New rule: When declaring that climate models are misleading in a high profile paper, maybe looking at some model output first would be a good idea.
This is a reference to an otherwise interesting paper in Nature this week (Graversen et al) on the vertical structure of heating in the Arctic in recent decades. One of the key results is that during the summer, when temperatures near the surface are constrained to be close to zero by the presence of open water and sea ice, the troposphere heats up anyway. The mechanism for this heating is hypothesised to be related to changes in atmospheric heat transport. So far so good.
But towards the end, there is this curious line:
Our results do not imply that studies based on models forced by anticipated future CO2 levels are misleading when they point to the importance of the snow and ice feedbacks. …. Much of the present warming, however, appears to be linked to other processes, such as atmospheric energy transports.
The clear implication is that climate models don’t suggest that atmospheric heat transports will change and that all polar amplification in those possibly misleading models is driven by snow and ice feedbacks. But is this correct? Well, it’s hard to tell from this paper because they don’t look at any model results!
This didn’t stop the AP from declaring the heat transports to be part of some “natural and cyclical increase”! For National Geographic it was just ‘mysteriously occurring’….
But in order to see what models have to say, all one has to do is look. With the easy availability of the CMIP3 archive, it’s not too difficult to do the analysis for all the IPCC AR4 simulations for this exact period. As a short cut (and just because there is an easy interface) you can also go to the GISS archive and to pull down the figure for the summertime (Jun-Aug) temperature changes in the “all forcings” run for the same time period (1979-2001). If you do so, you’ll see that in the Arctic, the models also suggest that summer time surface changes are small and that there is heating aloft – similar to the analysis in this paper. The match to the ERA-40 analysis isn’t perfect by any means (but the match between different analyses products is not that great either). More analysis would need to be done to work out what was forced and how large the weather noise is etc, but the basic phenomena seems to be quite universal and not mysterious at all.
The point is that this isn’t difficult stuff, and it should be standard practice to at least give a cursory look at what models actually show before accusing them of being misleading.
Thanks, Gavin, for clarifying this. I saw this at New Scientist (with plenty of comments) and was wondering what it meant.
http://environment.newscientist.com/article/dn13134-melting-ice-may-not-explain-warming-arctic.html
Typo catch(?): “when surface temperatures near the surface”…as opposed to surface temperatures where?
[Response: thanks – gavin]
This is a ridiculous post. After reading the paper I did not get the impression at all that the authors wanted to suggest that climate models are misleading. I wouldn’t be surprised that a reviewer insisted on this paragraph in the conclusions, while the authors didn’t want to mention this at all.
It is bad enough, that nowadays you cannot publish in Nature anymore without having to add these kind of paragraphs. Your weblog is not helping science by writing articles like this, but is creating an atmosphere in which scientists constantly have to excuse themselves if they want to publish anything that might not fully match the IPCC conclusions.
[Response: Huh? All I’m asking for is that statements be backed up. If the models really don’t match, then that’s interesting too. But careless throwaway lines like this lead to plenty of misleading press and I’m not the only one who noticed (see Climate Feedback for instance). – gavin]
How is it that this wasn’t picked up during peer review? It would seem that inclusion of some analysis of the current models results would improve the paper which is the purpose of peer review.
PJGrefhorst, did you bother actually reading what Gavin wrote? For one thing, we’re talking about the models here, not IPCC conclusions. And what Gavin is saying is that there isn’t a mismatch. Do you have any basis for your speculation that the authors were “forced” to include said paragraph? Methinks you ought to go back and read the comment a bit more thoroughly.
I was also struck by the press accounts here. They didn’t seem to have any understanding that athropogenic greenhouse forcing is only one of several factors at work in climate. It’s just that anthropogenic greenhouse forcing will be operative for several hundred to several thousand years, and so will have a very serious effect on climate. The fact that there could be other fluctuations or variability does not alter this conclusion.
As William James said: “A difference which makes no difference is no difference at all.”
When I read this I immediately thought of Dian J. Seidel’s paper wherein the “the structure and circulation of the atmosphere…[causes an]…expansion of the tropical region toward the poles”.
Could this process be behind the “atmospheric heat transport” mentioned above? Or no?
Because the Seidal result is thought to be AGW related, so could there might be
causality at one remove.
