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Susan Anderson

Temps in Alberta a couple days back (that fire, ongoing and getting bigger) was said to have been 33C (91F) (weather channel).

This is shocking, but I don't like to hear assertions that the Arctic will melt completely this summer. (If this is wrong, somebody please correct me.)

Northeast US is relatively cold; we're in that cool pocket in the US north Atlantic northeast. OT for Arctic, but all hell has been breaking loose in the US weatherwise.


Great post Neven.
This is the most alarming post I have read here since 2012, by far. Such a conjunction of very negative indicators right at the beginning of the melting season! Unless very cool weather counteracts this all in June, this really calls for catastrophe.

This is shocking, but I don't like to hear assertions that the Arctic will melt completely this summer.

Which is why you won't hear me say it, Susan. ;-)

I agree that there is no reason for proclaiming the Arctic will go ice-free this summer (below 1 million km2 extent/area). Initial sea ice conditions aren't that much different from previous low years like 2011, 2012 and 2013, although it looks like PIOMAS could go lowest on record once the next update is out (any day now).

At the same time, I dare say that if you're wondering how the start to that first fluke of ice-free conditions in September would shape up, well, this is how it would look.

Extremely warm/not-cold winter, relatively thin ice on the Pacific side of the Arctic, massive ice movement during the transition period when open water no longer freezes up to a meaningful thickness, continued high temps, high export through Fram Strait, extremely rapid loss of snow cover (there's a correlation there as Rob Dekker has shown through the years, something which Dr. Andrew Slater from the NSIDC is also working on).

If this is followed by lots of melt ponds during May and June, and melting momentum gets built up, it will take a helluva lot of cyclonic activity to keep this year from breaking all records. But not a GAC, of course. Not that much cyclonic activity. Just persistent cloudiness and cold temps.

Again, I don't think the Arctic will go ice-free this year, it's impossible to tell now anyway, but this is how that first ice-free year would start (if volume were significantly lower to start with).


I forgot to mention this excellent blog post by Chris Reynolds on Dosbat, with lots of additional information: Beaufort starts early


Fish, real name George here... powerful and disturbing graphics, excellent work Neven. I'm not surprised that this year's high pressure has been persistent. The dynamics this year is pretty shocking. I'm planning to write about it.

If you don't mind, I would like to include some of the great little animations you have put up here. I would like to get the story to a broader audience. The place I post is a mess now with idiotic political infighting but it's good to reach a general audience.

Robert Scribbler made the post that asserted a possible total melt out this year. Given the volume of ice that has piled up on northern Ellesmere Island and the difficulty of removing it from that region, I doubt that we will see a complete melt out this summer. The winds tend to push the remaining ice in that direction and pile it up so its very hard to melt it all out. Just looking at trend lines like Robert did isn't a very sophisticated way to analyze the situation.

However, the hot early start in early spring will be amplified by the darkening of the surfaces given that snow and ice cover is the lowest on record. This is a set up for a new sea ice minimum.

Susan Anderson

Thank you Neven, your gentle, thoughtful intelligence is a tonic. It was someone promoting RobertScribbler who got me so bovvered. Somewhere along the line my friend and I got tangled up in exaggeration; that's not quite what he said.

Good idea George/Fish/D!

John Bilsky

Is it my imagination or is just about the entire Arctic Ocean ice pack full of leads? If so, what are the implications?


Not imagination John,

If you travelled on this ice, leads are commonly made every day, but not refreezing or closing , as seen from space, is a sign of summer.


A continuation of my recent work likely pinpoints a possible error in Remote Sensing temperature data, In effect comparing what is observed optically, with rather sophisticated platforms. On the whole, the satellites gather good average temperatures, but may not do so at every top of sea ice location daily,


Kevin McKinney

Another joker thrown into the hand, at least as far as snow cover in the western Canadian Arctic and remaining Beaufort ice are concerned: the smoke plume from the Fort McMurray fire seems to be reaching the shore, according to this:


Don't know how long that may last, nor how much deposition may be expected, but if we're looking at a prolonged period of sunny skies, a fine dusting of soot will not help matters any.

(Hat tip to Michael Schneiders for asking the question over at RC.)

Kevin McKinney

"Schnieders", not "Schneiders." Damn autocorrect anyway!

John Bilsky

Thanks Wayne.
But it's not summer yet.

Kevin McKinney

Here's a screen shot of the Fort McMurray fire plume. I was remiss in my earlier comment not to state clearly that the smoke isn't currently reaching the Arctic shore, but rather that it is forecast to do so in the next couple of days (note the date on the screen shot.)

Hopefully this is the correct html:

Kevin McKinney

Apparently not.

Trying again:

 photo Fort McMurray Fire smoke plume PM 2.5.png

Colorado Bob

Scientists track Greenland's ice melt with seismic waves

Researchers from MIT, Princeton University, and elsewhere have developed a new technique to monitor the seasonal changes in Greenland's ice sheet, using seismic vibrations generated by crashing ocean waves. The results, which will be published in the journal Science Advances, may help scientists pinpoint regions of the ice sheet that are most vulnerable to melting. The technique may also set better constraints on how the world's ice sheets contribute to global sea-level changes. ................ "They happen 24 hours a day, seven days a week, and they generate a very small signal, which we generally don't feel," Prieto says. "But very precise seismic sensors can feel these waves everywhere in the world. Even in the middle of continents, you can see these ocean effects."

Read more at: Link

Rob Dekker

Regarding that smoke column from the McMurray fires, thanks Kevin.
Good that so far it stays clear of open sea ice, and populated areas.

However, it is astonishing how far and wide north that smoke drifts, and the smoke particles cannot be good for the remaining snow up there...

Rob Dekker

Did I see that correctly that the new PIOMAS numbers are out ?

And do I see that correctly, that volume at Arctic Sea Ice Volume this point is hovering at an all-time-low for the day, closely following the previous 2011 volume graph ?

Artful Dodger

Hi Kevin,

I thing the future risk for soot from YMM (Ft McMurray) is to Greenland. Given the prevailing wind, an injection of black carbon is going to impact Greenland ice sheet melt this summer.

Currently, the smoke plume from YMM

Artful Dodger

... is being felt (smelt?) in Atlanta, Georgia.


Say Kevin, how is the air quality down there?


I'm going to be off for a week, but will probably/hopefully be able to connect to the Internet (and post the PIOMAS update).


Finally breackup at Nome.
Dispite the high temperatures there it took rather long ...

Susan Anderson

Thanks Kevin, that's a great image. About that fire, Tenney sent us this Worldview link, and mentioned Greg Laden could smell the smoke in Minneapolis (1,125 miles SW) yesterday. Meanwhile, the news is that it may be months before the fire is tamed, requiring major rain; nature is not cooperating. Later it will be possible to move the pointer at lower left to 8 May, which is still blank.

