« EGU2015, my impressions | Main | PIOMAS May 2015 »

Comments

Feed You can follow this conversation by subscribing to the comment feed for this post.

Chris Reynolds

Thanks Neven,

The comments under the article on the Wagner/Eisenman paper raise a question I've sometimes pondered before. What is the correct collective noun for a collection of dumb-asses?

Anyway... Arghh! That article is paywalled. :( That complaint aside from reading various papers I'd long since assumed there was no irrevesibility (or hysteresis) inherent in the transition to a seasonally sea ice free state. But that due in part to cloud radiative feedback there could be hysteresis in the following transition, to a perenially ice free state. Unfortunately the article doesn't quite make it clear whether it refers to both transitions. Wagner does say (as Neven quotes) "“In other words, no tipping point is likely to devour what’s left of the Arctic summer sea ice." But it's not clear if the paper considers both transitions.

I would note that including a seasonal cycle in insolation allows the thickness/growth feedback to play a role.

I just had to look up

76 32'N 25 02'E

Chris Reynolds

The end of that post was a location for Hopen Island, 76 32'N 25 02'E. (Foiled by browser losing focus while tab swtiching.)

From the description in the article I don't think anything would be seen by satellite, so I've not bothered looking (but I may be wrong on that).

Chris Reynolds

Sorry for spamming with three initial comments...

Hot Whopper has a link to a paywall free copy of the Wagner and Eisenman paper.
http://eisenman.ucsd.edu/papers/Wagner-Eisenman-accepted-2015.pdf

The paper is indeed referring to the full range of behaviours from a year round ice pack (now) to a year round ice free state.

"...the present model simulates sea ice loss which is not only reversible but also has a strikingly linear relationship with
the climate forcing as well as with the global-mean temperature. This is in contrast with SCMs and EBMs, and
it is consistent with GCMs. The results presented here indicate that the nonlinearities in the model are essentially
smoothed out when latitudinal and seasonal variations are included."

They also note that the inclusion of weather would have the effect of smoothing non linearities.

It is worth pointing out that the paper notes:

"The model becomes seasonally ice-free at
2degC of warming, and it becomes perennially ice-free at 6degC"

This might be coincidental, but Mahlstein & Knutti produced a paper in 2012 entitled "September Arctic sea ice predicted to disappear near 2C global warming above present." That title says it all. They used 21 models, and found that "All but one climate model show that the close to linear relationship between September sea ice area and global surface temperature is robust and persists throughout the 21st Century."

And they noted that "There is no fundamental reason why the relationship
must be linear, so this is purely an empirical result. There might be some nonlinearities that the models do not
capture and have not been observed yet, but there is currently no evidence for that."

There is now less evidence with the Wagner & Eisenman paper.

However Mahlstein and Knutti actually find a broad range of uncertainty. That noted, the uncertainty is skewed towards the high end, not much below 2degC.

So as Neven notes: For those concerned about loss of sea ice and who think there is a likelihood of humanity changing course, this is very good news.

Mahlstein & Knutti.
http://www.iac.ethz.ch/people/knuttir/papers/mahlstein12jgr.pdf

Neven

Spam on, Chris.

Werther

 photo r04c02 day 119 29042015 detail enh draw small_zpsf5i4wlge.jpg

I have been going over details in MODIS tile r04c02 after the sad news concerning arctic explorers De Roo and Cornelissen. I guess in an attempt to rationalize what might have happened.
On the pic, I marked the main Devon and Cornwallis islands, as well as smaller Dundas and Baillie Hamilton. In the blue ovals, the known regular polynia’s have been highlighted. To the left, ‘Hell’s Gate’, to the top the Penny Strait polynia’s, center the two Queens-Wellington Strait polynia’s.
With arrows I marked three other polynia’s near Baring Island in the Queens Strait. These are also regular, as they are also indicated in a study by Hannah et al, “Polynyas and Tidal Currents in the Canadian Arctic Archipelago”, 2007. Baring Island seems to have been a beacon in the adjusted route that both explorers were on.

History, MODIS and NCEP/NCAR all indicate that there’s no exceptional 2015 situation; the sea ice is usually very ‘disturbed’ in this area. Tidal water movement between the islands mix warmer Atlantic water and keep the polynia’s open even in colder winters. Although April brought some anomalous warmer temps to the region, there’s not much indication that this contributed essentially to the fate of the two Dutch researchers. The region always has some treacherous ice features that have taken a toll.
May they rest in peace, their names to be remembered in a large list of brave explorers and scientists that have given their lives in these inhospitable Arctic quarters.