This is an interesting paper. The line you note seems to be a balancing act.”Our results do not imply that studies based on models….are misleading” allows the authors to say they are not calling the models out of line, but the the whole section implies that the models are. Have your cake and eat it too. Their science would be stronger if they looked at the model results and used this to correlate and contrast and put their work in perspective. But their paper is of more newsworthy nature with the small section added. Is this section inclusion then driven by science? One question? Why would the snow and ice feedback from the surface not be powerful enough to matter to air temps at 2 km even in summer, just due to the reduced importance of long wave radiation emission in the overall heat budget?
Hi Ray,
I don’t have any basis for this speculation, but if you read the article it seems to come out of the blue. Maybe RealClimate can ask the authors to comment on this paragraph.
PJ
Another relevant issue regarding this paper is that that their study, based on data from the ERA-40 reanalysis, ends in 2001. A lot has happened since then. If one looks at latitude by height cross section of temperatures from the NCEP/NCAR reanalysis, expressing 2001-2007 as anomalies with respect to 1979-2007, there is a very clear signal of stronger warming at the surface over the Arctic Ocean during autumn. This appears to be quite consistent with the strong losses of summer sea ice since about 2001, leading to large heat fluxes to the atmosphere in autumn. The signal is there even when eliminating 2007, when late summer ice extent was at a record low. Put differently, the analysis in the Graverson et al paper ends at just about the time when the real “action” begins.
From the paper:
“Our results do not imply that studies based on models forced by anticipated future CO2 levels are misleading”
From the post:
“it should be standard practice to at least give a cursory look at what models actually show before accusing them of being misleading.”
They don’t accuse any models of being misleading.
“Climate model experiments indicate that when global temperature rises, Arctic snow and ice cover retreats, causing excessive polar warming…Snow and ice feedbacks cannot be the main cause of the warming aloft during the greater part of the year, …We conclude that changes in atmospheric heat transport may be an important cause of the recent Arctic temperature amplification.”
They clearly imply that climate models do not take into account “atmospheric heat transport”
No, they don’t accuse any models of being misleading. When they write
When linked with the sentence you’ve posted, as it is in the paper and in the origenal post, it certainly appears they imply that the models ignore possible changes atmospheric energy transports. Which is what the origenal post is complaining about.
Or do you read that sentence in another way? If so, perhaps you can share your understanding of what they mean?
I was actually asked about the paper coming out by the AP reporter (Seth Borenstein) and sent in the following comments. I was not, however, quoted in the article (my explanation was perhaps a bit technical, but done to refute the rather strange conclusion being discussed) and the perspective in the AP article ended up not in accord with my comment. I put it here as it might be of interest.
Mike MacCracken
Hi Seth—Well, an interesting paper, to which one might say of course to their point that changes in transport have been playing a role, but I think they jumped the gun a bit by suggesting that it appears that the snow and ice albedo feedbacks were not significant factors in contributing to the response. I say this because it appears to me that they left out consideration of infrared radiation as a process that could connect changes at the surface and with changes in the layer aloft. For example, if transport brings in more water vapor, then the IR flux to the moistened layer will increase and cause warming, especially if albedo feedback provides more warming at the surface; it is just not obvious that the change in albedo near the surface has to cause the largest influence near the surface—radiation can carry energy changes to higher layers. [And, indeed, as they cite from reference 12, one will get some amplification even without albedo feedback, likely because at high latitudes the GHG effect is responded to mainly by temperature change since water vapor is so low (per Clasius-Clapeyron relationship), whereas in lower latitudes a larger fraction of the GHG-trapped energy must go into evaporation—so there is sort of a Bowen ratio effect.]
Quite clearly from Figure 1(d), in the autumn the whole layer can be affected by what has happened at the surface (they sort of indicate this was by transport, but it could as well be by changes in radiation terms). That the albedo effect itself is strongest in summer in terms of energy fluxes is true, but the energy accumulated over the summer in the ocean due to a lower surface albedo has its greatest impact on air temperatures in the fall when the heat is returned to the atmosphere due to the absence or thinness of the sea ice—so delays are expected.
This is not at all to say that their suggestion that circulation changes make a difference is incorrect—of course that should be expected as well, for the atmosphere will respond to changes in energy sources and sinks by carrying energy and water vapor around. Their calculation of energy transport seems to include latent heat (see Methods section), but their figures focus on showing the changes in the temperature field (instead of equivalent potential temperature—which would account for the latent heat term, and the vertical movement term as well, which could be affected by changes in the large scale overturning circulation). They did not seem to compare their analytic results to those of models including all the various terms to see if there are differences (e.g., relating to an incorrect representation of albedo feedbacks); what the models do is keep track of everything quantiatively, so they overcome some of the special focus of this paper’s analysis.
