[Prof. Ray Pierrehumbert]- Rancourt writes original version of article, HERE.
- Asks for and receives peer criticism, HERE.
- Rancourt writes significantly revised version of article, HERE.
- Asks for and receives further peer criticism about revised version, PRESENT POST.
- It appears that Rancourt's revised paper is correct: The predicted effect of CO2 is two orders of magnitude smaller than the effects of other parameters.
- Final June 2011 (Third) version is significantly augmented, LINK-HERE.
Following the posting of THIS significantly revised version of Denis Rancourt's paper about Earth's radiation balance, Rancourt asked the climate scientists at RealClimate for follow-up criticism -- resulting in this email exchange:
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From: Denis Rancourt
Date: Thu, May 12, 2011 at 3:57 PM
Subject: Re: climate
To: gschmidt@giss.nasa.gov, mann@psu.edu, ammann@ucar.edu, rasmus.benestad@met.no, rbradley@geo.umass.edu, rahmstorf@ozean-klima.de, rahmstorf@pik-potsdam.de, steig@u.washington.edu, d-archer@uchicago.edu, rtp1@geosci.uchicago.edu, garidel@marine.rutgers.edu, jrbouldin@ucdavis.edu, wconnolley
Revised version posted:
http://climateguy.blogspot.com/2011/05/radiation-physics-constraints-on-global_12.html
Please provide any feedback.
Denis Rancourt
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From: Eric Steig
Date: Thu, May 12, 2011 at 4:28 PM
Subject: Re: climate
To: Denis Rancourt
Cc: gschmidt@giss.nasa.gov, mann@psu.edu, ammann@ucar.edu, rasmus.benestad@met.no, rbradley@geo.umass.edu, rahmstorf@ozean-klima.de, rahmstorf@pik-potsdam.de, steig@u.washington.edu, d-archer@uchicago.edu, rtp1@geosci.uchicago.edu, garidel@marine.rutgers.edu, jrbouldin@ucdavis.edu, wconnolley
Denis,
I applaud your efforts to take Ray's criticisms into account, but your post is still full of errors. I really don't have the time to get into all of them, but case in point is where you write that
"The longwave atmospheric absorption in the CO2 absorption band is saturated in Earth conditions and this is important because it is the physical reality ..."
This is simply wrong. See here: for example an explanation of why.
http://www.realclimate.org/index.php/archives/2007/06/a-saturated-gassy-argument/
Eric Steig
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From: Raymond P.
Date: Thu, May 12, 2011 at 6:22 PM
Subject: Re: climate
To: Denis Rancourt
Cc: Gavin Schmidt
Yes, Denis, Eric is right about that. I did say that your failure to understand Kirchoff's law was only ONE of the problems with your post. I collaborated on writing the post Eric refers to, and I also wrote the accompanying post on "What Angstrom didn't know"
I appreciate your efforts to learn this material, but writing nonsense and having us correct it bit by bit is very inefficient of everybody's time. I suggest that before you make such sweeping pronouncements about the subject, you take the time to educate yourself on the basics. David Archer's book, "Understanding the Forecast" is a good place to start, and you can follow that with my book, Principles of Planetary Climate." For that matter, if you had read my Physics Today article, which I pointed out to you in connection with the G&T nonsense, you would have already known about the saturation fallacy.
--Ray
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From: Denis Rancourt
Date: 2011/5/12
Subject: Re: climate
To: "Raymond P."
Cc: Gavin Schmidt
Hi Ray and Eric,
Actually, Ray, the first version did not use the saturation approach so this could not have been an error in the first version.
The physical model I now use is a single-layer atmosphere that is longwave opaque withing a certain width on the main CO2 band and that does not emit at other wavelengths. It either lets ground longwave through or it blocks it within this "saturation band". The width of the assumed saturation opaqueness band increases with CO2 content by assuming a binary cutoff of transmission/opaqueness at a characteristic value of cross section giving opaqueness and a Gaussian cross section profile.
While these are simplifying assumptions they do not violate any physical law or principle. One can argue that the longwave absorption of the real atmosphere can be approximately parametrized in this way.
The model clearly shows how a saturating atmosphere would work (in the limit of black/white saturation circumstances) regarding surface temperature, without using a full thick infrared radiative transfer theory calculation. The model treats only the atmosphere's role in blocking or letting through ground thermal emission. It says that role for the CO2 15 um band works this way.
It seems to me that the (one-layer) atmosphere's own thermal emission is not relevant because half goes up and out while half goes down and back to be fully absorbed (e ~ 1). In the limit of all-thermalization of absorbed longwave, this only means that ~half that is resonantly absorbed at saturation actually gets out. This is easily handled by reducing the cross section by a factor of ~two. This factor of two would appear in the "ln(σm/σe)" term of my equations 8 and 9 and therefore would have no significant effect.
