Study: “It is clear … that the precipitous decline in September sea ice extent in recent years is mainly due to the cumulative loss of multiyear ice.”

Physicist: “If temperatures change just a few tenths of a degree then this oh-so-thin ice cap is doomed.”

Memo to media:  Ignore the misreporting on the Arctic that focuses on sea-ice extent or area.  The big Arctic news is the staggering decline in multiyear ice — ice volume. No study has yet been published undermining our understanding that human emissions are the primary cause of that long-term decline — a decline that shows no sign of reversal.

The real news from the Arctic is the staggering decline in thicker, multi-year ice [red line] — as seen in the above figure from leading cryoscientists who authored the 2009 study, “Thinning and volume loss of the Arctic Ocean sea ice cover: 2003-2008” (discussed here).  Studies that focus on trying to correlate sea ice extent (i.e. area) with variables that might reduce ice cover border on purely pointless right now because:

  1. Trends in multi-year ice — ice volume — are what matter most in terms of the long-term survivability of the Arctic ice in the summer (see New study supports finding that “the amount of [multi-year] sea ice in the northern hemisphere was the lowest on record in 2009”).
  2. It now appears that an unfortunate trick of Nature helped hide the ongoing decline of Arctic ice from satellite and other measurements — measurements that suggested two-dimensional recovery of sea ice extent in 2009.  See the study Perennial pack ice in the southern Beaufort Sea was not as it appeared in the summer of 2009.”

The latest media mashup began with a new study in Geophysical Research Letters (subs. req’d), “Influence of winter and summer surface wind anomalies on Summer Arctic sea ice extent.”  The study, by Masayo Ogi et al., finds that:

.. the combined effect of winter and summer wind forcing accounts for 50% of the variance of the change in September Arctic sea ice extent from one year to the next ( Δ SIE) and it also explains roughly 1/3 of the downward linear trend of SIE over the past 31 years.

That became a Guardian story by David Adam with an especially misleading subhed:

Wind contributing to Arctic sea ice loss, study finds

New research does not question climate change is also melting ice in the Arctic, but finds wind patterns explain steep decline

And of course we have a Daily Mail story by the infamous “Daily Mail Reporter”:

Arctic winds and not global warming ‘responsible for much of record loss of sea ice’

As an aside, I understand why “Daily Mail Reporter” wants to stay anonymous — he or she is a dreadful journalist at a dreadful newspaper (see “DailyMailGate: Error-riddled articles and false statements destroy Daily Mail’s credibility“).

The anti-science disinformers are dancing over this study, but they are dancing on thin ice — like a certain ice skater we know.

First off, this study isn’t even news!  As I blogged almost 2 years ago, a GRL study, “What drove the dramatic retreat of arctic sea ice during summer 2007?” concluded:

… preconditioning, anomalous winds, and ice-albedo feedback are mainly responsible for the retreat. Arctic sea ice in 2007 was preconditioned to radical changes after years of shrinking and thinning in a warm climate.The Arctic Ocean lost additional 10% of its total ice mass in which 70% is due directly to the amplified melting and 30% to the unusual ice advection, causing the unprecedented ice retreat. Arctic sea ice has entered a state of being particularly vulnerable to anomalous atmospheric forcing.

So the June 2008 GRL study found 30% of the sharp drop in sea ice in 2007 was due to “unusual ice advection” — and the new study says 1/3 of the downward linear trend in SIE is due to wind forcing.  The new study seems to confirm the older study (without ever referencing it).

The bigger point is the long-term trend is driven by human-driven warming, which makes the thinning ice more vulnerable to anomalous winds (assuming of course that the winds are anomalous and not themselves driven by climate change).  So the story is an old one.  What’s new is the disinformers are better at spinning these studies, and the media has gotten worse at actually reporting the science.