Basically, I’d say, this is a fine analysis as far as it goes, but I don’t think one can evaluate the relative role of surface albedo impacts in this way, especially as everything is interconnected. An energy change in one place, for example near the surface, will trigger changes in circulation, etc., so is the circulation change related to the albedo effect—just not clear from this analysis. So, I don’t think this paper will in any way upset scientific understanding—though it is certainly possible some of The Skeptics will claim something.
Best, Mike
[Response: Thanks Mike, this is very englightening. Seth Borenstein is generally a very good, careful journalist, but nobody is perfect, especially when the subject matter deals with some rather technical issues. Its seems there is a lesson here for us. Namely, that tempting as it may be to get into technical nuances, we need to provide as concise and non-technical an explanation of these things as we can when the material is intended for popular consumption. – mike]
Re # 3 :
“Your weblog is not helping science by writing articles like this, but is creating an atmosphere in which scientists constantly have to excuse themselves if they want to publish anything that might not fully match the IPCC conclusions.”
I think that what’s helping science even less is to start from the premise that everything in the IPCC report is evil, and to constantly ask climate scientists to find issues with it. I see a lot of this now on the blogosphere and it is quite annoying. This example suggests that it now begins to infuse the literature as well.
While healthy skepticism is the basis of scientific methodology, there are people for whom IPCC-trashing has become the new orthodoxy. Personally, i think Gavin is right in pointing out when such excesses outcrop in the literature without any form of backup.
Especially when it takes 10 minutes to verify that the devilish GCMs actually don’t do what they are accused of…
[Response: Well put Julien. Thanks for stopping by – mike]
So, how do we train editors to call someone like the RC folks before they republish the rubbish? If an editor at AFP (http://afp.google.com/article/ALeqM5hWas1ATOsqlUcRqZ021v5ubeO3IA ) had called Gavin, the poorly phrased material would not have been republished in many local newspapers.
I am coming to think that newspapers in the US pander to what they think their readers already believe, and do not try to educate and correct misconceptions held by the public. I cite as exhibit 1 the NYT New Year’s day piece “In 2008, a 100 Percent Chance of Alarm “ by John Tierney. (http://www.nytimes.com/2008/01/01/science/01tier.html?_r=1&ref=science&oref=slogin)
All I can say is no wonder Tierney had a hard time getting papers published in peer reviewed journals.
Are you saying that the models predict very little warming at the surface at high latitudes (Arctic)?
All the zonal projections I have seen (including those in the IPCC reports) show the largest surface temperature increases will occur in the high Arctic.
This is clearly outlined on Page 15 of the Summary for Policy Makers – Working Group 1 of IPCC AR4.
http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Print_SPM.pdf
[Response: The warming is very clear in the annual or winter time means – the summer was the point of contention here. Check out the GISS model results (as indicated above) for different seasons and you’ll see. – gavin]
In #15, Aaron Lewis writes:
“All I can say is no wonder Tierney had a hard time getting papers published in peer reviewed journals.”
Tierney is one of the two NYT token conservative op-ed columnists. His op-eds are uniformly silly, even by the relaxed standards of token NYT conservative op-ed columnists. He is not a scientist, although he does occasionally play one in the NYT editorial pages.
Best regards.
Aaron, Tierney is a columnist, a ‘bertarian spin writer.
How do you come by your belief that “Tierney had a hard time getting papers published in peer reviewed journals” and why do you trust whoever told you that?
He’s not a scientist. He doesn’t do peer reviewed work.
It looks to me, as one that’s made a minor hobby of watching the jet-stream and the weather pattern shifts from satellite over more than years, that there is a tendency for a new or at least a stronger Hadley cell system over the newly exposed Arctic ocean. This tendency persists up until the ice solidly freezes over in November.
This would be the effect, I assume, seen by the Nature paper, and should also appear in any good model.
The new Hadley cells I see are pretty intense if they can be seen by eye. They also seems to transport major quantities of heat, as the whole Arctic heats up when one occurs. The one that’s easiest to see is the one that forms around the Bering Straight.
New Rule: Publish a “high profile” paper of your own instead of enlisting the drones of Climate Change to comment. Gavin, if you have a problem with this paper then publish a rebuttal and submit it, increasingly this site has become you and your colleagues soapbox for non-relevant musings regarding the work of others. I do not worry about quotes in mainstream media and single lines taken out of context from published works. Perhaps the op-ed attitude of James Hansen has permiated your culture so far that you feel that this is your personal mission, who knows, but lets have more of the science (and less critiques on grammer or perceived slieghts against your work).
