Hot off the press: Dessler's record turnaround time GRL rebuttal paper to Spencer and Braswell

UPDATE: Dr. Roger Pielke Sr. has a comment on the paper here: Comments On The Dessler 2011 GRL Paper “Cloud Variations And The Earth’s Energy Budget also, physicist Lubos Motl has an analysis here. The press release from TAMU/Dessler has been pushed to media outlets on Eurekalert, see update below.

UPDATE2: Dessler has made a video on the paper see it here And Steve McIntyre has his take on it with The stone in Trenberth’s shoe

I’ve been given an advance copy, for which I’ve posted excerpts below. This paper appears to have been made ready in record time, with a turnaround from submission to acceptance and publication of about six weeks based on the July 26th publication date of the original Spencer and Braswell paper. We should all be so lucky to have expedited peer review service. PeerEx maybe, something like FedEx? Compare that to the two years it took to get Lindzen and Choi out the door. Or how about the WUWT story: Science has been sitting on his [Spencer’s] critique of Dessler’s paper for months”.

If anyone needs a clear, concise, and irrefutable example of how peer review in climate science is biased for the consensus and against skeptics, this is it.

I’m sure some thorough examination will determine if the maxim “haste makes waste” applies here for Dessler’s turbo treatise.

Cloud variations and the Earth’s energy budget

A.E. Dessler

Dept. of Atmospheric Sciences

Texas A&M University

College Station, TX

Abstract: The question of whether clouds are the cause of surface temperature changes, rather than acting as a feedback in response to those temperature changes, is explored using data obtained between 2000 and 2010. An energy budget calculation shows that the energy trapped by clouds accounts for little of the observed climate variations. And observations of the lagged response of top-of-atmosphere (TOA) energy fluxes to surface temperature variations are not evidence that clouds are causing climate change.

Introduction

The usual way to think about clouds in the climate system is that they are a feedback — as the climate warms, clouds change in response and either amplify (positive cloud feedback) or ameliorate (negative cloud feedback) the initial change [e.g., Stephens, 2005]. In recent papers, Lindzen and Choi [2011, hereafter LC11] and Spencer and Braswell [2011, hereafter SB11] have argued that reality is reversed: clouds are the cause of, and not a feedback on, changes in surface temperature. If this claim is correct, then significant revisions to climate science may be required.

Conclusions

These calculations show that clouds did not cause significant climate change over the last decade (over the decades or centuries relevant for long-term climate change, on the other hand, clouds can indeed cause significant warming). Rather, the evolution of the surface and atmosphere during ENSO variations are dominated by oceanic heat transport. This means in turn that regressions of TOA fluxes vs. ΔTs can be used to accurately estimate climate sensitivity or the magnitude of climate feedbacks. In addition, observations presented by LC11 and SB11 are not in fundamental disagreement with mainstream climate models, nor do they provide evidence that clouds are causing climate change. Suggestions that significant revisions to mainstream climate science are required are therefore not supported.

Acknowledgments: This work was supported by NSF grant AGS-1012665 to Texas A&M University. I thank A. Evan, J. Fasullo, D. Murphy, K. Trenberth, M. Zelinka, and A.J. Dessler for useful comments.

Dessler, A. E. (2011),

Cloud variations and the Earth’s energy budget, Geophys. Res. Lett., doi:10.1029/2011GL049236, in press. [Abstract] [PDF paywalled] (accepted 29 August 2011)

Dessler has a pre-print version of the paper on his server here

h/t to Marc Hendrickx

=============================================================

UPDATE: Here is the press release from Texas A&M via Eurekalert:

Texas A&M University

Texas A&M prof says study shows that clouds don’t cause climate change

COLLEGE STATION, Sept. 6, 2011 — Clouds only amplify climate change, says a Texas A&M University professor in a study that rebuts recent claims that clouds are actually the root cause of climate change.

Andrew Dessler, a Texas A&M atmospheric sciences professor considered one of the nation’s experts on climate variations, says decades of data support the mainstream and long-held view that clouds are primarily acting as a so-called “feedback” that amplifies warming from human activity. His work is published today in the American Geophysical Union’s peer-reviewed journal Geophysical Research Letters.

Dessler studied El Niño and La Niña cycles over the past 10 years and calculated the Earth’s “energy budget” over this time. El Nino and La Nina are cyclical events, roughly every five years, when waters in the central Pacific Ocean tend to get warmer or colder. These changes have a huge impact on much of the world’s weather systems for months or even years.