Indeed, Masayi Ogi also led another recent study (12/08), “Summer retreat of Arctic sea ice: Role of summer winds” (subs. req’d) that concluded:

The six summers that exhibited highest values of the SLP [sea level pressure] index (1995, 1998, 1999, 2005, 2007 and 2008) were all in the last half of the record. September SIE reached record lows in three of these years (1995, 2005, and 2007), and it nearly tied the record in 2008.  Yet it is clear from Figure 4c that the precipitous decline in September SIE in recent years is mainly due to the cumulative loss of multiyear ice:  summertime SLP anomalies have played an important role in setting the timing of record lows, but the long term trend is mainly due to preconditioning.

In other words, Ogi’s studies do nothing whatsoever to undermine the view that the long-term trend in Arctic sea ice — extent and volume — is being driven by human-caused warming.

That paragraph and the new study make clear the SLP index and winds have been higher more recently.  As the Guardian notes, “These winds have increased recently, which could help explain the apparent acceleration in ice loss.”  The climate is changing everywhere and humans are the primary cause.  Unless the authors (or anyone else) can show that this increase in winds is not also due to climate change, then their study again does nothing to undermine the view that the long-term trend is being driven primarily by human-caused warming.

Finally, the latest study is based on correlating sea ice extent (SIE) with other factors, like Arctic winds.  But another recent study — “Perennial pack ice in the southern Beaufort Sea was not as it appeared in the summer of 2009” (subs. req’d) by Barber et al. — suggests that standard measures of SIE extent may be unreliable.  I discussed that study here:  “Where on Earth is it unusually warm? Greenland and the Arctic Ocean, which is full of rotten ice.”  It found:

In September 2009 we observed a much different sea icescape in the Southern Beaufort Sea than anticipated, based on remotely sensed products. Radarsat derived ice charts predicted 7 to 9 tenths multi-year (MY) or thick first-year (FY) sea ice throughout most of the Southern Beaufort Sea in the deep water of the Canada Basin. In situ observations found heavily decayed, very small remnant MY and FY floes interspersed with new ice between floes, in melt ponds, thaw holes and growing over negative freeboard older ice. This icescape contained approximately 25% open water, predominantly distributed in between floes or in thaw holes connected to the ocean below. Although this rotten ice regime was quite different that the expected MY regime in terms of ice volume and strength, their near-surface physical properties were found to be sufficiently alike that their radiometric and scattering characteristics were almost identical.

Yes, satellite (and other) measurements of Arctic sea ice extent were apparently deceived by rotten ice.  [Hmm, is that why they call it rotten?]   You might even say that an unfortunate trick of Nature helped hide the decline of Arctic ice:

This case of mistaken identity is physically explained by the factors which contribute to the return to Radarsat-1 from the two surfaces; both ice regimes had similar temperature and salinity profiles in the near-surface volume, both ice types existed with a similar amount of open water between and within the floes, and finally both ice regimes were overlain by similar, recently formed new sea ice in areas of negative freeboard and in open water areas. The fact that these two very different ice regimes could not be differentiated using Radarsat-1 data or in situ C-band scatterometer or microwave radiometer measurements, has significant implications for climate studies and for marine vessel navigation in the Canada Basin.

Given Barber’s work calling into question traditional measures of SIE, I don’t know how much faith one can put in statistical analyses that correlate SIE with other variables.  Barber himself says:

I would argue that, from a practical perspective, we almost have a seasonally ice-free Arctic now, because multiyear sea ice is the barrier to the use and development of the Arctic,” said Barber [Canada’s Research Chair in Arctic System Science at the University of Manitoba].

Revkin has another Goldilocks post leaping on this study, linking to some of my much older posts, not the ones about Barber’s work.  He quotes one expert noting that the unusual conditions in the Arctic this winter — in particular the highly negative Arctic oscillation — may lead to less ice retreat.  Certainly it might lead to less observed sea ice retreat, but then again, this is likely to be the hottest year on record — and certainly we now know that atmospheric conditions do have an impact on year-to-year fluctuations in apparent SIE — so the jury is out on this summer.  In any case, we also know the traditional measurements of SIE may not be reliable and thus may well lowball the actual retreat.