Andy Lee Robinson

PIOMAS published last night - Record low for average April, and biggest drop over previous average April in the record.


659 km³ head start on 2012

1 2016 22,471
2 2011 22,510
3 2014 22,946
4 2012 23,130
5 2013 23,131
6 2007 23,764
7 2010 24,103
8 2015 24,239
9 2009 24,957


I want to caution people like D on making predictions for a new record minimum. It's still far too early to tell if it will be a record. I definitely agree it's more possible than last year, but let's hold on to our hats for a couple more months before making a prediction just yet. D, I might remind you that you predicted a record minimum last year, and you weren't even close.


Concur bobcobb - way too early, and last year there was a lot of excitement. The uncertainty of it is why most of us think in terms of probabilities now. In that regard, while a predicted new minimum wasn't reached, for many off us, the 2015 result was dead on in the middle of the range of possibilities we saw; in fact a bit lower than many.

To wit: Last year we saw a 15-20% chance of passing 2012. This year, at this point, I'd say we have at least double that, based on the last 10 years melt behavior. That's not because of any particular change in the melt season - we can reach that with rather modest melt numbers. Considering current conditions and short term weather predictions, there's a lot of pressure to presume more. I don't think it's a difficult stretch to imagine it.


I agree it's not hard to imagine, but it annoys me when D goes off on one his more extreme posts. I've seen him and others like tampaesski (not sure if I'm spelling that right), writing on Daily Kos, and I'm reminded why I don't use that site or robertscribbler as sources for climate news. A lot of times they presume the worst and are left with egg on their faces when they're abysmally wrong. That's why I prefer corresponding with actual scientists.



Sea ice projections incorporates many factors, its not easy to do, especially impossible without effort.

Making predictions is a scientific tool to gather insight. It does not mean anyones reputation will end when the projection fails. Nor does a group consensus forecast failure has meaning on the persons involved. It is an essential method which helps confirm whether or not the subject is understood. Then again, failure redoubles the study of why it did not happen as thought. When people predict things from a political stance, in line with bad science, WUWT style, then it needs not be appreciated nor commented on.

If there is a melt season prone to overtake 2012, it is this year,
I would be very surprised if it does not happen. On a scale of 1 to 10 surprised I would take 8.

This said, the biggest slow down possible of what is potentially the largest melt ever, may only come from steady cyclones at about the the Pole, like 2013. I do not see this happen because we are trending LaNina very very similar to 2007, a bit like 2011, more than a little like 2012 which had a small El-Nino which blitzed very quickly to LaNina during summer. 2015 El-Nino peak was so massive that it can only mean less clouds when exhausted. A history record breaking El-Nino can only mean one thing, less sea ice. After all, 1998 was the beginning of the great recent decline in sea ice extent.

But there is still a possibility of a cloud stall. 2010 is the only outlier to an otherwise stellar model of prediction, primarily unlike now, because it was cloudier during the spring. I had 3 times more sun observations taken this present year compared to the same April date in 2010. Iceland volcano Eyjafjallajokull eruptions might have contributed to this.

For 2016 a cloud stall driven by cyclones is a matter of timing, If a great part of the Arctic Ocean opens earlier, cyclones may move in just as quickly. But there are, at this time, no significant cloud formations as usually blossoming at this time of year. This implies a slight lack of cloud seeding on a greater planetary scale.


Um, so what is this cloud seeding all about in your last sentence?

Interesting post,... I just wish I understood it more!


It does have effects on the people involved from a reputation standpoint when they have a history of making rather extreme projections, which is exactly what D does. So I don't really take anything he says about sea ice seriously. Now if someone like Ruth Mottram or Cecilia Bitz predicted a record, then I would listen. Until then, people like robertscribbler don't do it for me. Believee, it's not hard to go into an article he writes and pick out the inconsistencies, kind of like that idiot Dahr Jamail. Every reputable climate scientist I've talked to (Mike Tobis, Ken Caldeira, Mark Brandon, just to name a few), thinks people like Jamail and Scribbler aren't doing climate science any favors.
Sorry I ranted there for a little bit, but the larger point I'm trying to make is that there are better sources to rely on. That being said, I'll make my own prediction of 4.1 square km.


Already a second century this year at ADS-NPR. Minus 130.413 km2.

Meanwhile 2006 remains the second worst. For now, of course.


Has there only been two drops of 100K this year?

Can't be that bad then...

Rob Dekker

bobcobb, D did not make any "extreme projections". He merely stated that "the hot early start in early spring will be amplified by the darkening of the surfaces given that snow and ice cover is the lowest on record. This is a set up for a new sea ice minimum."

Which is pretty darn accurate.
In fact, the most level-headed projection at this point is by Jim Petit, who uses the typical extent lost between now and Sept to come up with this graph :

which again shows that, based on best current knowledge, there is a good chance that the minimum will be broken this year or at least end up below 4 M km^2.

And this is not even considering the record-low land snow extent at this point, which typically implies that sea ice losses will be more than average.


the possibility of a record this year has been evident from the end of March when sea temperatures across the arctic and the globe were shown to be a full standard deviation above the previous records. When temperature records jump from 2 to 3 std deviations above the average speculation is inevitable.

A very conservative estimate at this stage would put the likelihood of a record at 30%. The question for many of us is how could a new record be avoided.

There is already a poll on the forum with 2/3rds of the respondents predicting a record.


Fish Here. Or, if you like call me George. The D is a fluke of the Google+ log on here.

About the commentary above. I'm a geochemist. I managed nuclear waste disposal safety research projects for many years then retired early. I have never made a sea ice prediction. Let's not confuse a comment on a blog with an actual scientific prediction.

Last year I made some comments early in the melting season that I clearly corrected by summer when it became clear that the recovery was over but it wasn't going to be a record.

This year, I am giving another opinion in a comment section. If I had a scientific model it would be a prediction. I'll let the folks who do the modeling make the predictions.

This year, given the astounding start to the melt year, the chance of breaking the 2012 record looks pretty good right now. I'm sticking with my opinion, but I'm not calling it a prediction or forecast.

Over at Dailykos I try to explain complicated climate problems in ways that will interest well educated people who aren't scientists. It's a challenge to balance the hard science with the emotional content that appeals to a broad audience.

FYI, I worked with a chemist who won a "big prize" despite making all kinds of off the wall "bad forecasts" and mistakes. It's ok to be wrong and make mistakes in scientific research. The real problem in science is not mistakes. Sloppy work is a problem. Small thinking is a problem. Spending huge amounts of time to get funding is a problem. Lack of funding for good work, as Neven discussed recently, is a problem.

