Tuttle Buttle Rebuttal Scuttled

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It seems Andy Dessler is so confident of his ability to see off those pesky contrarians Lindzen and Choi and Spencer and Braswell that he takes them all on in his rebuttal paper now in press with GRL:

Cloud variations and the Earth’s energy budget
A.E. Dessler
Dept. of Atmospheric Sciences
Texas A&M University
College Station, TX

I’ve had a quick look through the paper and it’s rubbish.

It opens with this:

““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 (false dichotomy). these are not the only two possibilities. Spencer is saying it’s the mixture of the two which confounds diagnosis of feedback amplitude (and sign in the warmist case). – FAIL

Then in the introduction there is this gem:

“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.”

Bzzzzzzt. Strawman argument. L&C and S&B do not argue that clouds are the cause of changes in surface T, but that unforced cloud variation contributes to changes in surface T. – FAIL

What about the meat? Dessler says:

“the conclusion here is robust: energy trapped by clouds
can explain only a few percent of the surface temperature changes. This is
consistent with previous work showing that heating of the surface and atmosphere
during ENSO comes from ocean heat transport [e.g., Trenberth et al., 2002;
Trenberth et al., 2010] and it means that clouds were not causing significant climate
change over this period.”

So according to Dessler the only way clouds can affect surface T is by absorbing energy on its way out of the Earth’s climate system. But Andy, what about the energy that clouds reflect which thereby never gets into the Earth’s climate system? No wonder Dessler thinks cloud feedback is positive, he ignores more than half of their effect. Doh! – FAIL

So, let’s head for the conclusion. Andy Dessler says:

“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.”

Well, Andy was the one who said earlier in the paper that if L&C and S&B were right
“then significant revisions to climate science may be required” [my bold]
So far as I’m aware neither Spencer nor Lindzen have said this. So since it’s his own suggestion which isn’t supported, we can conclude it is another strawman argument. – FAIL

So far as the observations not being in “fundamental disagreement with the models” is concerned, it comes down to a question of just how much disagreement there has to be for the models to be wrong enough to lead to the kind of mis-estimation of cloud feedback L&C and S&B suspect. I’ll leave that to them to determine. Let’s hope that they can get a rebuttal of this sorry assed piece of nonsense published before the AR5 cut-off date.

I see Lubos Motl has also made a critique of Dessler’s paper, far more amusing than my own:

http://motls.blogspot.com/2011/09/andrew-dessler-clouds-dont-reflect.html

[UPDATE 07/09] Steve McIntyre has a nice take on this, with a kicker in the tail showing that now Dessler goes along with Spencer’s four month lag, his 2010 positive cloud feedback becomes negative. 🙂

http://climateaudit.org/2011/09/06/the-stone-in-trenberths-shoe/