James Martin says:
7 June 2009 at 10:01 PM
I read today a claim that in the paper published recently by Dr Steig et al. in Nature regarding the Antarctic warming trend, there is a weighting problem. They claim that most of the weighting comes from the peninsula stations, which represents a relatively small part of the continent.
I was wondering if this is in fact the case? It doesn’t seem likely, but could you comment on this at all? If these assertions are left unchecked, before you know it they’ll be taken as fact.
[Response: The point of the Steig et al paper was to use spatial correlations in recent data to look at how under-sampled parts of the continent likely changed over longer time periods. Those correlations will necessarily weight different stations differently as based on the physical characteristics. The analysis you saw is simply a fishing expedition, an analysis of what the calculation is doing (fair enough), combined with an insinuation that the answer is somehow abnormal or suspicious (not ok). But how is this to be judged? What would be normal? No-one there can say and they would prefer simply to let people jump to conclusions. It’s kinda of typical of their tactics, but not a serious scientific point. – gavin]
I won’t be holding my breath for Gavin admitting he was wrong.
[Response: Gavin is not wrong very often. Nor in this case!–eric]
Good! Humour is a good antidote to both cynicism and hubris. Point is, of course, that the signal for widespread, i.e. global, warming is still equivocal. Statisticians and modelers might see the signs, but the are not yet large enough or “global” enough for the average Joe to see. Recognizable trouble is still 10 years away – a little different from the Al Gore cinematic impression. Unfortunate: if you yell Fire! in a theater, the crowd expects at least a lot of smoke.
[Response: Oh, there’s plenty of smoke. Unfortunately, there’s a crowd with a bunch of mirrors trying to distract your gaze from the fire.–eric]
I really like this quick-n-dirty summation, especially the spelling of geophysicists. Someone without a sense of humor is bound to tell you that you spelled that ALL WRONG, though.
[Response: They need to read up on their history then. See Walt Kelly’s Pogo around 1957/1958 (I.G.Y.). Though admittedly I may have spelled Walt’s spelling wrong.. didn’t have a copy of the comic strip handy.–eric]
Could someone please explain to me how O’Donnell et al. is a refutation of Steig et al.? Reading Ryans’ comments and the paper’s abstract I do not get that impression at all. To me, this look s like science advancing and building upon and improving and earlier (and seminal) work.
I bets this is how that paper came to be. SM: “Guys, we have to attack the “team” again”. SM faithful: “But how, oh wise master?”. SM:”How about we look into that Nature paper by Steig that is getting so much attention and showing inconvenient things?”. SM faithful “Oh master thou truly are wise”.
So they start all filled with hope and glee that Eric et al. messed something up big time. Nope. OK, dig deeper, and deeper and deeper still…until, voila we found some issues that were not adequately or properly addressed the first time round! Phew, good, science and peer-review still work.
Now the WUWT crowd will spin and milk this for all it is worth, and use it to make attack the integrity of Eric and his co-authors, and then extrapolate that to all those scientists involved in climate research.
What scared me upon looking at some of the images is how much more warming they found over large portions of the WAIS (especially the Peninsula) than Steig et al. originally did. Yikes, things are not looking good for the PIG. I’m sure Anthony will ignore that fact. And look at that warming over parts of the EAIS…fortunately that warming does not seem to be statistically significant just yet.
And why did WUWT show an image that appears to have less warming than the one shown here by Eric? Sorry but I have to fault you both there..the figures should show for what season they are valid, or if they are for annual temperatures.
[The figure here shows O’Donnell’s et al.s reconstruction for the same time period as our Nature cover image. These are annual mean estimates. I cannot speak to WTF WUWT has done.–eric]
In closing to quote Ryan
O’Donnell: “With that being said, I am quite satisfied that the review process was fair and equitable, although I do believe excessive deference was paid to this one particular reviewer at the beginning of the process.”
“My feeling is that Dr. Broccoli did a commendable job of sorting through a series of lengthy reviews and replies in order to ensure that the decision made was the correct one.”
“Overall, we find that the Steig reconstruction overestimated the continental trends and underestimated the Peninsula – though our analysis found that the trend in West Antarctica was, indeed, statistically significant. I would hope that our paper is not seen as a repudiation of Steig’s results, but rather as an improvement.” [Yet the WUWT headline is
“Skeptic paper on Antarctica accepted – rebuts Steig et al”]
“In my opinion, the Steig reconstruction was quite clever, and the general concept was sound. A few of the choices made during implementation were incorrect; a few were suboptimal. Importantly, if those are corrected, some of the results change. Also importantly, some do not.”