Neven

At least the dog has been rescued:

"Due to blizzard warning and rough weather, a helicopter flight to the site yesterday was cancelled. A new attempt was organized today 2 May (Canada time). The helicopter was able to fly over the site estimating necessary equipment for the recovery operation and taking pictures to be analysed by the experts. There is no news yet what will be done next.

When it was safe to land, the crew were able to rescue the dog Kimnik who has been such a loyal team member, protecting the site from polar bears. Kimnik is besides a little bit hungry doing well and will be reunited with her owner, the local wildlife ranger from Resolute. We thank Kimnik very much for her dedicated work protecting our team members Marc and Philip."

http://coldfacts.org/news/45/dog-has-been-saved-and-doing-well

Colorado Bob

Inuit hunters drown on thin ice more & more , and world does not bat an eye , Dutch researchers drown and we learn that :

A final voice recording posted online Tuesday by Cornelissen said: “Today was a good day.” describing the weather as surprisingly warm, “too warm actually,” saying that he ended up skiing in only his underwear and boots.

“We think we see thin ice in front of us, which is quite interesting,” Cornelissen said. “And we’re going to research some more of that if we can.”

http://churchillpolarbears.org/2015/05/dutch-sea-ice-researchers-presumed-drowned/

It would be nice if Apple, Google, or Facebook , took some that ocean of cash they are sitting on , and shared it with Inuit hunters.

Maybe even pay for Inuit guides for Dutch reseachers.

Philip Cohen

What surprised me about the reaction to the reversibility paper was that Watts was so confident in his misreading that he quoted material from the press release(?) that directly contradicted it. Is this SOP for WUWT? I never visit it but it was one of the top Google hits on Arctic sea ice so I thought I'd take a look.

Colorado Bob

Watts will bunk Hitler in hell.

Colorado Bob

Watts will bunk with Hitler in hell.

Neven

Oh, come on, Hitler never was that silly. ;-)

Colorado Bob

Oh, come on, Hitler never was that silly. ;-)

They were both pathilogical and right wing.

It never stops. Ever, See the Government in Australia, Canada, and the US .

They will all sleep with Hitler.
They were both pathilogical and right wing.

Colorado Bob

Oh, come on, Hitler never was that silly. ;-)

The US Congress has gutted the Climate Science NASA funding.

Colorado Bob

Hitler never died .

Robert S

Umm... OK, I gotta say it - getting away from that kind of rhetoric is why I haunt this site, Colorado Bob. I'm no fan of Watts... but I'm also no fan of that kind of trollish comment.

Cincinnatus

Re the "giant waves", I must say that the implicit power of assumption here (that such waves are not in the normal range in the long run) is so thick that I could spread it on my bread.

Yes, I know I should ignore the alarmism here, Neven, but it's a spectator sport like bullfighting -- hard not to watch.

jdallen_wa

Cincinnatus - the "Giant Waves" in the Arctic are not alarmism; they and their effect aren't even theoretical.

They're empirical phenomena which trained scientists have seen directly.

They are predictable given correct (and recently, frequently occurring...) weather conditions.

Jim Hunt

Cincinnatus - I thought you said you were going to keep mum until September?

Do you ever bother to read any of the links I helpfully provide you with?

Here's another academic paper for you:

Swell and sea in the emerging Arctic Ocean

Chris Reynolds

Cincinatus,

I really doubt that you are reading what is presented here, if you are parsing the words you don't seem to be understanding. I see nothing suggesting abnormally large waves outside the pack in the ocean. I read of observations of the pack ice acting as a low pass filter, damping the high frequency energy but allowing the low frequency energy to penetrate beyond the ice edge into the pack. That's why the 'largest waves ever recorded' seem to be happening, but it is clear that this is within the pack behind the ice edge.

As for fetch. These observations were recorded near Hopen, Svalbard. Wind direction is key, however assuming winds were blowing in off the North Atlantic the issue of fetch would be irrelevant. Fetch may become relevant in the region from Beaufort round to Kara during the summer.

Nonetheless, thinner, weaker, ice would be expected to lead to less damping of low frequency waves and greater penetration of swell into the pack. Basic mechanics suggests that.

Jim Hunt

Bob - A video which covers (amongst other things) the effect of unanticipated waves on Inuit hunters:

The New Arctic

Cincinnatus

Yes I did say that, Jim, but mum turned to mummpphhh -- as in the Dilbert cartoon. I do indeed view the links you "helpfully provide", but much of it is old news. My field is that of large data where small sample sizes give false hints because of small numbers fluctuations. To me it is clear that all of "climate science" suffers from this debility because of the very short time frame which has been well-studied to date. The notion that there's anything unusual about today's Arctic waves is an example. The only identifiably exceptional modern-day aspect is that of the rising CO2 levels, which are still way below that of earlier epochs. Now, we may have our different opinions about CO2-temperature sensitivity, but one thing we agree on is that there's precious little that can be done about it, barring the catastrophic end of civilization. Given that, we should stop panicking and take measures to cope as the Dutch did with their sea walls. And hey, be pro-nuclear power -- it's CO2 neutral. Pick your wins.

