How’s this for “rapid response“? This rebuttal comes out at exactly the same time the press embargo lifts in Science. We were able to obtain advance copies of the Dessler paper, plus Dr. Spencer had seen it as a poster at the recent A-Train satellite symposium. – Anthony
Update: Dessler responds here at Real Climate and makes the full paper available here at his TAMU website.
2PM EST, December 9th, 2010 by Roy W. Spencer, Ph. D.
How clouds respond to warming – the ‘cloud feedback’ problem – will likely determine whether manmade global warming becomes either the defining environmental event of the 21st Century, or is merely lost in the noise of natural climate variability.
Unfortunately, diagnosing cloud feedback from our global satellite observations has been surprisingly difficult. The problem isn’t the quality of the data, though. The problem is figuring out what the cloud and temperature behaviors we observe in the data mean in terms of cause and effect.
So, Andy Dessler’s (a Texas A&M climate researcher) new paper appearing in Science this week is potentially significant, for it claims to have greatly closed the gap in our understanding of cloud feedback.
Dessler’s paper claims to show that cloud feedback is indeed positive, and generally supportive of the cloud feedbacks exhibited by the IPCC computerized climate models. This would in turn support the IPCC’s claim that anthropogenic global warming will become an increasingly serious problem in the future.
Unfortunately, the central evidence contained in the paper is weak at best, and seriously misleading at worst. It uses flawed logic to ignore recent advancements we have made in identifying cloud feedback.
In fact, the new paper is like going back to using only X-rays for medical imaging when we already have MRI technology available to us.
What the New Study Shows
So what is this new evidence of positive cloud feedback that Dessler has published? Well, actually it is not new. It’s basically the same evidence we published in the Journal of Geophysical Research.
Yet we came to a very different conclusion, which was that the only clear evidence of feedback we found in the data was of strongly negative cloud feedback.
But how can this be? How can two climate researchers, using the same dataset, come to opposite conclusions?
The answer lies in an issue that challenges researchers in most scientific disciplines – separating cause from effect.
Dessler’s claim (and the IPCC party line) is that cloud changes are caused by temperature changes, and not the other way around. Causation only occurs in one direction, not the other.
In their interpretation, if one observes a warmer year being accompanied by fewer clouds, then that is evidence of positive cloud feedback. Why? Because if warming causes fewer clouds, it lets in more sunlight, which then amplifies the warming. That is positive cloud feedback in a nutshell.
But what if the warming was caused by fewer clouds, rather than the fewer clouds being caused by warming? In other words, what if previous researchers have simply mixed up cause and effect when estimating cloud feedback?
A Step Backwards for Climate Science
What we demonstrated in our JGR paper earlier this year is that when cloud changes cause temperature changes, it gives the illusion of positive cloud feedback – even if strongly negative cloud feedback is really operating!
I can not overemphasize the importance of that last statement.
We used essentially the same satellite dataset Dessler uses, but we analyzed those data with something called ‘phase space analysis’. Phase space analysis allows us to “see” behaviors in the climate system that would not be apparent with traditional methods of data analysis. It is like using an MRI to see a type of tumor that X-rays cannot reveal.
What we showed was basically a new diagnostic capability that can, to some extent, separate cause from effect. This is a fundamental advancement – and one that the news media largely refused to report on.
The Dessler paper is like someone publishing a medical research paper that claims those tumors do not exist, because they still do not show up on our latest X-ray equipment…even though the new MRI technology shows they DO exist!
Sound strange? Welcome to my world.
We even replicated that behavior see in the satellite data analyzed with phase space analysis — our ‘MRI for the climate system’ – by using a simple forcing-feedback climate model containing negative cloud feedback. It showed that, indeed, when clouds cause temperature changes, the illusion of positive cloud feedback is created…even when strongly negative cloud feedback really exists.
Why Dessler Assumed We Are Wrong
To Dessler’s credit, he actually references our paper. But he then immediately discounts our interpretation of the satellite data.
Why?
Because, as he claims, (1) most of the climate variability during the satellite period of record (2000 to 2010) was due to El Nino and La Nina (which is largely true), and (2) no researcher has ever claimed that El Nino or La Nina are caused by clouds.
This simple, blanket claim was then intended to negate all of the evidence we published.
But this is not what we were claiming, nor is it a necessary condition for our interpretation to be correct. El Nino and La Nina represent a temporary change in the way the coupled atmospheric-ocean circulation system operates. And any change in the atmospheric circulation can cause a change in cloud cover, which can in turn cause a change in ocean temperatures. We even showed this behavior for the major La Nina cooling event of 2007-08 in our paper!