When I make a post I always try to lay out the data and my analysis openly so that people who read my posts can come to their own conclusions. And if I make a mistake, if I have showed the figures and laid out my reasoning, hopefully, we can all learn from the mistake, not get confused by it.

Unfortunately, in climate change, scientists have erred on the side of scientific caution but not on the side of actual caution. The IPCC has been way behind the curve. Sea ice and glacial ice has been melting out at far higher rates than the IPCC predicted. Consistently making predictions that come on the low side is not a good thing. Society has not responded quickly enough to climate change, in part, because of excessive scientific caution by the IPCC.

I think we should all be alarmed by the shockingly high global and Arctic temperatures this year. The record low PIOMAS volume for April is but one more measure of the severity of the problem.


And may I ask how many of the respondents on the forum are actual climate or polar scientists? Probably none. With all due respect to Neven, a lot of information on the forum, particularly anything by abruptslr and jai mitchell, consists of unsubstantiated and wild extrapolations, pure bunk in other words.
Granted, I find people such as Petite and Wipneus to be good posters, but so many of the people posting there I find to have unwarranted extrapolations. Chris Reynolds has concurred with me on this point.
And George, I don't necessarily agree with you that scientists in general have erred on the side of caution. In the arctic, that's true to some extent, but not in other areas. I could point to various examples where scientists have gotten it right (gcm models for temperature) or overestimated (the amount if carbon forests lose with rising temperatures). I think it's rather arrogant of you to say that in general scientists have been way too cautious.
And Rob, what happens if there isn't a record? A lot of you were saying the same thing last year. There is a considerably greater chance of a record, but the rate of melting would have to be very large to catch 2012. As JDALLEN said, it's far too early to be assuming a record.


I was quite specific in discussing the IPCC.

Socially we err on the side of action and war when it comes to threats like ISIS. The climate threats are much more severe than a gang of brutal fanatics in the desert but socially we err on the side of inaction.

James Hansen's predictions, based on models and hard science, have been astonishingly accurate but I admire him almost as much for retiring to fight for the future of his grandchildren and future generations. The IPCC, on the other hand has a politically cautious approach that has let politicians behave like climate change is not an immediate threat.

Hats off to Neven for doing such a great job of pulling the information on this site together. He doesn't have to be trained in science to do a great service to us.


I never said anything about Neven's competence. He does an excellent job with sea ice. I was criticizing some of the people who post on his sites that make wacky predictions.
And if Cop21 has done anything, it's that politicians are taking climate change much more seriously. And Hansen's pedictions on sea level rise are very questionable. Even Eric Rignot thinks that.


Near the end of the last interglacial there was a rapid jump in sea level as the WAIS suddenly melted. That's the event Hansen tried to model.

No one has a good analog of how Greenland will melt. Hansen's latest paper made some assumptions and analyzed the results but the assumptions are not necessarily accurate. Of course, Hansen is aware of that criticism but that didn't stop him from modelling the scenario.

His last paper was visionary but the details should be taken in the context that they are only as good as the assumptions. In the case of Greenland the evidence to support the assumptions hasn't been found yet. Predicting sea level rise is a very hard problem.

Chris Reynolds

As Neven has linked to my post on Beaufort, I'd best update by linking to my latest blog post, in which I conclude that the most likely player in the current poor ice state in Beaufort is wind, not warmth.

Gideon Low

I have to come to the defense of Robert Scribbler. His efforts to inform people about the broad negative effects of climate change are an important public service, and an area where most other journalism and media have failed us. Considering the huge efforts of the Merchants of Doubt to misinform and confuse, we should all be thankful for his efforts. RS, Neven, and a precious few others are critically important voices.


I will admit that Scribbler isn't as fatalistic as others and does stress cutting emissions. However, he does tend to exaggerate sometimes, particularly when it comes to methane emissions.
That being said, I actually think the media is a lot better than it once was on reporting climate science. Certainly not with newscasts, but online the coverage is very good. Chris Mooney is an excellent source of information.


...some good words by D-fish,

Yes, the IPCC is conservative by it's very process as as all participating Governments have to agree what goes into it.

Entropy applies to all systems including mad made systems: according to Gary Kasparov atleast!!

Rob Dekker

Regarding the 2015 Arctic Sea Ice Blog polls on the Sept 2015 minimum, I recall this post :


which states :

Plenty of people took the time to vote, especially for the last poll, so thanks for that. Here are the results showing the average and the bin that received the most votes:


which explicitly states that last year, the majority of ASIB votes went into the 4.0 - 4.75 slots, consistent with the final result (4.6).

Also, Arctic Sea Ice Prediction Network published these results in Aug 2015 :

which also shows several entries from ASIB contributors.

None of this suggests that ASIB contributors were saying that in 2015 the record would be broken.

It is different this year, because frankly, the conditions are different, and considering the facts (record low extent for the date, record low volume for the date, and record low snow cover for the date) 2016 stands a good chance of breaking the record. Possibly shattering it.


I thought you meant the sea ice forum. Anyway, you're assuming an awful lot for the conditions in June, July, and August. A lot of which depends on a strong Dipole showing up. No Dipole, then quite possibly no record. You're also forgetting that the melting will have to be much bigger to catch the record. So I'm willing to bet anyone here it won't shatter the record. I tend to think you guys are calling a record a little too early. If it gets into late June/early July and the rate is precipitous and looks like it will catch 2012, then I'll reconsider my skepticism.



It's simply not true that Eric Rignot thinks that the projections on sea level rise in a paper that he co-authored are "highly questionable". Indeed, in this article 'Hansen’s co-author Eric Rignot said in an email that the exploration of such extreme scenarios was justified “because they are not unlikely, and they are more likely than the more conservative scenarios branded by [United Nations] reports.”'

Please don't make things up, that is the province of the deniers.

So far, 2016 extent is tracking well below 2012, so your skepticism has little foundation, anyway. But, yes, I've seen Arctic sea ice make sharp adjustments to its trajectory so that predictions made on the basis of the past few days (notoriously exemplified by the invented Sam Carana missives) often turn out to be highly premature. Eventually, 2012 will be beaten. I don't see any reason to suppose it will not be this year, though that may well turn out to be the case.


when you say "You're also forgetting that the melting will have to be much bigger to catch the record." I wonder what it will have to be bigger than.

2016 extent is currently 1.1 M km^2 lower than 2012 and 800K km^2 lower than 2007. A 2007 size decline will take the ice within 100K km^2 of the 3.177M record and a 2012 size decline within 100K km^2 of a 1.99 M km^2 record. All this during the hottest year on record with record warm sea temperatures both globally and aross the Arctic over winter.