Neven
The notion that there's anything unusual about today's Arctic waves is an example.

No one is saying that Arctic waves are an unusual phenomenon, silly! You really have to read better.

To save you time, here's what it's about: Arctic sea ice is thinning dramatically, which means wave force isn't dampened any longer, but cuts deep into the ice pack when it's stormy, causing the ice to thin even more. It's a positive feedback.

This blog post is about two positive feedbacks, that together with all other positive feedbacks - if correct and if we're lucky - won't lead to an irreversible tipping point.

Given that, we should stop panicking and take measures to cope as the Dutch did with their sea walls.

I'm Dutch, I moved to Austria. I don't want my children and grandchildren to pay huge taxes to update and upgrade those sea (and river) walls. ;-)

And hey, be pro-nuclear power -- it's CO2 neutral.

Interesting policy proposal. Much better than the silly climate risk denial.

Jim Hunt

Neven - Based on my admittedly limited time on the surface of this planet and evidently a lot more research than Cincinnatus has undertaken I feel compelled to point out at this juncture that large swells are a much more unusual phenomenon in the Beaufort than in the Barents!

Kevin McKinney
The only identifiably exceptional modern-day aspect is that of the rising CO2 levels, which are still way below that of earlier epochs. Now, we may have our different opinions about CO2-temperature sensitivity, but one thing we agree on is that there's precious little that can be done about it, barring the catastrophic end of civilization.

--Cincinnatus

Talk about 'assumptions'… and unsupported ones at that!

No, worse than unsupported: flat wrong. See, there's this whole report that deals with what is 'exceptional' today, in terms of the impacts that climate change is having on our world:

In recent decades, changes in climate have caused impacts on natural and human systems on all continents and across the oceans. Evidence of climate-change impacts is strongest and most comprehensive for natural systems. Some impacts on human systems have also been attributed to climate change, with a major or minor contribution of climate change distinguishable from other influences. See Figure SPM.2. Attribution of observed impacts in the WGII AR5 generally links responses of natural and human systems to observed climate change, regardless of its cause.

https://www.ipcc.ch/pdf/assessment-report/ar5/wg2/ar5_wgII_spm_en.pdf

Needless to say, the report goes into great detail, and in the course of it 1700+ pages, finds quite a number of 'exceptional' things to talk about.

Cincinnatus's weasel wording that we can do 'precious little about climate sensitivity' is itself pretty precious. No, we can't change the sensitivity. But we sure can change CO2 concentrations in the atmosphere--that capability is now very well-demonstrated indeed.

Chris Reynolds

Cincinnatus bores me.

PIOMAS gridded data for April is now out. Although the 'main series' of volume numbers doesn't seem to be.

The first of my April status blog posts is here:
http://dosbat.blogspot.co.uk/2015/05/april-2015-status-part-1.html

"...if I use the demarcation of above 3.3m thick, within the Central Arctic with an April 2015 volume of 1.48k km^3 (for ice over 3.3m thick) for the peripheral seas of the Arctic Basin (Beaufort round to Laptev), this is the second lowest volume in the post 2007 period. Whereas for the Central Arctic region, sub grid thickness volume over 3.3m thick is 5.87k km^3, that is the highest in the post 2007 period and is 3.6 standard deviations above the 2007 to 2014 average April volume for sub grid thickness ice over 3.3m thick."

There are two ice packs, the Central Arctic and the rest!

More will follow regards volume by grid box effective thickness and the sub grid thickness distributions in a few days.

Chris Reynolds

Oops, this makes more sense for the quoted part of the above comment:

"if I use the demarcation of above 3.3m thick, there is an April 2015 volume of 1.48k km^3 (for ice over 3.3m thick) for the peripheral seas of the Arctic Basin (Beaufort round to Laptev), this is the second lowest volume in the post 2007 period. Whereas for the Central Arctic region, sub grid thickness volume over 3.3m thick is 5.87k km^3, that is the highest in the post 2007 period and is 3.6 standard deviations above the 2007 to 2014 average April volume for sub grid thickness ice over 3.3m thick."

Neven

Thanks for the numbers, Chris. Very interesting.