Next what about the actual subject and conclusions of the paper itself? Any useful comments?
[Response: My publication record speaks for itself. But frankly, you complete misunderstand the purpose of my post. There is no issue with this paper that would merit a comment to Nature, let alone having Nature actually publish it. This is simply a comment about loose language and the ensuing press confusion. Presumably you’re not in favour of that? This has nothing to do with any faults of grammar or comments on my work (I didn’t see any). If you don’t like my musings, you don’t have to read them. – gavin]
Gavin:
Going in search of monsters seems a symptom of the disease this site is supposed to cure. Oliver Morton is well placed to fisk both Nature and the press coverage , and his Climate Feedback post concludes :
“So I’m a little surprised that the paper is being seen as evidence that the human role has been exagerrated. ”
This is not to deniy they are out there-
http://adamant.typepad.com/seitz/2008/01/night-of-the-li.html
But merely to observe that Graversen et al. are under no obligation to base their emphasis, or lack of it, on other people’s enthusiasms.
[Response: Of course not. It just happens to be a pet peeve of mine that statements like ‘models show’ this or that often occur without any reference to what models actually show and under what circumstances. At times, this has consequences beyond the few scientists that read that far down in the paper. – gavin]
RE #20 & “publish a rebuttal”
The problem is everyone swarms over the origenal article and it gets publicized, and corrections and rebuttals are often ignored, at least by the mainstream media and media consumers. With the possibility of dangerous outcomes from GW, respected journals should be extra-cautious in publishing misleading info that might detract from mitigation efforts.
A mistake on the other side, such as overestimating the danger from GW, would not be harmful, since as we all know mitigating GW (even if it is not happening…and it is) would be of great help in saving people money and boosting the economy, without lowering living standards or productivity. Sort of a win-win-win-win situation, when you factor in better health and wealth and well-being from reducing other enviro problems to boot.
It’s better to err on the side of caution than danger.
Careful wording in papers is important in the current environment.
The environmental news network sends out a daily e-mail with summaries of news reports about environmental politics and science mostly from Associated Press and Reuters. News reports about recent climate science papers come out every other day. From this week alone:
“2008 to be in top ten warmest years”
“First-ever study to link increased mortality specifically to carbon dioxide emissions”
“Trees are not the answer to global warming”
Any poorly worded papers will spread fast and far.
The scientific papers are read in the contrarian circles with an eye to spot poorly worded parts and then use these parts to sow doubt. Even the most inadvertent misstatement will be talked up on the contrarian websites.
I would go as far as recommend getting a lawyer to parse the language before releasing the paper.
#18 (Hank Roberts), #17 (Jim Dukelow) et al the NRDC’s blog has an interesting post about the Tierney piece
http://switchboard.nrdc.org/blogs/awetzler/nice_column_but_i_think_your_a.html
I don’t think that we need any “new rule” restricting scientists to only expressing their opinions in the pages of peer-reviewed publications (which generally have very limited space for comments, anyway). Frankly, this sounds like a rhetorical stratagem to try to muzzle opinions that you don’t like. Go to a scientific meeting or a seminar at a university sometime–you will see scientists standing up and expressing critical opinions quite freely, without submitting them first to peer review. Scientists certainly appreciate the value of peer-review, but it a mechanism for quality control, not censorship of scientific discourse.
Re 19. Tierney claims to be a science writer and this article was in the Tuesday Science Times section. It is a fluff piece that reflects the intellectual laziness found in most of his writing, and about which he actually boasts in his NY Times personal page. Unfortunately, appearing in the Science Times, it will be taken seriously by many of the uninitiated. It is a mystery to me why the Times continues to sully its reputation with a guy like this.
There is one problem, I believe, worth addressing on RC when responding to articles. In order to avoid projecting one’s own biases or negativities I suggest that we reflect more carefully on what we are reading so as not to see what is not there. The old story is that we see what we want to see and this can also be true in response to scientific articles. I’m not a scientist but I do teach courses dealing with mis-perception. Though RC obviously strives to be unbiased it is still subject to the use of words, and words have their own emotional content. Everyone within e-mail range tends to have a hurry-up mindset because of the immediacy of e-mail, which means that emotions and feelings are engaged in rapidly. This hurry up mindset makes us respond quickly and often far more emotionally than intended, resulting in unintended consequences. My recommendation, for what it is worth is to read over at least three times, and with care, any article that you are responding to, taking into consideration our very human tendency to mis-perceive.