We are reaching the point where the relevant question may be what would prevent a record rather than is it likely.
Stating opinions on the blog doesn't really have the scientific cachet of a peer reviewed paper or the ignomy of being wrong. It is after all for illumination and enjoyment not to demonstrate scientific credentials.


..it would seem fun is in the eye of the beholder !


Unfortunately no Internet connection where I am right now (had to look for an Internet café).

Nice to see a good discussion here as well, as the Forum seems to have snatched them all.

As to extreme predictions, I often feel that I am too careful, always adding caveats etc. RobertScribbler is willing to go closer to the edge, sometimes slightly over it even, but he can pull it off because he is a good writer. And his writings are almost always rooted in the possible, based on the science.

The same goes for Forum members who comment regularly, like AbruptSLR and jai mitchell. They always refer to the science, and rarely just make s**t up. The only folks I see doing that on a regular basis are those from the Arctic Methane Emergency Group.

But anyway, like I said to Susan earlier, this melting season has been 'perfect' so far for going very low. This is what the first ice-free summer of the future could look like.

A lot now depends on how much melting momentum is built up during May and June.

I'll be back next week, and you can bet I'll be looking a lot for that. With the usual caveats, of course (cyclones). ;-)

R. Gates

Not posted here in quite some time but read nearly everything Neven posts. Quite a nice discussion going on, especially on the extremes of being too conservative vs. too alarmist in talking about what is going on in the Arctic right now. Also of course, calling a record low year at this point, as we've learned is a fool's errand at best. This is a nonlinear chaotic system, and that cuts both ways. Related to that however, is that clearly some sort of significant black swan event is occuring this year meaning that we are close to a Dragon King event, or a real change of state in the Arctic. It may not occur this year, or it might, again, a chaotic and truly unpredictable event. But this is certainly what being on the edge of a momentous Dragon King event looks like for the Arctic, regardless of the exact year it occurs. This amazing forum that Neven provides is a diary of sorts giving a full accounting of the events leading up to that inevitable true Dragon King event when the Arctic changes forever.


Tony, I wasnt making stuff up: http://www.alternet.org/environment/oceans-could-reach-prehistoric-levels-earths-biggest-ice-reservoir-nears-collapse
And don't ever call me a denier, that's insulting both to my intelligence and yours.
Neven, I think your faith in Scribbler and the two posters I referred to is severely misplaced. I can't tell you the amount of times I've seen SLR make wild extrapolations from studies where it wasn't warranted, particularly with methane emissions. Same goes for Scribbler. He uses Paul Beckwith as a key source when talking about CH4 in the Arctic. If that's not bad enough, he inferred that emissions from the Arctic were responsible for the rise in atmospheric methane, but Ed Dlugokencky told me it had to do with tropical wetland and agricultural emissions. When I brought this up to Scribbler, he had the audacity to say Ed was wrong without providing any evidence. Who to trust: some science fiction writer or the chief of CH4 monitoring for the NOAA? I rest my case.
David, you're putting far too much focus on Daily totals. It was doing the same thing last year and look how well that worked out.


It is always best to go to primary sources. Here's a story on a 2016 paper on methane in Science. The stable isotopes indicate that the recently increasing methane source has a bacterial signature.

Because the atmosphere mixes rapidly, increasing methane levels from permafrost degradation by bacteria would be hard to identify if the primary source of increased emissions was agricultural methane.

"Our data indicate that the source of the increase was methane produced by bacteria, of which the most likely sources are natural, such as wetlands or agricultural, for example from rice paddies or livestock."

Previously published studies had determined that the methane originated from an area that includes South East Asia, China and India – regions that are dominated by rice production and agriculture.

"From that analysis we think the most likely source is agriculture."

"If we want to mitigate climate change, methane is an important gas to deal with. If we want to reduce methane levels this research shows us that the big process we have to look at is agriculture.

"The good news is that if the source was wetlands, we couldn't do anything about it. But there is ongoing research that is looking at reducing methane production in agricultural practices."

Read more at: http://phys.org/news/2016-03-scientists-attribute-methane-agriculture.html#jCp

Note that the scientists are very careful in not overstating their claims. This is quite appropriate for the discussion of a scientific study.

However, if Mr. Scribbler wrote in this kind of cautious way, he would have far fewer readers. I wish more people would be interested in the details of science but reality is that most readers never get past the headline. Sensationalist posts that are demonstrably wrong can get 100,000 Facebook shares in a day. Well written reasoned posts by scientists are generally ignored by social media and general audiences.

I recommend Dr. Isaac Held's blog over at Princeton GFDL. Unfortunately, very few people have the background to understand most of it.


Excellent post, George. Now that's exactly the type of thing I love :)



The link you provided contains this, regarding Rignot's views:

The recent Hansen paper was a “worse-case scenario,” said NASA scientist Eric Rignot, one of its coauthors.

Rignot said the Antarctic study published Wednesday was “absolutely realistic.”

“I think it is setting up a new paradigm for sea level projections, because their numbers are much higher than those from traditional ice sheet models with incomplete or simplified physics,” Rignot said. “Once the ice shelves are gone, melted away, calving of big walls will be the dominant process of mass wastage. It is a great paper.”

I'm amazed that you think that equates to Rignot thinking that the projections of the paper he co-authored are "highly questionable". Rather, he said "it is a great paper" and "absolutely realistic." Is there somewhere else that you believe he called the projections "highly questionable", because it certainly wasn't in the link you gave.


By the way, bobcobb, I didn't call you a denier, only that you were using the tactics of deniers.

Wayne Kernochan

D and bobcobb: I have to weigh in, as your characterization of Hansen et al. is badly off and possibly disingenuous.

(1) Hansen is not a lone wolf, as you seem to imply. His latest paper has 16 authors, all but 3 clearly climate scientists, who thereby agreed with about what was said in the paper. The paper cites more than 250 research articles as supporting evidence, with at least that many other climate scientists therefore in effect endorsing at least part of the conclusions.

(2) The paper in question does not make "1" prediction about sea level rise. It adduces very good reasons why land-ice melting in Greenland and the Antarctic should be proceeding exponentially (doubling every x years), rather than linearly as in previous models, and tests the likely sea-level rise under 4 cases: doubling every 10, 20, 30, and 40 years. It then notes what is indeed true, that present measurements indicate a doubling "towards the lower end" of the 10-40 span (in fact, best scientific estimates are that Greenland melting is doubling in slightly more than 10 years, the Antarctic in slightly less than 10 years).