Dessler found that clouds played a very small role in initiating these climate variations — in agreement, he says, with mainstream climate science and in direct opposition to some previous claims.

“The bottom line is that clouds have not replaced humans as the cause of the recent warming the Earth is experiencing,” Dessler says.

Texas is currently in one of the worst droughts in the state’s history, and most scientists believe it is a direct result of La Niña conditions that have lingered in the Pacific Ocean for many months.

Dessler adds, “Over a century, however, clouds can indeed play an important role amplifying climate change.”

“I hope my analysis puts an end to this claim that clouds are causing climate change,” he adds.

###

For more information about Dessler’s research, go to http://goo.gl/zFJmt

About Research at Texas A&M University:

As one of the world’s leading research institutions, Texas A&M is in the vanguard in making significant contributions to the storehouse of knowledge, including that of science and technology. Research conducted at Texas A&M represents an annual investment of more than $630 million, which ranks third nationally for universities without a medical school, and underwrites approximately 3,500 sponsored projects. That research creates new knowledge that provides basic, fundamental and applied contributions resulting in many cases in economic benefits to the state, nation and world.

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Richard Lawson

Warm biased climate scientists are the only people in the world who know all the unknown unknowns! So they tell us.

Lew Skannen

“Suggestions that significant revisions to mainstream climate science are required are therefore not supported.”
I suspect that this was actully the starting point of the paper and everything else was build around it.

geronimo

It`s simply a trick to ensure SB11 doesn`t make it into AR5 for consideration.

Dave Wendt

” Spencer and Braswell [2011, hereafter SB11] have argued that reality is reversed: clouds are the cause of, and not a feedback on, changes in surface temperature. If this claim is correct, then significant revisions to climate science may be required.”
30 sec passing scan. I believe S&B suggest the cloud feedback is bidirectional.

Sean Houlihane

How about we examine the paper rather than the process? It may not say much, but I don’t think SB11 did either. I think this is still an area for further investigation though.

Question …where did Lindzen, Choi, Spencer and Braswell write that “significant revisions to mainstream climate science are required”?

Alberto

Dave Wendt: “I believe S&B suggest the cloud feedback is bidirectional.”
Exactly. So this paper by Dessler doesn’t properly address the points that S&B made.

jason

Crikey, I’m an idiot an even I understood their paper suggest cloud feedback is bidirectional. Wonder if the MSM such as Richard Black will notice it when they write their balanced pieces…..

stevo

“If anyone needs a clear, concise, and irrefutable example of how peer review in climate science is biased for the consensus and against skeptics, this is it.”
The system is biased against bad science. So-called “skeptics” produce a lot of bad science, and it’s a good thing that they have difficulty publishing it.

220mph

Hmmm … thats funny … I don’t see any refererence to the EXISTING work on clouds as a forcing shown in the recently released CERN CLOUD study …
http://press.web.cern.ch/press/PressReleases/Releases2011/PR15.11E.html
Wasn’t that the major complaint with Spencer and Braswell – that they did not address the existing science on the issue?
Even Gavin Schmidt speaks positively (at least to the extent that’s possible for his group) about the CERN CLOUD study’s findings … this study would seem to be directly relevant to the S&B paper yet Dessler seemingly ignores it

JGR is normally fast. They gives the stats in this editorial:
“Publication is indeed rapid. For the past 3 years we have maintained an effi cient review process, with a median time to first decision of 36 days and, for 50% of accepted papers, an average time from submission to publication of 13.5 weeks.”

jono

Mr D is right you know, as it clearly states…
“These calculations show that clouds did not cause significant climate change over the last decade”
Is it not rather difficult to show how anything can change a system if the system as measured (climate change) has not changed over the last decade.
or to put it into easyspeak .. all that heat energy I put into my house last year can now be clearly seen not to affect my house, as it has not warmed up over the year. proof !!!

Jimmy Haigh

‘Clouds cause climate change.’
‘They do not!’
‘Oh yes they do!”
“Oh no they dont…..”

Roy

Even if the turnaround time for the paper is a record it is still obviously far too long. If it could have been published before Spencer and Braswell’s paper then there would have been absolutely no need for anyone to take any notice of their sceptical arguments, would there?
The peer review process needs to be redefined so that in cases where it is not possible for the referees to reject sceptical papers the rebuttal comes out first!

Alpha Tango

Good grief.
Indecent haste indeed, and does appear to be flawed. I think the team will live to regret this.