Robert S

Chris: Great work. The graph that really interests me is the one titled "April Arctic Ocean PIOMASS Volume in 5 Bands. Looking at that, it appears that although we are having a high 3m+ year, it's well within the range of noise for those bands (and in fact that those bands consist of essentially nothing but noise now - ie. they could go to +/-zero in any given year). The real action seems to be the progressive transfer from the 3m+ to the 2 - 3m band over the 1978 - 2006 period, and the inflection point at (around) 2006, where a transfer from the 2 - 3 m band to the 1 - 2 m band gets going. If we start to see a reversal of those long term dynamics, that might start to indicate the intervention of an unknown factor/negative feedback process. Otherwise...

navegante

Chris, thank you. I agree with Robert S, that graph is a killer pic, literally. Even with cold weather, 2013 and 2014 were pretty bad for ice, remember the 2013 "rotten" ice and lakes of the Pole, and 2014 Laptev bite. Why? That graph showing what 20 years ago was 3+ m thick is now 1-2 m thick ice.

One year of warm weather, and so much for 2012 record.

And thinking about tipping points: after a dramatic amount of thick MYI is lost in 2007
the Arctic would need a large number of years of colder weather to come back to the same state in terms of MYI volume. That looks like a hysteretic process to me and implies a tipping point. It can be recovered, but is not a reversible system, since that would require the system come back following the same way it went. No, there would be extra resistance to reverse the state back to what it was.
I mean: we have watched the tipping point being crossed in front of our noses, it was 2007

navegante

Sorry for double posting but I came to the following conclusion: what can be a better example of irreversible process than the loss of main bulk of 4+ year ice as it happened in 2007?


Chris Reynolds

Robert,

For the 4m and above thickness band, April 2015 volume is 2992.6km^3, you'd need to go back to 2002 to substantially beat that. And you'd need to go back to 1997 as one of the last years of a period when volume for ice that thick regularly exceeded 3000km^3. What is happening over the last few years is significant and important, I disagree that it is 'within the noise'.

Graphing those thickness bands in pairs is rather revealing.

4m and above together with 3 to 3.9m: Both decline - the volume loss has mainly come from thick ice.

3 to 3.9m and 2m to 2.9m - they behave very differently, 3 to 3.9 declines throughout, while 2m to 2.9 rises then falls.

Now for the interesting pair....

2 to 2.9m and 1 to 1.9m. In recent years these start to 'dance' together, it looks like they're almost mirror images of each other. This is because these thickness bands straddle the thickness of around 2m thick, which is typical thickness one would expect for growth of new ice from open water in September to ice in April. So variations in how much ice thickens moves bulk volume from one thickness band to another. As it goes up in one, so it goes down in another.

The base data from which I calculate those bands is in 10cm increments. In that finer data the transition of the two behaviours happens about 2.2m.

I've uploaded a couple of graphs they should be apparent from the above.
2m and 3m
https://farm9.staticflickr.com/8729/17381420841_cab87e74c2_o.png
1m and 2m
https://farm8.staticflickr.com/7714/17195536529_bb794c8d7c_o.png

So above 3m there is constant decline (until the recent uptick), while 1m to 2m start to mirror each other. Why? Here is where I get to a feedback that I think will dominate the remainder of this decade, and probably most of next.

That recent mirroring in 1m and 2m thick bands suggests a wall is being hit, I think it is.

The following is a plot of gice - the PIOMAS sub grid thickness distribution. It's a plot I've done for a blog post I'm working on. While the above stuff is all for the grid box effective thickness. Gice is the 'hidden' distribution of thickness that PIOMAS uses within the grid box, so a grid box reporting ice 2m thick doesn't just have ice 2m thick, it contains a wide range of thicknesses. The thickness bands can be seen on the horizontal axis of the following graph.
https://farm8.staticflickr.com/7748/16761477493_cf95c5d74a_o.png

The critical detail is this: The thicker ice declines as can be seen by the movement from dark blue (early years) to light blue (recent years), but look at the behaviour of thinnest ice. There is very little change in the ice below 1.46m thick. This is December ice, in December, even within a grid box that has ice at the end of the September, there is open water that freezes and forms new ice. The lack of change at the thinner side of the gice profile is the because of the thermodynamic thickening of sea ice. It is this that forms the 'surface' that forces the recent mirroring in the 1m/2m thickness bands.

As I have been arguing in some detail since last summer (I was 'outed' in responding to a comment by Neven), the thickness growth feedback is in the process of becoming dominant and will avert a crash in Arctic sea ice leading instead to a 'long tail' of summer sea ice persistence well into next decade at least.