Definition of “Rebut”:
v. re·but·ted, re·but·ting, re·buts
1. To refute, especially by offering opposing evidence or arguments, as in a legal case.
2. To repel.
To present opposing evidence or arguments.”
[Response: I suspect your history is quite accurate, but to be fair, these guys DID publish the paper, even though their results wound up not supporting their thesis very well. I commend them on that. Indeed, I think it speaks very well to the integrity of the authors, when it comes down to facts (as opposed to speculation).–eric]
I do give them credit for getting this published– I should have been clearer on that.
From what I can tell, I have no reason to doubt the integrity of O’Donnell. In fact, until yesterday I did not know of him. I’m afraid though, that past actions clearly dictate that two of the paper’s co-authors do in fact lack integrity and do not necessarily have honest intentions in this debate.
This is a good article and a great site. I have a comment regarding the public turning off or going to sleep over climate change. What do swine flu, bird flu, the ozone hole, resource depletion, and acid rain have in common? The are all science based issues with catastrophe threatened that turned out to be pretty moderate.
The problem you have is the public look at this and look at climate change and conclude it will likely be the same. The fact that the ozone hole is disapperaring and acid rain caused less damage than feared was because we took action but this is lost on them. It will take another truly big temperature spike or something similar to wake them up Im afraid.
” What do swine flu, bird flu, the ozone hole, resource depletion, and acid rain have in common? The[y] are all science based issues with catastrophe threatened that turned out to be pretty moderate.”
Yes, and except for resource depletion, all those catastrophies were avoided in great part because effective action was taken to prevent a catastrophic outcome, and those actions were based on scientific grounds.
Doesn’t that suggest you a proper course of action ? Hello ?
Still, West Antarctica is definitely warming significantly, as Steig et al. found. That’s interesting.
Not if all the warming is in the peninsula. That’s not as interesting as warming over the Ross Ice Shelf.
[Response: Actually, the area O’Donnell shows significant warming is more interesting. Your definition of ‘the Peninsula’ is a bit off, but in any case, as I’ll show in another post, O’Donnell et al. actually find warming over the Ross, though only recently. As we’ll see, that is an important finding — but not for the reasons (melting of ice) that your presume.–eric]
Comment by nanny_govt_sucks — 9 Dec 2010 @ 3:24 PM
“Your levity is good. It relieves tension, and the fear of death.”
— The Terminator
I’m afraid though, that past actions clearly dictate that two of the paper’s co-authors do in fact lack integrity and do not necessarily have honest intentions in this debate.
Sure… but the nice thing about the peer review regime is that it forces also basically dishonest persons to play straight, if they want to play at all. If the integrity of science depended on human nature alone, it wouldn’t exist.
…and I’m happy to see another amateur getting published, after BPL, Jim Prall, and semi-amateurs like Eli and Tamino. Poor show for the ‘priesthood’ :-)
Julian Day 2020.342
Scientists: Satellite data says Antarctica lost petatons of ice last year.
Sceptics: Antarctica completely frozen today – no warming visible.
Politics: Antarctica will not melt this legislative period.
Media: Melting ice cubes do not disintegrate your cocktail.
Public: Antarctica is last place on Earth for skiing.
Jeffrey: No. The definition of peak oil is the global peak in rate of oil extraction. It is not directly tied to rate of discovery.
As Matt Simmons used to say in many presentations, peak oil is a “rear view mirror event”, in that we won’t know for sure we’ve passed it until several years after the fact. This is because the rate of oil extraction is so tied to other things like economic activity, public policy (e.g. encouraging alternatives), etc.
Yearly worldwide consumption of petroleum passed discoveries in the early/mid 1980’s. We’ve been largely living off the ongoing production from the supergiant oil fields, like Ghawar in Saudi Arabia, for decades.
This now completes our digression into peak oil issues. Carry on, everyone.
“In response to MapleLeaf’s question in #6, the reason why WUWT showed an image that appears to have less warming than the one shown here seems to be that the scale has been altered on the RealClimate image, covering the range -0.4 to +0.4 rather than a range of -0.6 to +0.6 degrees C as used in the original and reproduced at WUWT. With the colour range used being much the same in both images, that obviously makes the warming trend appear greater in the image shown here. I can confirm that the continental 1957-2006 trend per our reconstruction, at 0.06 degrees C per decade, was only half the 0.12 level shown by the Steig et al. 2009 reconstruction.”