Peter Miller

The part I liked was:
“These calculations show that clouds did not cause significant climate change over the last decade (over the decades or centuries relevant for long term climate change, on the other hand clouds can cause significant warming)”.
I suppose this sort of logic sums up alarmist ‘science’ – something like: “The factual evidence for man made global warming cannot be found, but as the models show that climate change is caused by man, it means the science is settled.”
Climate change is the norm, it is simply not possible to fix climate – which is why goofy politicians have created Ministers for Climate Change in an attempt to regulate something, which simply cannot be regulated.

THe paper says;
“These calculations show that clouds did not cause significant climate change over the last decade (over the decades or centuries relevant for long-term climate change, on the other hand, clouds can indeed cause significant warming)”
A decade is a very short period and difficult to measure, especially when the temperature was mostly flatlining. But surely the author is saying that over a longer period clouds can have an effect? I will see what else is in the pdf before commenting further so jst an initial response to the abstract.
tonyb .

Entirely from physical experience of the world around me. It’s very simplistic and empirical, but I believe it’s relevant to these papers being discussed, so here goes…
It’s the morning, the skies are clear of cloud. Temperatures are cool to begin with, but it’s humid. Later on, some cumulus cloud begins to form. A pleasant sight….
It’s now late afternoon. It’s hot and it’s muggy. The initially small cumulus clouds have been growing bigger and taller. Central pillars inside the cumulus cloud are now shooting up – actually visibly, if you keep your eye on one of the pillars – it’s a majestic sight as you realise this upwards movement of the growing towers represents immense energies being expended in order for this to happen.
Where I am standing, the sun is blazing down on me and I feel very hot, but, one of the cumulus clouds has moved in front of the sun and I am now in shadow. I instantly feel that the heat from the sun has decreased by a large order of magnitude.
A little while later, the cumulus clouds have reached some kind of pinnacle, some certain boundary high up in the atmosphere. At this height, they begin to spread out, like the top of some gigantic fountain, only this water isn’t falling (yet) – it’s forming an anvil-shaped head at the top of the cloud. The cumulo-nimbus is born.
Shortly after that, I hear the first rumblings of thunder. Those little cumulus clouds have grown into monstrous thunderclouds and the storms begin.
There is gusty wind, heavy rain, even hail. There is numerous lightning and clamorous thunder with that. There is high drama all around me as I observe the weather.
A while later and the storms begin to wane, and eventually die out. It is much, much cooler! I’m going to get a decent sleep tonight after all.
And so now to the point;
The above is a very short and basic description of the birth and death of a thundery day. It describes the phenomenon below, namely;
1) The sun obviously heats up the ground and anything the sunlight hits – roofs of houses, etc.
2) If a cloud gets in between the sun and the ground, the ground – or a person standing on the ground – stops heating up because they’re in the cloud’s shadow – this to me means a negative forcing – i.e. sunlight is being prevented from hitting me or the ground by the cloud – the cloud is reflecting the energy of the sun that would have heated me/ground up. The cloud is not being heated up by the energy from the sun, seeing as cloud is not a solid object. At the very most, only the top “layer” (e.g. perhaps the water molecules forming the cloud down to a certain depth from the top of the cloud are absorbing any energy from the sun.)
3) Finally, the thunderstorm is transporting energy from the ground, upwards, to high altitudes, and cooler air is being transported down towards the ground. This, to me, also represents a negative feedback.
Now, how is it that this paper (and others) can claim that clouds can only produce a positive feedback, when from imperial, physical evidence and observation, I can deduce that clouds appear to produce more negative feedback than they do positive?

Silly me. I had thought the pdf link would lead to more information but it seems to be a paywall. Its very difficult to comment any further on such a brief abstract.
tonyb

Michael in Sydney

Stevo says
“So-called “skeptics” produce a lot of bad science, and it’s a good thing that they have difficulty publishing it.”
Stevo, why are they “So called”? What does that statement mean?
Kind Regards
Michael

Accepted aug 29.
GRL says that the median time to a first response after submission is 36 days
GRL says they can turn a review in as quick as 14 days
GRL says the average paper takes 13.5 week from submission to publication.
July 26th to august 29.
heck this paper got written, submitted, reviewed and accepted faster than 50% of papers
wait to get their first response.

jeanparisot

So, is this a defense soley against Spencer or does represent an opening against CERNs work as well? It is beginning to sound like the gambit has changed from: “the Sun doesn’t matter”, to add ” and neither do clouds”.

ldlas

What a pile of…….

