of the 21st century. Asymmetry of the Arctic SIE seasonal cycle with later freezing in fall and early melting in spring, would be more apparent in the future when the Arctic climate approaches to “tipping point”, or when the ice-free Arctic Ocean appears. Annual range of SIE (seasonal melting ice extent) will increase almost linearly in the near future 30–40 years before the Arctic appears ice-free ocean, indicating the more ice melting in summer, the more ice freezing in winter, which may cause more extreme weather events in both winter and summer in the future years.
Title: Re: How soon could we go ice free?
Post by: Ned W on June 15, 2018, 02:37:55 AM
The real answer is that we don't have a clue.

None of the models has been around long enough to have a valid skill metric assigned to them, and all the models have been way off in one way or another.  The "science" of Arctic Sea Ice is more like Alchemy than Chemistry.  We do not have an equivalent to the periodic table.  Everything that is said is based upon guesses about what is and has been going on.

(This is not to disparage the good work being done.  It is intended to reject the useless expectations people have about that work.)

I would disagree with DR's comment, because it seems much too sweeping in its scope.

It begins with a statement about "the models" but doesn't differentiate among many different types of models used for many different purposes in the Arctic. CESM is a model, PIOMAS is a model, colleagues of mine have their own model of how light is transmitted through sea ice to feed phytoplankton below.  Are they all equally and utterly worthless? 

The next sentence goes beyond carping about models to assert that the entire "science" (with scare quotes, natch!) of Arctic sea ice is "more like alchemy" ... in other words, it's all worthless.  Not just the models, all science (or "science") in the Arctic.

I don't agree, to put it mildly. 
Title: Re: How soon could we go ice free?
Post by: bbr2314 on June 15, 2018, 05:29:23 AM
I think stronger wintertime volume/extent losses may not necessarily correlate to the same occurring as we move forward in the summer months, i.e., additional volume deficits have the possibility of becoming increasingly seasonally lopsided.

It is important to note that the phenomena re: albedo / continental SWE observed in 2018, if rolled forward in the same way the posts in this thread project the losses of 2007 and 2012 (but worse) b the 2020s, likely results in an impossibility of an entirely blue Arctic.

The albedo feedbacks from excess water vapor / heat will translate into far greater and heavier continental snows, and if we ever manage summer extent numbers even half that of 2012, I would think the implications for the following winter would be catastrophic across large portions of the Northern Hemisphere.

So I would say that we are never going to see a truly blue Arctic of under 1M KM2 area/extent. But I think 1.5-2M or so is quite possible and when it does happen it will probably be the catalyst for a major reset a la 2013-2014 but even more prolonged / potent. From that point forward we may have enough cascading albedo momentum to head rather quickly off a cliff into "Younger-er Dryas".
Title: Re: How soon could we go ice free?
Post by: Archimid on June 15, 2018, 05:52:02 AM
Ken Feldman your assumptions are not correct.

 First you should use volume, not extent. Volume hits 0 much sooner than extent, but they must hit 0 at the same time. That means a poof. Volume has all the information of extent already in the calculation. Finally but most important, volume is a measure of the enthalpy of the ice.

Second the Maximum is a better measure than the Minimum. The maximum is the most sensitive to global warming as the winters are getting warmer much faster than the summers are getting warmer. From the maximum you can subtract the expected melt and obtain an expected minimum.

The attached graph shows the Maximum Volume according to PIOMAS from 1979-2018. Many analysis including mine acknowledge that after 2007 there was a significant change in the Arctic. The volatility of both anual losses and annual gains increased dramatically.  I think it is fair to say that there was a change in the system after 2007

I used a linear trend line using the years 2007-2018 and extended it until 2035. I then calculate the average and SD of the losses from 2007-2017.  The bottom lines represent the average, 1SD and 2SD. When the linear trend meets the bottom line Arctic sea ice volume is 0. Like real 0, not virtual.

As you can see if things behave as they behaved in the last 10 years, we'll be without an arctic in less than 10 years.

So when someone said

Quote
No chance of an ice-free Arctic for at least 20 years.

That statement is false. As I said before, there is a very low chance this year, only because we have more volume of ice than in 2017. As the globe keeps warming, winters will warm faster, less ice will be made until one year with low maximum meets a record melt year.
Title: Re: How soon could we go ice free?
Post by: jai mitchell on June 15, 2018, 06:29:23 AM
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2015GL065504

Quote
In the Arctic, it is estimated that approximately 60% of the warming induced by increasing greenhouse gases (GHG) concentrations over the twentieth century has been offset by the combined response to other anthropogenic forcing agents [Najafi et al., 2015], which are dominated by aerosols. Furthermore, Fyfe et al. [2013] argued that the observed decreasing trend in Arctic‐averaged surface temperature between 1939 and 1970 was mainly due to cooling from anthropogenic sulphate aerosols that overwhelmed a significant warming by well‐mixed greenhouse gases (GHG). After 1970, the forcing from continuously increasing GHG concentrations and black carbon emissions overwhelmed the forcing from declining sulphate aerosol loading, which led to a warming of the Arctic [Fyfe et al., 2013].

the 66percentile confidence interval shows a potential ice-free arctic as early as 2020 under RCP 2.6

(https://wol-prod-cdn.literatumonline.com/cms/attachment/3e630f65-e1b6-4b99-a63e-5491732c0dec/grl53504-fig-0004-m.jpg)


-----------
http://acmg.seas.harvard.edu/publications/2017/breider_decadal_arctic_2017.pdf

Quote
Our results show that anthropogenic aerosol yields a negative forcing over the Arctic, with a TOA RF of -0.19 ± 0.05 W /m2 in the present day (2005–2010) and even greater forcing -(0.67 ± 0.06 W/m2 ) in the early 1980s. We find that the 1980–2010 emission reductions in anthropogenic aerosols in the developed world may have contributed +0.27 ± 0.04 K warming to present-day Arctic temperatures at the surface or approximately 25% of the observed Arctic warming. About two thirds of the warming can be attributed to forcing from anthropogenic aerosols over the Arctic, with the rest from forcing over midlatitudes

Our results do not take into consideration RF from aerosol-cloud interactions (indirect effects) or deposition of BC to snow or ice surfaces. As context for our results, we note that AMAP [2015] estimated RFs from aerosol cloud interactions considering both anthropogenic and natural sources of +0.10–0.13 W/ m2 for BC and -0.40–0.75 W/ m2 for sulfate over the Arctic. In another multimodel study, Jiao et al. [2014] reported an RF from BC deposition to Arctic snow and ice of +0.17 W /m2
 
Title: Re: How soon could we go ice free?
Post by: Viggy on June 15, 2018, 06:41:32 AM
The real answer is that we don't have a clue.

None of the models has been around long enough to have a valid skill metric assigned to them, and all the models have been way off in one way or another.  The "science" of Arctic Sea Ice is more like Alchemy than Chemistry.  We do not have an equivalent to the periodic table.  Everything that is said is based upon guesses about what is and has been going on.

(This is not to disparage the good work being done.  It is intended to reject the useless expectations people have about that work.)

I would disagree with DR's comment, because it seems much too sweeping in its scope.

It begins with a statement about "the models" but doesn't differentiate among many different types of models used for many different purposes in the Arctic. CESM is a model, PIOMAS is a model, colleagues of mine have their own model of how light is transmitted through sea ice to feed phytoplankton below.  Are they all equally and utterly worthless? 

The next sentence goes beyond carping about models to assert that the entire "science" (with scare quotes, natch!) of Arctic sea ice is "more like alchemy" ... in other words, it's all worthless.  Not just the models, all science (or "science") in the Arctic.

I don't agree, to put it mildly.

To be completely honest, I thought I agreed with DR's point of view till I read Ned's. Calling current climate models alchemy is the equivalent of saying the Wright Brothers didn't contribute to the history of flight.

We are working with a system where not all the variables are known but it is definitely possible to know them all. And if all the variables are known, then a solution can always be obtained. Saying that our understanding of '5' of the '25' variables isn't of value is a gross misunderstanding of the scientific process.

You are meant to have high expectations of your own work, and others are meant to question it and your pride in your work is meant to defend against those criticisms. Expectations from the work done is the cornerstone of the science. IMO
Title: Re: How soon could we go ice free?
Post by: Feeltheburn on June 15, 2018, 07:25:42 AM
Based on the current weather forceast and low ice volume (I've been very depressed over this since April) could we be ice free by the end of June?

If the DMI modeled ice thickness has any validity, you should be very happy since the ice volume is significantly higher than the past few years at this date. As a result, it is doubtful the arctic will be ice free this year (or any year in the foreseeable future). Also, the NW passage is not likely to open this year. Just my guess.
Title: Re: How soon could we go ice free?
Post by: Dharma Rupa on June 15, 2018, 01:47:15 PM
To be completely honest, I thought I agreed with DR's point of view till I read Ned's. Calling current climate models alchemy is the equivalent of saying the Wright Brothers didn't contribute to the history of flight.

Alchemy became Chemistry.
Title: Re: How soon could we go ice free?
Post by: Tom on June 15, 2018, 02:13:43 PM
The problem I see with applying linear trends to estimate the "ice-free" date is that it doesn't make sense to me that the arctic will continue being able to melt xxx km3 of ice each year.

I assume that as the ice volume reduces it will retreat into the CAB, where it will be more resistant to melt (shorter melting season etc).

Currently the melting season starts first in the peripheral seas.  As warming continues in winter and max volume reduces, presumably comparatively more of the reduction in winter volume will be in the periphery than in the CAB, so it won't be there to be easily melted at the beginning of the melt season.

I'm sure this will make the ice in the CAB easier to melt, but not by enough to make up for the overall volume reduction.

In summary, I think that as the winter max volume reduces the volume of ice melted each year will decline, and there will be a slowing of the rate-of-change in volume reduction (a long-tail decline)

Having posted all this obviously I should point out that I'm just making stuff up based on opinions from this forum  :)  I also think that the system is incredibly complex and trying to predict the future is a fools errand.
Title: Re: How soon could we go ice free?
Post by: Archimid on June 15, 2018, 02:42:35 PM
Quote
As a result, it is doubtful the arctic will be ice free this year

True

Quote
(or any year in the foreseeable future)

False
Title: Re: How soon could we go ice free?
Post by: josh-j on June 15, 2018, 02:43:46 PM
If the DMI modeled ice thickness has any validity, you should be very happy since the ice volume is significantly higher than the past few years at this date. As a result, it is doubtful the arctic will be ice free this year (or any year in the foreseeable future). Also, the NW passage is not likely to open this year. Just my guess.

Archimid beat me to it but there is a massive difference between "this year" and "any year in the foreseeable future". I agree with you regarding the former, but certainly not the latter - and I doubt many scientists studying the ice would agree either.
Title: Re: How soon could we go ice free?
Post by: Daniel B. on June 15, 2018, 03:43:20 PM
Ken Feldman your assumptions are not correct.

 First you should use volume, not extent. Volume hits 0 much sooner than extent, but they must hit 0 at the same time. That means a poof. Volume has all the information of extent already in the calculation. Finally but most important, volume is a measure of the enthalpy of the ice.

Second the Maximum is a better measure than the Minimum. The maximum is the most sensitive to global warming as the winters are getting warmer much faster than the summers are getting warmer. From the maximum you can subtract the expected melt and obtain an expected minimum.

The attached graph shows the Maximum Volume according to PIOMAS from 1979-2018. Many analysis including mine acknowledge that after 2007 there was a significant change in the Arctic. The volatility of both anual losses and annual gains increased dramatically.  I think it is fair to say that there was a change in the system after 2007

I used a linear trend line using the years 2007-2018 and extended it until 2035. I then calculate the average and SD of the losses from 2007-2017.  The bottom lines represent the average, 1SD and 2SD. When the linear trend meets the bottom line Arctic sea ice volume is 0. Like real 0, not virtual.

As you can see if things behave as they behaved in the last 10 years, we'll be without an arctic in less than 10 years.

So when someone said

Quote
No chance of an ice-free Arctic for at least 20 years.

That statement is false. As I said before, there is a very low chance this year, only because we have more volume of ice than in 2017. As the globe keeps warming, winters will warm faster, less ice will be made until one year with low maximum meets a record melt year.

Estimating when the minimum will approach zero based on the maximum measurements is the real falsehood.  The warmer winters/cooler summers have resulted in less ice range over the year.  How can you determine an "expected ice loss", when it is constantly in flux? 
Title: Re: How soon could we go ice free?
Post by: Ned W on June 15, 2018, 04:09:32 PM
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2015GL065504

Quote
In the Arctic, it is estimated that approximately 60% of the warming induced by increasing greenhouse gases (GHG) concentrations over the twentieth century has been offset by the combined response to other anthropogenic forcing agents [Najafi et al., 2015], which are dominated by aerosols. Furthermore, Fyfe et al. [2013] argued that the observed decreasing trend in Arctic‐averaged surface temperature between 1939 and 1970 was mainly due to cooling from anthropogenic sulphate aerosols that overwhelmed a significant warming by well‐mixed greenhouse gases (GHG). After 1970, the forcing from continuously increasing GHG concentrations and black carbon emissions overwhelmed the forcing from declining sulphate aerosol loading, which led to a warming of the Arctic [Fyfe et al., 2013].

the 66percentile confidence interval shows a potential ice-free arctic as early as 2020 under RCP 2.6

(https://wol-prod-cdn.literatumonline.com/cms/attachment/3e630f65-e1b6-4b99-a63e-5491732c0dec/grl53504-fig-0004-m.jpg)

I'm a bit confused.  Where in the Gagne et al. paper that you cite do you find that claim ("the 66percentile confidence interval shows a potential ice-free arctic as early as 2020 under RCP 2.6")?

I don't see that anywhere in the paper.  What I do see is this:
Quote
Indeed, there is a significant difference between the onset of Arctic ice‐free summers in each scenario [...]

The RCP 4.5 simulations project the year of onset for the ensemble mean to be 2045 [...] with the ensemble range to be from 2036 to 2049. [...]

In the RCP 2.6 simulations, the ensemble mean year of onset is 2048 [...] and the ensemble spans the years 2042 to 2075,

while for RCP 8.5 simulations, the ensemble mean year of onset is 2033 [...] and the ensemble ranges from 2032 to 2044.

So that seems to be saying that under RCP 2.6, ice-free conditions in the Arctic appear between 2042 to 2075 in the model ensemble, not 2020, and it's not a "66% confidence interval".

I don't see the number "66" or the word "confidence" anywhere in the paper, nor the year "2020" anywhere except in a minor note about the changing forcing from black carbon.
Title: Re: How soon could we go ice free?
Post by: Archimid on June 15, 2018, 04:18:56 PM
The expected ice loss is the average of the ice lost every melting season from maximum to minimum. The variation of that loss is captured with the standard deviations. The average volume loss for the 2007-2017 is 18.09, with a standard deviation of 1.075.
 
If the winter degradation continues as it has steadily for decades, it's just a matter of a very bad year like 2012 and 0 will be true.

From here on we can discuss known and unknown negative and positive feedbacks all you want, but that is the current state of things.
Title: Re: How soon could we go ice free?
Post by: binntho on June 15, 2018, 04:41:20 PM
These three graphs from Arctische Penguin really say it all. Linear trend shows 0 volume in 2033, exponential in 2023 while gomperz curve seems to trend to the mid thirties. So a ballpark guess of 2025-2035 ?
Title: Re: How soon could we go ice free?
Post by: crandles on June 15, 2018, 04:49:17 PM
Ken Feldman your assumptions are not correct.

 First you should use volume, not extent. Volume hits 0 much sooner than extent, but they must hit 0 at the same time. That means a poof.
...
I used a linear trend line using the years 2007-2018 and extended it until 2035.


If the winter degradation continues as it has steadily for decades,

Just an observation: you attack others for their assumptions being incorrect, then immediately draw a wrong conclusion and use your own big iffy assumptions.

Just because extent and volume must hit zero does not mean there has to be a poof. It is quite possible for both extent and volume to slow down their rate of decline so they both reach zero at the same time which is well after the linear trends.

I can follow what you are saying as an explanation of what you think is the situation but with big iffy assumptions, that doesn't make it correct.

Title: Re: How soon could we go ice free?
Post by: Tor Bejnar on June 15, 2018, 04:59:13 PM
I particularly appreciate Jim Pettit's graphs, available through the ASI Long-term Graphs (https://sites.google.com/site/arcticseaicegraphs/longterm)  page, specifically (in this thread's context) the graph reproduced below.

Any year that maintains the low recent ice volume maximum that is coupled with the already experienced greatest ice loss year will achieve a record low of about 1,000 km^3 of ice. 

I have argued that the less ice there is to start with may decrease the possibility of 'maximum already experienced ice loss' [there is 'harder to melt ice' areas], but the history of actual Arctic-wide ice loss doesn't strongly support this.

I don't expect 'ice free' happening this year, but I see the potential for it happening any year now.  We've experience 'near perfect low ice freezing years' and 'near perfect high ice melting years'; they just haven't happened together, yet.


Title: Re: How soon could we go ice free?
Post by: crandles on June 15, 2018, 05:03:54 PM
These three graphs from Arctische Penguin really say it all. Linear trend shows 0 volume in 2033, exponential in 2023 while gomperz curve seems to trend to the mid thirties. So a ballpark guess of 2025-2035 ?

But why those three? There are any number of curves that fit the data and then do different things.

A 4 parameter gompertz fit is shown below and goes flat pretty much immediately and never gets down to 1000km^3 let alone 0. I don't believe it should or will go flat, as GW continues. But clearly 3 parameter gompertz hitting 1000 km^3 in 2025 is not the most conservative possibility so your 3 graphs don't show the full range of possibilities.
Title: Re: How soon could we go ice free?
Post by: jai mitchell on June 15, 2018, 05:06:53 PM

I don't see the number "66" or the word "confidence" anywhere in the paper, nor the year "2020" anywhere except in a minor note about the changing forcing from black carbon.

Ned,

Model Ensemble range is the range of model outputs without uncertainty estimates.  Go to the Supplemental information and you will find that the green shading in the graphic I posted is the confidence interval of the RCP 2.6 range of all model outputs.  The green shading shows potential ice free conditions under 66% confidence as early as 2020.
Title: Re: How soon could we go ice free?
Post by: jai mitchell on June 15, 2018, 05:11:03 PM
These three graphs from Arctische Penguin really say it all. Linear trend shows 0 volume in 2033, exponential in 2023 while gomperz curve seems to trend to the mid thirties. So a ballpark guess of 2025-2035 ?

But why those three? There are any number of curves that fit the data and then do different things.

A 4 parameter gompertz fit is shown below and goes flat pretty much immediately and never gets down to 1000km^3 let alone 0. I don't believe it should or will go flat, as GW continues. But clearly 3 parameter gompertz hitting 1000 km^3 in 2025 is not the most conservative possibility so your 3 graphs don't show the full range of possibilities.

Crandles,

Every time I see your 4 parameter gompertz fit curve it gives me a chuckle until I realize that you actually seem to believe that this is a potential reality going forward.

I see this assertion of future ice conditions without model or even realistic physical mechanism as a kind of magical thinking.  It would be akin to claiming that butterfly wings in the Amazon are driving sea ice variability and creating a curve to fit this idea.

Then I just figure you are trying to make a point about uncertainty and are just being contrary.
Title: Re: How soon could we go ice free?
Post by: crandles on June 15, 2018, 05:45:38 PM

Every time I see your 4 parameter gompertz fit curve it gives me a chuckle until I realize that you actually seem to believe that this is a potential reality going forward.

I see this assertion of future ice conditions without model or even realistic physical mechanism as a kind of magical thinking.  It would be akin to claiming that butterfly wings in the Amazon are driving sea ice variability and creating a curve to fit this idea.

Then I just figure you are trying to make a point about uncertainty and are just being contrary.

