Many readers will remember our critique of a paper by Douglass et al on tropical tropospheric temperature trends late last year, and the discussion of the ongoing revisions to the observational datasets. Some will recall that the Douglass et al paper was trumpeted around the blogosphere as the definitive proof that models had it all wrong.

At the time, our criticism was itself criticised because our counterpoints had not been submitted to a peer-reviewed journal. However, this was a little unfair (and possibly a little disingenuous) because a group of us had in fact submitted a much better argued paper making the same principal points. Of course, the peer-review process takes much longer than writing a blog post and so it has taken until today to appear on the journal website.
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The theme of this year's annual meeting of the European Meteorological Society (EMS) [European Congress on Applied Climatology (ECAC)] was adaptation to climate change. So what's more appropriate then, than hosting the meeting in Amsterdam - on a building site?

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Guest commentary from Mauri Pelto

Changes occurring in marine terminating outlet glaciers of the Greenland Ice Sheet and ice shelves fringing the Antarctic Peninsula have altered our sense of the possible rate of response of large ice sheet-ice shelf systems. There is a shared mechanism at work that has emerged from the detailed observations of a number of researchers, that is the key to the onset and progression of the ice retreat. This mechanism is shared despite the vastly different nature of the environments of Jakobshavns Isbrae, Wilkins Ice Shelf and the Petermann Glacier.
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Here at RealClimate we understandably have an intense interest in the positions of the Presidential and Vice-Presidential candidates regarding global warming and carbon emissions. What the stance bodes for future action on climate change is consequential in itself, but beyond that the ability to use sound science in this case serves as a bellweather for the candidates' whole approach to science. Whatever else you can say about the candidates, it has been encouraging that both John McCain and Barack Obama favor mandatory action to reduce US carbon emissions.

But, enter Gov. Sarah Palin, McCain's pick for VP. Palin's position on global warming has been stated quite clearly in this recent interview with the publication Newsmax , where she says "A changing environment will affect Alaska more than any other state, because of our location. I'm not one though who would attribute it to being man-made." How is this to be reconciled with McCain's position? Do they just agree to differ? What does this bode for future actions if McCain were to win the election, especially in view of the fact that, in a Cheney-esque way, Palin is likely to be put in charge of energy policy? The recent vice-presidential debate sheds some light on the issue. A full transcript of the debate is here.

Palin seems to be attempting to defuse the whole issue by claiming the cause doesn't matter. When the moderator asked her " What is true and what is false about what we have heard, read, discussed, debated about the causes of climate change," Palin responded as follows:

"PALIN: Yes. Well, as the nation's only Arctic state and being the governor of that state, Alaska feels and sees impacts of climate change more so than any other state. And we know that it's real.

I'm not one to attribute every man — activity of man to the changes in the climate. There is something to be said also for man's activities, but also for the cyclical temperature changes on our planet."

I'm pretty sure that that last statement is a garbled attempt to reiterate what she said in the Newsmax interview, but you be the judge. Unlike the previous quote, this one at least has a nod in the direction of acknowledging (tentatively) the possibility of a human influence. What's important is what comes next:

"But there are real changes going on in our climate. And I don't want to argue about the causes. What I want to argue about is, how are we going to get there to positively affect the impacts?"

Dare we say that it, in fact, very much makes a difference what is causing global warming? If CO2 really weren't a major part of the cause, what in the world would be the point of John McCain's (or anybody's) stated policy of acting to reduce emissions? And even if you were of the school that says adaptation is better than mitigation, knowing the cause is an important part of knowing what kind of climate change you have to adapt to, how long it is likely to last, and how much worse it is likely to get in the future.

Biden's answer, by comparison, was direct, straightforward, and simple:

"BIDEN: Well, I think it is manmade. I think it's clearly manmade. And, look, this probably explains the biggest fundamental difference between John McCain and Barack Obama and Sarah Palin and Joe Biden — Governor Palin and Joe Biden.

If you don't understand what the cause is, it's virtually impossible to come up with a solution. We know what the cause is. The cause is manmade. That's the cause. That's why the polar icecap is melting."

Well, maybe he left out the kind of caveats and qualifications you'd attach to the attribution of the recent loss of (North) polar sea ice if this were an AGU talk instead of a vice-presidential debate. Overall,though, the statement gets to the heart of the matter.