Most importantly, we know that thickness matters much more than area.  And in that regard, we have seen no significant recovery.  Nor are we likely too, according to one of Revkin’s own experts, “Rhett Herman, a physics professor at Radford University, [who] has been leading students on an expedition each spring break to study the condition of the sea ice off the coast near Barrow, Alaska.”  Last week, Revkin quoted Herman:

We’re also seeing just how frighteningly thin the ice is. When asked about the thickness of the north polar ice cap many people say things such as “hundreds of feet” and “thousands of feet” and “very thick like the South Pole.” None of these are true. The average thickness of the sea ice over the entire north polar ice cap is only a few meters! There isn’t much ice here, and that’s a major problem. If temperatures change just a few tenths of a degree then this oh-so-thin ice cap is doomed.

Well, we’re pretty much stuck with another 0.6°C warming even if GHG concentrations don’t rise further — and NASA just reported, “there has been no reduction in the global warming trend of 0.15-0.20°C/decade that began in the late 1970s.”

Many other leading experts share a similar view.  Peter Wadhams, head of the polar ocean physics group at the University of Cambridge, “believes the ice, which has been a permanent feature for at least 100,000 years, is now so thin that almost all of it will disappear in about a decade.”

Back in October, National Snow and Ice Data Center Research Scientist Walt Meier wrote me:

There is significant natural variability in the climate system, and particularly the sea ice. It is only by looking at long-term trends, after the short-term variability is averaged out, that you can make any judgments on long-term climate factors….

In the short term, winds can play an important role in the sea ice extent. If there are winds pushing the ice edge “inward”, then you either increase the seasonal decline or slow (or even temporarily reverse) the seasonal increase, depending on the season.

What about NSIDC director’s Mark Serreze “death spiral” of Arctic ice metaphor?  I noted back then that the NYT‘s Revkin had written:

So the “death spiral of the Arctic ice system” could well be more like a series of descending loop the loops.

Meier wrote:

Andy Revkin’s comment is quite apt. We don’t expect to see a continual downward trend, there will some fits and starts, but the overall trend will continue to be down.

NSIDC director Serreze then wrote me that “I share Walt’s views.”

So the ice cap is apparently doomed — and the overwhelming majority of CP readers will probably live to see an ice free summer Arctic.  I’ll end with this figure of mean monthly Ice Volume for the Arctic Ocean from a release by several scientific institutions:

I still like my odds on a 90% ice free Arctic by 2020 (see “Another big climate bet “” Of Ice and Men“).  By then, I assume they’ll have figured out how to deal with Nature’s sea-ice-decline-hiding trick “” or there will simply be too little ice for anybody to be fooled.

[NOTE:  This post has been updated.]


23 Responses to Study: “It is clear … that the precipitous decline in September sea ice extent in recent years is mainly due to the cumulative loss of multiyear ice.”

  1. Jim Eager says:

    A related item reported at Rabbet Run:

    “The Lunar Orbiter Image Recovery Project (LOIRP) is moving on to NIMBUS tapes from the 1960s. Among other things, once these tapes are analyzed it will be possible to follow ice extent back almost 20 more years. The National Snow and Ice Data Center believes it will be possible to figure out monthly averages as far back as the mid-60s.”

    Although the NIMBU tapes will only show ice extent, it might be possible to correlate the extent data with the ice thickness data from the same era that Al Gore got the US Navy to declassify.

  2. The Wonderer says:

    I won’t be visiting the referenced NYT blog, but I did note the NSIDC discussion that he’s probably (in part) referring to:

    “The pattern of winds associated with a strongly negative AO tends to reduce export of ice out of the Arctic through the Fram Strait. This helps keep more of the older, thicker ice within the Arctic. While little old ice remains, sequestering what is left may help keep the September extent from dropping as low as it did in the last few years. Much will depend on the weather patterns that set up this spring and summer.”

    I guess it’s the engineer in me that finds it interesting to track the sea ice weekly or sometimes daily on NSIDC and IJIS, and it will be interesting to see what happens this year. The engineer in me also wonders if we can’t devise better instrumentation with which to measure sea ice and the large ice sheets. If so, it would be a good national investment, I think.