I do try to say every time that I don't literally believe the completely horizontal path extrapolation. I do believe in a continuing downwards path but rate of decline could well be getting a less steep as practically all the models show

>"without model or even realistic physical mechanism"

I see lots of people here doing this (i.e. ignoring models and not considering some physical mechanisms which I believe are realistic) whereas I believe I have considered the major physics involved regarding the slow transition that MYI doesn't get replaced quickly but FYI does essentially get almost completely replaced each year. I don't believe I can prove this is highly significant nor that it is insignificant from basic reasoning of the physics. But discussion of it is in the scientific literature suggesting it is likely to be significant and the data of the last 5 to 12 years seems to be coming down on the side of a slowdown in the rate of decline.

If the models show a slowdown in the rate of decline as zero ice is approached and also the data is tending to show this recently, then assuming the rate will be steady or increase needs some substantial explanation. Without such substantial explanation, the default assumption should be of a declining rate of decline.

I see lots of people here just not wanting to see this.
Title: Re: How soon could we go ice free?
Post by: Ned W on June 15, 2018, 05:55:54 PM

I don't see the number "66" or the word "confidence" anywhere in the paper, nor the year "2020" anywhere except in a minor note about the changing forcing from black carbon.

Ned,

Model Ensemble range is the range of model outputs without uncertainty estimates.  Go to the Supplemental information and you will find that the green shading in the graphic I posted is the confidence interval of the RCP 2.6 range of all model outputs.  The green shading shows potential ice free conditions under 66% confidence as early as 2020.

Thanks for the reply, but:

(1) When I follow your link, the "Supporting Information" contains only two files, labeled Figure S1 and Figure S2.  They are EPS documents with figures that don't directly relate to the figure you posted, and have no explanatory text. 

(2) I do note that in Figure 3 from the paper itself, the caption states that "The shading shows the 5–95% range of uncertainty in the mean from each ensemble of simulations."

So it seems likely to me that the shading in Figure 4 also shows the 90% confidence interval, not the 66% confidence interval you claimed.  I still have no idea where you got that from.

If that's in fact the case, then the best explanation of this would be:

The model ensemble predicts the development of an ice-free Arctic in 2042 to 2075, with a mean of 2048.  The 90% confidence interval extends from approximately 2021 to some unknown year later than 2075.
Title: Re: How soon could we go ice free?
Post by: Ned W on June 15, 2018, 06:00:53 PM
Ken Feldman your assumptions are not correct.

 First you should use volume, not extent. Volume hits 0 much sooner than extent, but they must hit 0 at the same time. That means a poof.
...

Just because extent and volume must hit zero does not mean there has to be a poof. It is quite possible for both extent and volume to slow down their rate of decline so they both reach zero at the same time which is well after the linear trends.

Yes, I agree with crandles.  Currently, some ways of extrapolating the past data show volume reaching zero before extent reaches zero.  There are three possible implications of that:

(1) Extent loss could speed up to match volume
(2) Volume loss could slow down to match extent
(3) Both extent and volume could change to reach zero at some other point

For some reason, a lot of people around here simply assume that (1) is the only possible outcome.  That's wrong. 
Title: Re: How soon could we go ice free?
Post by: Daniel B. on June 15, 2018, 06:29:14 PM
Ken Feldman your assumptions are not correct.

 First you should use volume, not extent. Volume hits 0 much sooner than extent, but they must hit 0 at the same time. That means a poof.
...

Just because extent and volume must hit zero does not mean there has to be a poof. It is quite possible for both extent and volume to slow down their rate of decline so they both reach zero at the same time which is well after the linear trends.

Yes, I agree with crandles.  Currently, some ways of extrapolating the past data show volume reaching zero before extent reaches zero.  There are three possible implications of that:

(1) Extent loss could speed up to match volume
(2) Volume loss could slow down to match extent
(3) Both extent and volume could change to reach zero at some other point

For some reason, a lot of people around here simply assume that (1) is the only possible outcome.  That's wrong.

I agree.  In any three-dimensional object, volume will always change faster than area (or extent in the case of sea ice) initially.  This is simple mathematics; three dimensions changing, compared to two.  A linear change in area, will result in an exponential change in volume (unless the third dimension is somehow held constant.  With the sea ice, the volume has changed faster initially, but will slow as the overall volume decreases.  There is simply less ice to melt.  The most likely scenario is (2), that the extent (or area) will continue on its trend, and volume will adjust.  This is especially true with respect to the sea ice, which has two very large dimensions, and one extremely small dimension (thickness).

Does this preclude other possibilities?  No.  There could be another 2012, with significant wave action to decimate another large chuck of the total sea ice, such that ice-free occurs in a year or so, or it could resemble that gompertz fit, as negative feedbacks dominate, resulting in a higher, minimum sea ice level.  Hard to say, as so many factor influence the annual changes.
Title: Re: How soon could we go ice free?
Post by: Archimid on June 15, 2018, 06:52:52 PM

Just an observation: you attack others for their assumptions being incorrect, then immediately draw a wrong conclusion and use your own big iffy assumptions.

I didn't attack anyone. I merely stated the fact that using extent to determine the first year of 0 ice is wrong because volume hits 0 much sooner. No attack on Ken Feldman. He has been a gentleman so far and his points are backed up by good arguments.  I'm merely pointing at the flaw of his argument.

Quote
Just because extent and volume must hit zero does not mean there has to be a poof. It is quite possible for both extent and volume to slow down their rate of decline so they both reach zero at the same time which is well after the linear trends.

The linear trends clearly point to a poof. Using the minimum, extent hits 0 a few decades after volume. That will be perceived as a poof.

Quote
I can follow what you are saying as an explanation of what you think is the situation but with big iffy assumptions, that doesn't make it correct.

I'm not making any assumption, I'm only looking at the linear trends and that's what they show. Mathematically the most basic assumption one can make, a pair of linear trends clearly points to a poof.


(1) Extent loss could speed up to match volume
(2) Volume loss could slow down to match extent
(3) Both extent and volume could change to reach zero at some other point

For some reason, a lot of people around here simply assume that (1) is the only possible outcome.  That's wrong. 

No one is assuming that is the only possible outcome. That is merely the outcome the basic data points to. Also if you take ice melting mechanisms into account a poof is also quite likely.

Now the really bad news. Most if not all of these models you are talking about use extent (a very crude version of it) to calculate the first ice free Arctic.  That's why they match the extent calculation but not the volume calculation.
Title: Re: How soon could we go ice free?
Post by: Daniel B. on June 15, 2018, 08:16:25 PM
Have you looked at the annual change in ice?  The net change in ice extent (growth-melt) is slightly positive over the past decade.  Half the time, there has been a net loss over a full season, and the other half has seen a net gain.  That is a change from the previous decade, which witnessed much more losses than gains.
Title: Re: How soon could we go ice free?
Post by: Ken Feldman on June 15, 2018, 09:33:48 PM
Most methods used to predict an ice-free Arctic within the next decade are based on linear projections of current trends, with no consideration of feedbacks.  If any feedback is considered, it's usually to over estimate the ice-albedo feedback, which leads to more melt.

There are other feedbacks that impact sea ice, and there is a good summary of them in this study:

http://pubman.mpdl.mpg.de/pubman/item/escidoc:2461121/component/escidoc:2461125/PAGESmagazine_2017_14-19_Notz.pdf (http://pubman.mpdl.mpg.de/pubman/item/escidoc:2461121/component/escidoc:2461125/PAGESmagazine_2017_14-19_Notz.pdf)

Here's an explanation of the negative feedback, which lead to sea ice retention:

Quote
Annual variability: The importance of negative feedbacks

In addition to seasonal forecasts on time scales of a few months, also forecasts on time scales of a few years have made some headlines over the past decade. These headlines were usually related to claims that the Arctic would lose its remaining summer sea ice within just a few years. The underlying reasoning of such claims was often related to a discussion of a possible ’tipping point’ that is related to the ice-albedo feedback. Given the substantial loss of Arctic sea ice in the past few years, the ocean could potentially absorb enough heat to rapidly melt the remainder of the sea ice cover.

However, our current understanding of the Arctic climate system strongly suggests that this reasoning is unrealistic. A first indication for this finding derived from model experiments in which all Arctic sea ice was synthetically removed from the Arctic Ocean at the onset of summer, thus maximising the possible ice-albedo feedback (Tietsche et al., 2011). Despite such maximised feedback, the ice cover recovered in these experiments within just a few years. This is because on annual time scales, negative feedbacks dominate the evolution of the Arctic sea ice cover. Three negative feedbacks are particularly important: First, the open ocean very effectively releases its heat to the atmosphere during winter, causing a rapid loss of much of the heat that was accumulated in the icefree water during summer. Second, the thin ice that forms during winter can grow much more rapidly than ice that survived the summer, because heat can more effectively be transported from the ocean to the atmosphere when the ice cover is thin (Bitz and Roe, 2004). Third, as ice forms later in the season, it will carry a thinner insolating snow cover as any snow fall occurring before ice formation simply falls into the open ocean (Notz, 2009).

The effectiveness of these negative feedbacks on an annual time scale is not only apparent in our model simulations; the observed time series of Arctic summer sea ice also carries a clear signature of such mechanisms. A year with a strong drop in ice coverage during September is usually followed by an increase in September ice coverage in the following year. More formally, the time series shows significant negative autocorrelation (Notz and Marotzke, 2012). If indeed the ice albedo feedback was as effective on annual time scales as implied by statements supporting the entire loss of Arctic summer sea ice within this decade, one would certainly expect that any year with a strong drop in ice coverage would be followed by a year with yet another drop. This is found neither in the observational record, nor in model simulation. This underpins the dominance of negative feedbacks, which stabilize the Arctic ice cover and prevent a possible “tipping point”.
Title: Re: How soon could we go ice free?
Post by: johnm33 on June 16, 2018, 02:36:28 AM
I'm looking at ice dynamics, there are 3 main factors afaics, the main one being the expansion/dispersion of ice with every weather change. That is that as the ice moves creating gaps these are rapidly filled with new ice, the cumulative effect is to push the ice south away from the centre of the ice mass, generally south. As the ice moves south to maintain station it has to accelerate by about 24kph per deg, it doesn't, hence it appears to rotate c/w,  there are pinch points and the ice builds up against the coast, where?  (https://geology.com/world/arctic-ocean-bathymetry-map.jpg)  well as far south as Prince Patrick island on the american side, and after the freedom of Beaufort from the NSI through NZ-FJ to Svalbard on the Russian side.
The next factor is the entry of Atlantic water, previously the ice in Barents suppressed the tides, I think ocean currents are residuals of tidal movements, the tides are no longer suppressed and new currents are forming, these currents help to keep Barents free of ice, being free of ice gives the wind free reign, so over the continental shelf the waves thrash the ice, it melts and no longer rotates to accumulate on the american side.     
The third factor is an ice free Amundsen gulf, every tide there can shift a significant fraction of 20,0002km of seawater/ice westward across southern Beaufort, and conversely suck in a similar amount from further north in Beaufort.
Nothing to do with ice but one has to bear in mind that Atlantic/Pacific waters entering the arctic tend to rotate ccw.
If the growing currents coming in from the Atlantic can weaken the ice over the ESAS in concert with weather systems bringing heat from the south, and persistent winds from E/W then the Siberian shelf will also become a killing field for ice. Which gives the possibility of no ice to rotate into the islands, no ice to rotate back towards Amundsen, whats next?
 Well given that systems tend to hold on beyond any reasonable expectation and then suddenly collapse, it's remotely possible that it happens this year, but I don't think we've passed beyond reasonable expectation yet we're close.
Title: Re: How soon could we go ice free?
Post by: Dharma Rupa on June 16, 2018, 02:49:57 AM
If the models show a slowdown in the rate of decline as zero ice is approached and also the data is tending to show this recently, then assuming the rate will be steady or increase needs some substantial explanation. Without such substantial explanation, the default assumption should be of a declining rate of decline.

Given the currently demonstrated skill of the global models, the default assumption ought to be "we don't know."

Any other assumption is pure hubris.
Title: Re: How soon could we go ice free?
Post by: Archimid on June 16, 2018, 03:09:55 AM
Quote
(Tietsche et al., 2011)

That study is dated. Some of their results are already exceeded by real life events like winter temperature anomalies. Winters are getting significantly warmer, very fast. Their assumptions are now incorrect even before the first BOE.
Title: Re: How soon could we go ice free?
Post by: DavidR on June 16, 2018, 03:34:10 AM

I don't expect 'ice free' happening this year, but I see the potential for it happening any year now.  We've experience 'near perfect low ice freezing years' and 'near perfect high ice melting years'; they just haven't happened together, yet.
I  agree.  We have never seen a volume loss greater than 20K km^3 however the trend is clearly that we will be starting below that figure by 2025. On average each year we are seeing the loss in volume from the previous year increasing.

The loss from May  31st ranges from ~16.2K km^3 to  ~13.5K km^3 over the past  40 years but the trend value is a steady ~15.  However loss of volume does not equate directly  to loss of extent.  2015 lost  15.82K Km^3 after 31 May compared to  2012's 15.92, however 2012 lost more than 1.6 M km^2 more extent than 2015.  Even the volume loss from August  1st  was very  similar.  2012 lost  2.87K Km^3 whereas 2015 lost 2.80K Km^3.

Another example is that 2016 lost about 10% more volume and extent than 2012 after August 1st, despite not having a GAC. Basically confidence in any prediction from now should be low. But a minimum below 4K Km^3 in 2018 seems highly improbable.
Title: Re: How soon could we go ice free?
Post by: Wherestheice on June 16, 2018, 04:01:14 AM
Study: https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/grl.50316

" Time horizons for a nearly sea ice‐free summer for these three approaches are roughly 2020 or earlier, 2030 ± 10 years, and 2040 or later."
Title: Re: How soon could we go ice free?
Post by: Sleepy on June 16, 2018, 06:07:27 AM
How soon could we...? Within a week or so, if we really wanted to.
Title: Re: How soon could we go ice free?
Post by: slow wing on June 16, 2018, 06:11:27 AM
... If the models show a slowdown in the rate of decline as zero ice is approached and also the data is tending to show this recently...

Which models are you referring to? I've never seen a physics-based model with good predictive ability on this trend. True, there are models that don't work well, e.g. for the IPCC studies. If the model can't find the recent trend then it's not much use for predicting future trends.

Why do you say the data is showing a slowdown recently? If I look back at the linear fit of #97 then the residuals are all over the place and I don't see that trend. Based on the second plot, I suspect a quadratic fit would also curve downwards rather than upwards.


  If we're looking for a physical reason for a slowdown then I would point to the existence of a 'sanctuary region' against the North side of the CAA and Greenland where the ice hasn't melted out in any year.

  The prevailing combination of winds and current tends to push the ice against the coast - it has every single season we've been observing. It's deep water so the warm salty Atlantic waters can't get to it - their higher salinity makes them denser so they dive down instead.

   That's where the remaining multi-year ice is, so that also makes it harder to melt through.

   It might even be that it's cloudier there in the Summer than over the rest of the Arctic basin, so it sees less sun? (True or false? I have that impression but may be wrong.)
 
   So the first year below 1 million square kilometres should be the first year where the ice sanctuary is no longer effective, for whatever reason. The ice gets pushed away from there and/or melts in situ.


   When will that happen? I don't know. But the presence of an identifiable ice sanctuary region provides an arguable physical reason for a potential future slowdown in the rate of the year-to-year decline in minimum sea ice extent.
Title: Re: How soon could we go ice free?
Post by: crandles on June 16, 2018, 01:40:11 PM
I didn't attack anyone.

Sorry if the word attack came across as implying acrimonious discussion.


I'm not making any assumption, I'm only looking at the linear trends and that's what they show.

I think the observation stands.
Title: Re: How soon could we go ice free?
Post by: Archimid on June 16, 2018, 02:43:01 PM
What observation? That the basic data clearly indicates a poof? That's not iffy. That must be the base assumption. In my opinion, the "iffy" assumption is to use a 2 dimensional, enthalpy ignoring mechanism to determine the first ice free Arctic. Any model that uses a "slab of ice" to analyse the past and make projections for the future is missing the big picture.
Title: Re: How soon could we go ice free?
Post by: crandles on June 16, 2018, 03:10:37 PM
What observation? That the basic data clearly indicates a poof? That's not iffy. That must be the base assumption. In my opinion, the "iffy" assumption is to use a 2 dimensional, enthalpy ignoring mechanism to determine the first ice free Arctic. Any model that uses a "slab of ice" to analyse the past and make projections for the future is missing the big picture.



I'm not making any assumption, I'm only looking at the linear trends and that's what they show.

"I'm only looking at the linear trends" is just another way of saying 'if the linear trend continues' and that is an assumption you are making even if you want to try and say you are not making any assumption. FWIW I think you are making yourself sound ridiculous by clearly contradicting yourself.

As Ned W said

Yes, I agree with crandles.  Currently, some ways of extrapolating the past data show volume reaching zero before extent reaches zero.  There are three possible implications of that:

(1) Extent loss could speed up to match volume
(2) Volume loss could slow down to match extent
(3) Both extent and volume could change to reach zero at some other point

For some reason, a lot of people around here simply assume that (1) is the only possible outcome.  That's wrong. 

We both think the other is making big iffy assumptions. I think I have made the point and attempted clarification enough times, time to agree to disagree.
Title: Re: How soon could we go ice free?
Post by: crandles on June 16, 2018, 04:00:09 PM
... If the models show a slowdown in the rate of decline as zero ice is approached and also the data is tending to show this recently...

Which models are you referring to? I've never seen a physics-based model with good predictive ability on this trend. True, there are models that don't work well, e.g. for the IPCC studies. If the model can't find the recent trend then it's not much use for predicting future trends.

Why do you say the data is showing a slowdown recently? If I look back at the linear fit of #97 then the residuals are all over the place and I don't see that trend. Based on the second plot, I suspect a quadratic fit would also curve downwards rather than upwards.

Lots of models. There are lots of graphs like attached below, some with many more model runs on them.

>" good predictive ability on this trend."

Clearly not they are all over the place on level of ice and also the trend. While some don't have enough data to see, all the model runs where you can see the change in trend where ice approaches zero is for the trend to get less steep as zero ice is approached.

Do we throw out all evidence because they are all over the place wrt level and trend? Or, do we say yes not much good for level or trend, but it looks like they all agree on trend in slope as zero ice is approached? So don't use them where they are bad but do use them for what they are good at, ie suggesting the change in trend as zero ice is approached declines.

>"Why do you say the data is showing a slowdown recently?"

The 4 parameter gompertz fit has a single inflection point. Whether I use Sept or April, that inflection point occurs in 2005. We have 12 years data since that inflection point. If there was only ~6 or fewer years data since the inflection point, I would be inclined to the opinion that 4 parameters might be too many parameters and I was overfitting. So just random residuals in last few years was allowing a better fit by using too many parameters. However with 12 years data past the infection point, that is too much data led and seems to me to be indicative that the data is showing a decline in the rate of decline.

See 4 parameter gompertz fit at top of this page.

>"If we're looking for a physical reason for a slowdown then I would point to the existence of a 'sanctuary region' against the North side of the CAA and Greenland where the ice hasn't melted out in any year."

Certainly wouldn't disagree with that being one physical reason, but I think there are lots of others.

I would tend to add in albedo feedback to this explanation (as well as deep water). In areas where ice moves out of the area, melting and ice movement allows albedo to drop and more sunlight energy be absorbed and this obviously helps additional melting. In contrast where ice piles up against Greenland & CAA, ice tend to move into area. So rather than melting and movement of ice causing extra area to open up, movement tend to close up areas opened by melting so it is much harder to get albedo drops to assist the melting.


If the ice retreats to a smaller area, that relevant area receives less sunlight energy so less volume melts seems quite possible. I guess this is complicated by winds bringing warmer temperature air so it isn't clear whether this accelerates or decelerates the volume of melt so maybe we need to look to the data and/or models?

Then there is oft discussed failure of MYI to make it around Beaufort gyre leading to rapid collapse of MYI to much lower proportion of the ice over a few years, but once we are down to these lower levels there is more FYI which almost completely recoveres itself each winter.

Are the people on these forums thinking through these reasonings and rejecting them because they don't believe they are significant compared to positive feedbacks they believe in? Or are they just rejecting the reasonings because it is just not exciting or they want to see catastrophic decline in sea ice or .... ?