One can moreover doubt even Palin's commitment to dealing with the consequences of climate change. Surely, that would include doing something to save the polar bears,yet the State of Alaska (against the advice of its own wildlife biologists) is suing the Interior department over its decision to list the polar bear as "threatened" — and this despite the fact that the Bush administration put so many qualifications on the listing as to make it essentially toothless. What's even more telling is that the brief submitted to Interior drew heavily on a list of climate skeptics (including the Marshall Institute's Willie Soon) that could easily have been culled from the infamous Inhofe 400. (see this article). Palin's role in bringing this case has not been peripheral; she has been very much at the center of the effort, and has consistently questioned the causal link between CO2 and global warming in making the case. As early as Dec. 2006, she wrote to Secretary Kempthorne: ""When a species' habitat (in this case, sea ice) is declining due to climate change, but there are no discrete human activities that can be regulated or modified to effect change, what do you do?" Further information about Palin's long fight against the listing, and her view of the scientific issues involved, can be found here.

We will take this occasion to note also that Biden used the debate to reaffirm Obama's long standing position in favor of "clean coal." Whether this is a good or bad thing depends on the extent to which the candidates understand what should really be meant by this term. From the point of view of global warming, the only "clean" coal would be coal burned with 100% carbon capture and sequestration — certainly worthy of research and pilot implementation, but not by any means a technology that can be counted on at present to solve the problem. (And of course, the term "clean" is even then relative, since what mountain top removal mining does to the West Virginia hills and rivers is anything but "clean").

So there you are. We report, you decide.

Dennis Bray and Hans von Storch have been making surveys of climate scientists for a number of years with the reasonable aim of seeing what the community thinks (about IPCC, climate change, attribution etc). They have unfortunately not always been as successful as one might like - problems have ranged from deciding who is qualified to respond; questions that were not specific enough or that could be interpreted in very different ways; to losing control of who answered the questionnaire (one time the password and website were broadcast on a mailing list of climate 'sceptics'). These problems have meant that the results were less useful than they could have been and in fact have occasionally been used to spread disinformation. How these surveys are used obviously plays into how willing scientists are to participate, since if your answers are misinterpreted once, you will be less keen next time. Others have attempted similar surveys, with similar problems.

As people should know, designing truly objective surveys is very tricky. However, if you are after a specific response, it's easy to craft questions that will favour your initial bias. We discussed an egregious example of that from Steven Milloy a while ago. A bigger problem is not overt bias, but more subtle kinds - such as assuming that respondents have exactly the same background as the questioners and know exactly what you are talking about, or simply using questions that don't actually tell you want you really want to know. There are guides available to help in crafting such surveys which outline many of the inadvertent pitfalls.

Well, Bray and von Storch have sent out a new survey.

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What reduces emissions more?
A. Someone swapping their old SUV (which gets 12 miles per gallon) for a hybrid version (18 mpg) or
B. someone upgrading their 25 mpg compact to a new 46 mpg Prius?
(ignore for a minute manufacturing issues or driving habits and assume the miles driven are the same).

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In a recent post about sea level rise, we highlighted a paper by the University of Colorado's Tad Pfeffer and others in which they show that one can rule out more than 2 meters of sea level rise in the next century. While we liked the paper very much, we also complained that Pfeffer and colleagues had created a bit of a straw man, by implying that it had been seriously proposed that Greenland's near term contribution to sea level rise could be much larger than that. In fact (we said), none of us in the climate science community ever took such ideas seriously, even if the popular press thought we did. Tad responds by pointing out that in fact there is published work attributing considerable likelihood to such extreme scenarios, and that there are numerous studies that at the very least strong imply it. He also reminded me that their paper actually rules out a contribution of more than about 50 cm from Greenland, significantly below some other recent published estimates. That makes their work even more important, since there are several publications that definitely consider upwards of one meter (from Greenland alone) by 2100 to be plausible. Pfeffer et al. conclude that that is simply not the case (at least in their informed view). Still, we remind readers that our chief complaint was that Pfeffer et al.'s work was taken by many in the media as a downward revision to sea level rise estimates, whereas in fact most informed estimates had put an upper limit well below that. See our earlier post on the IPCC Sea Level numbers.