[Response: Yes. I never said otherwise. The point very simply is that Antarctica is not cooling, no matter how much some people try to make it so. Oh, and West Antarctic is still warming, even if you try to call parts of West Antarctica “the Peninsula”.-eric]
[Response: “smoothness” is just file conversion for web posting. ‘Less warming’ is in the eye of the beholder. If the debate is now about ‘how much warming’ rather than warming at all, I guess I’ve won the debate, eh? –eric]
Maple Leaf @ 8 – Why would you feel that 2 of the authors lack integrity? Did they not publish what the facts spoke to them? If they lacked integrity, they would have tried to bamboozle this study to their opinions. It appears to me that all 4 authors had the integrity to publish what their results stated.
If you take a breath and relax a second, you may realize that this is exactly what has been a thorn in the debate. The scientists have to play by the peer review rules, somewhat handcuffed, the bloggers do not. Well in this case the bloggers got together and played by the scientists rules. We should be celebrating this for a few moments, then let the process continue, with rebuttal and comment and hopefully more peer reviewed publishing by scientists and bloggers all. This is what will eventually break the log jam, and maybe allow the politicos to proceed with knowledgable legislation.
[Response: Yes, this is exactly my point. Of course, one could be excused for having a less charitable view if one were to be so foolish as to waste time reading what they write at their blogs….but as I said to Mcintyre some time ago, “I’ll meet you in the peer reviewed literature.” –eric]
“It is my understanding that the reconstruction methodology/technique is designed to estimate temperatures using the satellite data, so the image should be high resolution, with the temperature data having the same resolution the satellite data/pixels. The AVHRR satellite data from the NOAA satellites are fairly high resolution, although I am not sure exactly what; 1-km comes to mind.
Anyhow, the RC graph makes more sense, as the detail is consistent with the satellite data used to generate it. Smoothing the data potentially removes valuable information.
I’m confused and do not trust McI or WUWT. Does anyone have access to the graphs as they appear in the paper? I went to the AMS site and the paper was not available yet, even here:
Someone really needs to clear this all up and fast.”
[Response: Enough with the conspiracy theory already. I’m using their data — which the lead author sent me — presumably they are using their own data too. Evidently we are using different plotting routines. Nobody is doing anything nefarious here. Sheesh!–eric]
Thanks again for your feedback. Not to harp on this, but you seem to have misunderstood my post. I was not suggesting that you were smoothing the data or not displaying it correctly. IMHO, your reproduction (“RC” above) is the appropriate way to display the data.
I was taking issue with the fact that others are smoothing (or overly smoothing) the data, and as a result, information may be being lost. That is all.
[Response: I don’t know why I’m defending the lunatics, but no, I don’t think anything important is being lost. Spatial autocorrelation is huge in Antarctica so if you average a few pixels together it cannot possibly matter.–eric]
So, speaking for “the public” : can anybody clearly tell me whether the current data on Antarctic say anything about the anthropic origin of global temperature changes, or not ?
[Response: That’s raising a bigger question. Of course, there is the Gillett et al. paper in 2008 that says ‘yes’, this is anthropogenic — Antarctic temperature trends that is. I think the jury is still out, because the data is still (even with these reconstructions) too short. Except perhaps on the Peninsula where the 100-year warming trend makes ‘natural variability’ a bit harder to believe. In any case, proving Antarctic is warming due to ‘global warming’, or proving it isn’t, will not have very much bearing on understanding global temperatures in general.–eric]
Ryan’o, Jeff ID etc… just like to see stats done well at the end of the day. When they see a novel (or unusual) approach it sets off alarm bells – as it should. Plus the Steig graphic on the cover off Nature looked odd, particularly when compared with weather stations and previous work. Whilst many of the conclusions remain the same, the overall trend is reduced and greater resolution captured. I dont see any issue with that for anyone, as I have often heard people claim Antarctica should be cooling, based on GCM results.
The work they have done should set the bar for such studies and engagement with them would be of benefit to everyone. They have done what any good engineer is trained to do, look at everything with a critical eye and ask “could we do that better”. Its unfortunate in my opinion that the stats community is not engaged more and that the peer review process did not identify that better results could be achieved with a few tweaks of the methodology.
“Also, the warmist international conspiracy failed to block another paper. Damn! :)”
But they sure tried, or rather one of the reviewers:
“We did, indeed, submit a paper to Journal of Climate in February. The review process unfortunately took longer than expected, primarily due to one reviewer in particular. The total number of pages dedicated by that reviewer alone – and our subsequent responses – was 88 single-spaced pages, or more than 10 times the length of the paper.”