Title: Re: How soon could we go ice free?
Post by: Archimid on June 16, 2018, 05:04:01 PM
Quote
"I'm only looking at the linear trends" is just another way of saying 'if the linear trend continues' and that is an assumption you are making even if you want to try and say you are not making any assumption.

The good thing about linear trends is that they have no human introduced bias. When you all go on fantastical trips with gompertz curves or exponential fits all you are doing is adding your bias to the projection. Sure, your bias might be informed by smart speculation but it is also affected by your errors and incomplete knowledge.

Quote
FWIW I think you are making yourself sound ridiculous by clearly contradicting yourself.

I think you do not understand the power of simplicity and the risk of complexity. A linear trend has no human bias. It is the simplest operation that can be be used to fit a line to data. As such, it is what it is. Any projections made with it assumes the past will repeat. Assuming the past will repeat is not iffy, it's a pilar of science.

Quote
We both think the other is making big iffy assumptions. I think I have made the point and attempted clarification enough times, time to agree to disagree.

Nope. You are objectively making iffy assumptions.

1. Extent vs volume. Volume is a 3D measure and a measure that's directly related to the enthalpy of the ice. Extent is 2D abstraction with no information about enthalpy.

2. Projections made only using the Minimum. The minimum alone is a much a weaker measure to determine the future of the arctic. I used both, the Maximum directly and the Minimum represented as anual loss. I used the most basic representation I could think to keep my bias out. The only bias I used is the selection of  2007-2017 as the years to compute the loss average and I think the data justifies it as well as the physics.

3. Models that use a slab of ice are using a very iffy simplification.
Title: Re: How soon could we go ice free?
Post by: Dharma Rupa on June 16, 2018, 06:37:14 PM
Do we throw out all evidence because they are all over the place wrt level and trend? Or, do we say yes not much good for level or trend, but it looks like they all agree on trend in slope as zero ice is approached? So don't use them where they are bad but do use them for what they are good at, ie suggesting the change in trend as zero ice is approached declines.

I'm trying to remember the correct name for this fallacy, but it is basically a combination of following the herd and appeal to authority.

Is there any evidence of skill in any of these projections?  If you could show that any of them have in the past been skillful in projecting a decrease in the slope as the ice approaches zero, but since that is impossible to demonstrate...


Title: Re: How soon could we go ice free?
Post by: Dharma Rupa on June 16, 2018, 06:48:57 PM
The most common pattern in general systems dynamics is slow change until an inflection point is reached, followed by a sudden a dramatic change to a new state.  In the mathematics, these sudden changes at inflection points in the potential surface are called catastrophes.  This is where the potential surface no longer supports the current situation and the system has to fall to a new meta-stable state where the potential surface once again supports slow change.

The important thing to note is that we do not have the information required to determine the slope of the potential surface, and therefore cannot have a clue when there will be a catastrophe.



Title: Re: How soon could we go ice free?
Post by: magnamentis on June 16, 2018, 07:17:16 PM
interesting page thus far, keep going LOL

thing is that there is a lot of knowledge provided in such disputes and this is good for
neutral observers to learn.

just one thing caught my eyes, i'm an analyst not a scientist but that said:

if there is a given amount of ice volume, we can loose a certain percentage per years (average)
and that makes a certain amount of ice volume.

since the volume shrinks either the same loss in percent is less absolute volume lost
or the same absolute volume lost would be a higher percentage.

this thought to the last year of the process it we shall loose 100% of the ice in one single year as compared to last year, while the amount of volume lost that year will be much smaller than the volume we lost i.e. in the year 2012.

this is why i like to look at the big picture and keep it simple but if i say "I like" or "I prefer" that does not mean to keep others from trying to be more accurate but at a higher risk to err. ;)

thing is that the knowledge gathered in the process of finding different ways is good and useful
for everyone who joins the club later in time. this is how we develop.

Title: Re: How soon could we go ice free?
Post by: jdallen on June 16, 2018, 07:31:46 PM
The most common pattern in general systems dynamics is slow change until an inflection point is reached, followed by a sudden a dramatic change to a new state.  In the mathematics, these sudden changes at inflection points in the potential surface are called catastrophes.  This is where the potential surface no longer supports the current situation and the system has to fall to a new meta-stable state where the potential surface once again supports slow change.

The important thing to note is that we do not have the information required to determine the slope of the potential surface, and therefore cannot have a clue when there will be a catastrophe.
And I think one of those inflection points was 2012. 

Folding in points crandles makes about a system with mostly FYI vs MYI, 2012 and the following years have made exactly that transition.

As a result, a major, MAJOR variable in the dynamic has been taken out of play - something like 95% of the 3+ Meter MYI that used to exist for thousands of years in the Arctic is gone, and it happened in an eyeblink.

The over-all volatility of the system vis-a-vis extent, area and (albeit at a significantly lower level) volume has increased immensely.

With this volatility, statistically it may be we want to look more closely for modal points, rather than median or mean.  I think that will be more reflective of the actual state of the system - as governed by total heat content as affected by seasonal inputs/losses caused by weather and ocean currents.
[edit]
With the loss of MYI, particularly the thicker, 3+M 3+year old ice, the Arctic has lost its "long term memory".  As such the year over year relevance of a previous season's starting and ending states has diminished dramatically.  With out that "information" being carried over, each year is a completely new dice roll, increasingly independent of past ice states.
Title: Re: How soon could we go ice free?
Post by: Archimid on June 16, 2018, 07:37:52 PM
magnamentis, I think the attached graph illustrates what you are saying. It shows the total volume lost from Maximum to Minimum divided by the volume at Maximum. I haven't fully digested that graph yet but any insight would be appreciated.
Title: Re: How soon could we go ice free?
Post by: gerontocrat on June 16, 2018, 07:41:02 PM
How soon could we...? Within a week or so, if we really wanted to.

I gave up Ice for Lent. It was real heavy, man. Cold Turkey stinks.

Meanwhile - a little "reductio ad adsurdum" spreadsheet I did last year when the same discussion happened. This extremely crude effort does show that using the linear fit as in PIOMAS volume and NSIDC extent graphs to project the future must eventually crash against reality.

Title: Re: How soon could we go ice free?
Post by: jdallen on June 16, 2018, 07:45:42 PM
magnamentis, I think the attached graph illustrates what you are saying. It shows the total volume lost from Maximum to Minimum divided by the volume at Maximum. I haven't fully digested that graph yet but any insight would be appreciated.
And that, is a measure of increasing volatility.
Title: Re: How soon could we go ice free?
Post by: jdallen on June 16, 2018, 07:47:58 PM
I see better quantifying three factors and how they are changing over time will improve our skillfulness in determining when the ice will drop under 1 million KM2.

(1) Total Arctic ocean heat content
(2) Annual variations in oceanic heat transport into the Arctic
(3) Variations in the annual Arctic heat budget as modified by weather
Title: Re: How soon could we go ice free?
Post by: Daniel B. on June 16, 2018, 08:00:55 PM
Quote
"I'm only looking at the linear trends" is just another way of saying 'if the linear trend continues' and that is an assumption you are making even if you want to try and say you are not making any assumption.

The good thing about linear trends is that they have no human introduced bias. When you all go on fantastical trips with gompertz curves or exponential fits all you are doing is adding your bias to the projection. Sure, your bias might be informed by smart speculation but it is also affected by your errors and incomplete knowledge.

Quote
FWIW I think you are making yourself sound ridiculous by clearly contradicting yourself.

I think you do not understand the power of simplicity and the risk of complexity. A linear trend has no human bias. It is the simplest operation that can be be used to fit a line to data. As such, it is what it is. Any projections made with it assumes the past will repeat. Assuming the past will repeat is not iffy, it's a pilar of science.

Quote
We both think the other is making big iffy assumptions. I think I have made the point and attempted clarification enough times, time to agree to disagree.

Nope. You are objectively making iffy assumptions.

1. Extent vs volume. Volume is a 3D measure and a measure that's directly related to the enthalpy of the ice. Extent is 2D abstraction with no information about enthalpy.

2. Projections made only using the Minimum. The minimum alone is a much a weaker measure to determine the future of the arctic. I used both, the Maximum directly and the Minimum represented as anual loss. I used the most basic representation I could think to keep my bias out. The only bias I used is the selection of  2007-2017 as the years to compute the loss average and I think the data justifies it as well as the physics.

3. Models that use a slab of ice are using a very iffy simplification.

Choosing a linear trend is just as biased as choosing any other.  There is no mathematical reason that the sea ice should follow any mathematical expression.  Choosing the trend that gives your preferred answer is in itself subjective.  Past data does not follow a linear trend, why should future changes?  The Arctic is a complex environment.  Why would you think it can be represented by a simple expression?  We are all making assumptions.  You should not delude yourself by believing that your analysis is above that.
Title: Re: How soon could we go ice free?
Post by: Wherestheice on June 16, 2018, 08:57:37 PM
Quote
"I'm only looking at the linear trends" is just another way of saying 'if the linear trend continues' and that is an assumption you are making even if you want to try and say you are not making any assumption.

The good thing about linear trends is that they have no human introduced bias. When you all go on fantastical trips with gompertz curves or exponential fits all you are doing is adding your bias to the projection. Sure, your bias might be informed by smart speculation but it is also affected by your errors and incomplete knowledge.

Quote
FWIW I think you are making yourself sound ridiculous by clearly contradicting yourself.

I think you do not understand the power of simplicity and the risk of complexity. A linear trend has no human bias. It is the simplest operation that can be be used to fit a line to data. As such, it is what it is. Any projections made with it assumes the past will repeat. Assuming the past will repeat is not iffy, it's a pilar of science.

Quote
We both think the other is making big iffy assumptions. I think I have made the point and attempted clarification enough times, time to agree to disagree.

Nope. You are objectively making iffy assumptions.

1. Extent vs volume. Volume is a 3D measure and a measure that's directly related to the enthalpy of the ice. Extent is 2D abstraction with no information about enthalpy.

2. Projections made only using the Minimum. The minimum alone is a much a weaker measure to determine the future of the arctic. I used both, the Maximum directly and the Minimum represented as anual loss. I used the most basic representation I could think to keep my bias out. The only bias I used is the selection of  2007-2017 as the years to compute the loss average and I think the data justifies it as well as the physics.

3. Models that use a slab of ice are using a very iffy simplification.

Choosing a linear trend is just as biased as choosing any other.  There is no mathematical reason that the sea ice should follow any mathematical expression.  Choosing the trend that gives your preferred answer is in itself subjective.  Past data does not follow a linear trend, why should future changes?  The Arctic is a complex environment.  Why would you think it can be represented by a simple expression?  We are all making assumptions.  You should not delude yourself by believing that your analysis is above that.

The Arctic is changing rapidly. The ice is going away. How ever you think the data will go, the ice is gonna go away
Title: Re: How soon could we go ice free?
Post by: magnamentis on June 16, 2018, 10:31:34 PM
magnamentis, I think the attached graph illustrates what you are saying. It shows the total volume lost from Maximum to Minimum divided by the volume at Maximum. I haven't fully digested that graph yet but any insight would be appreciated.

yeah something along this line i meant, thanks.

you IMO there are many experts/scientists around here and on the other side there are the, let's call them "phiolosphers"

experts are often narrow minded but have gathered a huge knowledge in their specific field
while philosophers (thinkers translated from greek) often have the bigger picture in mind but lack specific and detailed knowledge in all the fields the ponder about.

only way to overcoe this gap is to overcome the personal bias and ego to join forces.

one of the greater difficulties is that people with a great mind often have great energy reserves and those are not easy to hold in check, which is probably one of the main reasons why genuinely wise men/women are usually of a certain advanced age. the good old council of the wise has most often if not always been the council of the elder.

so since this is more or less a given thing, the only thing we can do is to approach everything and any discussion with a huge amount of goodwill (good intention)  this will ultimately soften things and keep the animal like hormone driven macho behaviour in check LOL

( this is a general statement, no-one specific in mind except perhaps myself LOL)
Title: Re: How soon could we go ice free?
Post by: Richard Rathbone on June 16, 2018, 10:57:41 PM

Choosing a linear trend is just as biased as choosing any other.  There is no mathematical reason that the sea ice should follow any mathematical expression.  Choosing the trend that gives your preferred answer is in itself subjective.  Past data does not follow a linear trend, why should future changes?  The Arctic is a complex environment.  Why would you think it can be represented by a simple expression?  We are all making assumptions.  You should not delude yourself by believing that your analysis is above that.

Noise is normally higher frequency than signal, which means linear tends to fit the signal compared to higher order functions tending to fit the noise, which generally leads to much wider margins of error than when extrapolating a linear fit.
Title: Re: How soon could we go ice free?
Post by: magnamentis on June 16, 2018, 11:29:25 PM
linearity even though it does not necessarily predict the future correctly is an honest, hence NOT biased effort based on facts of the past while any algorithm contains an idea for the future development with a certain claim to do it better than others which is exactly the reason for
at times unpleasant discussions, it's a form of competition while linearity does not claim anything, it' simply draws a line based on the past and provides a rough visual where we're heading.

again, don't get me wrong, both are valid approaches, it just depends a bit on the motives. if the motives are some kind of profiling and elevate oneself over the rest it's of lesser value than if the motives are a kind of exchange and brainstorming.

it's similar to religions, if the motives are to make people behave ethical it's ok, if the motives are to get rich, recognized, renown etc. or to claim to be the only one who knows the truth it's not.

Title: Re: How soon could we go ice free?
Post by: Dharma Rupa on June 17, 2018, 12:01:29 AM
And I think one of those inflection points was 2012. 

I am rather unclear on 2012....there is a difference between the point of inflection and the point where the system has to fall away from the potential surface in order to reorganize.

It is, however, clear to me that in late December 2015 the Arctic climate became disconnected from its prior meta-stable state.

It could very well be true that the inflection was reached sometime in 2012 and it took 3 years to start into freefall.

[ed: Note: I am assuming a continuous potential surface.  There is no real known reason to assume that, but it has seemed to work in the past.]
Title: Re: How soon could we go ice free?
Post by: Neven on June 17, 2018, 12:41:13 AM
Comment by new member further upthread that I had to release first:

The problem I see with applying linear trends to estimate the "ice-free" date is that it doesn't make sense to me that the arctic will continue being able to melt xxx km3 of ice each year.

I assume that as the ice volume reduces it will retreat into the CAB, where it will be more resistant to melt (shorter melting season etc).

Currently the melting season starts first in the peripheral seas.  As warming continues in winter and max volume reduces, presumably comparatively more of the reduction in winter volume will be in the periphery than in the CAB, so it won't be there to be easily melted at the beginning of the melt season.

I'm sure this will make the ice in the CAB easier to melt, but not by enough to make up for the overall volume reduction.

In summary, I think that as the winter max volume reduces the volume of ice melted each year will decline, and there will be a slowing of the rate-of-change in volume reduction (a long-tail decline)

Having posted all this obviously I should point out that I'm just making stuff up based on opinions from this forum  :)  I also think that the system is incredibly complex and trying to predict the future is a fools errand.
Title: Re: How soon could we go ice free?
Post by: magnamentis on June 17, 2018, 01:03:55 AM
The problem I see with applying linear trends to estimate the "ice-free" date is that it doesn't make sense to me that the arctic will continue being able to melt xxx km3 of ice each year.

I assume that as the ice volume reduces it will retreat into the CAB, where it will be more resistant to melt (shorter melting season etc).

a) i agree with what you're saying about a slow down due to where the ice will be mainly located in the future while we don't know for sure what the impact on much more surrounding open water much earlier and with much lower albedo will have on melt-out and before that on general temperature level in the high arctic.

it may well be that positive feedbacks will even accelerate the death stroke to the reminder, after all the ice above 80N is not very thick and the north pole at times is already now showing larger areas of open water.

what i disagree with is the word "estimate"

a linear curve can very well provide a clue as to about when, +/- a few years, we shall reach zero ice while if you had used the word "predict" i'd fully agree because a prediction is stronger, claims more than an rough estimate, but that's a detail, i think i understand you general direction of thinking and the main content of your post and it's a valid possibility, even though, as explained above, not totally certain as well (IMHO)
Title: Re: How soon could we go ice free?
Post by: jdallen on June 17, 2018, 01:05:04 AM
And I think one of those inflection points was 2012. 

I am rather unclear on 2012....there is a difference between the point of inflection and the point where the system has to fall away from the potential surface in order to reorganize.

It is, however, clear to me that in late December 2015 the Arctic climate became disconnected from its prior meta-stable state.

It could very well be true that the inflection was reached sometime in 2012 and it took 3 years to start into freefall.

[ed: Note: I am assuming a continuous potential surface.  There is no real known reason to assume that, but it has seemed to work in the past.]
You may be right about 2015. 

My assumption was based around the disappearance of MYI it represented.  But then, both 2011 and 2010 were very hard on MYI as well. 

Perhaps we should look at it as a range instead - 2010-2015 - where the catastrophe took place, and the system tumbled into a new state sufficiently disconnected from the previous regime that we can't recover to it without serious changes elsewhere in the system.
Title: Re: How soon could we go ice free?
Post by: Dharma Rupa on June 17, 2018, 02:31:05 AM
And I think one of those inflection points was 2012. 

I am rather unclear on 2012....there is a difference between the point of inflection and the point where the system has to fall away from the potential surface in order to reorganize.

It is, however, clear to me that in late December 2015 the Arctic climate became disconnected from its prior meta-stable state.

It could very well be true that the inflection was reached sometime in 2012 and it took 3 years to start into freefall.

[ed: Note: I am assuming a continuous potential surface.  There is no real known reason to assume that, but it has seemed to work in the past.]
You may be right about 2015. 

My assumption was based around the disappearance of MYI it represented.  But then, both 2011 and 2010 were very hard on MYI as well. 

Perhaps we should look at it as a range instead - 2010-2015 - where the catastrophe took place, and the system tumbled into a new state sufficiently disconnected from the previous regime that we can't recover to it without serious changes elsewhere in the system.

I can buy into that.  The loss of MYI leads to the open water, leads to higher humidity -- leads to warmer winters, but not much warmer summers.  Basically, everything you would expect in a warming climate.  In that viewpoint the state of the ice is sort of a side-show.
Title: Re: How soon could we go ice free?
Post by: jdallen on June 17, 2018, 02:50:36 AM
And I think one of those inflection points was 2012. 
<snippage>
It is, however, clear to me that in late December 2015 the Arctic climate became disconnected from its prior meta-stable state.
<snippage>
You may be right about 2015. 
<snippage>
I can buy into that.  The loss of MYI leads to the open water, leads to higher humidity -- leads to warmer winters, but not much warmer summers.  Basically, everything you would expect in a warming climate.  In that viewpoint the state of the ice is sort of a side-show.
Precisely!

It does have some causal effect on changing conditions, but in and of itself, is more of an effect than a cause.

I was thinking that a blue water Arctic would be the next inflection point, but the more I think about it, it's not preventable.  We are already in the chute. Namely current changes which have already taken place cannot be undone quickly enough to prevent it, nor is it likely that  that even if some systems stabilized, the momentum of the system could be prevented from still carrying us over the edge.
Title: Re: How soon could we go ice free?
Post by: Dharma Rupa on June 17, 2018, 03:14:41 AM
I was thinking that a blue water Arctic would be the next inflection point, but the more I think about it, it's not preventable.  We are already in the chute. Namely current changes which have already taken place cannot be undone quickly enough to prevent it, nor is it likely that  that even if some systems stabilized, the momentum of the system could be prevented from still carrying us over the edge.

Since I am of the opinion that the Industrial Revolution sealed our fate about 200 years ago I don't worry too much about current affairs.  (We shall see, but the demonstrated skill of the global models isn't any better than my guess.)

I am just here watching the show while I am still alive.  (A 65-year-old lung cancer survivor with one lung.)

We can at least take heart that current measurements of the system state are not too bad.
Title: Re: How soon could we go ice free?
Post by: DavidR on June 17, 2018, 03:29:40 AM
The problem I see with applying linear trends to estimate the "ice-free" date is that it doesn't make sense to me that the arctic will continue being able to melt xxx km3 of ice each year.