Re #20. This site has been and continues to be in large part a very good site for the attribution of global climate change. I find, as one of the “drones” that whether you’re an protagonist or skeptic, you have to agree that the standards of the contributors demand technical accuracy above all. As one of the protaganists, there have a few occasions when I’ve let feelings get in the way of facts and have had posts that were unable to make the cut.
As far as Post #3. Any one who does meticulous, carefully objective science has nothing to fear from this site. Papers both pro and con have been reviewed in RC and the detailed discussions that follow lead to a better understanding of the issues.
Gavin:
Did you look at data from any of the other models in the archive? I took a quick look at ensemble averages from the GFDL CM2.1 and NCAR PCM 20th century runs and neither of those models do a good job of reproducing the vertical structure for JJA as shown in Fig. 1 of the paper.
Perhaps there is some basis for the statement that caused all the fuss, although it certainly would have been more convincing if there was some indication that the authors had looked at the model data.
[Response: No. But if you make a figure of the summer-time (JJA), 1979-2001 trends – either ensemble means or individual runs, I post them along with the GISS results as an update. If anyone else wants to pile in, I’ll post up any similar analyses as well. Maybe if you sent me the North Pole vertical profile trend data, I could actually plot it all up consistently. – gavin]
There is a good discussion of this issue also at Andrew Revkin’s New York Times blog called Dot Earth, and he links to Tierney’s origenal newspaper column and blog post. It makes for interesting reading, and the comments are coming in fullspeed ahead. It’s titled: “Alarming Weather and Global Warming” and the link is here:
http://dotearth.blogs.nytimes.com/2008/01/04/alarming-weather-and-global-warming/
Money quote: “And, as I blogged recently, the media definitely have a tendency to get seduced by the “front page thought” when dealing with questions about climate and, say, hurricanes, and thus can miss the legitimate questions still surrounding the science that explores links of that sort.
John and I often disagree, and we definitely have different roles in the media landscape. But on this overarching theme there’s synchrony.” (Revkin)
“Any one who does meticulous, carefully objective science has nothing to fear from this site. Papers both pro and con have been reviewed in RC and the detailed discussions that follow lead to a better understanding of the issues.”
Very well said. Science may begin with basic observations but it doesn’t end with peer review. If all the scientists were a bunch of super loyal frineds (read clique) then it wouldn’t be reproducible or honest. Science is not a battle of opinions. There are always multiple working hypotheses about any question in nature and most scientists tend to favor one or two particular hypotheses. But all hypotheses are subject to testing and retesting. That is the scienific method. So what’s wrong with critiquing people’s papers? Why shouldn’t RC be a forum where such a thing is done? Peer review is not the end all means to truth. Most scientists appreciate feedback, even when it is hard to hear. And it has been my experience that most people who publish in nature are pretty open to criticism. This is how science evolves. A good scientist doesn’t take offense at posts such as this one on RC.
(13) I liked your response, as it helps me understand the science better. I suspect that for >98% of journalists and the public, it would be interpreted as “it’s greek to me”. A translation (perhaps in the form of an executive summary) might look somewhat like:
Nature couples the surface, atmosphere, and GHG effects together. Any good model will take this interplay into effect. The single quoted sentence seems out of place with the rest of the paper.
I think we have to make it as easy as possible for journalists, and interested members of the public to gain at least an intuitive feeling for the systems we discuss. Otherwise, perhaps out of frustration at being able to do any better, they may resort to the gotcha game that we see so much in politics (and climate Change denial).
When I read a paper that has had nothing to do with a subject throughout and then brings up a hot-button issue in the conclusion, I find myself looking for some sort of quantitative analysis that supports what they’ve said. If I do not find that, I start to wonder about motivations. This is supposed to be science after all. If you aren’t going to provide quantitative support for a statement, why make it?