I have discussed the thickness growt feedback in detail here:
http://dosbat.blogspot.co.uk/2015/01/the-slow-transition-thickness-growth.html

Chris Reynolds

Nevagante,

Mmm, I'm not convinced it does contain hysteresis. The 2010 loss event involved a large loss of volume, resulted in a change to the seasonal cycle (in PIOMAS) and I don't think the 2011 and 2012 minimae were coincidences, I think they were largely caused by the 2010 volume loss event. Yet conditions now seem to have largely wiped out the 2010 event. No evidence of strong hysteresis for a volume loss event of similar magnitude and impact as 2007, instead it was quietly reversed five years later.

What acts against reversal of such events is the trend of regional warming, and the after effects persist, the more global warming plays a role in sustaining the impacts.

navegante

Chris, suppose in March 2007 there was a 10% 4+ year old ice and that became a 2% in March 2011. You need 8% of ice to survive four years to be back to 2007 figure. This may have happened (not sure what the percentage is right now) but it has required a build-up, and favourable chances.

Let me try this analogy. A city that has been destroyed by a hurricane has reached a tipping point. It will never be the same. The rebuilding requires extra effort and material (houses won't be rebuilt by blowing hurricane wind in opposite direction). And, it may never recover if hurricanes become too frequent and/or human efforts are not sufficient. This last part is what I see as tipping point in the Arctic. It may happen after a year of big loss that the Arctic is unable to recover old ice because year after year weather is too warm.

But maybe we are talking about different tipping points.

Chris Reynolds

Navegante,

I think we are talking about different defintions of tipping points. Amidst the ongoing forcing of climate change, yes a reversal is more unlikely (difficult even?) than an advancement.

What I mean by a tipping point is explained here, in paragraphs 3 to 6.
http://dosbat.blogspot.co.uk/2015/05/is-arctic-sea-ice-like-cup-or-ball.html

I don't think the Arctic has 'tipped over' like a cup. I think it is a ball rolling down a slope.

LRC

I saw a very good illustration of a tipping point.
You are going down river ahead of you is a raging falls. You know it is there, but you can not see it. You have 3 choices 1) depending on your exact definitions of possible events, get out of the river (this one is arguable as a possibility as time events may not allow it. 2) turn around and go back up stream. 3) continue down stream. The tipping point is not when you go over the falls, the tipping point is the spot when the force of the river prevents you from making to shore on time, is too powerful to go back up stream, and therefore the inevitable will happen in that you will go over the falls.
As you do not know where the edge of the falls is where that tipping point is, is unknown. The only time you know you have reached the tipping point is when you go over the falls despite your best too late efforts to make choice numbers 1 and/or 2.

Jim Hunt

Much more information on the tragic loss of Marc Cornelissen and Philip de Roo.

http://www.scientificamerican.com/article/thinning-arctic-ice-proves-deadly-for-veteran-explorers1/

The Coldfacts blog reports that:

A snowmobile team just left Resolute to approach the site by land. This recovery expedition will take about two to three days.

http://www.coldfacts.org/news/46/snowmobiles-just-left-resolute

Jim Hunt

An RCMP press release, via the Coldfacts blog:

On May 6th, the RCMP coordinated a team of local volunteers, who were highly skilled in working in the area and dealing with poor ice conditions to depart to the location via snowmobile. On May 7th, they arrived at the site and despite personal risk were able to recover a body of one of the two missing men. Unfortunately despite their best efforts, they could not locate the second missing man. The findings at the scene were consistent with both men perishing as a result of the accident. The ice conditions at the location of the incident could best be described as very poor.

http://coldfacts.org/news/47/rcmp-recovery-mission-update

Susan Anderson

Andy Revkin has constructed a lengthy tribute at New York Times DotEarth blog. NYT provides limited free articles each month, so here:
dotearth.blogs.nytimes.com/2015/05/09/scientists-praise-contributions-of-two-dutch-explorers-who-perished-on-arctic-ice/

[warning: DotEarth is a free for all; almost no comment monitoring by blog owner. Andy Revkin's research and writing remains excellent if lukewarmist at times: advise ignoring any snark in comments; ice may attract regulars from the resident posse of mean-spirited deniers, professionals, and crazies.]

Susan Anderson

Hopefully this link will work:
http://dotearth.blogs.nytimes.com/2015/05/09/scientists-praise-contributions-of-two-dutch-explorers-who-perished-on-arctic-ice/

D

I've given up on Revkin. He has excellent writing skills, but his skills at discerning the difference between science and BS are weak.