I assume that as the ice volume reduces it will retreat into the CAB, where it will be more resistant to melt (shorter melting season etc).

Currently the melting season starts first in the peripheral seas.  As warming continues in winter and max volume reduces, presumably comparatively more of the reduction in winter volume will be in the periphery than in the CAB, so it won't be there to be easily melted at the beginning of the melt season.

I'm sure this will make the ice in the CAB easier to melt, but not by enough to make up for the overall volume reduction.

In summary, I think that as the winter max volume reduces the volume of ice melted each year will decline, and there will be a slowing of the rate-of-change in volume reduction (a long-tail decline)

Having posted all this obviously I should point out that I'm just making stuff up based on opinions from this forum  :)  I also think that the system is incredibly complex and trying to predict the future is a fools errand.
The ice is not really retreating into the CAB but into the sheltered coast north of Greenland and Canada.  We can see from the behavior of Okhotsk, Kara and the Canadian Archipelago  that protected waters shelter the ice.  These areas retain ice long after open ocean and similar latitudes.  Summer Ice is already  melting  out very  close to the North Pole on the Russian side which gets the bulk of the heat from the south.  Both the currents and the geography point to  greater warmth on that  side of the Arctic. 

Warmer water, which is the primary driver of the increasing volume melt  continues to  flow into the Arctic via the Atlantic current and to a  lesser extent the Bering  strait, driving colder water out through Fram and the Canadian Archipelago.

The fact that both ocean and air temperatures are increasing means that the Arctic will continue to absorb increasing levels of warmth. According to GISS the last two years in the Arctic have been warmest on record and a step upwards from the previous 10 years.    https://data.giss.nasa.gov/gistemp/tabledata_v3/ZonAnn.Ts+dSST.csv.

As you  can see from the attached graph arctic temperature anomalies were fairly steady  from 2005 to 2015 but then leapt  significantly in 2016, 2017 beat every year prior to 2016 and 2018 is shaping up  to be warmer than 2017 according to NOAA particularly in the high Arctic. 

I can't see any reason for this heat transport into the Arctic to weaken, or for the current increasing annual decline in volume to slow in any way. The peripheral seas that retain summer extent can not maintain a million km ^2 in area or 1000 km^3 in volume. One year soon we will see a small increase in volume combined with a large decline the following year and the CAB will  be essentially blue all over.  Following that a blue arctic will become normal in summer very  quickly. By 2030 we could be seeing three months a year of open water in the Arctic. 
Title: Re: How soon could we go ice free?
Post by: Sleepy on June 17, 2018, 07:50:05 AM
How soon could we...? Within a week or so, if we really wanted to.

I gave up Ice for Lent. It was real heavy, man. Cold Turkey stinks.

Meanwhile - a little "reductio ad adsurdum" spreadsheet I did last year when the same discussion happened. This extremely crude effort does show that using the linear fit as in PIOMAS volume and NSIDC extent graphs to project the future must eventually crash against reality.
Crash against reality they will. 2030's seems most likely right now.
The somewhat amusing part for me was that this topic started on May 28 2017 with this question; "could we be ice free by the end of June?"

(https://forum.arctic-sea-ice.net/index.php?action=dlattach;topic=1021.0;attach=98826;image)
(https://forum.arctic-sea-ice.net/index.php?action=dlattach;topic=1021.0;attach=95373;image)
Title: Re: How soon could we go ice free?
Post by: crandles on June 17, 2018, 12:25:37 PM
To me, the residuals look fairly random and have no obvious particular trend in residual size.
Title: Re: How soon could we go ice free?
Post by: crandles on June 17, 2018, 12:57:26 PM
Can we stick to 2005 as the point of inflection.

For piecewise linear fits there may well be discontinuities in the rate of decline at around 2000 and 2012. Can we call these turning points?

Then there is catastrophe theory and its state changes.

Catastrophe theory is discussed in the literature so shouldn't be dismissed. I admit the possibility but it doesn't seem very likely. Even if it is likely, is it useful? Or do we just end up concluding well something might happen at some time?

Is it likely? Weather is chaotic but generally climate is stable. Arctic sea ice seems to be showing slow steady changes. Do we have any evidence of chaotic / catastrophic behaviour?

So wrong to conclude there won't be catastrophic change but if no such evidence is it reasonable to conclude it is unlikely in the near term?

Maybe we don't need much possibility to judge we need more action on cc, but for the purpose of predicting what will happen in next few years to decades is low probability and low usefulness a reasonable conclusion?
Title: Re: How soon could we go ice free?
Post by: dnem on June 17, 2018, 01:31:07 PM
Personally, I think the analogy of the spinning top is relevant.  As the top begins to slow, its overall motion is predictable: the rotational speed slows and the movement about the axis is tightly constrained.  As it continues to lose speed, the wobbles about the axis increase in amplitude and become more chaotic.  In the final revolutions before it topples over, the motions are chaotic and unpredictable.

I think most here believe the top WILL topple over: the arctic will go functionally seasonally ice free with enormous implications for global climate.  There will likely be a refuge along the CAA and Greenland for quite some time, and whether it is + or - 1 M km2 is almost irrelevant. 

I do not believe that ANY curve fitting exercise is useful in predicting when the next big inflection point will come.  There is ample evidence that the metrics (especially SIE) are becoming more variable and more difficult to interpret.  Volume is straightforward to interpret but difficult to measure (and model).

My guess would be that sometime before 2025 the 2012 minimum will be obliterated and we will be left with a highly mobile jumble of ice that is functionally entirely different than the previous coherent pack.  There will be no 2013/2014 recovery the next time.  Albedo will not recover and knock on impacts will be huge.

I would not be the least bit surprised if this happened during a seemingly "normal" season where the ASIF community is having its annual debate about slow vs fast transition, the reliability of the metrics, the likelihood of a new record and so on. 

I would be surprised but not flabbergasted if 2018 was the year.  I will be entirely shocked if it does not happen before 2025.
Title: Re: How soon could we go ice free?
Post by: gerontocrat on June 17, 2018, 04:03:43 PM
"This is my speculation and it belongs to me""

A good many posts ago, A-Team suggested that it was of more use to consider how even now there are climatic effects as individual seas such as the Barents become emptier of ice.

Others have commented on when there is less ice, the less ice there is to melt.

As I have NSIDC area graphs for each sea sitting in my laptop I thought - let us have a look. This first post looks at the melting behaviour of seas that melt out early, late or never.

The first observation is that the S-Curve applies in all cases, i.e. independently of the time of year melt out is finished or minimum is reached. (Yes, individual years have lots of wobbles due to the weather and other local conditions, but that is noise disguising the underlying characteristic.)

I attach graphs of -
- The St Lawrence, melts out May to June,
- The Barents Sea, melted out by 1st August,
- The Kara Sea - minimum late September (well below 5% of 1980's average maximum).
- Canadian Archipelago - mid-September minimum.
To repeat, loss of ice declines late in the melting no matter the time of year.
 
Thinks about what might happen to individual seas ice-free days as warmth (ocean and atmosphere) pushes north, in fits and starts, in the years to come.

They are going to be knocked off one by one, until surely the only two left with significant summer ice, but less of it, will be the Central Arctic and the Canadian Archipelago. But as A-Team might agree, as the years go by, the number of ice-free days in the other seas must increase and with increasing feed-backs on the climate.

But that requires more thought. It is Sunday, I is tired and my brain hurts. Ta ra
Title: Re: How soon could we go ice free?
Post by: oren on June 18, 2018, 03:47:47 AM
Hullo gerontocrat, your post inspired me to look at the same data from my favorite perspective - that of the transition of regional seas to a seasonally ice-free state. While trying to extrapolate the arctic ocean to the future, people have used linear fits, gompertz and other curves.
Looking at the Chukchi, which has already completed its transition, shows how linear turned out to make good predictions, and how the first "BOE" happened before the linear extrapolation hit zero because of the inherent volatility of the data.
Notes: I am using a 5-yr average of the annual extent minimum as it gives a better approximation of the variability of the whole arctic data. I've marked the BOE threshold at 7% of max extent.
The same analysis can be made for other seas, and is especially interesting for those that started the data-set as ice-covered at minimum, but have transitioned to seasonally ice-free, or are advanced in the transition.

Note: of course, the Chukchi is not a true approximation of the behavior of the whole arctic, due to many varied reasons (ice export and import, one region instead of amalgamation, different MYI distribution over time, etc.). I still found the result interesting.

Edit: Another such chart for the Laptev. Very interesting IMHO.
Title: Re: How soon could we go ice free?
Post by: jai mitchell on June 18, 2018, 04:53:21 AM
Can we stick to 2005 as the point of inflection.



98 is more significant I think
Title: Re: How soon could we go ice free?
Post by: Peter Ellis on June 18, 2018, 12:25:28 PM
I think Figure 1 from Tietsche et al 2011 is important.
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2010GL045698

This shows two things - firstly, the general shape of the (modelled) decline in Arctic ice over the coming decades, and secondly the time taken to recover from extreme events such as the summers of 2007 and 2012.

For the latter, the conclusion is quite simple - the Arctic has a "memory" of about two years, and so any major excursion will bounce back to the long-term trendline within a couple of years.  They only modelled downward excursions, but my guess is that it holds the other way too - even if by chance we have a particularly good year for ice retention, it'll be gone in another couple of years.  The paper discusses the mechanisms for this, but fundamentally it's quite simple - if you have a massive loss of ice one autumn, that means a correspondingly massive extra heat loss in the following winter.  By the end of spring, first year ice has grown back. A low summer minimum has very little effect on the following maximum.  This is believable, and we've seen it after every major loss year for more than a decade now.

For the longer term decline, look at the shape of the curve.  Note how it's staggered and stepped.  This reflects the shape of the Arctic ice basin. There are shallow seas around the edge, and a deep central portion that covers about 5 million square km. So, as ice loss progresses, there's an initial period of rapid decline that plateaus at around 4.5 to 5 million until about 2020.  That's exactly where we are now, in that plateau, where the summer minimum roughly covers the deep parts of the Arctic Ocean but the peripheral seas melt out each summer. Subsequently, there's another period of rapid decline that plateaus again at 1.5-2 million.  This is the "remnant above Greenland" stage.  The final collapse comes after that.

The shape looks entirely plausible to me, all that we need to work out is the scaling on the X axis, and to be honest I'd be surprised if they're far off. Right now we're on the verge of the second period of decline - but it'll plateau again in another couple of decades, probably before hitting the "ice free" threshold of 1 million.

It may be we need to squash the X axis up by 10% or so to fit reality - someone with more time than I can probably make an overlay - but it's really not far off.
Title: Re: How soon could we go ice free?
Post by: gerontocrat on June 18, 2018, 01:10:35 PM
Hullo gerontocrat, your post inspired me to look at the same data from my favorite perspective - that of the transition of regional seas to a seasonally ice-free state.

Is not the next stage to consider the length of time that each sea has been, is and will be ice free? The longer the time the ice is not there the greater the climatic effects.  You may remember an exercise I did looking at the history of the number of days each sea was 95% ice-free, 85% ice free and 50% ice free..

but perhaps off-topic for this thread.

Title: Re: How soon could we go ice free?
Post by: crandles on June 18, 2018, 01:16:15 PM
Can we stick to 2005 as the point of inflection.

98 is more significant I think

With data to 2017, 1998 may well be a more significant turning point than the 2012 turning point. (There is only 5 years data after 2012 which might not be enough. Maybe with more data which one of these turning points is more significant might change.)

There is only one point of inflection which is 2005.

I am trying to say, please get the nomenclature right. Only 2005 (+/- a year or 2) is a point of inflection. Getting nomenclature right helps avoid talking at cross purposes.

Quote
noun: point of inflection
1. MATHEMATICS
a point of a curve at which a change in the direction of curvature occurs.

https://en.wikipedia.org/wiki/Inflection_point#/media/File:X_cubed_plot.svg

You might find two turning points at circa x=-1 and +1 but the curve only changes direction of curvature once ie there is only one inflection point at x=0

(Turning point probably isn't strictly correct term but discontinuity in rate of decline seems a bit of a mouthful.)
Title: Re: How soon could we go ice free?
Post by: Dharma Rupa on June 18, 2018, 02:05:35 PM
(Turning point probably isn't strictly correct term but discontinuity in rate of decline seems a bit of a mouthful.)

Are you referring to the jerk?

(speed is rate of change in distance over time.  Acceleration is rate of change in Speed. Jerk is rate of change in acceleration.  By analogy the same terms have been used for other basic derivatives.)
Title: Re: How soon could we go ice free?
Post by: crandles on June 18, 2018, 02:36:17 PM
(Turning point probably isn't strictly correct term but discontinuity in rate of decline seems a bit of a mouthful.)

Are you referring to the jerk?

(speed is rate of change in distance over time.  Acceleration is rate of change in Speed. Jerk is rate of change in acceleration.  By analogy the same terms have been used for other basic derivatives.)

Jerk is nice and short rather than a mouthful. Is it a non smooth change in speed rather than a "rate of change in acceleration"?

Might work OK as long as not misinterpreted as a name calling insult. 'kink' in the graph may have different interpretation issue.
Title: Re: How soon could we go ice free?
Post by: Archimid on June 18, 2018, 02:53:54 PM
The observations in that  Tietsche et al 2011 are obsolete and nonsensical. Maybe in 2011 made sense when they thought winter temperatures will remain close to average for a few more decades.

From Tietsche et al 2011
Quote
The SST anomaly only lasts until November; by then sufficient heat has been extracted from the surface water to cool it to the freezing temperature. Sea ice then forms from open water very rapidly, and partly recovers. In the next summer the sea‐ice cover is still below normal, and larger shortwave absorption leads to a second positive SST anomaly. However, after the second year the SST anomalies are not larger than the natural variability of the reference run.

According to this model freezing doesn't start until November.  The study argues that rapid refreeze will commence then even tho air temperature will be highly anomalously warm.  Last year Chukchi Sea growth disproves this point. After a warm year, sea ice growth is slowed down to a crawl by higher temperatures.


Quote
[18] For SAT a large positive anomaly occurs between October and February after the initial perturbation, with a peak of almost 11 K in November (Figure 2). After February, there are no further SAT anomalies stronger than natural variability. The warming is mainly restricted to the lower troposphere (see auxiliary material), which is a result that has also been found in GCM studies that prescribed permanent ice‐free conditions in the Arctic Ocean [Royer et al., 1990; Winton, 2008] and in observations of recent Arctic climate change [Screen and Simmonds, 2010]. The peak of the SAT anomaly occurs about four months later than the SST anomaly; the reason for this becomes clear when considering the energy budget

This is already false, and we haven't even had a BOE in June as the study pretends to simulate. Winter temps are already surpassing the anomalies they expect after the year of the first BOE.  Heat anomalies do not end in February, they continue until the end of the freezing season. This assumption does not match observations.

As bad as this assumptions are, the model as a whole is worse. What this model is doing is assuming a one time black swan event that makes the Arctic disappear followed by perfectly normal years. That's ridiculous.
Title: Re: How soon could we go ice free?
Post by: Daniel B. on June 18, 2018, 02:55:05 PM
(Turning point probably isn't strictly correct term but discontinuity in rate of decline seems a bit of a mouthful.)

Are you referring to the jerk?

(speed is rate of change in distance over time.  Acceleration is rate of change in Speed. Jerk is rate of change in acceleration.  By analogy the same terms have been used for other basic derivatives.)

Jerk is nice and short rather than a mouthful. Is it a non smooth change in speed rather than a "rate of change in acceleration"?

Might work OK as long as not misinterpreted as a name calling insult. 'kink' in the graph may have different interpretation issue.

Agreed.  That is roughly the year that the annual ice loss shifted from accelerating to decelerating. 

With regards to terminology, remember that all turning points have a corresponding jerk, but not all jerks have a corresponding turning point.
Title: Re: How soon could we go ice free?
Post by: Dharma Rupa on June 18, 2018, 04:11:26 PM
(Turning point probably isn't strictly correct term but discontinuity in rate of decline seems a bit of a mouthful.)

Are you referring to the jerk?

(speed is rate of change in distance over time.  Acceleration is rate of change in Speed. Jerk is rate of change in acceleration.  By analogy the same terms have been used for other basic derivatives.)

Jerk is nice and short rather than a mouthful. Is it a non smooth change in speed rather than a "rate of change in acceleration"?

Might work OK as long as not misinterpreted as a name calling insult. 'kink' in the graph may have different interpretation issue.

Agreed.  That is roughly the year that the annual ice loss shifted from accelerating to decelerating. 

With regards to terminology, remember that all turning points have a corresponding jerk, but not all jerks have a corresponding turning point.

Heheh.

The way jerk was pointed out to me by a physics professor when I was a kid, was to ask what the rate of change of acceleration was, and when I couldn't answer he said: "Jerk, jerk."  (He was a physics prof, but to me he was a climbing companion.)

Obviously, there are big jerks, and there are little jerks.


Title: Re: How soon could we go ice free?
Post by: Dharma Rupa on June 18, 2018, 04:27:46 PM
Jerk is nice and short rather than a mouthful. Is it a non smooth change in speed rather than a "rate of change in acceleration"?
If the jerk is 0 then you are smoothly accelerating.  If the jerk is high then your rate of acceleration is changing rapidly.

For example:  If you are tied to the end of a slack rope and fall you start with almost no jerk and it is like being in outer space, but when you reach the end of the rope and it stops you then the large jerk is extremely painful.

Title: Re: How soon could we go ice free?
Post by: jai mitchell on June 18, 2018, 04:41:25 PM
The observations in that  Tietsche et al 2011 are obsolete and nonsensical. Maybe in 2011 made sense when they thought winter temperatures will remain close to average for a few more decades.

From Tietsche et al 2011
Quote
The SST anomaly only lasts until November; by then sufficient heat has been extracted from the surface water to cool it to the freezing temperature. Sea ice then forms from open water very rapidly, and partly recovers. In the next summer the sea‐ice cover is still below normal, and larger shortwave absorption leads to a second positive SST anomaly. However, after the second year the SST anomalies are not larger than the natural variability of the reference run.

According to this model freezing doesn't start until November.  The study argues that rapid refreeze will commence then even tho air temperature will be highly anomalously warm.  Last year Chukchi Sea growth disproves this point. After a warm year, sea ice growth is slowed down to a crawl by higher temperatures.

Here is my bit on Tietsche et. al. from 2014

https://forum.arctic-sea-ice.net/index.php/topic,1017.msg38135.html#msg38135

Quote
Re: Arctic Summer Sea Ice transition
« Reply #2 on: October 12, 2014, 10:34:15 PM »

3.  Slow vs. fast transition.

I told you that I do not believe that tietsche correctly modeled atmospheric feedbacks in the paper.  you responded by saying that they used a GCM for the arctic.  That is good that they did, I would expect that they did.  However, I do not believe that they included the regional land and extreme ocean surface warming that a June 1 ice free state would bring.  I have seen the enthalphy increase curves for 2007 near shore ESAS and they are MASSIVE, having an ice-free state on June 1st is a scenario that has not been properly modeled.  The primary near term effect is high humidity and residual heat preventing surface air temperatures to drop far below zero for a significant period. 

The second is that the high temperature body of water below the halocline will continue to produce under ice melt.

Finally, relying on those models as a projection of future warming is not realistic because. . .

4.  DURACK et al.

You said that the information doesn't change the 1.5 to 6 C ECS value, are you sure you are not still a climate denier? (being tongue-in-cheek here)

I said that the cumulative energy gain over the last 30 years has been underestimated by between 10 and 30%.  And that the models appeared to fit the northern hemisphere.  Which likely means that the effect of northern hemisphere aerosols has also been severely understated.

These two factors indicate then that the lower range of the ECS is no possible so instead of a 1.5C it is closer to 2.5C as an unlikely minimum.  The fat tail of ECS is now fatter and the most likely value of 3C is now 3.6 to 4 C with a high end range of 8C for a doubling of CO2. 