  3. Andy Revkin says:


    I’m sure Rhett Herman, who contributed the Dot Earth “postcard” on his students’ fieldwork, will readily admit that while he’s a great teacher (and that’s why that post was done) he is not a heavily published specialist on sea-ice trends and drivers. Stacking his informal comment against the input of a heap of published sea-ice specialists (see my coverage since 2000) seems a bit strained?

    [JR: Honestly, Andy. You quote this guy at length on your blog, and now walk away from him. You always tout your group of Arctic experts. How am I supposed to know which experts you quote that you believe and which you don’t! I did NOT stack his comment against anything. His comment is consistent with many experts I have quoted. This quote just happened to be new and from DotEarth. How about this — Peter Wadhams, head of the polar ocean physics group at the University of Cambridge, “believes the ice, which has been a permanent feature for at least 100,000 years, is now so thin that almost all of it will disappear in about a decade“:]

    The reason I didn’t write on Dave Barber’s paper when it came out (even though he was featured in our 2005 Discovery-Times “Arctic Rush” documentary and is a highly regarded scientist), is that I got a lot of pushback from a batch of Arctic Ocean ice specialists who immediately said that the Beaufort is a special case and cited various reasons to handle those findings cautiously. I may revisit and query Dr. Barber and them anew. That’s how I try to avoid what I call “whiplash journalism” (or blogging). Covering every paper can lead to real neck trauma when focused on the more complicated parts of climate science (even as the basics are clear).

    [JR: So you only cover the published peer-reviewed papers that your group of experts are okay with? Awesome. Essentially, you are negatung the peer review process. So these “batch of Arctic Ocean ice specialists” apparently aren’t reviewers who can affect the content of the piece before it is published.

    BTW, aren’t you now a blogger? What was the point of that comment?

    And you are missing half the reason I’m quoting Barber — his research calls into question the accuracy of traditional SIE measurement, which in turn calls into question any effort to do correlations between SIE and other variables! I can see why that by bother your specialists.]

    I don’t imagine you tried contacting any other ice scientists before publishing your posts on the Beaufort finding? (I know, my need to check things out is just the old retro journalist trait in me.)

    [JR: Again, if I understand your methodology, you ask your group of experts about peer-reviewed science and if they don’t like it then maybe you don’t write about it. Not what I do. Sometimes I talk to other scientists, sometimes I don’t. Depends on the study. You don’t actually have to contact other scientists to write about a new peer-reviewed paper — especially if you are very familiar with the peer-reviewed literature and especially if this study pretty much agrees with one that was written two years ago! In this case, it seemed clear to me it was being misreported, and I wanted to correct the record.]

    Finally, you forgot to mention the paragraph in my post where I expressly described the great spasm-like flushes of the true multi-year (as opposed to young two-year-old) ice you focus on. Those big flushes show the situation up there is not nearly as simple as some would like it to be. Don’t take my word for it, though. This animation from Ignatius Rigor at U. of Washington vividly shows the big pulses of lost meters-thick ice (long before the losses that you highlight above):

    [JR: Awesome. Looks like a death spiral for me. I take it this is one of the experts you quote whom you actually believe. Is this in the peer-reviewed literature, because I would like the link, if so. In any case, the last time I checked, 1989 was the tail end of what was the hottest decade on record at the time, before the 1990s became the hottest decade on record, and before the 2000s overtook them both. I don’t focus on two-year-old ice — I do cite peer-reviewed literature on multiyear ice.

    I can’t imagine anybody reading this post would come away with the impression that I think this situation is “simple.” Obviously the apparent SIE is affected by many things year-to-year, just like the apparent global temperature. But the ice volume appears much less susceptible to such fluctuations and appears to be doomed.]

    Here’s video I shot of one of the processes that generates such ice (also a function of ice motion, not just temperature):

    I really do think you need to take a field trip sometime.