It doesn’t mean that “clouds cause El Nino”, as Dessler suggests we are claiming, which would be too simplistic and misleading of a statement. Clouds are complicated beasts, and climate researchers ignore that complexity at their peril.
Very Curious Timing
Dessler’s paper is being announced on probably THE best day for it to support the IPCC’s COP-16 meeting here in Cancun, and whatever agreement is announced tomorrow in the way of international climate policy.
I suspect – but have no proof of it – that Dessler was under pressure to get this paper published to blunt the negative impact our work has had on the IPCC’s efforts.
But if this is the best they can do, the scientists aligning themselves with the IPCC really are running out of ideas to help shore up their climate models, and their claims that our climate system is very sensitive to greenhouse gas emissions.
The weak reasoning the paper employs – and the evidence we published which it purposely ignores! – combined with the great deal of media attention it will garner at a time when the IPCC needs to regain scientific respectability (especially after Climategate), makes this new Science paper just one more reason why the public is increasingly distrustful of the scientific community when it comes to research having enormous policy implications.
===============================================================
Abstract:
On a global scale, clouds presently influence climate in a way that cools the planet. But, they will lose some of that cooling capacity as climate warms, according to a study that supports current ideas about how atmospheric carbon dioxide affects global temperature. Clouds can potentially have both positive and negative feedback effects on climate, and this is responsible for much of our uncertainty about the amount of warming that will be caused by increasing concentrations of carbon dioxide in the atmosphere. It’s generally agreed that overall this feedback is positive, with warming being exacerbated as clouds trap larger quantities of outgoing infrared radiation, but so far we have only a general idea of this effect. Andrew Dessler has estimated the actual magnitude of the feedback effect by analyzing ten years of satellite data on the flux of radiation through the top of the atmosphere. He concludes that the feedback effect is indeed positive and of a value that agrees with the canonical range of estimates of how much warming will occur for a doubling of atmospheric carbon dioxide.
Article #10: “A Determination of the Cloud Feedback from Climate Variations over the Past Decade,” by A.E. Dessler at Texas A&M University in College Station, TX.
Contact: A.E. Dessler at +1-979-862-1427 (office phone), +1-979-220-4513 (mobile phone), or adessler@tamu.edu (email).
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I was moderated out at RealClimate.. I wanted clarification, thats all, as it was not clear to me what the e-mail exchange between Dessler and Spencer actually said, since what is presented is an abridged version(apparently). Here is what I asked for:
Ed_B says:
Your comment is awaiting moderation.
9 December 2010 at 4:26 PM
“We assumed it was clear that this was short a paraphrase of the much longer chain of email exchanges linked to”
I was under the impression that the link above(in RC) gave me a full reading of the e-mail exchange. Could Mr Dessler provide 100% of what was said by both parties?
Dr. Spencer, you didn’t use the word “robust” enough.
This all seems to be rather unsettling.
Good exposition, Anthony. At least the warmers are attempting to explain the effects of cloud on climate, and not just human carbon emission, although they will say that there is positive feedback always. And they will always invite ridicule and skepticism from the independent minded researchers and scientists.
Wait, really? The response to a new method for determining a feedback is/was:
Really? That’s not a response, that’s a straw man the size of the wicker man put in the wrong place with fake fire painted on. It’s like they just don’t want to learn any new math so their science gets better for it.
C’mon climatologists, math isn’t that friggin hard, go learn some linear algebra and statistics.
The ONLY way to characterize complex feedbacks is through analyzing the data phase space. Any paper that claims to make any statement regarding complex feedbacks that does not employ phase-space analysis, does so to be deliberately misleading.
Dr Spencer, there was a paper by a team of IPCC faithful and Jouzel/Le Treut colleagues Cattiaux et al. 2010 in GRL that is supposed to explain why winters should be colder but are not because of global warming. This paper uses NAO flow-analogues at 500hPa levels and compare them to statistically correlated surface temperatures and O miracle, detects the sugnature of GHG global warming!
This acrobatic pseudo-demonstration was just released ahead of Cancun and finished that fact that 2009/2010 European winter would probably be the coldest to be experienced in the 21st century… of course until winter 2010/2011 they should have added but that was going against the script… But it does not stop Jouzel or any Meteo France propagandist to quote this paper to try deflecting the bitting cold off their warmists’ shoulders.
So there is plenty of bad science opportunistically published…
The warmistas are basically afraid of that we live in an unstable regulator.