If long and slow feedbacks are also included (i.e. albedo changes,  ice free arctic, carbon cycle responses) we are already looking to push global temperatures past 4C at CURRENT CO2 abundance levels.
Title: Re: How soon could we go ice free?
Post by: Richard Rathbone on June 19, 2018, 02:39:54 PM
The observations in that  Tietsche et al 2011 are obsolete and nonsensical. Maybe in 2011 made sense when they thought winter temperatures will remain close to average for a few more decades.

From Tietsche et al 2011
Quote
The SST anomaly only lasts until November; by then sufficient heat has been extracted from the surface water to cool it to the freezing temperature. Sea ice then forms from open water very rapidly, and partly recovers. In the next summer the sea‐ice cover is still below normal, and larger shortwave absorption leads to a second positive SST anomaly. However, after the second year the SST anomalies are not larger than the natural variability of the reference run.

According to this model freezing doesn't start until November.  The study argues that rapid refreeze will commence then even tho air temperature will be highly anomalously warm.  Last year Chukchi Sea growth disproves this point. After a warm year, sea ice growth is slowed down to a crawl by higher temperatures.


You are misrepresenting the paper here. You are quoting from a discussion of what happens if all ice is removed from the Arctic July 1st not what happens in a typical year.
Title: Re: How soon could we go ice free?
Post by: Archimid on June 19, 2018, 03:15:30 PM
Quote
You are misrepresenting the paper here. You are quoting from a discussion of what happens if all ice is removed from the Arctic July 1st not what happens in a typical year.

Read the context. He posted that paper out of context since we are talking about the first ice free arctic, not the year after the first ice free arctic, which is the context of the paper. But if he posted thinking that there is value in examining the boundary cases then I agree with him. My reply was meant to show that even worst case scenarios like the ones examined by that 2011 paper are already proving not to be worst case at all.
Title: Re: How soon could we go ice free?
Post by: Daniel B. on June 19, 2018, 04:50:52 PM
Are you saying that the worst case scenarios are not so, because we have not come close to experiencing them?
Title: Re: How soon could we go ice free?
Post by: crandles on June 19, 2018, 05:34:40 PM
Are you saying that the worst case scenarios are not so, because we have not come close to experiencing them?

I think he is saying

'the worst case scenarios are not so, because we have already come close to experiencing worse.'

Quote
For SAT a large positive anomaly occurs between October and February after the initial perturbation, with a peak of almost 11 K in November (Figure 2). After February, there are no further SAT anomalies stronger than natural variability.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fplots%2FmeanTarchive%2FmeanT_2017.png&hash=59eb65f128ffbe7ae10e4673b1a7d998)
doesn't seem to get to 11C but perhaps
(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Focean.dmi.dk%2Farctic%2Fplots%2FmeanTarchive%2FmeanT_2016.png&hash=ed3bc1964e488b5d83cfae05c243a1bc)
does on some days in November.

This is comparing 2016 to 1958-2002 average whereas paper is presumably comparing year with ice removed to nearby years without ice removal.

Hmm. not exactly apples to apples comparison? Since both are large differences we shouldn't be surprised both show large anomalies, is partly my reaction.

Still at least there is some substance to the arguments rather than just saying Tietsche et al is 'dated'. Schroeder and Connolley reached similar conclusions to Tietsche et al.

Just saying Tietsche at al is rubbish isn't very robust/sufficiently complete, where are the rebuttal papers or where is something better?
Title: Re: How soon could we go ice free?
Post by: Archimid on June 19, 2018, 06:09:08 PM
Quote
I think he is saying

'the worst case scenarios are not so, because we have already come close to experiencing worse.'

Correct.

Quote
Just saying Tietsche at al is rubbish isn't very robust/sufficiently complete, where are the rebuttal papers or where is something better?

I don't think it is rubbish. To the contrary, I think it is a good paper, well written and provides a lot of insight. That said, I think observations make it obsolete.  The Arctic  before 2011 was a different beast from today, specially during the Arctic night.

Title: Re: How soon could we go ice free?
Post by: Ken Feldman on June 19, 2018, 06:44:56 PM
The observations in that  Tietsche et al 2011 are obsolete and nonsensical. Maybe in 2011 made sense when they thought winter temperatures will remain close to average for a few more decades.

From Tietsche et al 2011
Quote
The SST anomaly only lasts until November; by then sufficient heat has been extracted from the surface water to cool it to the freezing temperature. Sea ice then forms from open water very rapidly, and partly recovers. In the next summer the sea‐ice cover is still below normal, and larger shortwave absorption leads to a second positive SST anomaly. However, after the second year the SST anomalies are not larger than the natural variability of the reference run.

According to this model freezing doesn't start until November.  The study argues that rapid refreeze will commence then even tho air temperature will be highly anomalously warm.  Last year Chukchi Sea growth disproves this point. After a warm year, sea ice growth is slowed down to a crawl by higher temperatures.


Quote
[18] For SAT a large positive anomaly occurs between October and February after the initial perturbation, with a peak of almost 11 K in November (Figure 2). After February, there are no further SAT anomalies stronger than natural variability. The warming is mainly restricted to the lower troposphere (see auxiliary material), which is a result that has also been found in GCM studies that prescribed permanent ice‐free conditions in the Arctic Ocean [Royer et al., 1990; Winton, 2008] and in observations of recent Arctic climate change [Screen and Simmonds, 2010]. The peak of the SAT anomaly occurs about four months later than the SST anomaly; the reason for this becomes clear when considering the energy budget

This is already false, and we haven't even had a BOE in June as the study pretends to simulate. Winter temps are already surpassing the anomalies they expect after the year of the first BOE.  Heat anomalies do not end in February, they continue until the end of the freezing season. This assumption does not match observations.

As bad as this assumptions are, the model as a whole is worse. What this model is doing is assuming a one time black swan event that makes the Arctic disappear followed by perfectly normal years. That's ridiculous.

I think you misunderstand the Tietsche et al 2011.  It showing that the known feedbacks in the climate system mitigate against a tipping point where one extreme melt year leads to a perennial ice-free Arctic, at least until the greenhouse gases reach a level where the excess heat absorbed during the summer can't be released in the winter.  (BTW, those higher winter temperatures you like to talk about are evidence that the excess heat is being released.  As long as those temps are below freezing, new ice is forming.)

I entered Tietsche et al 2011 into Google Scholar and found that it has been cited 148 times since it's publication.  I can't find any of those cites that refute the findings in the paper.

Here's a 2015 paper that cites Tietsche et al 2011 and examines the trends in Arctic sea ice declines (including 2012's extreme season):

http://rsta.royalsocietypublishing.org/content/373/2045/20140159 (http://rsta.royalsocietypublishing.org/content/373/2045/20140159)

A few excerpts from that study:

Quote
September Arctic sea ice extent over the period of satellite observations has a strong downward trend, accompanied by pronounced interannual variability with a detrended 1 year lag autocorrelation of essentially zero. We argue that through a combination of thinning and associated processes related to a warming climate (a stronger albedo feedback, a longer melt season, the lack of especially cold winters) the downward trend itself is steepening. The lack of autocorrelation manifests both the inherent large variability in summer atmospheric circulation patterns and that oceanic heat loss in winter acts as a negative (stabilizing) feedback, albeit insufficient to counter the steepening trend. These findings have implications for seasonal ice forecasting. In particular, while advances in observing sea ice thickness and assimilating thickness into coupled forecast systems have improved forecast skill, there remains an inherent limit to predictability owing to the largely chaotic nature of atmospheric variability.

Quote
The other key driver of sea ice variability, reflected in the lack of autocorrelation in the detrended September sea ice extent (and modest autocorrelation with volume), is that autumn and winter heat loss acts as a strong negative (stabilizing) feedback [5,8]. If anomalous atmospheric forcing leads to a large negative anomaly in September ice extent, there will also be large oceanic heat losses in autumn and winter from open water areas that in turn foster a large production of new ice. One manifestation of this ocean heat loss is that autumns following large negative anomalies in extent are attended by large positive anomalies in surface and lower tropospheric air temperatures. Indeed, the downward trend in September ice extent is one of the major drivers of Arctic amplification—the observed outsized rise in surface and lower tropospheric temperatures in the Arctic relative to the hemispheric average [28,29]. It follows that, unless a September with a large negative sea ice anomaly is followed by another summer with weather conditions favouring ice loss such as the DA pattern, extent will tend to climb back towards the trend line.
Title: Re: How soon could we go ice free?
Post by: Peter Ellis on June 19, 2018, 08:15:08 PM
Read the context. He posted that paper out of context since we are talking about the first ice free arctic, not the year after the first ice free arctic, which is the context of the paper.

No, you missed the two points I was making.

1)  In their model, when you perturb the system - even a perturbation as massive as removing all ice - it returns to the long-term trendline within two years.

This means that it's important for us not to get misled by single extraordinary years, but instead concentrate on the shape of that long term trendline and how it declines towards zero. The claimed two-year "memory" of the Arctic for extraordinary shocks is consistent with what we see in the real world, where there was a short-term "rebound" after both 2007 and 2012, but in each case the "rebound" only took us back up to the long-term downward trendline. 


2)  Leaving aside any of the artificial non-physical perturbations, the SHAPE of the approach to zero is not linear, not quadratic, not exponential, and not a sudden "poof" to zero.

The prediction is for a "stepped" decline with plateaus at ~5 million and ~1.5 million km^2. These plateaus are dictated by the overall geography of the Arctic and the bathymetry of the Arctic ocean. In my view regardless of whether their precise predicted timetable for the fall towards zero is accurate or not, these plateaus make physical sense, and so we should expect a similar "stepped" decline to play out in the real world.



As it happens, the real world progression of September extents seems to be reasonably close to their model, which predicts a plateau until ~2020 and then a comparatively rapid collapse to about ~1.5 million.  I would hazard a guess that we're on the verge of that transition.
Title: Re: How soon could we go ice free?
Post by: Archimid on June 19, 2018, 08:46:41 PM
Quote
I think you misunderstand the Tietsche et al 2011

Ditto. A model is an abstraction of reality, some of them can be useful. In the reality created by Tietsche et al 2011 Arctic sea ice extent does not reach 0 until 2070. That goes against observations and many models, particularly more recent models.  In that universe where Arctic extent decay is so slow that it won't disappear until 2070, the arctic recovers after a BOE.

If you show me a model that predicts an ice free Arctic anywhere from now to 2040 (as the adjusted consensus indicates)and then run the same simulation we can talk.

From a few comments up thread:

Quote
Time horizons for a nearly sea ice‐free summer for these three approaches are roughly 2020 or earlier, 2030 ± 10 years, and 2040 or later.

If you run the same experiment on a model that predicts an earlier BOE the results will be very different.
Title: Re: How soon could we go ice free?
Post by: Peter Ellis on June 19, 2018, 09:11:39 PM
Quote
I think you misunderstand the Tietsche et al 2011

Ditto. A model is an abstraction of reality, some of them can be useful. In the reality created by Tietsche et al 2011 Arctic sea ice extent does not reach 0 until 2070. That goes against observations

No it doesn't. Arctic ice has not reached zero yet, nor has the year reached 2070.


...and many models, particularly more recent models. 

This would be more believable if you linked to the models and publications derived therefrom.

In that universe where Arctic extent decay is so slow that it won't disappear until 2070, the arctic recovers after a BOE.

I wish I hadn't mentioned the BOE aspect.  The point I was making was not about what happens in the event of a BOE, it was to discuss the shape of the way the long term trend approaches zero, i.e. a stepped decline.  The Tietsche model is not really "so slow" - it predicts that the current slight plateau is temporary, that the trendline is about to accelerate sharply downwards, that there will be a rapid collapse over about a decade or so to leave a rump of about 1.5 million square km hanging out above Greenland.  Their error bars show a dip below 1 million square km (i.e. the generally accepted "ice free" threshold for the Arctic) as early as 2035.

If even that isn't alarmist enough for you, I honestly don't know what to say.
Title: Re: How soon could we go ice free?
Post by: Peter Ellis on June 19, 2018, 09:18:40 PM
Seriously - ignore the blue bits on this and just look at the black line and dotted surround, i.e. the long term trend and the variability around that trend.

The variability goes below 1 million square km from 2035 onwards, i.e. it's predicting that from 2035 onwards, a "bad year" for the Arctic will count as ice-free for the entire month of September, not just a day or so.  From ~2055 on, the UPPER bound is below 1 million, meaning that EVERY year is ice-free for the entire month of September, even the good years.

This paper, and that graph are SCARY AS FUCK.  They say we are on the edge of a precipitate decline (the trend from ~2020-2035 is 2.5x the trend from 1985 to 2010) to a "remnant rump" state with a residual amount of ice hanging around northern Greenland.
Title: Re: How soon could we go ice free?
Post by: Dharma Rupa on June 19, 2018, 09:44:34 PM
I see a lot of discussion of "models" but I still have never seen any good analysis for demonstrated skill of same.

A good weather model does well three days out.  Please show me a global model that does a good job three years out.
Title: Re: How soon could we go ice free?
Post by: Neven on June 19, 2018, 10:28:08 PM
You can't compare weather and GCM models like that. They do different things. It is actually a climate risk denier talking point.

A GCM can't tell you what whether it will be on August 7th 2021. It can, however, give you an idea of how much warmer it will be globally on average in 2100, given various conditions.

There are hundreds of examples of climate models accurately predicting things, because they rely on physics. That doesn't mean they're perfect. No tool is perfect.
Title: Re: How soon could we go ice free?
Post by: Dharma Rupa on June 20, 2018, 01:09:10 AM
A GCM can't tell you what whether it will be on August 7th 2021. It can, however, give you an idea of how much warmer it will be globally on average in 2100, given various conditions.

I personally think our fate was sealed by the Industrial Revolution 200 years ago.
Title: Re: How soon could we go ice free?
Post by: Archimid on June 20, 2018, 03:03:22 AM
Quote
Seriously - ignore the blue bits on this and just look at the black line and dotted surround, i.e. the long term trend and the variability around that trend.


Let me try again. In a model where ice hits 0 in 2070, ice will not return after 2070. In this model ice hits 0 in 2070 and it doesn't return afterwards. If the model predicted 0 ice by 2030, then Ice probably wouldn't return afterwards.  All this "perturbations" are artificially induced.
Title: Re: How soon could we go ice free?
Post by: Archimid on June 20, 2018, 03:40:04 AM

No it doesn't. Arctic ice has not reached zero yet, nor has the year reached 2070.

Ok. I'll rephrase. The model observations for the period after an ice free Arctic do not match recent winter warming observations

Quote
This would be more believable if you linked to the models and publications derived therefrom.


As I said, I got those numbers from a paper posted a few comments ago in this thread. Look it up.

Quote

I wish I hadn't mentioned the BOE aspect.  The point I was making was not about what happens in the event of a BOE, it was to discuss the shape of the way the long term trend approaches zero, i.e. a stepped decline.  The Tietsche model is not really "so slow" - it predicts that the current slight plateau is temporary, that the trendline is about to accelerate sharply downwards, that there will be a rapid collapse over about a decade or so to leave a rump of about 1.5 million square km hanging out above Greenland.  Their error bars show a dip below 1 million square km (i.e. the generally accepted "ice free" threshold for the Arctic) as early as 2035. [/quote

If even that isn't alarmist enough for you, I honestly don't know what to say.

It is not alarmist enough. Even if that model was the best model our physics were capable of showing, it is still a model with tons of uncertainties. A bad freeze year followed by a 2012 like melt year is probably enough for the Arctic to go ice free any year now.   
 
Policy makers need to know this risk. They can't go in thinking "there is no chance for this to happen in less than 20 years" or something like that. They need to know there is imminent danger ahead and could happen sooner than expected.
Title: Re: How soon could we go ice free?
Post by: bbr2314 on June 20, 2018, 03:48:26 AM
You can't compare weather and GCM models like that. They do different things. It is actually a climate risk denier talking point.

A GCM can't tell you what whether it will be on August 7th 2021. It can, however, give you an idea of how much warmer it will be globally on average in 2100, given various conditions.

There are hundreds of examples of climate models accurately predicting things, because they rely on physics. That doesn't mean they're perfect. No tool is perfect.
I think the albedo situation this spring has disproven the climate models. It may not yet be apparent but as we see repeats / worsening of this year's event as we head deeper into the 2020s, it is going to be obvious. It is actually a far worse scenario than current projections but because it doesn't follow a line directly upwards the negative impacts are incomprehensible to most of the apes.

In any case I don't take give models beyond the simulations of Hansen et. al any dose of credibility. They are literally so wrong as to be absurd.
Title: Re: How soon could we go ice free?
Post by: bbr2314 on June 20, 2018, 03:53:14 AM
The models show blanket red etc. Patently absurd. 2018 is proving we are at an inflection point / entering hysteresis in transition to colder continents + growing ice sheets, and the switch could accelerate exceedingly quickly.

By the 2030s I think the current scientific thought will be derided on a scale worse than the 70s projections for cooling, that is, if we haven't blown up the planet due to crop failures etc by then.

Title: Re: How soon could we go ice free?
Post by: Daniel B. on June 20, 2018, 02:18:07 PM
You can't compare weather and GCM models like that. They do different things. It is actually a climate risk denier talking point.

A GCM can't tell you what whether it will be on August 7th 2021. It can, however, give you an idea of how much warmer it will be globally on average in 2100, given various conditions.

There are hundreds of examples of climate models accurately predicting things, because they rely on physics. That doesn't mean they're perfect. No tool is perfect.
I think the albedo situation this spring has disproven the climate models. It may not yet be apparent but as we see repeats / worsening of this year's event as we head deeper into the 2020s, it is going to be obvious. It is actually a far worse scenario than current projections but because it doesn't follow a line directly upwards the negative impacts are incomprehensible to most of the apes.

In any case I don't take give models beyond the simulations of Hansen et. al any dose of credibility. They are literally so wrong as to be absurd.

Yes, but I believe that is because the models do not know how to handle many of the heat transfer effects.  Open water will absorb more heat in summer, but lose more in winter.  How do these compare?  Clouds are having a much greater effect than anticipated, as evidenced by cooler summer temperatures.  Increased snowfall in areas is having a large albedo effect.  Obviously, the models predicted an ice-free Arctic several years ago were wrong, but what about those predicting ice-free in the 2020s, 2060s, never?
Title: Re: How soon could we go ice free?
Post by: crandles on June 20, 2018, 02:59:52 PM
Obviously, the models predicted an ice-free Arctic several years ago were wrong, but what about those predicting ice-free in the 2020s, 2060s, never?

What models? Only extrapolations produced results like in 2020s or 2016 +/-3 years
Title: Re: How soon could we go ice free?
Post by: Daniel B. on June 20, 2018, 03:46:19 PM
Obviously, the models predicted an ice-free Arctic several years ago were wrong, but what about those predicting ice-free in the 2020s, 2060s, never?

What models? Only extrapolations produced results like in 2020s or 2016 +/-3 years

Is not an extrapolation just a continuation of a model outside of the data range?
Title: Re: How soon could we go ice free?
Post by: Dharma Rupa on June 20, 2018, 04:05:29 PM
Obviously, the models predicted an ice-free Arctic several years ago were wrong, but what about those predicting ice-free in the 2020s, 2060s, never?

What models? Only extrapolations produced results like in 2020s or 2016 +/-3 years

Is not an extrapolation just a continuation of a model outside of the data range?

crandles is right.  No well-known models projected an ice-free Arctic earlier than 2016+/-3.  Unlike the people using the models, I don't think the people making the models really believe them yet.

Title: Re: How soon could we go ice free?
Post by: crandles on June 20, 2018, 04:57:46 PM
What models? Only extrapolations produced results like in 2020s or 2016 +/-3 years
Is not an extrapolation just a continuation of a model outside of the data range?

That is talking about extrapolating a model but the data extrapolations use actual data not model output.

It may well be possible to claim a data extrapolation is a model but it is a very simple naive model whereas a GCM type model has lots of physics built into it. Very different things even if you want to claim the term model can be applied to both.
Title: Re: How soon could we go ice free?
Post by: crandles on June 20, 2018, 05:11:57 PM
Maybe there are some but not many. If they are outliers perhaps we shouldn't pay too much attention to such outliers.