  4. Aaron Lewis says:

    Volume is important, but the heat content of the remaining sea ice is also of interest. Dr. Barber suggests, and satalite data confirms that the remaining ice may already have absorbed most of the heat it needs to melt. And, this is in situ HEATING not wind. Cold hard ice would have been strong enough to not blow through the straits. The same satalite data tells me that the Ross ice shelf and the sea ice on the Weddle sea are also absorbing heat from the warming oceans below.

  5. The Wonderer says:

    Classic Revkin. He can’t see the forest through the trees (or global warming through the sea ice), and is confused as ever.

  6. mike roddy says:

    OT (I’m weak on ice), but this subject is always OT, and as long as you and Andy are listening-

    I just had a meeting with Jerry Franklin at UW, who is widely considered to be the leading forest ecologist in the nation, and a pioneer in studying the forest carbon cycle. In a 1990 paper, he calculated that the Northwest coastal forests, which in their natural state contain the most carbon per acre in the world (though the Australians would argue), are currently at about 25% of their carbon storage capacity. The US northwest coastal forest is a sea of stumps and pygmy trees. Google Earth a closeup sometime if you really want to be horrified.

    If our formerly magnificent coastal forests are spared from the chainsaws and allowed to return to their former majesty, the carbon sequestration benefits would be enormous. Macken of Australia calculated a 131 mt of CO2 annual sequestration benefit from leaving their considerably smaller southeastern eucalyptus forest alone. The opportunity is larger here, because the destruction is more comprehensive.

    There are a number of financail incentives available that would enable us to move in that direction. It’s not just about offsets or cap and trade.

    Both Climate Progress and Dot Earth have neglected this key subject, even when I have bugged you about it. It’s probably because forest emission and sequestration patterns are complex and understood by few, including most prominent climatologists. It is a specialized field, and the data is not accurately recorded by our government, either.

    I humbly ask both of you to listen to me this time, and begin a series of posts on a path that can help our emissions immediately, and accomplish much else, at minimal cost. Besides the carbon sequestration benefits, wildlife, including salmon and steelhead, would return to the rivers in force. I recommend that you ask Dr. Franklin to contribute the lead post on this subject in both of your blogs. He has some excellent ideas, and so do others, including yours truly.

    [JR: You really should address things to Revkin on his blog. I have blogged many times on the value of restoring forests. Always open to guest posts by scientists.]

  7. Ivy Bear says:

    What was Mr. Revkin’s PhD in again? Oops – he doesn’t have one.

  8. MapleLeaf says:

    Joe, an excellent post.

    I saw reference to this study earlier today at the Guardian and just new that this paper was primed to get misrepresented by the media and those in denial. I’m sure WUWT will be all over it, and Revkin is helping them along to misinform people.

    The scientists have known for a long time that winds and ocean currents play an important role in the Arctic sea ice extent. There is no silver bullet here Andy Revkin. I wish it were not true, but the MY Arctic ice is on its knees and unlikely to make a long-term recovery, even under favourable wind regimes which will just delay the inevitable. Look at this:

    It is so very disappointing that Andy Revkin, has once again railed against the science and failed to accurately represent the big picture here. I’m curious to know exactly who this cadre of Arctic ice scientists is whom he consults with.

    On a happier note, Eli Rabett has an article on how they have tapes of satellite data going back to the 60s, and NSIDC are hoping o generate monthly ice extent stats going back to the mid sixties. That will be very helpful placing the recent loss in context. See link @ #1 by Jim Eager.

  9. Wonhyo says:

    mike roddy (#6) says: “…the Northwest coastal forests, which in their natural state contain the most carbon per acre in the world (though the Australians would argue), are currently at about 25% of their carbon storage capacity…Macken of Australia calculated a 131 mt of CO2 annual sequestration benefit from leaving their considerably smaller southeastern eucalyptus forest alone. The opportunity is larger here, because the destruction is more comprehensive.”