Also the warming for the continent is within the error bars so I wouldn’t say more then that Antarctica might be warming.
One further note this whole article is way off since the press gladly shouts out any claim about globalwarming. If you think you got the press against you I dont know what press you read, but it certainly ain’t Swedish press.
“..overall, the continent has warmed by 0.12C each decade over the same period [since 1957]. This matches the warming of the southern hemisphere as a whole and removes the apparent contradiction [Antarctica not warming with Southern Hemisphere].”
The article goes on to quote you:
“The issue, which had been highlighted by global warming sceptics, was an annoyance, said Steig, despite the science having been reasonably well understood. “But it has now been killed off,” he said.”
Given that the O’Donnell improvement to your original work shows a much smaller (0.06) warming, this no longer presumably “matches” the warming of the southern hemisphere. A contradiction remains, and given your acknowledgement at #27 above that the jury is still out, would you be gracious enough to concede that announcing the death of an annoying mis-match between southern hemisphere warming and Antarctic warming was premature?
[Response: I doubt that quote is mine. The Guardian is not exactly a reliable outlet in my experience. But sure I’ll concede this point is probably technically correct. The CRU data give about 0.12 for S.H. as a whole so that’s roughly twice O’Donnell et al. Of course, we made it very clear in the paper that the rate of warming was not necessarily distinct from zero at 95% confidence, so this isn’t a new result.–eric]
What warming at the margin of the continent (which is stronger in the O’Donnell paper) is important is for sea level rise, not only from melting but also from weakening of the ice sheet at the discharge point and speeding up of discharge into the oceans.
However, as Sarcasto would say, this is all to the good as dilution will decrease the effect of adding additional CO2 to the atmosphere on ocean acidification.
Eric, since you have both sets of data, it would really help if you provided maps plotted on the same temperature scale and also maps with mean summer temperatures in the coastal regions rather than anomalies re the melting/weakening/acceleration of discharge issues, since as glaciologists should say, that is where the ice meets the water.
[Response: Eli, yes, a future post will show differences, and discuss where they might be interesting.–eric]
Alex: No, that is peer review you are talking about. The warmist international controls all journals and can make papers (maybe even people) disappear! Don’t take it from me, that is what has been reported on the internet.
Not to be pedantic, but your implication that we included a portion of West Antarctica in the Peninsula is not correct. Our Peninsula mask accurately reflects the official definition of the Peninsula by the US Geological Survey, and includes less of Ellsworth Land than most rule-of-thumb definitions (i.e., land northward of 75S). Rather, I would submit that the definition used in your paper (land northward of 72S) is the outlier.
[Response: Ryan, I’m not referring to what you wrote in the paper. I was referring to what people (who may or may not have read the paper) have claimed your paper said. I quote from a prominent blog: “Steig’s West Antarctic warming results from a spreading of warming in the Peninsula to the West Antarctic through choices made in their principal components.” Uh huh. So where does O’Donnell’s West Antarctic warming from?–eric
Alex and Rocco, I don’t know why none of the moderators have asked this, but please stop with the conspiracy theories. These discussions are for science, questions and answers, and reasoned argument. “Reported on the internet” doesn’t cut it – lots of things get reported on the internet that have nothing to do with reality.
One other small clarification . . . the reason that Eric’s plot at the top of the page appears to show more warming is due merely to choice of temperature scale and coloration. The scale Eric chose (-0.4 to +0.4) is different from what we used in the paper (-0.6 to 0.6) and the coloration scheme is different as well. The colors we chose were such that the transition between light yellow and orange roughly correspond to statistically significant trends.
… Don’t take it from me, that is what has been reported on the internet.
Boy howdy, you sure know it. Why, you can find canned unicorn meat on the Internet. You can learn how Obama is Socia-list, fasc-ist, not an American citizen who is out to destroy if not the world at least the US. Rachel Maddow is a les-bian vam-pire. The list goes on….
Ryan, (#39) if you look at both maps together you see clearly that there are significant places where your data indicates much higher warming, principally the Antarctic Peninsula and large areas of the west Antarctic near the Peninsula. The map at the top of the post also appears to have much higher resolution than the ones at climate audit and the ones from Steig, et al., at least the versions that appeared on RC and CA
At the link, Steig and Co.’s map is from +0.5 to -0.4 which is pretty close to the map at the top of this post. What Eli would say to both of you is that best practice is to set the scale so all of the colors in a false color map are used consistent with not changing scales between instances.