Overland and Wang 2013 paper "When will the summer Arctic be nearly sea ice free?" abstract includes

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/grl.50316

Quote
Three recent approaches to predictions in the scientific literature are as follows: (1) extrapolation of sea ice volume data, (2) assuming several more rapid loss events such as 2007 and 2012, and (3) climate model projections. Time horizons for a nearly sea ice‐free summer for these three approaches are roughly 2020 or earlier, 2030 ± 10 years, and 2040 or later.

Graph from paper:
Title: Re: How soon could we go ice free?
Post by: Daniel B. on June 20, 2018, 05:37:45 PM
Yes, that graph is from 89 ensemble runs under RCP8.5 emission scenario.  The mean value is still above 1.0 M km2 by 2100.  The large variability is due to how much weight is placed on various factors, such as albedo, clouds, radiation losses, and observational data. 
Title: Re: How soon could we go ice free?
Post by: jai mitchell on June 20, 2018, 05:56:29 PM
Yes, that graph is from 89 ensemble runs under RCP8.5 emission scenario.  The mean value is still above 1.0 M km2 by 2100.  The large variability is due to how much weight is placed on various factors, such as albedo, clouds, radiation losses, and observational data.

The test of whether a model is good or not is performed by seeing how it has been able to replicate historic conditions.  If it is good at that then it is a pretty good bet that it will do well going forward.

There is no good models in that squiggly bunch of lines that I can see.

the best  and most recent assessment on climate science says the following:

https://science2017.globalchange.gov/chapter/15/

Quote
Another surprise has come from arctic sea ice. While the potential for powerful positive ice-albedo feedbacks has been understood since the late 19th century, climate models have struggled to capture the magnitude of these feedbacks and to include all the relevant dynamics that affect sea ice extent. As of 2007, the observed decline in arctic sea ice from the start of the satellite era in 1979 outpaced the declines projected by almost all the models used by the Intergovernmental Panel on Climate Change’s Fourth Assessment Report (AR4), and it was not until AR4 that the IPCC first raised the prospect of an ice-free summer Arctic during this century. More recent studies are more consistent with observations and have moved the date of an ice-free summer Arctic up to approximately mid-century (see Ch. 11: Arctic Changes). But continued rapid declines—2016 featured the lowest annually averaged arctic sea ice extent on record, and the 2017 winter maximum was also the lowest on record—suggest that climate models may still be underestimating or missing relevant feedback processes. These processes could include, for example, effects of melt ponds, changes in storminess and ocean wave impacts, and warming of near surface waters. , ,

and

Quote
third potential tipping element is arctic sea ice, which may exhibit abrupt state shifts into summer ice-free or year-round ice-free states. , As discussed above, climate models have historically underestimated the rate of arctic sea ice loss. This is likely due to insufficient representation of critical positive feedbacks in models. Such feedbacks could include: greater high-latitude storminess and ocean wave penetration as sea ice declines; more northerly incursions of warm air and water; melting associated with increasing water vapor; loss of multiyear ice; and albedo decreases on the sea ice surface (e.g., Schröder et al. 2014; Asplin et al. 2012; Perovich et al. 2008 ). At the same time, however, the point at which the threshold for an abrupt shift would be crossed also depends on the role of natural variability in a changing system; the relative importance of potential stabilizing negative feedbacks, such as more efficient heat transfer from the ocean to the atmosphere in fall and winter as sea declines; and how sea ice in other seasons, as well as the climate system more generally, responds once the first “ice-free” summer occurs (e.g., Ding et al. 2017 ). It is also possible that summer sea ice may not abruptly collapse, but instead respond in a manner proportional to the increase in temperature. , , , Moreover, an abrupt decrease in winter sea ice may result simply as the gradual warming of Arctic Ocean causes it to cross a critical temperature for ice formation, rather than from self-reinforcing cycles.
Title: Re: How soon could we go ice free?
Post by: crandles on June 20, 2018, 05:57:15 PM
The mean value is still above 1.0 M km2 by 2100.

The models keeping mean value above 1m km^2 by 2100, have absurdly high levels of ice at all times, way above what we actually have now. Obviously these models do their own thing and have not been adjusted to observations. If they were adjusted to realistic ice now by moving line up or down to match observation or applying a scaling factor, the projections arrived at would be much more consistent.
Title: Re: How soon could we go ice free?
Post by: Dr Freeze on June 20, 2018, 06:58:21 PM
Yes, that graph is from 89 ensemble runs under RCP8.5 emission scenario.  The mean value is still above 1.0 M km2 by 2100.  The large variability is due to how much weight is placed on various factors, such as albedo, clouds, radiation losses, and observational data. 

Due to the non-normal distribution of the models mean should not be counted, median is the correct value to use.  Basically the models in red are ridiculous outliers that are shifting the mean too high.
Title: Re: How soon could we go ice free?
Post by: Daniel B. on June 20, 2018, 07:46:46 PM
The mean value is still above 1.0 M km2 by 2100.

The models keeping mean value above 1m km^2 by 2100, have absurdly high levels of ice at all times, way above what we actually have now. Obviously these models do their own thing and have not been adjusted to observations. If they were adjusted to realistic ice now by moving line up or down to match observation or applying a scaling factor, the projections arrived at would be much more consistent.

Yes.  Those are probably the models giving low weighted value to the observational data.  Hard to say if the observations will ever match those models again.
Title: Re: How soon could we go ice free?
Post by: Peter Ellis on June 20, 2018, 08:10:45 PM
Yes, that graph is from 89 ensemble runs under RCP8.5 emission scenario.  The mean value is still above 1.0 M km2 by 2100.  The large variability is due to how much weight is placed on various factors, such as albedo, clouds, radiation losses, and observational data.
The mean is the wrong measure to use when there are significant outliers like the red series of lines.  Try something more robust like the median.  A median which - with five more years of data to include after the plotted values that stop at 2017 - the real world is pretty much bang on.

Of course, do also remember that this isn't a prediction of the FIRST ice free year.  When the median hits 1.0 M km^2 (in around 2045), it means that ~every other year will be ice free.  The first ice-free year could easily come a decade earlier in 2035 or so.
Title: Re: How soon could we go ice free?
Post by: Dharma Rupa on June 20, 2018, 09:10:45 PM
The test of whether a model is good or not is performed by seeing how it has been able to replicate historic conditions.  If it is good at that then it is a pretty good bet that it will do well going forward.

Actually, I have to disagree with that.  I have never seen any analysis of skill that indicated that hindcast models are better at predicting the future.  They can be better at predicting the past...
Title: Re: How soon could we go ice free?
Post by: crandles on June 21, 2018, 12:48:46 AM

The models keeping mean value above 1m km^2 by 2100, have absurdly high levels of ice at all times, way above what we actually have now. Obviously these models do their own thing and have not been adjusted to observations. If they were adjusted to realistic ice now by moving line up or down to match observation or applying a scaling factor, the projections arrived at would be much more consistent.

Yes.  Those are probably the models giving low weighted value to the observational data.  Hard to say if the observations will ever match those models again.

No, observational data haven't been given low weight. Observational data just is not a feature of how the model works at all.
Title: Re: How soon could we go ice free?
Post by: crandles on June 21, 2018, 12:55:15 AM
The test of whether a model is good or not is performed by seeing how it has been able to replicate historic conditions.  If it is good at that then it is a pretty good bet that it will do well going forward.

Actually, I have to disagree with that.  I have never seen any analysis of skill that indicated that hindcast models are better at predicting the future.  They can be better at predicting the past...

I have to disagree with that. Everybody believes models(/parameter sets) that do well in hindcast mode will in general be better in forecast mode. Very little has been done with this because it opens up all sorts of tricky issues. Which data obs do you use to say a model is good? Inevitable you want lots of data not just a single data item to be good but then how do you weight importance of each.
Title: Re: How soon could we go ice free?
Post by: Dharma Rupa on June 21, 2018, 02:50:50 AM
...believes...

I think that is the operative word there.  I believe lots of things I do not have sufficient data to demonstrate.  Maybe in 100 years we will have enough data about the models to know which ones actually have any skill.

Title: Re: How soon could we go ice free?
Post by: Cid_Yama on June 22, 2018, 01:28:04 PM
Since the ice loss will not be linear, arguing which linear function is best is ridiculous.

Quote
The distinction between linear and nonlinear systems in mathematics defines the boundary between the relatively knowable, and the frustratingly elusive. Both types of systems can describe the dynamics of many different processes, such as planets orbiting each other, fluctuations in animal populations, the behavior of electrical circuits, and so on. The difference between linear and nonlinear lies in the details of the equations that govern how these systems interact. For systems that behave linearly, it is relatively easy to find exact solutions that we can use to predict future behavior within the system. For nonlinear systems, we are lucky to find any such solution. Indeed, in nonlinear dynamics, we often have to redefine what we consider to be a solution.

Here is an excellent introduction to Sensitive Dependence, Iteration, Bifurcation and Feigenbaum's Constants.

http://www.learner.org/courses/mathilluminated/units/13/textbook/04.php
Title: Re: How soon could we go ice free?
Post by: Daniel B. on June 22, 2018, 03:37:32 PM
Since the ice loss will not be linear, arguing which linear function is best is ridiculous.

Quote
The distinction between linear and nonlinear systems in mathematics defines the boundary between the relatively knowable, and the frustratingly elusive. Both types of systems can describe the dynamics of many different processes, such as planets orbiting each other, fluctuations in animal populations, the behavior of electrical circuits, and so on. The difference between linear and nonlinear lies in the details of the equations that govern how these systems interact. For systems that behave linearly, it is relatively easy to find exact solutions that we can use to predict future behavior within the system. For nonlinear systems, we are lucky to find any such solution. Indeed, in nonlinear dynamics, we often have to redefine what we consider to be a solution.

Here is an excellent introduction to Sensitive Dependence, Iteration, Bifurcation and Feigenbaum's Constants.

http://www.learner.org/courses/mathilluminated/units/13/textbook/04.php

Very nice.  For most systems, there exists a zone of linearity, beyond which a linear function fails.
Title: Re: How soon could we go ice free?
Post by: RoxTheGeologist on June 22, 2018, 06:36:49 PM
Since the ice loss will not be linear, arguing which linear function is best is ridiculous.

Quote
The distinction between linear and nonlinear systems in mathematics defines the boundary between the relatively knowable, and the frustratingly elusive. Both types of systems can describe the dynamics of many different processes, such as planets orbiting each other, fluctuations in animal populations, the behavior of electrical circuits, and so on. The difference between linear and nonlinear lies in the details of the equations that govern how these systems interact. For systems that behave linearly, it is relatively easy to find exact solutions that we can use to predict future behavior within the system. For nonlinear systems, we are lucky to find any such solution. Indeed, in nonlinear dynamics, we often have to redefine what we consider to be a solution.

Here is an excellent introduction to Sensitive Dependence, Iteration, Bifurcation and Feigenbaum's Constants.

http://www.learner.org/courses/mathilluminated/units/13/textbook/04.php

Very nice.  For most systems, there exists a zone of linearity, beyond which a linear function fails.

e.g. Newtonian and Relativist laws of motion.... Newtonian physics are very linear at small fractions of the speed of light.
Title: Re: How soon could we go ice free?
Post by: litesong on June 23, 2018, 01:49:24 AM
Average Arctic sea ice VOLUME for June 1, for the period 1980-89, was ~ 29,000 cubic kilometers. Present June 1, 2018 sea ice VOLUME was ~ 20,000 cubic kilometers, ~ 9000 cubic kilometers less than the 1980-89 period for June 1, the equivalent energy needed to melt such...... 28 times the annual energy consumption of the USA.
Title: Re: How soon could we go ice free?
Post by: Cid_Yama on June 23, 2018, 02:14:49 AM
Since the ice loss will not be linear, arguing which linear function is best is ridiculous.

Quote
The distinction between linear and nonlinear systems in mathematics defines the boundary between the relatively knowable, and the frustratingly elusive. Both types of systems can describe the dynamics of many different processes, such as planets orbiting each other, fluctuations in animal populations, the behavior of electrical circuits, and so on. The difference between linear and nonlinear lies in the details of the equations that govern how these systems interact. For systems that behave linearly, it is relatively easy to find exact solutions that we can use to predict future behavior within the system. For nonlinear systems, we are lucky to find any such solution. Indeed, in nonlinear dynamics, we often have to redefine what we consider to be a solution.

Here is an excellent introduction to Sensitive Dependence, Iteration, Bifurcation and Feigenbaum's Constants.

http://www.learner.org/courses/mathilluminated/units/13/textbook/04.php

Very nice.  For most systems, there exists a zone of linearity, beyond which a linear function fails.

e.g. Newtonian and Relativist laws of motion.... Newtonian physics are very linear at small fractions of the speed of light.

And how does that even come close to applying to the subject at hand?  Either: 1. You do not understand the math.  or 2. That was an attempt to obfuscate.

The article I linked to was designed to allow even a layman to understand.  Give it a try.

Might I suggest starting back a page, or even from the introduction on the link I gave.  Give special attention to Poincare.

http://www.learner.org/courses/mathilluminated/units/13/textbook/03.php
Title: Re: How soon could we go ice free?
Post by: gerontocrat on June 30, 2018, 12:33:44 PM
Nice article at https://www.carbonbrief.org/atlantification-arctic-sea-tipping-towards-new-climate-regime

Specifically on the process of Atlantification of the Barents Sea. It seems that the process that inhibits winter re-freeze is the key. I attach a graph that seems to illustrate that (though 2018 bucked the trend).

And I've added an image from the article.
Title: Re: How soon could we go ice free?
Post by: Shared Humanity on June 30, 2018, 05:20:38 PM
Nice article at https://www.carbonbrief.org/atlantification-arctic-sea-tipping-towards-new-climate-regime

Specifically on the process of Atlantification of the Barents Sea. It seems that the process that inhibits winter re-freeze is the key. I attach a graph that seems to illustrate that (though 2018 bucked the trend).

And I've added an image from the article.

Barents bucking the trend could be due to ice transport not freezing. Did we see significant ice transport from the CAB into the Barents this winter?
Title: Re: How soon could we go ice free?
Post by: Pagophilus on June 30, 2018, 08:58:56 PM
Thanks for the useful graph gerontocrat. 

2018 might also seem to 'buck the trend' since it is an individual year plot, which could be expected to show more variability than a multi-year average plot.  2018 seems firmly back on track now... (and indeed all the plots smooth out after May).

Nice article at https://www.carbonbrief.org/atlantification-arctic-sea-tipping-towards-new-climate-regime

Specifically on the process of Atlantification of the Barents Sea. It seems that the process that inhibits winter re-freeze is the key. I attach a graph that seems to illustrate that (though 2018 bucked the trend).

Barents bucking the trend could be due to ice transport not freezing. Did we see significant ice transport from the CAB into the Barents this winter?
Title: Re: How soon could we go ice free?
Post by: Ned W on September 07, 2018, 01:57:58 PM
[Moved from the 2018 area & extent data thread]


Earlier this summer I posted four scenarios for extent loss:

https://forum.arctic-sea-ice.net/index.php/topic,2057.msg158764.html#msg158764

In one of them, extent doesn't approach zero until the 2070s.  At the opposite extreme it happens around 2022.  I mildly prefer the 2035 scenario, but it could be much earlier or much later.

Here are the scenarios, see the earlier post for comments (https://forum.arctic-sea-ice.net/index.php/topic,2057.msg158764.html#msg158764):

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

(https://i.imgur.com/E8lsNd5.png)

(https://i.imgur.com/s78EhnX.png)

(https://i.imgur.com/PEOlnX2.png)

For 2018, one can mentally add an additional point at the end of each of those graphs, at or slightly above the value of the previous endpoint (2017).
Title: Re: How soon could we go ice free?
Post by: Dharma Rupa on September 07, 2018, 03:05:08 PM
[Moved from the 2018 area & extent data thread]


Earlier this summer I posted four scenarios for extent loss:

https://forum.arctic-sea-ice.net/index.php/topic,2057.msg158764.html#msg158764


I think it will be some variant of scenario 4, except I wouldn't know which year.  I think "the end" will come suddenly, and I don't think anyone has a handle on when that end will happen.

Basically, I expect the Arctic Cell collapsing and the CAB becoming part of the Atlantic to happen at the same time -- I just don't know the time.
Title: Re: How soon could we go ice free?
Post by: jdallen on September 07, 2018, 04:59:07 PM
[Moved from the 2018 area & extent data thread]


Earlier this summer I posted four scenarios for extent loss:

https://forum.arctic-sea-ice.net/index.php/topic,2057.msg158764.html#msg158764


I think it will be some variant of scenario 4, except I wouldn't know which year.  I think "the end" will come suddenly, and I don't think anyone has a handle on when that end will happen.

Basically, I expect the Arctic Cell collapsing and the CAB becoming part of the Atlantic to happen at the same time -- I just don't know the time.
Good arguments behind that happening.  It would be a natural follow-on from a point I made earlier.  Once the enthalpy in the Arctic builds up to a sufficiently high level we could easily see major changes in heat transport that will rapidly flip the system into an entirely new state.
Title: Re: How soon could we go ice free?
Post by: Dharma Rupa on September 07, 2018, 08:36:02 PM
[Moved from the 2018 area & extent data thread]


Earlier this summer I posted four scenarios for extent loss:

https://forum.arctic-sea-ice.net/index.php/topic,2057.msg158764.html#msg158764


I think it will be some variant of scenario 4, except I wouldn't know which year.  I think "the end" will come suddenly, and I don't think anyone has a handle on when that end will happen.

Basically, I expect the Arctic Cell collapsing and the CAB becoming part of the Atlantic to happen at the same time -- I just don't know the time.
Good arguments behind that happening.  It would be a natural follow-on from a point I made earlier.  Once the enthalpy in the Arctic builds up to a sufficiently high level we could easily see major changes in heat transport that will rapidly flip the system into an entirely new state.

OK.  We agree on the what, but what about the when?  I am inclined to think it will be soon, but so far I have seen nothing persuasive to argue sooner or later.  I think it will be soon simply because the Industrial Revolution started in the early 1800s; which is not a good argument for timing.  I think asking for timing from the global models is simply casting bones.
Title: Re: How soon could we go ice free?
Post by: magnamentis on September 07, 2018, 08:49:17 PM
[Moved from the 2018 area & extent data thread]


Earlier this summer I posted four scenarios for extent loss:

https://forum.arctic-sea-ice.net/index.php/topic,2057.msg158764.html#msg158764


I think it will be some variant of scenario 4, except I wouldn't know which year.  I think "the end" will come suddenly, and I don't think anyone has a handle on when that end will happen.

Basically, I expect the Arctic Cell collapsing and the CAB becoming part of the Atlantic to happen at the same time -- I just don't know the time.
Good arguments behind that happening.  It would be a natural follow-on from a point I made earlier.  Once the enthalpy in the Arctic builds up to a sufficiently high level we could easily see major changes in heat transport that will rapidly flip the system into an entirely new state.

in this thread i agree 100%, just not in the "year round thread" ;) ;)

5 years are still pessimistic (considering we don't WANT to see a BOE any time soon) but as you say, the possibility for a sudden death of summer sea-ice cannot be entirely discarded.

Title: Re: How soon could we go ice free?
Post by: Tor Bejnar on September 07, 2018, 08:52:48 PM
An alternative: we could try actually casting bones! ;D ::) :P
If they float, BOE this year; if they land, BOE in a geologic 'instant'.
Title: Re: How soon could we go ice free?
Post by: karl dubhe2 on September 07, 2018, 09:16:22 PM
I do believe that it could go ice free this year, iff there was an incoming large asteroid that happened to hit  the floating ice at the North Pole.  :)  That would melt the stuff, mix up the ocean's water, and be one heck of a disaster.