    This is the type of information I am now most interested in: opportunities for natural carbon sequestration. I’m not convinced that stabilizing at 450 ppm or even 350 ppm is enough to avoid widespread catastrophic effects. We need to reduce carbon emissions as aggressively as possible, and even target net negative emissions. Reforestation sounds like an excellent idea.

    What is the state of research on reforestation as a carbon sink? Can reforestation in the Northwest succeed in the face of climate change? I’m worried that droughts and floods might hinder or negate reforestation efforts.

    How long would it take to bring Northwest forests up to 100% carbon storage? How much of a dent will this put in CO2 emissions and resulting concentrations?

  10. Wonhyo says:

    I mention reforestation (sorry to be off-topic) because I see a very tangible way to do it: plant trees to replace the ones we cut down!

    Is there anything (practical) we can do to directly save the polar ice caps from further (and complete) melt?

    Am I being too pessimistic to think that 450 ppm or 350 ppm is not low enough? Are there climate models that show climate stabilization (to a livable condition) at either of these targets?

    [JR: Need to get back to 350 as soon as we can. Lower would be ideal. Tough.]

  11. Heraclitus says:

    Am I oversensitive or is there a spate of exaggerating the climate scientists’ exaggeration?

    The Guardian article says “[the study] could raise doubts about high profile claims that the region has passed a climate ‘tipping point'”, but following the link I find a BBC report that quotes one scientist saying that we *could* be in a downward slide in terms of passing a tipping point. I’m not sure that counts as high profile claims, maybe there were others.

    Then on Radio 4 this morning Lord Krebs from the Royal Society discussed perception of risk and the crisis in scientific authority. He seemed to be saying that some climate scientists had overstated the risk – possibly true, but surely many more have understated it and this didn’t seem to be an issue. The balance is very much towards understatement of risk and very definite statements of uncertainty from the scientists – not so much from the media of course.

    [JR: Precisely.]

  12. The figures below (Rothrock, et al., 1999 and Kwock & Rothrock, 2009) show sea ice thickness has substantially declined. Using data from submarine cruises, Rothrock and collaborators determined that the mean ice draft at the end of the melt season in the Arctic has decreased by about 1.3 meters between the 1950s and the 1990s.

    When combining this data with recent satellite data:

    “The overall mean winter thickness of 3.64 m in 1980 can be compared to a 1.89 m mean during the last winter of the ICESat record—an astonishing decrease of 1.75 m in thickness. Between 1975 and 2000, the steepest rate of decrease is 0.08 m/yr in 1990 compared to a slightly higher winter/summer rate of 0.10/0.20 m/yr in the five-year ICESat record (2003–2008). Prior to 1997, ice extent in the DRA was >90% during the summer minimum. This can be contrasted to the gradual decrease in the early 2000s followed by an abrupt drop to <55% during the record setting minimum in 2007. This combined analysis shows a long-term trend of sea ice thinning over submarine and ICESat records that span five decades."

  13. mike roddy says:


    The reforestation opportunities in the US and many other places are huge. In answer to your question, I see the potential in this country at 300 Mmt CO2 emissions savings per year, for starters.

    To give you an idea of the scale here, annual CO2 emissions are about 30 billion mt per year. Vegetation and land emits 439 billion mt per year, which is offset by 450 billion mt of sequestration, mostly from forests. Sequestration potential is much greater if we allow natural processes to recur. Our own forests are among the most degraded in the world, worse than Brazil’s by any measure.

    Joe, it’s true that you and Andy for that matter bring up deforestation from time to time, but you almost always precede it with “tropical”, because the NGO’s, with timber industry ties, have trained you to do so. The damage and opportunities are greater in North American temperate forests. A greater percentage of them have been destroyed, they cover a larger land area, and sequestration per acre is higher. The media have suppressed this, because they use newsprint.

    I apologize for being so OT, and you’re right, I shouldn’t have been lazy in also addressing Revkin here, but you have the best climate blog, and it’s where I want to make this message heard.

  14. jorleh says:

    This winter was rather warm in the Arctic region? Let´s have a look for 9/25 2010.