(3) Measurement of Greenland melting has been going on and being tested against alternative interpretations for nigh on 4 decades. To say that "no one has a good analog of how Greenland will melt" has nothing to do with Hansen et al. coming up with good reason why we would expect the total melt to be exponential when we are well before a "half-way" melt, and certainly does not make Hansen et al.'s testing of a model with exponential Greenland melting an "assumption".

(4) Hansen et al. did not "attempt to model" the late Eemian (interglacial). They used data from 55 million years ago, 250 million years ago, and the present to come up with a climate model that reflected both trends in global temps and in ocean features that would affect "uptake" by the deep ocean of changes in temps. The late Eemian was then incorporated to verify certain assumptions about how this model would behave in an "intermediate scenario", when atmospheric carbon was 350-400 ppm and there was a rapid spurt in temps -- i.e., increased storms and increased meltwater affecting deep-ocean "uptake".

(5) You say Hansen et al. were "aware" of (criticisms? assumptions?) "but that didn't stop [them] from modeling the scenario." No, they ran the model and found that it reflected measurements of real-world data like ocean temp changes off Antarctica much better than previous models. They also found that it did not yet model some additional features of today's changing climate. Unfortunately, those shortfalls by and large meant that the model almost certainly underestimated the speed of climate change. So what is most likely is that Hansen et al.'s model is too optimistic about the rate of sea level rise.

Finally, let's all remember that this is not about "sea level rise". The last time atmospheric carbon was at 360ppm, the Antarctic was subtropical and most land ice had melted. From every indication of the data points I just cited, that ship has already sailed. The question really is the speed of sea level rise. The uncertainties going forward are effectively the speed which which we add more carbon to the atmosphere, and the actual reaction of the climate to an unprecedentedly rapid human-caused addition of carbon to the atmosphere. The Hansen et al. paper shows that the climate and sea-level rise react more rapidly to the changes in atmospheric carbon than previous models thought, and that the new speed-of-reaction estimate from the model is still very likely to be an under-estimate. That, in turn, means that climate change is going to put a major "burden" on the world economy sooner than we thought, making our cost of "adaptation" greater in the next 85 years and thus the job of "mitigation" that we really need to do immediately that much harder.

Susan Anderson

Since I was an early troublemaker in this (just kidding) I confess I used a pronoun, "he" which referred to my friend instead of to RobertScribbler. When I actually looked at the RS article, I found it reliable. Amongst you all, I am a true amateur, but do pay attention; often that's enough to debunk the worst nonsense. Fish puts together a variety of sources in an accessible way, and like here, provides visual aides which reach over the gap in understanding. We are in enough of a pickle that normal scientific reticence is not good enough.

Lately I've been finding myself a voice for moderation, which surprised me (particularly evident in the Bernie Hillary wars here in the US). Wholesale attack and anger and attacks on credibility tend to discredit the speaker here, since Neven is skillful at keeping us on topic. Discussion proceeds in a way that wouldn't be acceptable in a scientific publication, but is useful as a developmental tool. This blog has been recognized by experts as such.

The IPCC by its nature is a conservative document, as it requires consensus from governments and businesses as well as scientists. It is a tribute to its accuracy that the extremes appearing on the world stage are still contained within the high end of its predictions.

RobertScribbler is a fine writer, and I apologize for misrepresenting his material in the heat of the moment, in reaction to my friends who do sometimes go off the deep end. In the end, it matters that the ice-free Arctic is within reach, whether it happens in five years or fifteen. But as noted, for this year it is still too soon to tell, though the signs are ominous. It seems unlikely that it will not at the least be lower than 2012, and that is sufficiently startling.

Susan Anderson

Forgot to include this neat new graphic (sorry, should learn how to embed it).


(My peculiar history includes daughter of PW Anderson (physicist), student of biochemistry at MIT, teaching scientists to draw (MIT) and lifetime colleague and friend to scientists, so it might be disingenuous to call myself a complete layperson. However, I would say my nemesis at MIT was differential equations, which demonstrates my shortcomings fairly well; true scientists want to know everything about something, not something about everything.

Chris Reynolds


"However, if Mr. Scribbler wrote in this kind of cautious way, he would have far fewer readers."

If I use the word 'crash', 'rout', or 'rapid decline' in a blog post I can guarantee to at least triple the number of readers above the usual rate for a post. And suddenly all sorts of doomer hang-outs start to appear on my referral list.

Oddly the single most important post series I've written (Slow Transition) got average numbers, even the summary post only got 380 pageviews (maybe 30% above average), while 'Are we facing a crash in 2015' got 1165 pageviews, four times average. That latter post was based on incorrect data from a US Navy model, the correction post got 186 views, 36% below average.

Ho hum.



Some general comments on your post.

1) I sometimes agree with your point on extreme predictions, although this board and forum are better than many other places. However, part of the scientific method is to make predictions and then test them against actuality. Often more is learned from the predictions which are wrong than those that are correct. So rather than switch off entirely I would suggest nudging people to make predictions that are testable (no more "torch"!), reviewing the accuracy of the prediction and then attempting to learn from the results. (And I speak here as a person who has a record of over-estimating ice melt in Neven's prediction polls ;-) ) Making incorrect predictions without scientific foundation but repeating them indefinitely is a trait of denier websites. Hopefully places like this one can rise above that.

2) Robert Scribbler is a story teller. Melting ice does not very often produce a dramatic scenario. I therefore often find his posts on arctic ice to be the weakest of his posts. So don't read 'em - it's your choice. I would however encourage you to read the comment sections because the group of posters there provide a brilliant resource of climate change related stories from around the globe.

3) On a more technical level, it is my own personal view that arctic ice melt is often over-estimated on this forum because the impact of warm, clear, high-pressure weather conditions on the ice is over-estimated. The 2012 record is unlikely to be broken until we get another GAC like 2012. The detail of this argument is most probably best in another place. The negative feedbacks on ice melt are also more than likely underestimated.


I point you to this article, where Rignot clearly disagrees with Hansen's projections: http://mobile.nytimes.com/2015/11/15/magazine/the-secrets-in-greenlands-ice-sheets.html?_r=0&referer=https://www.google.com/">https://www.google.com/">http://mobile.nytimes.com/2015/11/15/magazine/the-secrets-in-greenlands-ice-sheets.html?_r=0&referer=https://www.google.com/
I would be willing to bet everything I have that the Arctic isn't going ice-free in the summer this year or the next five. I'm also skeptical, as is Chris Reynolds, that 2016 will break 2012. I'll revisit my skepticism at the end of June. I may very well have to eat my words, but we'll see


"I point you to this article, where Rignot clearly disagrees with Hansen's projections:"

No, Rignot produced some research which produced different figures. Two projections can come up with different results and not disagree with each other. The methodology and the questions being asked were completely different so it's not surprising that a different result was reached. AFAIK Rignot's research is mainly a bottom up exercise. Taking the warming so far, analysing the geography of each ice-sheet/shelf individually and modeling what melt will happen in future. If melting is above non-linear then this will be a lower-bound. Hansen's paper takes more of a top-down approach of ice-sheet mass loss, feeds in mechanisms why this is and will continue to be exponential and produces a figure for SLR. If, for any reason mass loss is not exponential (and many people have put foward reasons why not) then this will be an upper-bound figure. Rignot says himself that it is hard to come up with an upper bound.