Needless to say, that's an unlikely scenario.  Maybe I should pitch it to Hollywood...
Title: Re: How soon could we go ice free?
Post by: Dharma Rupa on September 07, 2018, 09:37:43 PM
[Moved from the 2018 area & extent data thread]


Earlier this summer I posted four scenarios for extent loss:

https://forum.arctic-sea-ice.net/index.php/topic,2057.msg158764.html#msg158764


I think it will be some variant of scenario 4, except I wouldn't know which year.  I think "the end" will come suddenly, and I don't think anyone has a handle on when that end will happen.

Basically, I expect the Arctic Cell collapsing and the CAB becoming part of the Atlantic to happen at the same time -- I just don't know the time.
Good arguments behind that happening.  It would be a natural follow-on from a point I made earlier.  Once the enthalpy in the Arctic builds up to a sufficiently high level we could easily see major changes in heat transport that will rapidly flip the system into an entirely new state.

in this thread i agree 100%, just not in the "year round thread" ;) ;)

5 years are still pessimistic (considering we don't WANT to see a BOE any time soon) but as you say, the possibility for a sudden death of summer sea-ice cannot be entirely discarded.

I don't care to predict the end of Summer Ice, since I don't think anyone has any real handle on that, but I say that when the Summer Ice goes the Winter Ice will soon, if not immediately, follow.

The collapse of the Arctic cell and Atlantification will feed each other to end it.

P.S.  I am only talking about the CAB.  Ice near the continents might keep showing up for decades.
Title: Re: How soon could we go ice free?
Post by: Klondike Kat on September 08, 2018, 02:16:06 PM
[Moved from the 2018 area & extent data thread]


Earlier this summer I posted four scenarios for extent loss:

https://forum.arctic-sea-ice.net/index.php/topic,2057.msg158764.html#msg158764


I think it will be some variant of scenario 4, except I wouldn't know which year.  I think "the end" will come suddenly, and I don't think anyone has a handle on when that end will happen.

Basically, I expect the Arctic Cell collapsing and the CAB becoming part of the Atlantic to happen at the same time -- I just don't know the time.
Good arguments behind that happening.  It would be a natural follow-on from a point I made earlier.  Once the enthalpy in the Arctic builds up to a sufficiently high level we could easily see major changes in heat transport that will rapidly flip the system into an entirely new state.

in this thread i agree 100%, just not in the "year round thread" ;) ;)

5 years are still pessimistic (considering we don't WANT to see a BOE any time soon) but as you say, the possibility for a sudden death of summer sea-ice cannot be entirely discarded.

I don't care to predict the end of Summer Ice, since I don't think anyone has any real handle on that, but I say that when the Summer Ice goes the Winter Ice will soon, if not immediately, follow.

The collapse of the Arctic cell and Atlantification will feed each other to end it.

P.S.  I am only talking about the CAB.  Ice near the continents might keep showing up for decades.

I cannot say that I agree.  Why would the ice in the center of the ocean make that much more difference than the ice near shore?  The ice will retreat slowly (sometimes more rapidly) towards land.  I would expect the effects of this to be roughly proportion to the amount of ice present.  Why would the loss of 80% of the ice make that much more difference than 60%?
Title: Re: How soon could we go ice free?
Post by: Dharma Rupa on September 08, 2018, 02:30:54 PM
...
I don't care to predict the end of Summer Ice, since I don't think anyone has any real handle on that, but I say that when the Summer Ice goes the Winter Ice will soon, if not immediately, follow.

The collapse of the Arctic cell and Atlantification will feed each other to end it.

P.S.  I am only talking about the CAB.  Ice near the continents might keep showing up for decades.

I cannot say that I agree.  Why would the ice in the center of the ocean make that much more difference than the ice near shore?  The ice will retreat slowly (sometimes more rapidly) towards land.  I would expect the effects of this to be roughly proportion to the amount of ice present.  Why would the loss of 80% of the ice make that much more difference than 60%?

The Arctic Cell is already in the process of collapsing.  That is what all the Jet Stream talk is about.  It is collapsing because of the reduction in sea ice.  When it collapses completely then the climate over the Arctic Ocean will be much like that over the North Atlantic, reinforcing the end of the Arctic Cell and the sea ice.

The continents are not going to warm in Winter nearly as quickly, therefore you are likely to find ice near (surrounded by) land.

Title: Re: How soon could we go ice free?
Post by: Pmt111500 on September 08, 2018, 03:04:12 PM
... iff there was an incoming large asteroid that happened to hit  the floating ice at the North Pole.  ....
Needless to say, that's an unlikely scenario.  Maybe I should pitch it to Hollywood...
 

::) ;D :D ;)
Title: Re: How soon could we go ice free?
Post by: jdallen on September 08, 2018, 08:45:04 PM
An alternative: we could try actually casting bones! ;D ::) :P
If they float, BOE this year; if they land, BOE in a geologic 'instant'.
Tor, you owe me screen cleaning tools.  ;D
Title: Re: How soon could we go ice free?
Post by: gerontocrat on September 13, 2018, 09:27:55 PM
OPEN WATER SEAS
A Blue Ocean Event is when the Arctic Seas (even for one day) become an open water sea. We all look at the ice , when perhaps we should be looking at the change to Open Water Seas with a maritime climate as opposed to ice-covered deserts. This is what this series of posts is all about.

Ice Area is the measure that best shows for each of the 14 Arctic Seas (and the Arctic Seas in total) the amount of each sea covered by ice. It is that measure as a proportion of the area of each sea (and the total area of the Arctic seas) that indicates the balance between a maritime or sea-ice climate environment. So the area of each sea is the measure against which sea ice area is measured.

Measuring the Open Water proportion is a simple calculation.
1.    Average Daily Ice Area for each year = Sum of the sea ice area for the 365 days of the year and  divide by 365
2.   Divide by the area of the sea to give the proportion of sea covered by ice during the year.
3.   Then Open Water Percentage is 1 minus the proportion of sea covered by ice during the year expressed as a percentage.

This has also been done for
- March, when sea ice is at the maximum,
- September, when sea ice is at the minimum,
- The year to date.
________________________________________________________________________
The Arctic Seas are in very different environments. I have done some rough groupings. This first grouping is about bbr's favorite part of the world - Hudson Bay, the Baffin Sea, and the Canadian Archipelago (CAA). The graphs are attached.

The most striking feature is that the average open water of all three seas has changed very little over the 4 decades. One would think AGW has passed them by. Baffin and Hudson Bay are "Blue Ocean" seas for the month and September (and longer) while the CAA is between 60 to 70 percent open water in this minimum month.

On average, the CAA is only 20-30% open water, very much an ice desert, completely so in winter.
The Baffin Sea (includes the Labrador Sea) is around 70% open water on average, and 40% during the minimum month. On balance, very much an open water sea.
Hudson Bay is around 50% open water on average, and almost zro during the minimum month. On balance, neither one nor the other.

One wonders when increasing Arctic temperatures will really impact these seas.
Title: Re: How soon could we go ice free?
Post by: Archimid on September 14, 2018, 12:03:47 AM
I though the BOE was going to happen in 2016, concurrent with peak global temperatures. It didn’t happen.

When will it happen depends on whether global temperatures enter another hiatus or they keep climbing. If we enter another hiatus we may have a decade until the next peak planetary temperature destroys the Arctic. If temperatures keep climbing it will happen much sooner.
Title: Re: How soon could we go ice free?
Post by: johnm33 on September 14, 2018, 11:54:52 AM
"One wonders when increasing Arctic temperatures will really impact these seas."
A significant fraction of the Arctics freshwater passes through these seas, the more the CAA melts the larger that fraction. I think a good proxy for this flow are the sea levels on the eastern seaboard, the inert arctic waters pressing hard against the continent as they move south, sufficient to slow the Gulf stream. With less ice there may be a threshold when the Russian rivers form their own seasonal freshwater current, think of the Amazons penetration into the Atlantic, that reaches the CAA. These seas may well be the last refuge for ice.
Title: Re: How soon could we go ice free?
Post by: gerontocrat on September 14, 2018, 12:50:15 PM
OPEN WATER SEAS
A Blue Ocean Event is when the Arctic Seas (even for one day) become an open water sea. We all look at the ice , when perhaps we should be looking at the change to Open Water Seas with a maritime climate as opposed to ice-covered deserts. This is what this series of posts is all about.

The graphs look at open water (i.e. free of ice) as a percentage of the area of each sea. The sea ice measure used is NSIDC ice area
________________________________________________________________________
The Arctic Seas are in very different environments. I have invented some rough groupings. This second grouping I have named the Pacific Gateway, being the Bering and Chukchi seas. The graphs are attached.

The Bering Sea was around 80% ice free, with minimum open water during March of around 40% until the late 2000's.
From 1979 the sea has been ice free for 3 or more months of the year. 

Then in 2012 something very strange happened. While the Arctic as a whole was undergoing record melt, the reverse happened in this sea, the average ice free percentage dropping to around 55%, minimum open water during March down to less than 10%.

Since then ice has rapidly declined. Open water during the sea ice maximum sea ice month of March has risen from less than 10% in 2012 to over 80% in 2018. Average open water for 2018 looks set to be above 90%.

This is new. Is the Bering Sea going through a permanent sea change towards a truly open water maritime climate sea?

The Chukchi Sea
An open Bering Sea, in theory, promotes ocean warmth entering the Arctic Ocean which in turn assists melting of the Chukchi. Does the data support this, i.e. changes in the Bering apparent in the Chukchi ? Not really - until 2012.

Until 2012, average open water gradually increased over time from 20% to 40%, maximum open water in September from around 60% to nearly 100%, and minimum open water in March at around 5% or less. However, in 2012 there was a significant drop in open water average to 35%, and a more significant drop in maximum open water from 100% to 85%. Since that date, the upward trend in open water has been restored.

If the Bering Sea continues the trend to year round open water maybe the consequences for the sea ice in the Chukchi will be significant.

Title: Re: How soon could we go ice free?
Post by: Shared Humanity on September 14, 2018, 02:54:07 PM
While the Bering Sea at max was 80% open water, the longer term trend does not rule out the past couple of years as anomalous.

I love these charts by the way. It captures very clearly the degradation of the ice cover across the Arctic and does it in a way not previously tracked.
Title: Re: How soon could we go ice free?
Post by: Shared Humanity on September 14, 2018, 03:01:08 PM

________________________________________________________________________
The Arctic Seas are in very different environments. I have done some rough groupings. This first grouping is about bbr's favorite part of the world - Hudson Bay, the Baffin Sea, and the Canadian Archipelago (CAA). The graphs are attached.

The most striking feature is that the average open water of all three seas has changed very little over the 4 decades. One would think AGW has passed them by. Baffin and Hudson Bay are "Blue Ocean" seas for the month and September (and longer) while the CAA is between 60 to 70 percent open water in this minimum month.

On average, the CAA is only 20-30% open water, very much an ice desert, completely so in winter.
The Baffin Sea (includes the Labrador Sea) is around 70% open water on average, and 40% during the minimum month. On balance, very much an open water sea.
Hudson Bay is around 50% open water on average, and almost zro during the minimum month. On balance, neither one nor the other.

One wonders when increasing Arctic temperatures will really impact these seas.

While the impact is far less than other seas, there is still a slight, very noticeable increase in the annual open water percent.
Title: Re: How soon could we go ice free?
Post by: Shared Humanity on September 14, 2018, 03:11:17 PM
Basically, I expect the Arctic Cell collapsing and the CAB becoming part of the Atlantic to happen at the same time -- I just don't know the time.

This isn't happening in the Chukchi which is more or less ice free for extended periods and has increasing salinity due to mixing and intrusion from the Bering. The long, dark, frigid Arctic winters will continue to cause ice to form after the first BOE.
Title: Re: How soon could we go ice free?
Post by: El Cid on September 14, 2018, 05:13:51 PM
Now, I don't know if this one makes sense or even if it belongs here, but I attach a chart showing sunspot numbers (proxy for insolation) and arctic winter temperatures (here shown as a 3 yr moving average). It seems that low sunspot numbers "lead to" higher winter temperatures while high sunspot numbers "cause" lower winter temperatures (correlation for the past 30yrs: -0,55). We have just had the 3 warmest winters in the arctic and also, we are around the lows of the current solar cycle. If the above holds, we should not see much more warming in the winters in the arctic for the next few years (same as 2009-15).

Is this utterly stupid or just completely?
Title: Re: How soon could we go ice free?
Post by: Archimid on September 14, 2018, 05:50:06 PM
Quote
Is this utterly stupid or just completely?
I think the weak correlation you see is a form of echo. The difference between maximum sunspots and minimum sunspots is minimal relative to the total energy of the Sun is almost trivial.

However, that "almost trivial" energy difference has been operating in an ~11 years cycle since before life emerged. In a chaotic system, if you introduce very small perturbations for a very, very long time you can shift the system in a way that it develops a correlation to the very small but constant force, essentially decreasing chaos.

I think Sunspots are correlated with some Earth system phenomena because over the course of billions of years the constant regularity of solar cycles makes the system have a memory of solar cycles.

Disturbances like CO2 warming eventually overwhelm that constant regularity to transform the climate system into something new. The biosphere is probably very much aligned with these cycles. It will suck to lose that alignment.
Title: Re: How soon could we go ice free?
Post by: gerontocrat on September 14, 2018, 07:24:49 PM
OPEN WATER SEAS
A Blue Ocean Event is when the Arctic Seas (even for one day) become an open water sea. We all look at the ice , when perhaps we should be looking at the change to Open Water Seas with a maritime climate as opposed to ice-covered deserts. This is what this series of posts is all about.

The graphs look at open water (i.e. free of ice) as a percentage of the area of each sea. The sea ice measure used is NSIDC ice area
________________________________________________________________________
The Arctic Seas are in very different environments. I have invented some rough groupings. This third grouping I have named the AtlanticGateway

Group 3 :- the Atlantic Gateway, being the Greenland, Barents, Kara & Laptev and seas.
The Atlantic Gateway dwarfs the Pacific Gateway, being many times wider and deeper. As global ocean heat content and high latitude air temperatures remorselessly increase, one might expect sea ice in these seas to respond accordingly. It is these seas that started the conversation on “Atlantification” of the Arctic (and me to embark on this little (ha-ha) exercise – thanks A-Team).

The Greenland Sea is affected by export of sea ice from the Central Arctic (The CAB) down the Fram Strait, and warming air and ocean from the south. In years when that export of ice is high, one might expect higher levels of ice in this sea. The decline of multi-year (MYI) and thick ice in the CAB in recent years has led to a reduction in ice export.

Yearly average open water has increased from around 50% to approaching 70%.

In March (maximum sea ice) open water has increased from just over 30% to just over 50%.

In contrast, in the 3 months of August to October (minimum ice) open water has increased by a more modest 10%, from around 75% to 85%.

Volatility from year to year is also high, though moderating in recent years, perhaps reflecting variations in Fram export.

The Barents Sea is regarded very much as the poster child for “Atlantification”.

Yearly average open water has increased from around 55% to around 90% from 1980 to date.

In the 3 months of August to October (minimum ice) open water has increased from around 95% open water to 100% in most years since 2008.

March open water (the month of maximum ice) has increased from 30% to 70%.

This is now a sea that just has a bit of ice for a bit of the year. It is now a maritime sea especially as it has lost most of its winter ice.

However, despite being totally ice free for long periods, this has only reduced winter sea ice forming. It gives every sign of gradual transformation, and no sign of abrupt total loss of winter sea ice.

The Kara Sea is again in a unique environment. To the north the island of Novaya Zemla blocks warmth from the Atlantic; to the south, western Siberia can be somewhat cold in winter and very hot in summer.

Yearly average open water has increased from around 25% to around 50% from 1980 to date.

In the 3 months of August to October (minimum ice) open water has increased from around 70% to 95% in most years since 2006.

March open water (maximum ice) has increased from under 10% to around 15% since 2012 despite ice to the south in the Barents and the frigid Russian winter . Volatility has also increased.

This is also a sea that shows the impact of the 2012 great melt.

In 1980 this sea was an ice sea for most of the year. It is now approaching 50-50 status.

The Laptev Sea is totally surrounded by ice in winter to the north, and Central Siberia to the south – sometimes even colder than the Arctic in winter. This is evidenced by no change in open water in March – more or less none.

Yearly average open water has increased from just under 20% to around 30% from 1980 to date.

In the 3 months of August to October (minimum ice) open water has increased from around 45% to around 80% in most years since 2006.

March open water (maximum ice) has not increased from under 10%

The most striking feature of the Laptev is the extreme volatility of the maximum open water months August to October.

In 1980 this sea was an ice sea for most of the year. It still is, apart from the period late summer to autumn.
Title: Re: How soon could we go ice free?
Post by: gerontocrat on September 14, 2018, 07:49:24 PM
Now, I don't know if this one makes sense or even if it belongs here, but I attach a chart showing sunspot numbers (proxy for insolation) and arctic winter temperatures (here shown as a 3 yr moving average). It seems that low sunspot numbers "lead to" higher winter temperatures while high sunspot numbers "cause" lower winter temperatures (correlation for the past 30yrs: -0,55). We have just had the 3 warmest winters in the arctic and also, we are around the lows of the current solar cycle. If the above holds, we should not see much more warming in the winters in the arctic for the next few years (same as 2009-15).

Is this utterly stupid or just completely?
If I remember rightly, it was a Russian Scientist, an authority on sunspot cycles (but not on Global atmospherics) who re-ignited this debate. I know very little about it except for that lovely butterfly graph.

I might be a bit more convinced if someone chucked the data into an excel spreadsheet as an x-Y graph and told excel to put in various trendlines (easy to also tell excel to automatically do the correlations).

Some individual seas show little or no decrease in winter sea ice, others a lot. It seems to me that their vulnerability to increasing temperatures (air and ocean) all depends on their location that determines their climatic environment.

For the Arctic as a whole, increase in winter open water / decrease in winter sea ice seems a much more gradual and even process. Graph attached

Title: Re: How soon could we go ice free?
Post by: Dharma Rupa on September 14, 2018, 09:02:47 PM
OPEN WATER SEAS

I'm hoping, and half expecting that you are going to follow with grouped analyses and a general conclusion.  I am impressed with what this measure is showing so far -- though it isn't clear it portends my predictions.  Seems to hint more at a slow Oceanification, rather than a sudden one.
Title: Re: How soon could we go ice free?
Post by: El Cid on September 14, 2018, 09:12:59 PM
It seems that low sunspot numbers "lead to" higher winter temperatures while high sunspot numbers "cause" lower winter temperatures (correlation for the past 30yrs: -0,55). We have just had the 3 warmest winters in the arctic and also, we are around the lows of the current solar cycle. If the above holds, we should not see much more warming in the winters in the arctic for the next few years (same as 2009-15).

Is this utterly stupid or just completely?
If I remember rightly, it was a Russian Scientist, an authority on sunspot cycles (but not on Global atmospherics) who re-ignited this debate.

For the Arctic as a whole, increase in winter open water / decrease in winter sea ice seems a much more gradual and even process. Graph attached

The point I wanted to make is that although obviously greenhouse gases define the long term temperature trend (up),but short term winter temperature oscillation might somehow be influenced by solar output (dont know how). If this is true, then  the next few winters should not be warmer than the past 3 very warm ones, as the "solar downswing" would be balanced by the ongoing greenhouse gas forcing. If this is true then the next "window of opportunity" for an ice free arctic would be the bottom of the next solar cycle, some time around 2030...
Title: Re: How soon could we go ice free?
Post by: gerontocrat on September 14, 2018, 09:35:25 PM

The point I wanted to make is that although obviously greenhouse gases define the long term temperature trend (up),but short term winter temperature oscillation might somehow be influenced by solar output (dont know how). If this is true, then  the next few winters should not be warmer than the past 3 very warm ones, as the "solar downswing" would be balanced by the ongoing greenhouse gas forcing. If this is true then the next "window of opportunity" for an ice free arctic would be the bottom of the next solar cycle, some time around 2030...

Increasing CO2 ppm might well force more air and ocean temperature increase than  any -ve effect from decreased solar radiation. How does one separate these two effects ? Add in a possible change in ocean currents that could either chuck loads of extra heat from the Atlantic ocean at the Arctic (or vice-versa) and you are talking big math and big computers.