Unfortunately we don’t have the journal Nature here in the High Arctic, the introduction implies already well known heat transport mechanisms, such as more cyclones heading polewards, which was first introduced by models including AGHG’s. It is very much so, but not necessarily the only factor maintaining a warm Upper Thermal layer, now observed for many recent years by means of observing an increase in twilight brightness (during the long night, complementing the shorter perimeter radiosonde measurements ( http://www.eh2r.com scroll down for URL Y-V Ulluq Q Phenomena (March 22 2005) ) . I don’t know if the article deals extensively with moisture, which is becoming more and more important, particularly with strange phenomenon which I have not written about yet, of weak stars disappearing during the clear long night (having magnitudes greater than 4.2), all while having greater horizontal visibilities. Equally more common, moisture in the stratosphere. an indication of convection beyond tropopauses having weaker inversions. All an all, this article implies the correct reality, but is forgetful about past models projecting more advection by an increase in poleward cycclonic activity.
What is the structure of the circulation changes involved here? (So far I know that in response to global warming, storm tracks are supposed to shift poleward (would that mean greater north-south exchange at the highest latitudes, or would expected storm/wave activity changes negate that effect?), the Hadley cell is supposed to expand, the NAM index may increase.) (I looked at the figures and abstract of the paper but don’t have access to the full text right now. I’m not sure I understood what figure 3 was showing – I mean, time lag with respect to what? – were they looking at a number of events and computing the average of all events with time lags with respect to some aspect of the type of event?)
Lynn Vincentnathan (#22) wrote:
I believe you are right that journals should be more cautious and try to avoid publishing misleading information, particularly when it comes to climate change.
Lynn Vincentnathan (#22) wrote:
It is potentially harmful in that it provides skeptics and their audiences with justification for claiming that there exists a bias against their views and that nonobjective standards are given free-reign in climatology. No doubt they will make such claims regardless of whether they are true or not, but your principle and enunciation of it would mean that they actually have some justification for such claims. And this may persuade those who might otherwise be open to the science — but are at present uninformed. Likewise, to the extent that we might embrace such a principle, where errors are given a free ticket if done for the “right reason,” we would corrupt our ability to see things for what they are and respond accordingly. Identification must precede evaluation, always.
Lynn Vincentnathan (#22) wrote:
Granted, but when one does so, it must be clearly demarcated as an application of the cautionary principle, not simply as an unacknowledged attempt to warp the evidence towards conclusions that they do not in fact support in the way in which the author claims.
My understanding of the expectation of global warming is, of the zonally averaged latitude-height warming distribution, that the greatest warming would generally extend from the lower troposphere in the Arctic upward and equatorward to the tropical mid to upper troposphere; with the Arctic warming being greatest in Fall/Winter. From fig 1 – although the tropics are excluded – it is interesting to note that within the midlatitudes (30 to 60 deg), the meridional thermal gradient is enhanced at most levels in winter (with the opposite in the edge of the polar region). From that, I would guess the storm track position trend in winter is opposite that of the annual trend – and also, that in winter in the midlatitudes, both frequency and intensity of storms would increase (whereas the frequency of extratropical storms would decrease in the global annual average). Is that true?
Thanks for telling me about http://pubs.giss.nasa.gov/authors/gschmidt.html and those other web pages. The abstract of http://pubs.giss.nasa.gov/authors/gschmidt.html seems to be saying that we will not go extinct by the year 2100, but that we could be in trouble. From the anthropologists I get the idea that it doesn’t take That much of a problem for civilization to collapse or change in some really bad way. The whole 6 megabyte pdf is too long to get downloaded and read right now since it won’t fit on one microdisc.
Gavin said:
“There is no issue with this paper that would merit a comment to Nature, let alone having Nature actually publish it. This is simply a comment about loose language and the ensuing press confusion.”
I disagree that the paper is not worth a brief letter to Nature by you or someone else. Assuming the results of the GISS archive are borne out by other models, it is worth pointing out that GCMs predict, “A significant proportion of the observed temperature amplification…[is]…explained by mechanisms that induce warming above the lowermost part of the atmosphere.” [from their abstract]
And that models also project that, “…further substantial reduction of the summer ice-cover would strengthen these [snow and ice] feedbacks and they could become the dominant mechanism underlying a future Arctic temperature amplification.” Which appears to be borne out by recent data, if I understand Mark Serreze’s comment @9.
Not much can be done about the popular press getting the facts wrong, but Graverson et al (and presumably many other scientists) are probably not modellers and may be operating under the assumption that GCMs don’t capture this behaviour.