    [JR: It was warm, but a very negative AO kept ice from being blown out.]

  15. chris peterson says:

    Dear Colleagues,

    THis is not a response to the above post, but a general question because I didn’t know who else to ask. Can you direct me to any online sites that give the long-term temperature trends averaged for a given nation? Tabular is okay, a graph is better. I have found the info for the U.S., U.K., Canada, and Australia. I’d very much like to include 3 or 4 more of the biggest countries (Russia, China, Brazil, Indonesia, and Argentina….perhaps Japan & South Africa as well, since they are more developed). This is in part to respond to the denialists that think global temperature datasets are “tainted” or “manipulated”. My idea is to present the long-term trends of several (up to a dozen) of the largest countries, and say “okay, if you don’t believe the global datasets, how about these graphs which show steady warming in U.S., Canada, Australia, U.K., Russia, and China?” I’m not an atmospheric scientist at all (I’m a plant ecologist), but I teach several detailed lectures on climate change in several of my introductory courses, and I have a great passion to refute the denial machine in every way possible.

    Chris J. Peterson
    Associate Professor
    Dept. of Plant Biology
    University of Georgia

  16. jcwinnie says:

    Professor Joe, no amount of bludgeoning with charts & graphs will convince people who pay the editors who pay Andy Revkin that “human emissions are the primary cause of that long-term decline — a decline that shows no sign of reversal” because that is a really, really scary concept and no one, not even smarty-pants scientists reporting the loss have a non-inconveniencing, profitable solution that they can buy.

    Uh-oh, loss of control. Unacceptable! Danger, Will Robinson, Danger!

    So better to keep denying such things at the Gray Lady Mushroom Farm and elsewhere in Media Land.

  17. MapleLeaf says:

    Hopefully CryosatII will be up and running soon, b/c the GLAS on IceSAT has not been working since last fall.

    As for fall ice extent in 2010, the predominant phase of the AO this coming summer and fall will play a role. We’ll have to wait and see what happens.

  18. Dr. Peterson, although Alan Buis is not directly related to your interest, he might be able to give you a name of someone who can help you:

    Alan Buis 818-354-0880

  19. Joe, did you not see John Cook’s latest post at Skeptical Science about the new paper by Stone et al. on what range of CO2 would cause the collapse of the GrIS? True, it is a modelling study, but gives a range of between 400 and 560 ppm.

    And, as far as I can see, the paper does not go into CO2 equivalents.

    [JR: Looks about right.]

  20. barry says:

    My mistake. Somehow I missed the 2009 paper linked to in your article. Please ignore the above post.

    Having read Ogi 2009 now, (I searched for it unsuccessfully in google scholar, before realizing you’d linked to it here), I think the best the the deniers can say is that – minus the influence of winds – whereas before it could be said the IPCC had underestimated Arctic sea ice loss, now it would seem the IPCC has fairly accurately predicted it.

    Based on only one paper, of course….

  21. Ray Welch says:

    What will happen to the weather when the ice cap collapses, and the Arctic inverts from heat reflector to heat sink? What will happen to the seasonal highs and lows that are driven by seasonal temperature gradients? What will happen to the jet stream? What will happen to the methane-laden tundra that surrounds the Arctic Ocean? No one knows, but here’s my guess: we won’t like it.

    Is not the disappearance of the ice cap the trigger of abrupt climate change to fear most? Is this not a cause for great urgency?

  22. riverat says:

    Some folks mentioned reforestation to help combat rising CO2 levels. I think it is good and useful step.

    But it’s probably balanced by the deforestation that is occurring in the inter-mountain west. Bark beetles are killing large areas of pine forest. Plenty of that will burn putting a pulse of the carbon stored in the trees into atmospheric CO2.

  23. J4zonian says:

    Thanks for the discussion. Only one slight reservation:

    Physicist: “If temperatures change just a few tenths of a degree then this oh-so-thin ice cap is doomed.”

    You/she/he mean “WHEN temperatures change…” right?