The best post I've seen in the last month is Tamino's annihilation of the "hiatus" and all of its proponents. Revkin is one of the many clueless reporters who can't discern the difference between signal and noise. You don't have to be a statistician like Tamino, aka Grant Foster, to learn to ignore the short term variability in a data set, but journalists are trained in pretty much to wrong way to see than. They are trained to report 2 sides to the story even if one side is random noise. But thanks for the link to the tribute.

Wayne Kernochan

@Neven: I had been delayed in responding to your "reversibility" part of the post, and just saw this from Joe Romm:

"The interesting conclusion from the study from the scientists’ viewpoint (and Scripps’) was that a more sophisticated model of the Arctic found that contrary to previous models, the ice loss is not, technically, irreversible. If you could somehow reverse temperatures on the earth, the ice would come back. But in practice it is all but impossible to get temperatures back down again.

Heck, we’ve got another 1° Fahrenheit baked in just because it takes a while for the climate system to come into equilibrium. And unless we cut global greenhouse gas emissions to zero by mid-century, we can’t avoid another 1°F after that. And, unless we stop listening to climate science deniers like those at the Daily Caller, we will add another 5°F or more after that. Bye bye summer ice and possibly virtually all the ice year-round!

The scientific literature is quite clear that warming-driven temperature rise is irreversible on a time scale of centuries. As the world’s top scientists explained in November in their final IPCC synthesis report summarizing the scientific literature: “Surface temperatures will remain approximately constant at elevated levels for many centuries after a complete cessation of net anthropogenic CO2 emissions”!"

I believe that Joe is actually lowballing the amount of global temp increase (not to mention temp increase in the Arctic) because he is considering the effects of atmospheric carbon (2-2.8 degrees C per doubling) alone. In Hansen's draft study, which I attempted to summarize in a blog post, he sees 4 degrees C per doubling, due partly to increases in other greenhouse gases like black carbon (as seen 55 million years ago). So 400 ppm corresponds to roughly 2.3 degrees C increase from 1850 "in the bag". So to reverse to a steady-state Arctic with sea ice even centuries from now, we would need to bring atmospheric carbon down somehow 50 ppm to reach 350-360 ppm (Hansen says past data shows the Arctic was ice-free at 350 ppm).

Wayne Kernochan

oops 360 ppm - w

Rob Dekker

Regarding the paper by Wagner and Eisenman, here :
http://eisenman.ucsd.edu/papers/Wagner-Eisenman-accepted-2015.pdf

The issue addressed in this paper is if there is a "bifurcation" point in Arctic sea ice loss, meaning that Arctic sea ice could appear in two states given a certain amount of climate "forcing". Not inconceivable given the fact that sea ice reflects sunlight and thus keeps itself in place, and thus that if sea ice is gone, that a state of dark ocean could be equally likely.

If that is the case, then for example, will Arctic sea could "flip" over from summer sea ice to virtually ice free all year around, and we may not be able to regain Arctic sea ice after it is gone.

Such "bifurcation" behavior are apparent in SCMs (single column models) and EBMs (energy balance models) but interestingly NOT in the big GCMs (General Circulation Models) that IPCC uses.

This Wagner and Eisenman paper shows that if you take heat latitudial heat transport and seasonal variation into account, that the "biforcation" behavior of the SCM and EBM models disappears.

So essentially the paper surrenders to GCMs as the more realistic way in which Arctic Sea Ice would develop under increased GHG forcing.

Meanwhile the paper suggests that seasonally ice free conditions in the Arctic may occur at lower temperature increase than previously thought.

Which means that the GCMs are probably right that Arctic sea ice will not flip over to year-around ice free state any time soon, but they may reach seasonally ice free state sooner than expected.

That is a conclusion that seems to be sustained by simply comparing Arctic sea ice development compared to these GCMs :
http://neven1.typepad.com/.a/6a0133f03a1e37970b017744cf5360970d-pi

Rob Dekker

Neven, I'm sorry that I just jump in here with a summary of a scientific paper after a year of absence. I've been busy fighting denial on (shorter term) issues like Keystone XL, Canadian tar sands, MH17 and Russian aggression in the Ukraine.

Neven

Jump in whenever you feel like it, Rob.

Jim Hunt

Welcome back Rob.

I wondered if I might idly enquire what your next SIPN prediction might say?

Keep up the good work!

Wayne Kernochan

@Neven - typepad ate my last post. Try again. I can't share your feeling that "reversibility" is good news. Here's Joe Romm summarizing:

"The interesting conclusion from the study from the scientists’ viewpoint (and Scripps’) was that a more sophisticated model of the Arctic found that contrary to previous models, the ice loss is not, technically, irreversible. If you could somehow reverse temperatures on the earth, the ice would come back. But in practice it is all but impossible to get temperatures back down again.