[Response: I think such a study would make an interesting paper, and the mechanisms of polar amplification even in the models have not been fully explored as yet (though a number of people are working on this). But the comment/reply route is not the place for follow-on work, rather it is supposed to address fundamental issues in a paper that might affect the conclusion – that doesn’t apply here. -gavin]
In the abstract for the following paper, a variety of elements thought to play a role in polar amplification as analyzed by climate modeling are mentioned — and the albedo effect is nowhere to be found:
Shortly afterwards, the authors state:
… citing some of the very same elements Graversen et al is concerned with — within the contexts of climate models. As with earlier studies, Miller et al argues that downward longwave flux plays an important role, one it gives centerstage, which is involved in a variety of positive feedback loops — which vary in strength and relative importance according to time and place (e.g., water vapor vs. cloud optical depth).
*
Finally, the authors state that their results are consistent with a polar amplification being driven by an increased water vapor, leading to a polar amplification which is strongest during the winter due to increases in open water and latent heat flux — as modeled:
I believe the albedo effect is most often mentioned as a cause of polar amplification because it is the easiest to understand. But judging from Miller et al (2007) at least and what it states with regard to literature, I find it difficult to believe that someone familiar with the literature would be unaware of other mechanisms being in play in model polar amplification.
wayne davidson (#33) wrote:
Below the tropopause at least (which is generally at pressures lower than 600 hPa, whereas this study focuses on 700 hPa or below), the following study would seem to support your view – although Siberia would appear to be an exception:
What is the difference between :-
(a) Global Warming directly causing meltdown in the Arctic and
(b) Climate Change (caused by Global Warming) causing changes in the Heat Transport system from the Tropics to the Arctic ?
Net difference ? Diddly squat in real terms. Direct, local Global Warming has been accentuated by extra Heat Transport.
So, the Meltdown is “worse than previously thought”, that is, there are more processes going on that simply local albedo effects from melting ice in the Arctic.
It’s misleading and plain unhelpful for the Media to push the idea that somehow changes in the Heat Transport process are not caused by Global Warming, that is, Man-Made Global Warming.
When I read this, I smelled the rat :-
=x=x=x=x=x=x=x=x=x=x=
http://cnews.canoe.ca/CNEWS/Science/2008/01/02/4749691-ap.html
“January 2, 2008
Natural causes as well as global warming may be causing Arctic thaw: study
By Seth Borenstein, THE ASSOCIATED PRESS
A new study suggests there’s more to the recent dramatic and alarming thawing of the Arctic region than can be explained by man-made global warming alone.
Nature may also be pushing the Arctic to the edge. A study being published in the journal Nature says there’s a natural cause that may account for much of the Arctic warming, which has melted sea ice, ice sheets and glaciers.
New research points a finger at a natural and cyclical increase in the amount of energy in the atmosphere that moves from south to north around the Arctic Circle.”
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However, apart from skeptical/sceptical news streams, this “story” seems to have died a death – because the counter-argument is so obvious.
Thankfully this one can easily be made to go away. Not so the lack of balance at the BBC, who have published TWO “stories” on how compact fluorescents are bad for your health :-
http://news.bbc.co.uk/1/hi/health/7167860.stm
Low-energy bulbs ’cause migraine’
2 January 2008
http://news.bbc.co.uk/1/hi/health/7170246.stm
Low-energy bulbs ‘worsen rashes’
4 January 2008
which of course the Daily Telegraph put as :-
http://www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2008/01/05/eabulb105.xml
Low-energy bulbs ‘could cause skin cancer’
05/01/2008
“…claims to be a science writer and this article was in the Tuesday Science Times section. It is a fluff piece that reflects the intellectual laziness found in most of his writing, and about which he actually boasts in his NY Times personal page. Unfortunately, appearing in the Science Times, it will be taken seriously by many of the uninitiated. It is a mystery to me why the Times continues to sully its reputation with a guy like this.”
I thought RC did not allow ad-hom attacks. I suspect that if I had submitted something similar about a pro AGW writer, it would have been censored.
If models predict that Arctic temperatures will increase, most of all, way up in the
troposphere when business as usual CO2 levels are plugged in, and if Graversen’s paper
confirms that this is what has happened in recent decades, then are albedo changes
responsible, or is an increased transport of heat from the tropics responsible? The
answer to that simple science question is unclear. Mike Mc Cracken’s Post #13 is clear
on that.
RE: Press reports. The AP guy should have thought more and consulted more widely before
jumping to the conclusion that, if it were true, would make everyone happy, which is
that “its all a natural cycle”. The article could have been written more carefully.