I and my laptop retire from the field. Wait and see becomes my plan of action, if I live that long. (My epitaph - "damn, I wanted to see what happened next")
Title: Re: How soon could we go ice free?
Post by: gerontocrat on September 14, 2018, 09:40:11 PM
OPEN WATER SEAS

I'm hoping, and half expecting that you are going to follow with grouped analyses and a general conclusion.  I am impressed with what this measure is showing so far -- though it isn't clear it portends my predictions.  Seems to hint more at a slow Oceanification, rather than a sudden one.

The grouped analyses will be a pig. Simple averages will not do, need to weight by area involved etc.
Patience, Dharma, I did not realise what I was letting myself into, starting this.
Title: Re: How soon could we go ice free?
Post by: Dharma Rupa on September 14, 2018, 10:00:58 PM
OPEN WATER SEAS

I'm hoping, and half expecting that you are going to follow with grouped analyses and a general conclusion.  I am impressed with what this measure is showing so far -- though it isn't clear it portends my predictions.  Seems to hint more at a slow Oceanification, rather than a sudden one.

The grouped analyses will be a pig. Simple averages will not do, need to weight by area involved etc.
Patience, Dharma, I did not realise what I was letting myself into, starting this.
My poor suffering slave.

It looks really good so far!
Title: Re: How soon could we go ice free?
Post by: gerontocrat on September 15, 2018, 04:05:05 PM
OPEN WATER SEAS
A Blue Ocean Event is when the Arctic Seas (even for one day) become an open water sea. We all look at the ice , when perhaps we should be looking at the change to Open Water Seas with a maritime climate as opposed to ice-covered deserts. This is what this series of posts is all about.

The graphs look at open water (i.e. free of ice) as a percentage of the area of each sea. The sea ice measure used is NSIDC ice area

The Arctic Seas are in very different environments. I have invented some rough groupings. This fourth grouping I have named the Central Arctic Basin Protected Seas
________________________________________________________________________
Group 4 :- the protected seas of the Central Arctic Basin – being the Beaufort, Eastern Siberia and Central Arctic Seas
In winter, these seas are bounded by frozen land and/or frozen water, and are the last to be exposed to open water. It is often assumed that they will be the last to lose their ice.

The Beaufort Sea, bounded by Alaska and Canada to the South, the Chukchi to the West, and the Central Arctic to the North and East.

Yearly average open water has increased from around 15% to 30%.

In March (maximum sea ice) open water has decreased from around 5% almost zero.

In contrast, in the 3 months of August to October (minimum ice) open water has increased more than doubled, from around 35% to 75%.

It is therefore entirely a story about summer melting. It is still very much an “ice desert” sea.

The Eastern Siberian Sea (ESS)
has the Central Arctic Sea to the North, the Chukchi to the East, the Laptev to the West, and Central- Eastern Siberia to the South. It is, on occasion, vulnerable to Atlantic winds and currents when the Laptev has melted out.

Yearly average open water has increased from just under 10% just under 30% from 1980 to date.

In the 3 months of August to October (minimum ice) open water more than doubled  from around 30% open water to 75%. In these months volatility from year to year is also very high.

March open water (the month of maximum ice is zero as near as makes no difference.

It is therefore entirely a story about summer melting. It is still very much an “ice desert” sea.

The Central Arctic Sea
is the largest sea by far, at 3.2 million km2 and over 20% of the total area of the Arctic Seas. Centred on the North Pole, t is bounded by the CAA, Beaufort, Chukchi, ESS, Latev, Kara, Barents, and Greenland Seas plus North Greenland and Canadian Islands.

Yearly average open water has increased from around 5% to around 10% from 1980 to date. Most of this increase happened abruptly, at around 2006.

In the 3 months of August to October (minimum ice) open water has increased from around 15% to 30%  Again, most of this increase happened abruptly, at around 2006. At that time annual volatility also increased markedly.

March open water (maximum ice) has increased from nearly zero to approaching 5% since 2012.

At an average open water percentage during the year of 10%, it is still very much an “ice desert” sea. This sea is never ice free, and at current rates of decline, it will be many years before it is ice free even in the month of minimum ice area.

The graph makes it clear how much of that sea is permanently ice covered
Title: Re: How soon could we go ice free?
Post by: Dharma Rupa on September 15, 2018, 05:48:01 PM
That's a pretty shocking change in the CAB in 2006-7...  When was the term Atlantification invented?
Title: Re: How soon could we go ice free?
Post by: Stephan on September 15, 2018, 07:50:11 PM
A simple question: Is the summer increase of open water in CAB since 2006/7 directly or mainly caused by a more northern ice boundary N of Svalbard and FJL?
Title: Re: How soon could we go ice free?
Post by: El Cid on September 15, 2018, 08:01:02 PM
great charts gerontocrat, they show a "systemic change" in 2006-7 but no seismic shifts since then
Title: Re: How soon could we go ice free?
Post by: gerontocrat on September 15, 2018, 08:24:33 PM
A simple question: Is the summer increase of open water in CAB since 2006/7 directly or mainly caused by a more northern ice boundary N of Svalbard and FJL?
I don't know,but in 2006 there is a general burp upwards in the Laptev but not the Kara, and a burp up int winter sea ice decline in the Barents on the Atlantic side, and a general upwards burp in the Chukchi, Beaufort and East Siberian on the Pacific side.
Title: Re: How soon could we go ice free?
Post by: gerontocrat on September 16, 2018, 05:35:04 PM
OPEN WATER SEAS
A Blue Ocean Event is when the Arctic Seas (even for one day) become an open water sea. We all look at the ice , when perhaps we should be looking at the change to Open Water Seas with a maritime climate as opposed to ice-covered deserts. This is what this series of posts is all about.

The graphs look at open water (i.e. free of ice) as a percentage of the area of each sea. The sea ice measure used is NSIDC ice area

The Arctic Seas are in very different environments. I have invented some rough groupings. This fifth grouping I have named the Seas south of the Arctic Ocean – being the Okhotsk, and the St. Lawrence
________________________________________________________________________

Group 5 :- Seas south of the Arctic Ocean – being the Okhotsk, and the St. Lawrence

The Okhotsk Sea, at around 50o North has no connection with the Arctic Ocean, and the St Lawrence, at around 52o North, very little. They form part of the NSIDC analyses and so they are included.

The Okhotsk Sea area is 1.583 million km2. This analysis uses 1.617 km2, the maximum extent in the NSIDC record since 1979. This is because the NSIDC grid includes part of the Sea of Japan. The 1.617 km2 figure is probably too low, but I do not have the technical skills to establish the size of the grid used by NSIDC, and NSIDC do not have the data readily available. (This also applies to a few other seas but is not significant).

Yearly average open water has gradually increased from around 80% to around 90% from 1980 to date.

In the 3 months of August to October (minimum ice) open water is always 100%, often more than 95% open water for more than 6 months

March open water (maximum ice) has increased from under 40% to over 60%. That percentage plunged downwards from 1997 to 2001, recovered to the upward trend by 2006, but has not changed much since then.

Yet another sea that shows no sign of being unable to reform sea ice in winter.

The St. Lawrence
Yearly average open water has gradually increased from around 90% to around 95% from 1980 to date.

In the 3 months of August to October (minimum ice) open water is always 100%, often more than 95% open water for more than 6 months. Apart from two years (’87 and ’88), ice was less than 5% of maximum for between 180 and 184 days – remarkably consistent.

March open water (maximum ice) has increased from around 60% to over 80%, but volatility from year to year is very high.

Nevertheless, the St. Lawrence is yet another sea that shows no sign of being unable to reform sea ice in winter.

ANALYSIS BY GROUPINGS TO COME NEXT - it may take some time.
Title: Re: How soon could we go ice free?
Post by: NACK on September 17, 2018, 11:39:00 AM
Gerontocrat,

I really appreciate what your hard work has accomplished. Thanks.

One area of interest is a subset of the CAA; the area south of Devon, Cornwallis, Bathhurst and Mellville Islands - i.e. the Northwest Passages.

The CAA, although geographically an entity, could really be split into two sections; north and south of this line; as they are two dissimilar sections regarding the open water analysis.

A year-round ice-free shipping route appears to be many years in the future but it would be interesting to see the graphs for open water the last several decades.

Title: Re: How soon could we go ice free?
Post by: gerontocrat on September 17, 2018, 04:24:37 PM
Gerontocrat,

I really appreciate what your hard work has accomplished. Thanks.

One area of interest is a subset of the CAA; the area south of Devon, Cornwallis, Bathhurst and Mellville Islands - i.e. the Northwest Passages.

The CAA, although geographically an entity, could really be split into two sections; north and south of this line; as they are two dissimilar sections regarding the open water analysis.

A year-round ice-free shipping route appears to be many years in the future but it would be interesting to see the graphs for open water the last several decades.
It would, but the NSIDC system does not go down that far. My understanding is that data sent by the satellite is plonked into a matrix that adds a code to say which sea each bit of data belongs to. That is the the code used for the numerical analysis of area and extent for each sea. That code does not split the CAA into sub-sets. (Other codes I presume are used to allow the GIS mapping of area and extent and concentration).

Many wish finer detail was available, especially for the massive Central Arctic Sea so change between, e.g. The Atlantic and Pacific sides could be analysed numerically. But to do so would be a massive exercise to reanalyse the daily matrices from 1979 - all 14,000+ of them.

It ain't going to happen, methinks. Ice-sat2 will produce the data to do it -from 2019. The data will be freely available (I hope), but this person has not the GIS skills to have a go. (I wish I did but there you are).
Title: Re: How soon could we go ice free?
Post by: gerontocrat on September 17, 2018, 09:02:28 PM
OPEN WATER SEAS
A Blue Ocean Event is when the Arctic Seas (even for one day) become an open water sea. We all look at the ice , when perhaps we should be looking at the change to Open Water Seas with a maritime climate as opposed to ice-covered deserts. This is what this series of posts is all about.

The graphs look at open water (i.e. free of ice) as a percentage of the area of each sea. The sea ice measure used is NSIDC ice area

The Arctic Seas are in very different environments. I have invented some rough groupings. This analysis now looks at overall totals for each group
________________________________________________________________________

Group I – Baffin (including Labrador) Seas, Hudson Bay, and The Canadian Archipelago (CAA) - 3.8 million Km2
The most striking feature is that the average open water of all three seas has changed very little over the 4 decades. One would think AGW has passed them by.

I am tired, and it is late. Do it properly tomorrow
Title: Re: How soon could we go ice free?
Post by: Dharma Rupa on September 17, 2018, 09:11:05 PM
OPEN WATER SEAS
I am tired, and it is late. Do it properly tomorrow

That is fine...are we going to call these continental seas?
Title: Re: How soon could we go ice free?
Post by: oren on September 17, 2018, 11:14:58 PM
I think the gridded data IS available from NSIDC, and at least Wipneus and probably some others can analyze it. I fantasize on being able to do it myself at some point.
Title: Re: How soon could we go ice free?
Post by: gerontocrat on September 17, 2018, 11:25:21 PM
I think the gridded data IS available from NSIDC, and at least Wipneus and probably some others can analyze it. I fantasize on being able to do it myself at some point.
Yes it is, and I read it up. My fantasy duly evaporated.
Title: Re: How soon could we go ice free?
Post by: gerontocrat on September 18, 2018, 10:50:42 PM
A better attempt, I hope.

OPEN WATER SEAS
A Blue Ocean Event is when the Arctic Seas (even for one day) become an open water sea. We all look at the ice , when perhaps we should be looking at the change to Open Water Seas with a maritime climate as opposed to ice-covered deserts. This is what this series of posts is all about.

The graphs look at open water (i.e. free of ice) as a percentage of the area of each sea. The sea ice measure used is NSIDC ice area

The Arctic Seas are in very different environments. I have invented some rough groupings. This analysis now looks at overall totals for each group
________________________________________________________________________

Group I – Baffin (including Labrador) Seas, Hudson Bay, and The Canadian Archipelago (CAA) - Area 3.8 million Km2

The most striking feature is that the average open water of all three seas has changed very little over the 4 decades. One would think AGW has passed them by.

Yearly average open water has increased marginally from around 50% in 1980 to around  55% by 2018.

In March (maximum sea ice) open water has stayed at around 20% , i.e. mostly ice-covered.

In the 3 months of August to October (minimum ice) open water has increased by a marginal 5%, from around 90% to 95%.

The loss of sea ice over the years is therefore basically confined to the summer months. Volatility from year to year is also comparatively low.  These seas are in a stable condition.
__________________________________________________________________________

Group 2 :- the Pacific Gateway, being the Bering and Chukchi seas. (Area 2.0 million Km2)

]The Pacific Gateway allows warm from the Pacific into the Arctic Ocean through the Bering Strait, which is both narrow and shallow.  In theory, increasing warm the in the North Pacific should have leads to loss of ice year round in the Bering Sea, in turn making the Chukchi vulnerable to melting.

Yearly average open water has increased from around just under 60% in 1980 to 70% in 2018, mostly in the last three years

From 1979 in the three minimum ice months of August to October open water has increased from 80% to nearly 100% from 2007. 

Winter sea ice shows and even more dramatic change, open water being at between 30% and 40% from 1980 to 2011, collapsing in 2012 ( the year of massive summer melt) to less than 20%, and then rapidly rising to 50% in 2018.

This is a new development. Is the Bering Sea going through a permanent sea change towards a truly open water maritime climate sea, to be followed by the Chukchi? (Or is this change temporary only)
_____________________________________________________________________
Group 3 :- the Atlantic Gateway, being the Greenland, Barents, Kara & Laptev and seas. (Area 4.2 million Km2)

It is these seas that started the conversation on “Atlantification” of the Arctic. The Atlantic Gateway dwarfs the Pacific Gateway, being many times wider and deeper. As Atlantic Ocean heat content and high latitude air temperatures remorselessly increase, one might expect sea ice in these seas to respond accordingly. Is it the case?

The image attached – from University of Bremen, suggests that this is the case. The numerical analysis supports it.

Yearly average open water has increased from around 45% in 1980 to 60% in 2018, fairly evenly over the years.

In the three minimum ice months of August to October open water has increased from 80% to over 90%, also fairly evenly over the years. 

In the maximum ice month of March open water has increased from 25% to 40%, also fairly evenly over the years. 

The conclusion must be that until now ice has declined in both summer and winter. With summer open water now at well over 90%, the question must be – will winter sea ice continue to decline and at what rate? Winter Sea Ice loss leading to earlier melt and later freeze  in these 4 seas may be the real key to Atlantification of the Arctic Ocean.
_____________________________________________________________

With luck, tomorrow a look at the big beasts - the Beaufort, the ESS and the Central Arctic and then some thoughts, if I am still capable of thought by then

Title: Re: How soon could we go ice free?
Post by: gerontocrat on September 19, 2018, 04:59:41 PM
OPEN WATER SEAS
A Blue Ocean Event is when the Arctic Seas (even for one day) become an open water sea. We all look at the ice , when perhaps we should be looking at the change to Open Water Seas with a maritime climate as opposed to ice-covered deserts. This is what this series of posts is all about.

The graphs look at open water (i.e. free of ice) as a percentage of the area of each sea. The sea ice measure used is NSIDC ice area

The Arctic Seas are in very different environments. I have invented some rough groupings. This analysis now looks at overall totals for each group
________________________________________________________________________

Group 4 :- the protected seas of the Central Arctic Basin – being the Beaufort, Eastern Siberia and Central Arctic Seas (Area 5.5 million Km2)

Yearly average open water has increased from just under 10% just under 20% from 1980 to date.

In the 3 months of August to October (minimum ice) open water more than doubled from around 20%  to approaching 50 %. In these months volatility from year to year is also very high.

March open water (the month of maximum ice is zero as near as makes no difference, but with a hint of a small increase from 2016 to date to around 5%.

It is therefore entirely a story about summer melting. Even in September, the month of minimum ice, open water only increased to above 50% from 2007, and only exceed 60% in one year – the record melting year of 2012. To approach 100% open water at any time of year looks to be a good many years ahead.

These are still very much “ice desert” seas.

______________________________________________
Group 5 :- Seas south of the Arctic Ocean – being the Okhotsk, and the St. Lawrence (Area 1.9 million Km2)

The Okhotsk Sea, at around 50 North has no connection with the Arctic Ocean, and the St Lawrence, at around 52 North, very little. They form part of the NSIDC analyses and so they are included. Also see the last remark.

Yearly average open water has gradually increased from around 80% to around 90% from 1980 to date.

In the 3 months of August to October (minimum ice) open water is always 100%, often more than 95% open water for more than 6 months.

March open water (maximum ice) has increased from around 45% to around 65%, but volatility from year to year is quite high.

The seas are in the mid-latitudes. Nevertheless, winter sea ice forms substantially. Much has been said about how after a BOE in summer, Arctic winter sea ice would dramatically reduce. Winter sea ice is declining, but not dramatically in these seas, even though they are south of the Arctic in a much milder climatic and ocean environment. So the evidence from these seas contradicts that hypothesis.
Title: Re: How soon could we go ice free?
Post by: gerontocrat on September 19, 2018, 05:20:07 PM
OPEN WATER SEAS
A Blue Ocean Event is when the Arctic Seas (even for one day) become an open water sea. We all look at the ice , when perhaps we should be looking at the change to Open Water Seas with a maritime climate as opposed to ice-covered deserts. This is what this series of posts is all about.

The graphs look at open water (i.e. free of ice) as a percentage of the area of each sea. The sea ice measure used is NSIDC ice area

The Arctic Seas are in very different environments. I have invented some rough groupings. This analysis now looks at overall totals for each group
________________________________________________________________________

Summary - Total Arctic Seas Area 17.4 million Km2 (includes some seas outside or partly outside the Arctic Ocean)

The images attached show extent in September 1979 and September 2018, and March 1979 and March 2018 (from NSIDC Spatial Tools). Note that extent covers any water with more than 15% ice, so gives a perhaps exaggerated view of the ice.

It is obvious that reduction in winter ice is low and basically confined to the Bering Sea and Atlantic margin. While summer ice loss is high, it is basically confined to an arc from the Atlantic, along the coast of Siberia, across the Pacific gateway and along the coast to the Alaska – Canada border.

And here is the Open Water Analysis.

Yearly average open water has increased from 40% to 50% from 1980 to date.

In the 3 months of August to October (minimum ice) open water from just over 60%  to just over 80%.

March open water (the month of maximum ice has increased from 20% to just under 30%.

With average open water creeping up to above 50%, can one claim the Arctic Seas in total are on balance now Open Water Seas more than Ice Deserts? A moot point. However, there is a lot more ice to melt for a BOE.

Some individual seas show little or no decrease in winter sea ice, others a lot. It seems to me that their vulnerability to increasing temperatures all depends on their location that determines their climatic environment.

As one can see, the 2012 record melt only had a marginal effect on the open water percentage for the year. Change is gradual – there is no sign of a dramatic change.
Title: Re: How soon could we go ice free?
Post by: Ned W on September 19, 2018, 06:08:59 PM
I think the gridded data IS available from NSIDC, and at least Wipneus and probably some others can analyze it. I fantasize on being able to do it myself at some point.
Yes it is, and I read it up. My fantasy duly evaporated.

Earlier this summer, I used the NSIDC gridded concentration data to recalculate extent using a 30% threshold, 1978-present, to see whether 15% vs 30% made any difference in the trend (it didn't).
Title: Re: How soon could we go ice free?
Post by: gerontocrat on September 19, 2018, 06:29:20 PM
I think the gridded data IS available from NSIDC, and at least Wipneus and probably some others can analyze it. I fantasize on being able to do it myself at some point.
Yes it is, and I read it up. My fantasy duly evaporated.

Earlier this summer, I used the NSIDC gridded concentration data to recalculate extent using a 30% threshold, 1978-present, to see whether 15% vs 30% made any difference in the trend (it didn't).
Arithmetic is a harsh master. It destroys so many hypotheses and gut feelings.

(If I remember rightly the computer works simply by adding and taking away, but very quickly, though in IBM Fortran it added and took away logs).