Therefore it appears that your negation relies mostly on the differences that there would be between a one-layer radiating and absorbing atmosphere and a thick (multi-layer) atmosphere. It seems to me that this would only lead to yet another small re-normalization of my characteristic model parameters. But I will examine this.
Do you have a simple code that simulates the radiation transfer in a multi-layer model atmosphere?
Thank you for your help.
-denis
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From: Denis Rancourt
Date: 2011/5/12
Subject: Re: climate
To: "Raymond P."
Cc: Gavin Schmidt
Also, is it possible that you did not read my revised article beyond the word "saturation"?
I actually apply what you describe here:
http://www.realclimate.org/index.php/archives/2007/06/a-saturated-gassy-argument-part-ii/comment-page-13/#comments
The only difference is that I make the estimation quantitative by using a Gaussian shape cross section and a sharp cut-off.
The warming on increasing CO2 in my model directly comes from the extra absorption in the wings of the band...
-denis
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From: Raymond P.
Date: Thu, May 12, 2011 at 9:00 PM
Subject: Re: climate
To: Denis Rancourt
Cc: Gavin Schmidt
Denis, you are making a small amount of progress. The single layer version catches up with Arrhenius, and (when used with modern spectroscopy) has the exact same problems that Arrhenius had, as only became clear later when things got sorted out in the 60's by Manabe. There is a full discussion of this in The Warming Papers.
I still recommend you would do better to educate yourself on the basics, and show a bit of humility about those things of which you are ignorant, before you make sweeping pronouncements.
--Ray
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From: Raymond P.
Date: Thu, May 12, 2011 at 10:05 PM
Subject: Re: climate
To: Denis Rancourt
Cc: Gavin Schmidt
Dear Denis,
This conversation started out well, but now it's degenerating. I was pleased that you were able to learn something about Kirchoff's Law, and were willing to update your essay to correct that blunder. Every little bit that eliminates propagation of nonsense, and gets some truth out into the arena, is a step forward. But you still clearly have a lot to learn, and I'm suspicious because so far as I can tell, you seem to have made up your mind before you even have gotten pinkie deep into learning the subject matter you'd need to pass judgment.
So, what's especially on my mind (and I would love to be proved wrong) is that back in 2007 you declared that the entire man made global warming movement is nothing more than "a corrupt social phenomenon." That statement has been featured prominently by Marc Morano, which is indeed where I first came across your name. This quote has been picked up widely by inactivists everywhere, and is particularly choice to that community because it comes from a self-professed leftist.
So were you quoted fairly? If not, have you ever taken steps to rectify the way your name is being used? If you were indeed quoted correctly, to you still stand by this statement? Have you ever retracted it in the face of things you have learned since? I am much disturbed by the fact that you would make such a statement years before you had progressed to the point where you even understood Kirchoff's Law (that point being evidently the day before yesterday, or thereabouts). How can you justify having made such a pronouncement at a time when you had such a thoroughly inadequate understanding of the subject? And, the fact is, you still have a thoroughly inadequate understanding of the subject.
I would like to think that we have some common ground, but I need an explanation as to how in the world you came to the opinion you expressed without having an inkling of the physical basis of the subject.
--Ray
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From: Denis Rancourt
Date: Thu, May 12, 2011 at 10:44 PM
Subject: Re: climate
To: "Raymond P."
Cc: Gavin Schmidt
Hi Ray,
It's good that you accepted to engage on the science despite my political statements.
I think it is possible to examine and evaluate the science separately from our evaluation of the political and social forces that drive the science establishment.
I also think that one can evaluate the latter without being a specialist in the former. Otherwise, we will need to eliminate the field of social history of science and technology.
In addition, my understanding of the science, having corrected my Kirchoff's Law error and having implemented a reasonable model of longwave absorption by CO2, suggests that my "sweeping statements" about the science are worthy of attention.
In particular, given the simplicity of my model, you would need to provide a quantitative estimate showing how my single-layer model with the correct absorption cross section and relevant characteristic parameters can be off in terms of estimated relative sensitivities compared to a multi-layer model.
Since my model uses the most straightforward and simplest assumptions and the actual known characteristic parameters, you need to show where it is wrong, beyond waving a broad "read my book - multi-layer or die" magic wand.
Is that not fair for a seasoned expert such as yourself?
I have already demonstrated how I respond to being correctly shown to be in error. And I assure you that I am open to changing my views.
Do you have a simple code that simulates the radiation transfer in a multi-layer model atmosphere? (If not, then how do you gauge the importance of using a multi-layer model?)
cheers,
-denis
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From: Denis Rancourt
Date: Fri, May 13, 2011 at 5:44 PM
Subject: Re: climate
To: "Raymond P."
Cc: Gavin Schmidt
Dear Ray,
I have posted our exchange here:
http://climateguy.blogspot.com/2011/05/peer-criticism-revised-version-of.html
(The picture links to your web site.)
I await any next installment in our communication about these simple models that allow an estimation of climate sensitivity to different key parameters.
best,
-denis
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