Dave Springer

With an as yet undetermined appendage Dessler writes:
“These calculations show that clouds did not cause significant climate change over the last decade”
I wasn’t aware there was any significant climate change due to any cause during that period of time. Global average temperature hasn’t significantly changed in the past 10 years.
Seems like a rather glaring flaw. Am I missing something?

Henry Galt

There has not been “significant climate change over the last decade”.
I fail to see the point, or the point of reading further????

Ryan

“peer review in climate science is biased for the consensus”
Is it really biased towards a consensus?
Consensus: An opinion or position reached by a group as a whole
Is that really what has happened here? From what I can see we have a dozen, or maybe half a dozen scientists with a shared agenda that are spreading what amounts to unchallenged propaganda in certain scientific publications. As a result, hundreds of other scientists have not “reached a position” but rather had a position thrust upon them as a fait accompli.

Espen

stevo says:
The system is biased against bad science.
That’s how the system is supposed to work. But in Climate Science, bad science has made it into the mainstream.

charles nelson

Let’s have a picnic.
That’s a good idea, it’s a nice cloudy day…that won’t affect the temperature.
Clowns!

liontooth

“In recent papers, Lindzen and Choi [2011, hereafter LC11] and Spencer and Braswell [2011, hereafter SB11] have argued that reality is reversed: clouds are the cause of, and not a feedback on, changes in surface temperature.”
Are there statements in the 2 papers that directly refute this conclusion?

jeanparisot

Is Dressler suggesting that a significant component of climate, clouds, have effects that cannot be measured on a decade scale? If so, then how are those water vapor tipping point feedbacks going to work – are the AGW models artifically compressed?

“Abstract: The question of whether clouds are the cause of surface temperature changes, rather than acting as a feedback in response to those temperature changes, is explored… ”
Bzzzzzzt Logical fallacy of the excluded middle. these are not the only two possibilities. Spencer is saying its a mixture of the two which confounds the quantification of cloud feedback.

John Marshall

It doesn’t matter what calculations are done if the wrong formula is used then the wrong answer follows.
We all know from experience that when cloud covers the sun it gets cooler so a negative feedback is almost certain.

Mike Bromley the Kurd

Dave Springer says:
September 6, 2011 at 1:15 am
Seems like a rather glaring flaw. Am I missing something?
No, you are not missing something. Haste makes waste. In this case, taxpayer money, I believe.

Atomic Hairdryer

Re Dave Springer

Seems like a rather glaring flaw. Am I missing something?

Possibly Santer et al’s backstop paper just published in JGR:
http://www.agu.org/pubs/crossref/pip/2011JD016263.shtml
Trends >17 yrs are required for identifying human effects on tropospheric temp.
So the last decade’s lack of warming simply isn’t sufficient to demonstrate any influence, and the modellers need 7 more years of funding before the lean years start.

Leo Norekens

What I note from the conclusion is that “over the decades or centuries relevant for long-term climate change (…) clouds can indeed cause significant warming”, and that -as for the past decade- “the evolution of the surface and atmosphere during ENSO variations [are] (sic) dominated by oceanic heat transport”.
Meaning: yes, clouds cause warming, but not during the last decade because El Nino/La Nina was so dominant.
So what about carbon and other geenhouse gases?

” Rather, the evolution of the surface and atmosphere during ENSO variations are dominated by oceanic heat transport.”
And presumably, the heat that the oceans are transporting is primarily derived from the solar shortwave that got past the clouds….
Ah.

Dave Springer

Trenberth et al are asserting that clouds don’t drive temperature changes but rather temperature changes drive clouds and non-condensing greenhouse gases drive temperature changes. Lindzen, Spencer, and many others assert that the Trenberth et al (a.k.a. the hockey stick team) cannot empirically establish that uni-directional relationship from gas to temperature to cloud. Trenberth et al assert that clouds are sources of feedback only and have no effect as primary drivers of temperature change. Lindzen, Spencer, et al assert that cloud respond to more than simple temperature changes and are also governed by things like global ocean circulation, wind patterns, GCR, aerosols from volcanic emissions, and lots of other things aside from non-condensing greenhouse gases. Lindzen, Spencer, et al are certainly correct in that clouds are governed by a lot more than just surface temperature change and they can certainly cause huge surface temperature change as everyone knows who’s ever been outside on a hot sunny day when a big cloud passes overhead. Clouds generally cover about 60-70% of the earth’s surface at any one point in time and radically change the planet’s albedo. A 1% decrease in global cloud cover reduces insolation at the surface by more than all anthropogenic forcings can raise it. Global average cloud cover isn’t known to better than 5% range and interannual variability or trends in interannual variability is largely unknown as albedo measurements are difficult and different methods of measuring it are not in satisfactory agreement. Ergo there’s no certain fixed figure for albedo that can be plugged into climate models so it’s basically used as fudge factor. If a particular model isn’t performing well albedo figure is something that can be tweaked to make it better match the temperature data.
Albedo modeling is so poor in climate models it would be funny if the naive and gullible didn’t put so much faith in computer models regardless of the uncertainties and ad hoc tweaking of poorly known parameters critical to model performance.