Wayne. Disingenuous? I don't profess to be an expert on glacial melting. However, It's very hard to extract precise rates from 55my records. You're talking about geologic time there and the uncertainties and counting statistics at 55MY out are large enough to make it pretty damn hard to get the details of the melting kinetics.

But perhaps, there's a paper I don't know about that has some precise geologic markers I don't know about. Please educate me if there's something I have missed.

I have been reading many papers on the process of deepwater formation in the north Atlantic and the possible slowdown as meltwater lowers the density of near surface waters. I'm trying to understand how much the meltwater acts as a negative feedback on the melting of Greenland's glaciers. It's not clear to me that Greenland melting can continue doubling for very long before it causes the overturning circulation to slow down and the local climate to cool.

Then there's the question of how much Greenland's glaciers will melt from below by interaction with intermediate water.

So I'm not convinced that anyone has the answer to Greenland glacial melting but maybe there are some papers you all can point to that would inform me of the answer(s).

I'm here to learn.

Susan Anderson

BobCobb. I'll definitely give you three, and beyond that neither one of us should risk any money. So I'm not interested in risking my money when I think you're right.


You and I apparently disagree on exponential melting. That's okay. As Michael Mann says (not in so many words), we don't want to push the system much more (not anymore would be nice as well) than we already have

Kevin O'Neill

bobcobb writes: "I would be willing to bet everything I have that the Arctic isn't going ice-free in the summer this year or the next five."

Dr. Wieslaw Maslowski of the Oceanography Department at the Naval Postgraduate School was the first scientist that I know of who predicted an ice-free arctic in the very near future. In 2006, before the 2007 wake-up call, he said the arctic could be ice free in 10 years. His prediction was 2016 +/- 3 years. This is 2016 and I think there's a better than 50% chance his prediction will come true this year. And if not this year it will definitely happen within 5 years.

Now how do we reconcile that bobcobb is completely confident that it won't happen and I'm completely confident that Maslowski's prediction will come true? If bobcobb is confident that Maslowski's ice-free prediction is wrong, then I'll take that bet. Otherwise, I suggest bocobb be a little more reticent in attacking others for predicting an ice-free arctic.

BTW, Maslowski's prediction had nothing to do with sea-ice extent or area. It was all about volume. His definition of 'ice-free' was an 80% drop in volume from the 1979-2000 summer average. In 2012 we almost reached the 80% mark - falling just 3% shy. So, if this year's volume ends up lower than 2012 there's a very good chance it will also reach that 80% mark that Maslowski predicted - and right on schedule.


The current standard definition for ice-free is extent below 1000 km2, so you're kind of splitting hairs. Indeed, I'm pretty sure that's what most people refer to. So if you're willing to put money on ice-free extent, I will take that bet


bobcobb, ice-free is usually defined as below 1,000,000 square kilometres, not 1,000.

Regarding Rignot, again you failed to support your claim that Rignot thinks Hansen's projections are "highly questionable". The worst he said, in your latest linked article, is that he doesn't think the worst projection will happen. But even in that article his stance is that the situation is worse than commonly portrayed.

There has been much said about that Hansen et al paper but, as far as I can tell, no-one has shown that it is wrong. I think we have to take it seriously as Hansen and other co-authors are serious climate scientists who have demonstrated their capabilities.

Meanwhile, Arctic sea ice continues to track well below 2012.

Rob Dekker

Guys, I don't think that Sept 2016 is going to be ice-free, although it is heading for a position close to the 2012 record.

It is still early in the melting season, but when I use the statistical method based on 'white'-ness of the Arctic (based on snow cover, ice extent and ice area) employed here (and what I as my entries for SIPN)
then, depending on how you tweak the parameters, and which regression period you choose, the April data on snow cover and (estimated) NSIDC area and extent numbers suggests that Sept 2016 is heading conservatively for 3.59 M km^2, and more aggressively to 3.23 M km^2 extent in September.

Note that these projections carry a standard deviation of some 450 k km^2 (which is much better than the 550 k km^2 of linear trend, but still quite big), which means that anything from "shattering the record" to "moderate 2nd or 3rd place" is still possible within the realms of the statistics.

But it does suggest a chance of breaking the 2012 minimum of some 15% - 40% depending on parameter choice and regression intervals.

And it does suggest that the chance for an ice-free Arctic (less than 1 M km^2) in 2016 are next to nil.

Rob Dekker

That said, I'm getting quite annoyed by bobcobb's responses.

For starters, Rignot never said that the Hansen paper was "highly questionable", and it is about time that you admit that, rather than taking us all on a wild goose chase across multiple references neither of which sustain your argument.

Second, when you are pointed out to these facts, you don't go and claim an unrelated statement like "You and I apparently disagree on exponential melting". That is simply off-topic, and a very poor response to a valid argument against your unsustained claim.

Just put-up or shut-up. Either you have evidence that Rignot said that Hansen's claims were "highly questionable" or (what seems more likely now) you don't.

If you don't, just tell us.

Kevin O'Neill

bobcobbwrites: "The current standard definition for ice-free is extent below 1000 km2...."

Sorry, wrong answer. There is no 'standard definition' of 'ice-free.' Maslowski's is the most publicized and prominent scientific prediction of an 'ice-free' arctic. Many people have written about it over the past decade.

That others choose to mean something different by 'ice-free' does not impact Maslowski's prediction. And that others ignore his definition speaks to their ignorance, not his prediction. As I said, perhaps you should be more reticent in attacking others unless you already know the context and definitions which they are using.

So, a scientist made a prediction ten years ago that the arctic would be ice-free in 2016 +/- 3 years. Are you still completely confident that it won't be? Apparently not as you refused to take the bet.

Nice to see a good discussion here as well, as the Forum seems to have snatched them all.

Okay, now I remember why I set up the Forum. ;-)

As I'm in an Internet café again, I can't comment too much, but just two things:

1) I'm willing to cut RobertScribbler some slack, because he mostly gets things right/referenced and he writes well. Different people play different roles, but on the whole I believe that scientists are being way too reticent, and this could damage society. It's possible to discuss extreme consequences without being alarmist. Staying silent is not a caveat.
2) I believe Maslowski's prediction was wrt volume going below 10% of the long-term average, can't remember the details. It wasn't a prediction of extent/area going below 1 million km2. I'm still kicking myself for not having a chat with him at EGU2016.