Nature has proven again and again that the regulator is very very stable.
I saw this on Curry’s blog about the email exchange between Spencer and Dessler.
http://geotest.tamu.edu/userfiles/216/emailExchange.pdf
Looks like Real Climate is using Dessler to light up a counter fire to the huge blow the refutation of Steig et al. 2009 has dealt the Team and the IPCC zealots…
BTW: Notice how “Maple Leaf” is commenting right off the bat at RC? A stalwart at deepclimate… Yep, instead of working at finally getting his PhD in an institute paid for by a retired Canadian oilman, this student keeps insulting scientists on blogs, as he did with Judith Curry recently…
Interesting comments at Fenton Communications,
What a nice guy Mr. Halpern is.
u.k.(us) says:
December 9, 2010 at 2:16 pm
This all seems to be rather unsettling.
=======================================================
How so? Please note the points made here and the lack of response. (Crickets chirping)
Eyes Wide started with a great comment, (albeit a bit sarcastic) Nothing.
Steeptown asks about the review process.
David C…..pretty much the same.
At that point Andrew Dessler pops by to redirect the conversation or the lack thereof to RC.
latitude pipes in with his usual witted insights.
Lady Life Grows gives us a different, but not incorrect, view.
danj questions the timing of the release.
I added more sarcasm but hopefully a point not lost………
and so it went….. several more by several others. Good points, biting sarcasm, invitations to engage……..nothing.
Respectful questions were asked, salient points made, Leif even popped by to give his 2 cents.
Others even tried to engage at RC……..how’s that working out Ed_B?
Apparently, a character named Robuk only had a pejorative to add to the conversation and couldn’t think of anything else clever.
Nothing………. more cricket chirping. They’ve lost. Receding back into the cocoon. Sure, they’ll emerge again after yet another metamorphosis, but the current one is done.
Sorry, I had to laugh…at this in the RC comments:
This hilarious pronouncement about “honest colleagues” is from people that can’t even bring themselves to use their own names when pontificating on the honesty of others that do.
Anyone that thinks heat causes clouds to disappear has never lived in the tropics.
When there is sufficient moisture, heating produces clouds, which produces cooling. Otherwise the tropics would be the hottest place on earth, which they are not. The hottest places are in the subtroppical zones.
Feedback appears positive only when water is restricted.
During an eclipse the sun is blocked and the umbra undergoes noticeable cooling.
Why not measure the rate at which the temperature drops and then rises during an eclipse, along its track, and compare the two rates of change to the amount of clouds?
If clouds do cause a positive feedback that cloudy skys will cool more slowly and return to their previous level quickly.
If clouds have a negative feedback then the cooling will be more rapid and re-heating will be slow.
I have tried and tried to understand the logic in this paper by Dessler. I failed.
My observations are that when a cloud obscures the sun it gets colder. At night when it is cool, clouds usually mean it keeps warmer, but as it is warmer Dessler tells me the clouds should not be there, so it will get cooler or warmer, or perhaps both at the same time, who knows! I give up!
The question is simply do clouds cause warming or cooling? I don’t think we have to answer the question of whether clouds are a “feedback” or an “initial driver”.
Overall cloudiness (world average) does increase slightly when it is warmer. This is just a very small change, less than the climate models assume (and one has to ignore the ISCCP cloud project data to reach this conclusion).
But Temperature versus Cloudiness is a monster scatterplot. In the old days of proper statistics, the professor would say this a random plot. Chart of Hadcrut3 versus all the measures of cloudiness back to 1901. Noone should be able to say clouds cause the temperature or temperatures cause the clouds.
http://img202.imageshack.us/img202/9148/hadcrut3cloudcover.png
Do clouds cause warming or cooling is the question. I think if you take locations which receive the same amount of solar radiation at the TOA, one would find the more humid, more cloudy locations are cooler than the dryer, less cloudy locations.
The dryer, less cloudy locations have more variation from night to day but on average they are warmer. The Sahara versus tropical rainforests is an example.
Low, thick, convection clouds block more solar radiation than they hold outgoing longwave radiation in.
High thin clouds, hold more radiation in than they block incoming solar radiation.
On average, the majority of clouds are the lower, thicker type and thus, on average, they produce a net cooling. But it is not a large amount.
I’m afraid I simply dont understand the thinking.
In the summer in the UK, the mornings often start out sunny and warm(ish).
As the day goes on, it gets hotter. Late morning, clouds start to build up. Now by the reasoning given, surely this is impossible? Yet it something seen every sunny day in the summer period here.