Dave Springer

correction to my previous:
“A 1% decrease increase in global cloud cover reduces insolation at the surface by more than all anthropogenic forcings can raise it.”

Dave Wendt

“Conclusions
These calculations show that clouds did not cause significant climate change over the last decade (over the decades or centuries relevant for long-term climate change, on the other hand, clouds can indeed cause significant warming). Rather, the evolution of the surface and atmosphere during ENSO variations are dominated by oceanic heat transport. This means in turn that regressions of TOA fluxes vs. ΔTs can be used to accurately estimate climate sensitivity or the magnitude of climate feedbacks.
How exactly do clouds generate “significant warming” in the long term if they have no effect in the short term? And if they cause significant warming in the long term how can ignoring them in the decade scale yield accurate estimates of climate sensitivity?
Just a day or so ago they were pimping “Sluggo” Santer’s latest effort of which the following is still all that seems to be publicly available.
“Key Points
Models run with human forcing can produce 10-year periods with little warming
S/N ratios for tropospheric temp. are ~1 for 10-yr trends, ~4 for 32-yr trends
Trends >17 yrs are required for identifying human effects on tropospheric temp.”
It’s hard to know what he actually has to say, but it seems antagonistic to using short scale data in this regard.

I will be interested to see the full paper, but based on the abstract and conclusions alone, we can see this paper is not addressing the complexity of bi-directional feedback between albedo and ocean.
It simply fails to address Spencer and Braswell’s core argument.
” observations presented by LC11 and SB11 are not in fundamental disagreement with mainstream climate models, nor do they provide evidence that clouds are causing climate change.”
They are in enough disagreement to show that there is bi-directional feedback. The logical upshot of this is that clouds are forcing climate part of the time. Providing (empirical) evidence they are causing climate change is exactly as difficult as providing evidence that they are not.
Which was one of Spencer’s main points – uncertainty.

220mph

This work of Spencer & Braswell:
On the diagnosis of radiative feedback in the presence of unknown radiative forcing
http://www.drroyspencer.com/wp-content/uploads/Spencer-Braswell-JGR-2010.pdf
… seems to be largely on the same topic and very detailed. It was not Spencer and Braswell’s first paper on the subject either:
Spencer, R. W., and W. D. Braswell (2008), Potential biases in cloud feedback diagnosis: A simple model demonstration, J. Clim., 21, 5624–5628.
Spencer, R. W., W. D. Braswell, J. R. Christy, and J. Hnilo (2007), Cloud and radiation budget changes associated with tropical intraseasonal oscillations, Geophys. Res. Lett., 34, L15707, doi:10.1029/2007GL029698.

I would be interested in Trenberth etals response to these papers – and how they tie with S&B 2011??

David Schofield

I know I’m really stupid – but if clouds can amplify or ameliorate climate – then if something else causes clouds to change then that something else is a cause of climate change? Or is it only man made CO2 that alters clouds? They can’t not matter and matter at the same time.

The journal page for the paper – containing abstract for free – is here:
http://www.agu.org/pubs/crossref/pip/2011GL049236.shtml
The speed is really amazing.

David Schofield

Nick Stokes says:
September 6, 2011 at 1:00 am
JGR is normally fast. They gives the stats in this editorial:
“Publication is indeed rapid. For the past 3 years we have maintained an effi cient review process, with a median time to first decision of 36 days….”
How about adding in the time he took to read and digest Spencer’s paper, prepare and write his own, getting it proofed etc. Admit it – it was obscenely fast.

220mph

tallbloke says:
September 6, 2011 at 1:34 am
“Abstract: The question of whether clouds are the cause of surface temperature changes, rather than acting as a feedback in response to those temperature changes, is explored… ”
Bzzzzzzt Logical fallacy, these are not the only two possibilities. Spencer is saying its a mixture of the two which confounds diagnosis of feedback amplitude.