Where is the paper itself? I thought it was supposed to come out on the 7th? JOC website does not show it.
Comment by PolyisTCOandbanned — 10 Dec 2010 @ 11:45 PM
Has anyone looked at what portion of the continent has statistically meaningful warming, versus statistical meaningful cooling? If I recall, the decadal trends are accurate to roughly +/-0.1 deg C.
It appears from the maps at the Eli Rabett link, that O’Donnell found statistically meaningful warming in about 30% of East Antarctica, with less than 5% showing meaningful cooling. The previous paper by Steig had far less resolution, and showed less than 5% of East Antarctica showing meaningful warming (with the rest of the area not showing any meaningful warming or cooling trends).
In West Antarctica, both the O’Donnell paper and previous work by Steig show statistical warming over 70% of the area, but the O’Donnell paper shows much warmer anomalies across much of West Antarctica, particularly the Antarctic Peninsula. O’Donnell shows most of the Peninsula warming over 0.4 deg C per decade.
So the lead paragraphs in an accurate news article on the O’Donnell paper would read something like this:
NEW STUDY SHOWS SIGNIFICANT WARMING OVER MUCH OF ANTARCTICA
A new paper published in the highly regarded Journal of Climate shows statistically significant warming in over 70% of West Antarctica, consistent with a previous study. However, the new study shows much higher warming throughout the Antarctic Peninsula than the previous work showed. West Antarctica has some of the most threatened ice sheets, glaciers, and ice shelves on the continent.
The new study also shows significant warming over 30% of the much larger East Antarctica ice sheet, whereas previous studies showed no statistically significant warming. In contrast, less than 5% of East Antarctica showed significant cooling, inconsistent with some forecasts expecting significant cooling due to effects from the ozone hole over the South Pole.
Is this a reasonable summary of the new results?
[Response: Probably something like that. We’ll have to look at those numbers carefully when we get a chance.–eric]
Would the two groups of authors be willing and able to do a better, more comparable set of maps?
— Maps drawing isobars (contour lines) would be much easier to understand and compare.
— A map showing the differences between the two maps could help.
I realize the maps don’t convey uncertainty.
Statistically significant warming in our study is restricted to approximately 33% of West Antarctica (not 70%) for the RLS reconstructions, and slightly less for the E-W reconstructions. Statistically significant warming is restricted to approximately 5% of East Antarctica (not 30%) for both reconstruction methods.
Your guess concerning areas of statistically significant cooling were far closer to the mark. The RLS reconstruction method yields < 1% of East Antarctica with statistically significant cooling, while the E-W method yields about 2% showing statistically significant cooling (not 5%).
I have re-created an image with the statistically insignificant trends overlaid in gray for the 1957 – 2006 period of the RLS reconstruction here:
This image also appears in the paper, which Eric can confirm as he has a copy of a preprint.
[Response: Ryan, thanks, you save me some work. It would be good to have, with the data on-line, the exact pixels you used to define West and East Antarctica, so everyone can make comparisons on the same page. I’m thinking a 5509-size grid with 1=Penin, 2=West, 3=East or something like that.–eric]
Those are contained in the code (in the section called “VARIABLE ASSIGNMENTS”). As the early on-line release is not yet available (and I don’t know if the supplemental data will be posted with it), I have placed the code and Supporting Information here:
It’s the denialists who make people disappear. And it’s no joke.
For example, Gazprom mogul Alisher Usmanov’s business daily “respectible” Kommersant (a Kremlin/Gazprom mouthpiece)trashed British climate scientists. The English version of this mendacious article is posted on the Heartland Institute site and is cited (but mischaracterized!) in Cuccinelli’s EPA suit.
Not too long after Gazprominvest’s Usmanov took over the paper, a Kommersant reporter named Ivan Safronov “fell” out of a stairway window one flight above his apartment while carrying a bag of oranges home from the grocery store.
Would the two groups of authors be willing and able to do a better, more comparable set of maps?
– Maps drawing isobars (contour lines) would be much easier to understand and compare.
– A map showing the differences between the two maps could help.
I realize the maps don’t convey uncertainty.