Presumably we’ve all been hallucinating the cloud all these years???
Or maybe things are completely different in the part of the world they come from?
Dr A Burns says:
December 9, 2010 at 11:40 am
Positive feedback at work:
Incorrect. The structure is a negative feedback system, otherwise it would be self-exciting and breakup without any particular forcing. But, the negative feedback via structural damping is weak, leading to a high Q factor at the resonant frequency. When excited by the winds at that frequency, the oscillations grew exponentially, until they reached a point great enough to induce structural fatigue and failure.
“If positive feedback is present in our climate, why didn’t this happen to our atmosphere billions of years ago ?”
Because there is a much stronger negative feedback overall, at the very least from T^4 radiation. In such a system, an internal minor positive feedback produces amplification rather than instability.
Anthony Watts says:
December 9, 2010 at 4:08 pm
Sorry, I had to laugh…at this in the RC comments:……….
========================================================
lol, well there is a bit to laugh at……..“…..If Dr. Dressler does nothing else than this it will be as if he did nothing.”…………. hard to argue, but kinda humorous.
As far as the insult to the integrity of Lindzen and Spencer, that’s sad and pathetic. I’m curious as to what inconsistencies either have shown that either anonymous commenter thinks it warrants name calling. It shows the emotional maturity of a 5 y/o, but then I’ve never considered Eli nor Grant peers of Spencer and Lindzen, much less colleagues. Dr. Dressler, OTOH, has shown a willingness to engage in civil discourse(albeit, not here) without engaging in name calling. As they say, good on you, Dr. Dressler.
In my estimation, Tamino and Eli are nothing but faceless, nameless, commenters, much like myself, except I’ve the eggs to put my name behind my writings. I’ve gone to every alarmist site I can think of, only to be denied a full voice to my thoughts, they won’t even come here knowing they won’t be denied a voice. They think they are peers to Lindzen and Spencer? Tami and Eliane can’t even find the intestinal fortitude to engage laymen and laywomen! As far as I know, neither Lindzen nor Spencer has ever shrank from adversity. But Tami and Eliane won’t come and play with the rest of us here. Anthony always gives a fair shake to alarmists and ensures their points can be made; no matter how inane the points are. I’ve much more respect for the alarmists that come here willing to exchange thoughts and ideas than ones that supposedly are experts but shrink from challenge. It makes one wonder if they ever really got through college.
Another possibility, consistent with your idea, is that:
El Nino and La Nina change cloud cover, then changed cloud cover changes temperature.
Andy Dressler: Just in case my comment gets lost over at RealClimate, I’ll reproduce it here.
http://www.realclimate.org/index.php/archives/2010/12/feedback-on-cloud-feedback/comment-page-1/#comment-194119
*************
Bob Tisdale says:
Your comment is awaiting moderation.
9 December 2010 at 8:12 PM
Andrew Dessler: Your email correspondence with Roy Spencer included the following discussion of ENSO: “First, people have been studying ENSO for decades and my sense is that the basic theory that it is caused by changes in surface winds driving changes in ocean circulation seems to be quite successful and explains almost all of the details of the observations (e.g. the evolution of thermocline depth).”
The increase in trade wind strength associated with La Niña events decreases total cloud amount over the tropical Pacific east of the Pacific Warm Pool, which, of course, results in an increase in DSR.
You continued, “Second, I did a quick back of the envelope calculation and in order to get 1°C of warming in a 50m column of water in one year you need about 7W per square meter of heating. That seems a bit high. And if the warming occurs in just a few months (which it can, then the required radiative heating would be correspondingly larger).”
Pavlakis et al (2008), in part, write in their abstract, “A clear anti-correlation was found between the downward shortwave radiation anomaly (DSR-A) time-series, in the region 7° S–5° N 160° E-160° W located west of the Niño-3.4 region, and the Niño-3.4 index time-series. In this region where the highest in absolute value DSR anomalies are observed, the mean DSR anomaly values range from −45 Wm−2 during El Niño episodes to +40 Wm−2 during La Niña events.”
An increase in DSR of 40W per square meter far exceeds your annual requirement of 7w per square meter from your back-of-the-envelope calculation. Link to Pavlakis et al:
http://www.atmos-chem-phys-discuss.net/8/6697/2008/acpd-8-6697-2008-print.pdf
Regards
Climatology today is like a giant Used-Car Lot. Buyer Beware!
Well I found the e-mail exchange quite satisfying. Nice to see a couple of hard working scientists trying to convince each other of their take on the data. You know, how science is supposed to work.