Heck, we’ve got another 1° Fahrenheit baked in just because it takes a while for the climate system to come into equilibrium. And unless we cut global greenhouse gas emissions to zero by mid-century, we can’t avoid another 1°F after that. And, unless we stop listening to climate science deniers like those at the Daily Caller, we will add another 5°F or more after that. Bye bye summer ice and possibly virtually all the ice year-round!

The scientific literature is quite clear that warming-driven temperature rise is irreversible on a time scale of centuries. As the world’s top scientists explained in November in their final IPCC synthesis report summarizing the scientific literature: “Surface temperatures will remain approximately constant at elevated levels for many centuries after a complete cessation of net anthropogenic CO2 emissions”!"

Also, I think that Joe is underestimating the amount already "baked in", because according to a recent Hansen draft study, 1/4-1/3 of warming comes not from carbon but from accompanying increases in black carbon and methane plus albedo change. By this measure, about 2.3 degrees Centigrade of warming is already "baked in" at 400 ppm carbon, or an additional 2 degrees F.

navegante

Rob, your comment seems to imply that a two-state, hysteretic, irreversible Arctic requires one of the two states to be year-round ice free. Cannot this state be just a seasonally ice free Arctic?
Anybody?

Chris Reynolds

Navegante,

That's not what I am reading in what Rob is saying. But I agree that the following from Rob is a fair summary:

"This Wagner and Eisenman paper shows that if you take heat latitudial heat transport and seasonal variation into account, that the "biforcation" behavior of the SCM and EBM models disappears."

Wagner and Eisenman state that:

"This result may help to reconcile the discrepancy between low-order models and comprehensive GCMs in previous studies. Specifically, it suggests that the low-order models overestimate the likelihood of sea ice “tipping point”."

My reading of the whole paper leads me to the conclusion that the bifurcation seen in various EBM/SCM (Energy Balance Model/Single Column Model) studies is actually an artefact of these simple models, i.e. it is not real. By combining the two types of model into an intermediate complexity model the bifurcations disappear. And this intermediate complexity model is more like the more complex GCM type models.

Where Rob suggests that:

"Meanwhile the paper suggests that seasonally ice free conditions in the Arctic may occur at lower temperature increase than previously thought."

I'm not sure I agree with this. Wagner & Eisenman state that:

"The model becomes seasonally ice-free at
2 C of warming, and it becomes perennially ice-free at 6 C (Figure 4b). These values compare with comprehensive GCM results from Armour et al. (2011), who find the complete loss of winter and summer ice to occur at 4degC and 7degC, respectively."

Note that in stating seasonal and perennially ice free, the authors imply three states in the transition.

1) Perennially ice covered. - NOW.

2) Seasonally ice free.

3) Perennially ice free.

Armour et al "The reversibility of sea ice loss in a state-of-the-art climate model" use CCSM3 to find their result, and it is higher than Wagner & Eisenman's intermediate complexity model.

But it should be noted that Mahlstein and Knutti published a paper in 2012 entitled "September Arctic sea ice predicted to disappear near 2degC global warming above present." Here's a graphic from their paper.
http://1.bp.blogspot.com/-yBoKKsILj_8/VUUWeiaGd9I/AAAAAAAABz4/idkzqNywQnc/s1600/M%26K.png

This conclusion is based on observed data, with the utilisation of data supported by a suite of GCMs, also the use of observations to adjust GCM data. However their results show the 2degC is from observed temperature, and extent, with the GCMs producing temperatures of around 3 to 4 degC global warming for a seasonally sea ice free Arctic.

So I conclude not that the Wagner & Eisenman suggests a lower temperature, it doesn't, it agrees with earlier results, rather the agreement between Wagner & Eisenman and Mahlstein & Knutti might be coincidental. The observed data used by Mahlstein & Knutti is extrapolated substantially to give the 2degC GW for an ice free September, also the Wagner & Eisenman paper is a simple version of what is going on in a GCM - so this lower temperature for summer ice free state might itself be an artefact of simplicity, much as the Wagner & Eisenman paper shows bifurcations to be an artefact of the simplicity of EBMs and SCMs.

Chris Reynolds

Wayne Kernochan,

Granted irreversibility is mainly a theoretical argument. As there is scant evidence the human forcing (notably CO2 emissions) will reduce, the pack will transition. However with Bifurcations often comes rapid transitions. This paper suggests that this is not likely. As earlier suggested by Tietsche et al, this also means that a succession of catastrophically good melt weather might make what looks like a crash. But as the linear relationship between AGW and sea ice loss suggests, when such a run of good melt weather summers is followed by a succession of more normal summers (like 2013 and 2014), the ice will recover. So the first virtually ice free state may be followed by what looks like a recovery.