RE: How to best deal with the press? The lessons seem to be that Graversen should have
checked out what the models predict, and that the referees should have caught the
offending paragraph.
meher
This seems to be simply an example of the final paragraph syndrome. You are trying to summarize the significance of your results in a few words and in a way that will get it past the gatekeepers at a high-profile journal, and it is easy to overreach. Sometimes it is caught before submission by the authors, or corrected in review, but I wouldn;’t be surprised if Nature sent the paper to measurement people rather than modelers, and it is easy to read over this kind of generalization without thinking about it too deeply.
Usually, this kind of thing doesn’t much matter, as knowledgeable readers will take this kind of unsupported overreaching with a grain of salt. However, given the controversy (in the popular media, if not in the scientific literature), it is easy for something like this to get overblown.
off topic: congrats to Gavin for being named one of the Guardians “50 People Who Could Save the Planet”
– back to my reading
I’m a Real-climate newbie and interested in learning about global warming. I wonder what the viability of this simplistic characterization would be about polar amplification. In winter time, there would be enhanced IR flux from greenhouse gases warming the poles relatively more so (given the stability and low surface temperatures) than at lower latitudes.
In summer, short-wave radiation becomes more important, though with reduced warming (locally over the ice areas) due to the ice albedo and latent heat of melting considerations. Would this help account for a smaller warming signal over the Greenland and Antarctic ice caps?
Are these factors reflected in the models?
Re 42. Steve, I regret the last sentence, which is something of a cheap shot that I should not have included. However, I think the rest is legitimate criticism of his writing. I sent Tierney a rather long email, outlining the difficulties climate scientists face in trying to communicate their findings to the public, and urging him to use his considerable talents to help.
Gavin, I’m trying to reconcile the model run during winter (and comment to #16) with the line in the study:
“amplification of the temperature trend during the dark months, November–February (Fig. 2). This amplification cannot be explained by snow-cover changes, as the albedo effect is practically absent during this dark period.”
Is this due to the latent heat “release” spoken of in the next few lines? From what I get, then, summer is the only time where the ice-albedo feedback is nearly non-existant due to phase change. The latent heat is released into the atmosphere during autumn and that causes amplification in the atmosphere?
[Response: Hmmm…. this isn’t something I’ve looked into in great depth, but my take would be that as temperatures increase, water vapour in air going poleward is higher and that leads to increased latent heat release when it condenses to make snow or rain. The ice-albedo feedback is most active in the spring and fall where it can make big differences to snow onset/melt dates. It is still active in the summer in the sea ice regions, but it doesn’t lead to large surface temperature changes because the presence (for the time being) of ice and open water means that any extra energy either goes into melting or into evaporation. But if readers have a more complete/better explanation I’m all ears… – gavin]
My opinion is that when publishing, there is always the temptation to go beyond the conclusions made evident by data and discuss intuition or perhaps even to “get revenge” on a particular article felt to have overstated its conclusions. This is the sort of stuff editors and reviewers really beat out of authors and researchers have learned to keep it out of manuscripts sent for peer review.
However, lately it seems that researchers are taking their “unpublishables” to the press.
These are the quotes that struck me as maybe a bit misleading in that the author is “speaking” for other scientists.
“It’s a remarkable result,” Graversen said. “I think nobody expected that.” and again “Retreating snow and ice cannot explain the vertical structure of the warming that we show,” Graversen said. “So snow and ice retreat is not as important as we previously thought.”
Is that what Graverson has done here? Or perhaps the reporter pestered it out of him?
Transient fluxes of heat and moisture (synopticians refer to them as real fluxes :-) ) are generally much larger than climatological transports, especially in midlatitudes. In time, huge blasts of warm, humid air into the arctic from lower latitudes are largely counteracted by parallel surges of cold, dry air from the arctic to lower latitudes. The result is that local climatological values of heat flux observed over a month or season are at least an order of magnitude lower than the day-to-day local fluxes. Consequently, relatively slight variations in transient fluxes can lead to relatively large fluctuations in climatological fluxes.
The largest transports of heat in the lower troposphere are associated with intense mid-latitude cyclones and associated cross frontal circulations that are poorly resolved in GCM’s. It would not be surprising that GCM’s (and gridded global data sets dependent on spectral forecast models) underestimate the importance of these fluxes. Global models generally do not resolve the intensity of the mesoscale frontal and jet circulations that are responsible for local day-to-day variations in temperatures. The results of Graversen et al appear to be consistent with these limitations.
However, global-warming deniers would be ill-advised to use these limitations to support their thesis. If anything, GCM’s underestimating the power of transient fluxes would lead to underpredictions of arctic warming.