On-topic: It's difficult to get some rest here with so much going on up North! Temps are insane!

John Christensen

Kevin said:

Dr. Wieslaw Maslowski of the Oceanography Department at the Naval Postgraduate School was the first scientist that I know of who predicted an ice-free arctic in the very near future. In 2006, before the 2007 wake-up call, he said the arctic could be ice free in 10 years. His prediction was 2016 +/- 3 years. This is 2016 and I think there's a better than 50% chance his prediction will come true this year. And if not this year it will definitely happen within 5 years.

The 2006/07 prediction by Dr. Maslowski was actually for an ice-free Arctic in terms of extent by 2013 (with the qualifications), as you can hear in this Dec. 2007 podcast by Dr. Maslowski himself:


In the same podcast he mentions that the ice volume is decreasing faster than the extent or area, and that the Arctic ice volume would 'probably hit zero by mid-next decade'.

In 2011, the Arctic ice extent prediction was modified to 2016 +/- three years:



Ice free?

Not a chance. A continuous slow decline yes.. There is the problem of extra clouds generated by stable cyclones settling over open water mixed with non compacting sea ice . 2013 had a great melt, even though it did not look like it.


I meant to say 1 million, my bad.
Rob, I'm quite honestly pissed that you're grasping at straws. I have put up by giving two links where Rignot has said that he thinks Hansen's projections are more or less on the extreme side. You're simply looking for an excuse to disregard facts. Honestly very close-minded on your part.


you suggested "David, you're putting far too much focus on Daily totals. It was doing the same thing last year and look how well that worked out."
Daily totals are just a quick shorthand to illustrate the current state of the ice.

However they are backed up by other factors not least that the daily total has been at record levels for 41 days, the second longest run since 2007, and is likely to stay at records level until late June unless we have a melt that is a record low melt for the last decade.

On top of that Air and Sea Surface Temperatures's have been 1 std dev above the previous record both in the Arctic and globally so far this year with an obvious impact on ice formation.

Thirdly this will clearly be the hottest year on record for the Arctic with the nine hottest years becoming 2005, 2006, 2007, 2010, 2011, 2012, 2014, 2015, 2016. Note the pattern there.

All records set since the satellite record began in 1979 have occurred in the third year of three exceptionally hot years. And as shown above this is going to be an extraordinarily hot year even when compared with the hottest years on record.

On top of that we haven't seen the DMI 80+ measurement drop below average this year another indication of unprecedented continuous warmth.


Kevin, I'm willing to take the bet on extent. Apparently you're not.
Tony, I point you to an article by John Church, a pretty damn good authority on sea level rise: https://theconversation.com/what-does-the-science-really-say-about-sea-level-rise-56807
And the coauthors of Hansen's paper don't necessarily agree with him on the projections he gives, as I've shown with Rignot.
Neven, I can't say I agree with you on most scientists being too reticent. That's not what I've heard from Michael Mann, Ken Caldeira, Terry Hughes, Kim Cobb, and a myriad of others.


We will see, David

Susan Anderson

bobcobb: I don't know if I failed to make myself clear, or if your concern about the subject affected your reading.

What I said was I agree with you about the next three years, and after that I'm not prepared to guess.

I think it likely but not definite this year will be less than 2012, and to me that is sufficient matter for concern.
For everyone, since this is Neven's site, I think we should agree that his reminder of the common definition of "ice free" above should be our standard.

"below 1 million km2 extent/area"


I definitely agree with you that this year and going forward is of major concern. We Democrats herein the US need to make sure the Repugnant don't control the Senate or White House in this election . Then maybe Paris will start to have some teeth.

Chris Reynolds


The weather this winter has been exceptionally weird. What impact does this have on the likelihood of a summer development of the Arctic Dipole set up, and what impact will it have on the persistence of such a set up through the summer?

I ask because I don't know.


bob, isn't it a guaranteed Republican win this year as they get two terms each and switch with absolute precision?



I see you're changing tack now, with Rignot. Rather than admit that Rignot doesn't think the Hansen et al projections are "highly questionable", you've now switched to a fairly bland statement that he thinks the projections are "extreme". Well, duh! He's definitely admitted that they are possibly worst case scenario but also that they are "not unlikely" and "absolutely realistic" (those quotes from the links you, yourself, provided).

Now please divest yourself of the notion that Rignot somehow disagrees with the projections of a paper he co-authored and stop misrepresenting his views.

Rob Dekker

I agree, Tony.
Nowhere in the references bobcobb provides is there any quote that he finds the paper he co-authored "highly questionable", not any suggestion that "he thinks Hansen's projections are more or less on the extreme side", not any indication that Rignot as a co-author "don't necessarily agree with him on the projections he gives".

All these claims are simply made-up by bobcobb himself, and have no basis in fact.

Rob Dekker

The statistics on albedo of the Arctic suggest that there may not be a need for a strong dipole to develop. Just an average summer would get 2016 pretty darn close to the 2012 record.


I put forward the idea that 2.00 should be considered dangerous territory!
From my point of view I will consider the Arctic free of sea ice when it gets to 2.00!!


You seem to be unable to comprehend reality when it comes to Rignot. If anyone's misrepresenting his ciew, it's you. You seen to quibble with terms to defend your preconceived notion when evidence to the contrary is right in front of you.
Kevin, same goes for you. You don't seem to like it when someone provides evidence you don't agree with. I would say "highly questionable" is a perfect way to describe it. You're both grasping at straws and making up your own interpretations to what he said. The bottom line is that he clearly has different ideas than Hansen, and you're rationalizing to fit it your own narratives.


Sorry, I meant Rob

Roger Boyd


My first language is English, and "highly questionable" is a significant misrepresentation of the statements that Rignot has made. Let it go.


Really? So if I email one the coauthors and they tell me they're at odds with Hansen as well, what then? Hmm, I'll do that. Your opinion is that I misrepresented it, but I, and many others, don't think so.