Neven

Wayne, like I said:

Good news (maybe)

and

On the condition, of course, that the Earth's oceans and atmosphere stop warming up.
Rob Dekker

Jim said

I wondered if I might idly enquire what your next SIPN prediction might say?

Short answer : By June 3 or 4 Rutgers will publish their NH snow numbers for May, and that's when I can publish a prediction.

The long answer :

For starters, I owe Slater et al an apology.
Their 2014 prediction, based on melting pond data from in early May, came through while my, and many other, predictions that were smack in the middle of the pack ended up almost 2 SD's off.

However, I noticed that the standard deviation of the September extent predictions by the SIPN contributors (including me) is stubbornly close to 500 k km^2 or more, no matter WHICH method was used.

Which puts Hamilton's Gompertz fitting method at the same accuracy as Slater et al's early May melting pond method (both of which reported a 500 k km^2 standard deviation for the June->Sept prediction). My own method (which relies on snow cover in the NH) obtains a better SD, but turned out not serve as a good predictor for the 2013 and 2014 melting season.

Which is somewhat concerning, since it suggests that (1) physical effects are less important than summer weather, but (2) the long term down trend is indisputable and does not depend much on the weather in summer.

And I'm not even sure if that is a paradox simply an indication that Arctic summer weather create a 500 k km^2 SD on June to Sept sea ice extent.

Rob Dekker

Either way, based on SIPN prediction June-Sept methods that have 500 k km^2 SD or less, the 2013 and 2014 Arctic summers were COLD compared to the long term "trend" line.
Including my method that uses NH snow cover as a predictor.

Rob Dekker

navegante said

Rob, your comment seems to imply that a two-state, hysteretic, irreversible Arctic requires one of the two states to be year-round ice free. Cannot this state be just a seasonally ice free Arctic?

Yes, that is true. A two-state, hysteretic Arctic does not need it's second state to be year-round ice free. I only gave that as an example of bifurcation. A more accurate description was made by Chris Reynolds, above :

However with Bifurcations often comes rapid transitions. This paper suggests that this is not likely.

although, while we witness the reduction of Arctic sea ice over the years, it may be difficult to judge afterwards if it was due to transition to a bifurcation state, or simply a rapid change due to underestimation of positive feedback factors.

Either way, the real issue is in my opinion that even GCMs still appear to underestimate Arctic sea ice decline :
http://neven1.typepad.com/.a/6a0133f03a1e37970b017744cf5360970d-pi

Chris Reynolds

Rob,

I have found the same problem with every method I have tried, not just this year, but last year too. The summer weather is the killer and I don't see how anyone is going to get past it.

Using peripheral seas volume I get a sigma of 0.62. If I take the residuals from that model I can get a R2 of 0.45 for a linear fit to temperature at 500mb. Incorporating the temperature/residuals relationship means my sigma for the hindcast drops to 0.43. But I cannot predict temperature from April.

Anyway here is one of the hindcast plots.
https://c4.staticflickr.com/8/7695/16988968294_151f3d1953_o.png

'Actual' is actual NSIDC September extent, 'Model' is model based on the relationship between April volume and September Extent, 'Adjusted Model' is the same as Model, but with the temperature adjustment. The improvement in recent years using 500mb temperature is marked.

Neven

@Neven - typepad ate my last post.

Sorry about that, Wayne, I just released two of your comments. The spam filter has been working great these past couple of months, and so I tend not to check that often.

Wayne Kernochan

Hi Neven, Chris. Thx for insight as always.

Actually, Neven, those two comments were hopefully just repeated in my third one. So, not necessary to resuscitate those posts, but much appreciated. Fyi, my last two comments went through when I logged in to typepad via Facebook. Apparently, your spam filter regards the Facebook "brand" as spam-free :)

Chris, I appreciate the insight on the paper. My old crude model (now, alas, probably discredited) suggested to me that there would be no tipping point or hysteresis, and Hansen's review of data from 3 million years ago found that the Arctic was ice-free year round at 360 ppm atmospheric carbon, but this is a unique situation, so I wasn't sure.

Verify your Comment

Previewing your Comment

This is only a preview. Your comment has not yet been posted.

Working...
Your comment could not be posted. Error type:
Your comment has been posted. Post another comment

The letters and numbers you entered did not match the image. Please try again.

As a final step before posting your comment, enter the letters and numbers you see in the image below. This prevents automated programs from posting comments.

Having trouble reading this image? View an alternate.

Working...

Post a comment

Your Information

(Name is required. Email address will not be displayed with the comment.)