Comment by Hank Roberts — 11 December 2010 @ 6:27 PM
the code will be out in due course. One of the benefits of posting code and data is that authors are released from “step and fetch it” requests like yours. Learn R, do the plots yourself. It’s a bit harder than googling
Re #4. I would just like to say that I agree that there is lots of smoke with this fire. Unfortunately, especially for the general public who just watch the TV news, the smoke is extremely subtle combined with the mis-direction from the sceptics who get as much time as the scientists involved. The result is that the evidence is mostly well hidden from the average voter.
There is an earlier paper which presents seasonal patterns:
Johanson, C. M. & Fu, Q. Antarctic atmospheric temperature trend patterns from satellite observations. Geophys. Res. Lett. 34, doi:1029/2006GL029108 (2007).
Their analysis used the MSU channels 2 & 4 data, not the UAH TLT product, which has a strong influence from the surface. You may recall that I found a slight warming during what I called “the freeze season” using UAH TLT data, which I presented in a paper back in 2003:
R. E., Evidence of possible sea-ice influence on Microwave Sounding Unit tropospheric temperature trends in polar regions, Geophys. Res. Lett., 30(20), 2040, doi:10.1029/2003GL017938, 2003.
[Response: Ah yes, Johansen and Fu. Cited in our paper and in my ‘brief history’. Not mentioned in O’Donnell et al., of course. –eric]
Antarctic Peninsula – warmer ocean waters and warmer air temperatures are causing ice shelves to break up because of thinning from below as well as surface meltwater causing or forcing open cracks leading to higher glacial discharge rates and thus significant land ice loss.
WAIS is thinning from below due to increased ocean temperatures caused by warm deep waters flowing onto continent’s margins caused by increased wind speed largely from ozone depletion. Global warming may soon cause or is beginning to cause warmer waters beneath the ice as well with similar results. The thinning ice sheet causes it to lose its grounding points with the sea bed and so increases flow and losses to the ice sheet.
Though surface melt within the WAIS could cause wedging and much larger losses, it isn’t necessary for the slow, ongoing but ever accelerating losses from warmer margin waters.
Ongoing Peninsula and WAIS losses will cause about a half meter or so of sea level rise this century.
Significant surface melt isn’t anticipated this century, but would require the whole deal to be rethought.
Did I get that right?
[Response: Three corrections: 1) I don’t think ozone changes have anything to do with the warm deep water advection, but that’s just my (in review) opinion. 2) Surface melt *is* anticipated in the Pine Island Region, at least if you belief O’Donnell’s climate-alarmist results ;), which show significant summer melting there. 3) I don’t think 1/2 m is likely, from this one source. It’s probably possible.–eric]
One minor correction to your inline to Andy. In Ellsworth and adjacent Marie Byrd Land, our reconstructions show the least warming in summer, and both the RLS and E-W reconstructions show comparable or less (respectively) warming in summer than your reconstruction.
[Response: My joke about you being a ‘climate-alarmist’ is just based on the figures in your paper, which show significant warming — by your calculations of significance — in the Amundsen Sea Embayment (where Pine Island Glacier is) in summer, in both sets of reconstructions –eric]
My source from this was David Vaughan of the British Antarctic Survey, but I quoted him incorrectly. His presentation this past spring shows that he gave some fairly wide ranges. My best recollection of his unrecorded spoken lecture was a best guess of 0.8m to 1.2m rise from all sources and about 0.3m from Antarctica as a whole by 2100. All of the presentations can be seen here.
[Response: ] Currently, ice sheets are contributing between 1 and 2 mm/year. If that didn’t change, it would be ~10 cm by 2100. So David is extrapolating that Antarctica will contribute a lot more than it is now. This is definitely possible — I’ve seen estimate that suggest the Pine Island Region — which is going to collapse next week if you believe O’Donnell’s results ;) — could easily contribute 2 mm/year *by itself* if it really gets going. But it is by no means assured. I think the jury is very much out on whether Antarctic changes — except on the Peninsula — are anything but ‘natural variability.’ –eric]
[Response:Thoma et al. show that an ocean model forcing by observed climate (NCEP reanalysis data) produces the increase in upwelling warm ocean water under the ice sheets. The big increase is between the 1980s and 1990s, and is intimately linked to the winter and spring warming seen in our data, as well as in O’Donnell et al.’s results. Stay tuned for a forthcoming paper on this.–eric]
What was the novel result in your paper? Just trying to get clear on what you thought that was
[Response: Significant warming in West Antarctica, like the abstract says. Also, the fact that it warmed most places prior to ~1980, and then cooled somewhat over East Antarctica. Both results are reproduced in O’Donnell et al.–eric]