Judy on Pielke on the mainstream

You don't need to read anything here tonight - read Judith Curry instead.

Comments

[Martin A]

BBD: Someone explaining the last several decades worth of work - often using standard texts - in commendable detail and clarity. What you think about JC's comment is absolutely irrelevant, since you have just passed up the opportunity to find out whether she's correct. In fact you have forfeited the right to any opinion on this or any other deriving from radiative forcing.

Don't you see that?

Er, no, sorry, I don't see that.

But I think I have understood why you directed me to something that did not give what I was seeking - and also, perhaps, why you are bemused by Professor Curry's statement.

Here's my hypothesis: To you "The greenhouse effect" is what leads a planet to be warmer on average than it would be without an atmosphere. This is just a guess - but am I right?

In contrast, I think that, to many people, "The greenhouse effect" is not that. To them, it is the name given to the effect where the presence of trace gases such as carbon dioxide leads to greatly increased average temperatures compared to what they would be if the atmosphere contained only nitrogen, oxygen and water vapour.

For example, Judith Curry says (in the passage I referenced):

Physics of the atmospheric greenhouse(?) effect
(...)
The skeptics thread has shown that it is plausible to be skeptical of a number of issues (...). However, whether atmospheric gases such as CO2 (and H20, CH4, and others) warm the planet is not an issue where skepticism is plausible.
(...)
We need to raise the level of our game in terms of explaining the planetary warming by infrared absorption of CO2 etc. The missing area of understanding seems to been, oxygen and water v the actual physical mechanism.

To me, this makes it clear that she was stating that a simple rigorous explanation of how trace quantities of CO2 can result in increased temperatures does not exist.

The sort of thing I would like to see might be further along the lines of equations (6.35) and (6.36) in A First Course in Atmospheric Radiation (2nd Ed) by Grant W. Petty (use Look Inside on amazon.com). He takes a relatively simple model and, without having to resort to qualitative arguments, derives equations for the temperature at the top of the atmosphere and at the surface. He then takes a couple of limiting cases to get insight into the role of the atmosphere in controlling global surface temperature.

I had surmised that a model such might be adapted to illuminate the effect of a small proportion of IR absorbing gases. The analysis of the model would not need to involve hand-waving qualitative reasoning about the behaviour of radiation. If such a model were to exist, I imagine it would be the sort of thing Professor Curry is hoping for.

But a good mechanistic explanation of the physical processes occurring seems absent, including an explanation of how local thermodynamic equilibrium is established in response to the absorption of infrared radiation by a small number of molecules.

Again she has made it clear she is talking about CO2 causing increased warming when she refers to "The greenhouse effect".

[Shub]

Ok, you did not praise yourself. Kind of caught me off-guard there.

[not banned yet]

BBD

Sorry to disappoint but it is a genuine question, seeking the benefit of your wisdom.

"The quote you provide is for the no-feedbacks forcing!" - Correct.

No doubt you are far ahead of me, but please can you explain the difference. From your bolding am I right to assume that you think the difference is due to "feedback"?

[BBD]

not banned

Feedbacks are the response to forcings. If net feedbacks are high, the climate sensitivity will be high. In the case of this climate system, it looks as though a forcing from CO2 sufficient to raise the surface temperature by ~1C will be amplified to ~3C by net positive feedbacks.

Hansen & Sato's empirical estimate based on paleoclimate behaviour supports this.

.
Shub

Thank you for your gracious apology.

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Martin A

I gave you the best source I know for fair-minded and detailed discussion of the physics. There's more detail on CO2 here. Look at Parts 5, 6, 7 and 9 in particular. Perhaps this is what you were after.

To be clear, the GHE is caused by atmospheric trace gasses and WV - I definitely don't say that it's a with/without atmosphere phenomenon ;-)

I had surmised that a model such might be adapted to illuminate the effect of a small proportion of IR absorbing gases. The analysis of the model would not need to involve hand-waving qualitative reasoning about the behaviour of radiation. If such a model were to exist, I imagine it would be the sort of thing Professor Curry is hoping for.

Please follow up at SOD, and particularly the Ramanathan & Coakley (1978) discussion in CO2 Part 5.

If you can find hand-waving qualitative reasoning about the behaviour of radiation in that or any other reference paper on this subject you should publish a clarification.

Do you think that vast errors perpetuate unnoticed? Or perhaps suppressed?

Or is it more likely that if it was flawed then someone would by now have debunked the whole thing comprehensively?

[not banned yet]

Thanks BBD - so do you have any comment on this post at Science of Doom and how it relates (or otherwise) to H&S11?:

http://scienceofdoom.com/2011/09/22/measuring-climate-sensitivity-part-one/

[BBD]

not banned

The SOD post discusses some of the problems with defining and modelling the problem. H&S11 is an attempt to get a good estimate for CS without engaging in unnecessary complexity.

I quoted this upthread, but let's have it again (emphasis added):

Climate models, based on physical laws that describe the structure and dynamics of the atmosphere and ocean, as well as processes on land, have been developed to simulate climate. Models help us understand climate sensitivity, because we can change processes in the model one-by-one and study their interactions. But if models were our only tool, climate sensitivity would always have large uncertainty. Models are imperfect and we will never be sure that they include all important processes. Fortunately, Earth's history provides a remarkably rich record of how our planet responded to climate forcings in the past. Paleoclimate records yield, by far, our most accurate assessment of climate sensitivity and climate feedbacks.

[...]

In contrast to climate models, which can only approximate the physical processes and may exclude important processes, the empirical result includes all processes that exist in the real world – and the physics is exact.

[...]

Regardless of the exact error-bar, this empirically-derived fast-feedback sensitivity has a vitally important characteristic: it incorporates all real-world fast-feedback processes. No climate model can make such a claim.

H&S estimate climate sensitivity to be 3 ± 0.5C for doubled CO2 (3/4 ± 1/8 °C per W/m2).

[not banned yet]

BBD - "without engaging in unnecessary complexity."

Sorry BBD, but aren't you of the gospel of the RTEs? Please can you comment on the numbers SoD finds and clarify your position on necessary vs. unnecessary complexity?

[BBD]

not banned

You are taking the piss. I'm happy to talk about this, but only on a constructive basis.

[not banned yet]

BBD - you draw the wrong conclusion.

My question still stands - how do you account for the difference between the numbers you quote from H&S11 and those found by Science of Doom, your reference of choice using (AFAIK) your methodology of choice? Instead of answering this you are now refering to "unnecessary complexity".

Given that there have been many times past that you have referred people to SoD, (including on this thread with the claim "it is all there" re: "The radiative physics of CO2 and their role in warming the atmosphere are extremely well documented." Oct 28, 2011 at 6:56 PM), unless you can offer some perspective on why you are now prepared to set all SoD's painstaking work to the side as "unnecessary complexity" I find it hard to believe your claim you are "happy to talk about this ... on a constructive basis".

[BBD]

not banned

We both know that you haven't read more than a few words of any link I provide. I know it because if you had, then the conversation would develop instead of stagnate. You know it because it is true.

Since you are clearly an intelligent chap, you will acknowledge this and pose the obvious question: why am I refusing to engage with BBD constructively?

That question is more interesting than anything in our exchange to date.

[not banned yet]

Night night BBD - feel free to come back and answer my question if you'd like to "unstagnate the debate"...

[BBD]

What question? You confused the no-feedbacks forcing with the climate response (includes feedbacks). You are still doing it.

There is no question to answer. You do need to sort out your thinking on this though.