A response to RealClimate’s post on our paper about sea level rise

W.T. Pfeffer, J.T. Harper, and S. O’Neel
15 September 2008

We have read with interest – and, we admit, surprise – the RealClimate post concerning our 5 September publication in Science entitled “Kinematic Constraints on 21st Century Sea Level Rise.” The source of our surprise, however, is probably not what the RealClimate authors imagine – we had fully expected a vigorous defense of very high rates of sea level rise (greater than 2 m/century), but not a denial that such rates had ever been hypothesized.

We do not state anywhere in our paper that 2m or more of SLR by 2100 has been published as a peer reviewed and “informed estimate”. We do state that this has been ‘inferred’ and ‘argued’ as a “viable 21st century scenario”. We believe there is value in constraining the upper limits to the role of ice dynamics in future SLR. And, from what we know about historical rates of SLR in conjunction with what ‘we know we don’t know’ about ice dynamics, we believe it is reasonable to ponder very high rates of SLR in the next century. However, we also believe that it is problematic to project such a ‘hypothesis’ as a supported theory without proper testing by the scientific method. The question raised by RC is whether or not this hypothesis has circulated within the scientific community.

In his 2007 paper (Environ. Res. Lett. 2(2007)) Hansen proposes a rate of sea level rise of “5 m this century.” This is hypothetical, but he is confident that it is a “far better estimate than a linear response”. This is accompanied by his statement that he finds it “almost inconceivable that BAU climate change would not yield a sea level change of the order of meters on the century timescale.” The provisional nature of his discussion is irrelevant; it is an explicit statement that 5 m of sea level rise in this century is a possibility he regards as viable, published in the scientific literature by the person who is arguably (and deservedly) the most visible and authoritative climate scientist in the world. No reader of this paper would assume that Hansen didn’t actually mean what he said. Hansen reinforced this idea in other publications and statements, including in his briefing to Congress on 23 June 2008 (“sea level rise of at least two meters is likely this century”). Our analysis specifically tested the likelihood of next-century sea level rise of more than 2 m, and Hansen explicitly hypothesized 5 m of sea level rise in this century.

Hansen has gone on record with specific numbers, but other published studies including the 2006 Overpeck and Otto-Bliesner Science papers left the upper limit open ended, and certainly implied it could be quite high. The fact that this idea was present in the scientific community was confirmed for us by 8 scientific presentations we gave on this topic in the past year (5 in the US, including the Fall 2007 AGU and 3 in Europe). At none of those talks did anyone in the audience question what high forecasts we were referring to. The comments we got back on our work were overwhelmingly positive, and were along the lines that what we had presented was a good next step – both to move past the IPCC’s low sea level forecasts, and as a response to the persistent hypotheses of very high rates of sea level rise that were circulating. Criticisms, where they were voiced, were largely that we were underestimating the power of dynamics and that rates of sea level rise well in excess of 2 m/century might occur in spite of our conclusions.

We agree that the media coverage of our paper (as well as others before it) has undesirable side effects. Wherever we had the opportunity we pressed media writers not to use terms like “exaggerated” or “high sea level forecasts debunked,” and we have consistently stressed that our results indicate a very significant sea level rise and are no justification for any kind of complacency. We have stressed that even our low end scenario of 0.8 m of SLR would have tremendous consequences. However, we stand by our statements that sea level rise at rates of substantially more than 2 m this century were in fact put forward as a likely possibility.

Earlier this summer Andy Revkin published a piece in the New York Times about what he has termed the “Whiplash Effect”: confusion created in the public mind by media coverage of rapidly evolving scientific ideas. There has certainly been some whiplash in this case. However it is others who cracked the whip. We have simply refused to let go of the other end.

Billet par l'invité Spencer R. Weart, American Institute of Physics (traduit par Jean-Denis Vauguet)

… is the question people have been putting a lot of thought into since the IPCC AR4 report came out. We analysed what was in the report quite carefully at the time and pointed out that the allowance for dynamic ice sheet processes was very uncertain, and actually precluded setting a upper limit on what might be expected. The numbers that appeared in some headlines (up to 59 cm by 2100) did not take that uncertainty into account.

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What makes science different from politics?

That's not the start of a joke, but it is a good jumping off point for a discussion of the latest publication on paleo-reconstructions of the last couple of millennia. As has been relatively widely reported, Mike Mann and colleagues (including Ray Bradley and Malcolm Hughes) have a new paper out in PNAS with an update of their previous work. And this is where the question posed above comes in: the difference is that with time scientists can actually make progress on problems, they don't just get stuck in an endless back and forth of the same talking points.

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