Add to that the CERN CLOUD work which shows cosmic rays cause an increase in cloud producing droplets … which would make the clouds created as a result yet another CLOUD FORCING – not a feedback.

Paul Deacon

Behind a paywall… Hahahahahaha!
Ah, the unbearable transparency of climate science!

Keith Battye

So . . .
It’s not the sun that I can see and feel when it shines on me.
It’s not the clouds that I can see and feel when they block the sun or rain on me.
It’s CO2 that I can’t see or feel . . .
OK, I get it.

Magnus Olert

It’s hard to judge a paper based just on the sections Abstact, Introduction and Conclusions. However, there seem to be serious errors in those sections:
1) “…and Spencer and Braswell [2011, hereafter SB11] have argued that reality is reversed: clouds are the cause of, and not a feedback on, changes in surface temperature.” This is not correct, SB11 argues that it goes both ways.
2) “These calculations show that clouds did not cause significant climate change over the last decade ” As far as I understand SB11 it does not argue that clouds has caused a significant climate change over the last decade. It does just say that clouds does affect temperature and that this effect will contaminate your analysis of the cloud feedback if not accounted for.

richard verney

It is difficult to comment upon the paper until this is reviewed in full. Since it is behind a pay wall, I have not seen it. There is no need to comment further on (i) the thoroughness of the examination of the issue in hand (clouds are they cause or feedback) nor (2) the process of peer review, since the time that it has taken to get this paper in print says all.
Clouds are clearly one of the key battle grounds that will determine the correct outcome of the debate on man made GW. Clouds are incredibly complex since many factors determine what effect they will have on temperature during the course of the day, viz to name but a few of the many variables: the latitude of where a cloud(s) may develop, the albedo surface below the cloud, the nature of the surface below the cloud and its heat capacity, the time of day when cloud(s) develop and time of duration of cloud cover, the area of cloud cover, the volume of cloud cover, the composition of the cloud. Cloud formation is chaotic and random, although there may be a number of identifiably underlying causal components (including possibly cosmic rays or changes in Earth’s magnetic field or changes in particuate aerosols), which lead to cloud formation. It is probable that not all underlying factors are known, still less how they operate and interlink with other factors that are in play in cloud formation.
Like so much in this debate, the data is lacking. We do not possess sufficientl high scale resolution of all the variabilities associated with clouds on a daily basis going back 40 years, still less 150 years. It is therefore not possible to even attempt a correlation between cloud cover and temperatures since say the 1880s. In fact, I doubt we have a data set with the necessary high scale resolution of ALL the variables involved to even evaluate the last decade!
Given this variability and complexity, it is no surprise that models do not model clouds well. I understand that both sides accept that the models do not model clouds as well as they could. Many would say the modelling is poor. Given this, it is no surprise that model projecdtions/predictions on temperature from year to year does not correlate well with empirical observation.
Clouds and the role they play in driving temperatures is certainly one of the most important areas of study and of empirical data gathering. A better knowledge and understanding of clouds is essential.
I have these past 20 years considered that natural variability in clouds could and probably does explain any real temperature increase that has taken place the past century. It will be interesting to see how examination of this issue pans out and the insights that it will reveal.

Viv Evans

Not having seen the calculations on which Dessler et al base their conclusions, I was nevertheless amazed when I read this statement:
“These calculations show that clouds did not cause significant climate change over the last decade (over the decades or centuries relevant for long-term climate change, on the other hand, clouds can indeed cause significant warming).”
Part one of the above states that ‘clouds did not cause significant climate change over the last decade’ – so are climate scientists now using decades to determine climate change, rather than spans of 30 years, or 17, as Santer et al propose here http://www.agu.org/pubs/crossref/pip/2011JD016263.shtml
Part two of the above quote tells us that clouds do have an effect, however, over decades and centuries ‘relevant’ for long-term climate change, where they can cause ‘significant’ warming.
Are there any data about clouds going back decades or even centuries? If so – how were they obtained?
Where are the data to show that clouds, over ‘relevant’ centuries, cause ‘significant’ warming?
What about clouds causing significant cooling, over ‘relevant’ centuries?
Finally, can someone explain to me how something (e.g. clouds) can have no influence on climate change when looked at over a decade – but can have significant influence on warming when looked at over a span of decades, even centuries, regardless of having data on clouds fore.g. centuries?
Basically, aren’t Dessler et al saying that clouds have an influence on warming, over a ‘relevant’ century, because it has been warming during that century?