Noone here corroborates your view of Rignot's position on his own paper. And yet you continue to have utter faith that your characterisation of Rignot's view is accurate. By all means email Rignot, or any of the other authors to find out what they think of that paper but please post any responses exactly, rather than giving your interpretation of them (though you are welcome to do that after quoting the responses accurately).

michael sweet


From your reference in the New York Times magazine:

"When I asked Richard Alley, almost certainly the most respected glaciologist in the United States, whether he would be surprised to see Thwaites collapse in his lifetime, he drew a breath. Alley is 58. ‘‘Up until very recently, I would have said, ‘Yes, I’d be surprised,’ ’’ he told me. ‘‘Right now, I’m not sure. I’m still cautiously optimistic that in my life, Thwaites has got enough stability on the ridge where it now sits that I will die before it does. But I’m not confident about that for my kids. "

Richard Alley is the same age I am. He cannot possibly live much past 2050. He states that he thinks it is possible Thwaites could collapse in his lifetime. That would be meters of sea level rise in his lifetime. He thinks that is unlikely, but possible. He agrees with Hansen.

In the same article Rignot agrees with Hansen. You need to let this go, your references contradict what you claim.

Colin Maycock


It is highly unlikely that a highly published scientists such as Rignot (with a H-factor of 63 and 493 papers to his name) would agree to be a co-author on a paper that he found "highly questionable".Co-authorship is voluntary and the norm is to remove your name from a paper you disagree with.

Also reading the links you provide - I also can't see how you interpret what he said as highly questionable. Especially as he also stated:
"Hansen’s co-author Eric Rignot said in an email that the exploration of such extreme scenarios was justified “because they are not unlikely, and they are more likely than the more conservative scenarios branded by [United Nations] reports.” http://www.slate.com/blogs/the_slatest/2016/03/22/james_hansen_sea_level_rise_climate_warning_passes_peer_review.html

Kevin O'Neill

John Christensen: You have made the same mistake that many others have made. Neither Maslowski's original AGU presentation nor the radio interview you pointed to support your claim that he originally said 2013 and then modified it.

His AGU presentation (given in 2006) said,

“If this trend persists for another 10 years-and it has through 2005-we could be ice free in the summer.”

In the radio interview he says,

[starting at 16:15] "...if we already have lost probably about 40% volume in the arctic so far if we project this trend ongoing for the last 10, 15 years we probably will hit zero sometime mid next century -- mid next decade, I'm sorry." [ending at 16:33]

The NY Times does not give a quote. So it's impossible to know exactly what Maslowski said. But elsewhere I've seen him say as early as 2013, which matches the 2016 +/- 3 years.

It also makes no sense that he updated his prediction to 2016 +/- 3 years in 2011; you can find the same prediction at least as early as 2010. Arctic death spiral: Naval Postgrad School’s Maslowski “projects ice-free* fall by 2016 (+/- 3 yrs) which Joe Romm wrote in response to a WUWT article. Here you will also find,

"By “ice-free,” Maslowski tells me he means more than an 80% drop from the 1979-2000 summer volume baseline of ~200,00 km^3."

Again, this was in 2010.

Rob Dekker

Thanks for those references, Kevin !
There is simply too much mis-information going around regarding Maslowski's projections.

By the metric of 80% drop from the 1979-2000 summer volume baseline of ~20,000 km^3 (which is about 4,000 km^3), it seems that 2012 (at 3,600 km^3) already crossed Maslowski's boundary.

Not to mention that 2016 may very well be on track to dip below 3,000 km^3 in September..

Rob Dekker

Regarding the issue of ice volume and how it is important to the determination of ice extent at the minimum in September, I'd like everyone to read this great explanation by Chris Reynolds :

Note specifically that there will be a point where ice extent no longer reduces linearly with reduced volume, but instead will start to fall through the bottom. That is this graph :

That non-linearity should start to happen when minimum volume is below 4,000 km^2, and we may already have seen a pre-cursor of that in 2012 (minimum at 3600 km^3), when large swats of the Arctic Ocean were shattered individual ice flows, that were still counted at 100% "extent", while in reality the Arctic was very close to a total "collapse".

Point is that there will be a limit (of volume) below which "extent" will very rapidly reduce, and the indicators for 2016 suggest we will be pushing that limit.

As Wadhams ones stated (in regards to Maslowski's projections of volume decline) : "In the end, it will just melt away quite suddenly.".


Rob, you mean the point at when such a critical mass of multi-year sea ice melts away as to ruin the structural integrity of the whole shebang?

Artful Dodger

Hi folks,

There's a simple physical process that keeps the sea ice pack in place in the Central Arctic Basin: the fresh water lens.

This is the ~50ft deep surface layer of water with about 25 ppm or less salt content.

The fresh water lens is maintained by:
1. brine rejection from 0-1 yr-old sea ice over the Winter months,
2. fresh water inflows from Siberian rivers and the MacKenzie delta during Spring/Summer, and
3. reduced mechanical mixing due to the wave dampening effects of sea ice.

This layer of relatively fresh water literally floats on the warmer yet denser water below, which is mostly Atlantic water at 35 ppm salt content. This top layer freezes at a higher temperature, and resists mixing with the denser layer.

So no matter what any individual year's melt season ends with in terms of Area/Extent/Volume, if the fresh water lens survives, the sea ice WILL recover. It's physics. Ask SHEBA.

More ominously however, if the fresh water lens is broken up (ie: folded into the mixed layer by wave action and Ekman pumping from another GAC), then the sea ice is NEVER coming back. Here's why:

1. There is more that enough heat content from Atlantic water (an ~2000ft thick layer) at +4C to survive multiple Winters w/o freezing.

2. Cloud cover from surface evaporation provides ample insulation against the cold of space throughout the long Winter night.

Note: Review the paleoclimate record of the Arctic basin to see how this works: Lily pads and Crocodiles in the Arctic 55 MYA.

3. Continuing the next Summer following the breakup of the fresh water lens, the albedo flip ensures that the surface layer warms up again.

4. Storms and long fetchs provide sufficient wave action to ensure the surface layer remains mixed, preventing the Northern rivers from reforming the fresh water lens in the CAB.

Then, we arrive in the situation where Arctic bottom water formation ceases (there can be no brine rejection w/o new sea ice formation). The force driving the Atlantic overturning current disappears, and the current stalls.

Here my science background fails me, as we are indeed entering uncharted waters. Perhaps the Gulfstream shuts down? London and Berlin freeze in the dark like Moscow?

But I do know that it's gonna be ugly. Because people hate change. Or a kick in the gut. Or the head.



Yes, when the deep water formation off Greenland shuts down, things will change very seriously, globally.


So, a rare question from an original lurker:
Lodger ... could the wave action from the usual series of storms be sufficient to destroy the fresh-water lens over a single season if the CAB was essentially ice free some September?


Kevin O'Neill

Rob Dekker: "...it seems that 2012 (at 3,600 km^3) already crossed Maslowski's boundary."

Chris R and I both did the math a few years back and we had 2012 coming up just a few percent shy of an 80% loss.

Chris' numbers are here: Go on, say something outrageous

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