Beam me to Planet Gore !
Posted on 09/20/2011 9:57:49 PM PDT by Ernest_at_the_Beach
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Oh dear, now we have three peer reviewed papers (Lindzen and Choi, Spencer and Braswell, and now Richard P. Allan) based on observations that show a net negative feedback for clouds, and a strong one at that. What will Trenberth and Dessler do next? Maybe the editor of Meteorological Applications can be persuaded to commit professional suicide and resign? The key paragraph from the new paper:
…the cloud radiative cooling effect through reflection of short wave radiation is found to dominate over the long wave heating effect, resulting in a net cooling of the climate system of −21 Wm−2.
After all the wailing and gnashing of teeth over the Spencer and Braswell paper in Remote Sensing, and the stunt pulled by its former editor who resigned saying the peer review process failed, another paper was published last week in the journal Meteorological Applications that agrees well with Spencer and Braswell.
This new paper by Richard P. Allan of the University of Reading discovers via a combination of satellite observations and models that the cooling effect of clouds far outweighs the long-wave or “greenhouse” warming effect. While Dessler and Trenberth (among others) claim clouds have an overall positive feedback warming effect upon climate due to the long-wave back-radiation, this new paper shows that clouds have a large net cooling effect by blocking incoming solar radiation and increasing radiative cooling outside the tropics. This is key, because since clouds offer a negative feedback as shown by this paper and Spencer and Braswell plus Lindzen and Choi, it throws a huge monkey wrench in climate model machinery that predict catastrophic levels of positive feedback enhanced global warming due to increased CO2.
The cooling effect is found to be -21 Watts per meter squared, more than 17 times the posited warming effect from a doubling of CO2 concentrations which is calculated to be ~ 1.2 Watts per meter squared. This -21 w/m2 figure from Richard P. Allan is in good agreement with Spencer and Braswell. Here’s the paper abstract, links to the full paper (which I located on the author’s website) follow.
And the current Supercomputer Climate Models....have no knowledge of clouds.....
262 Responses to New peer reviewed paper: clouds have large negative cooling effect on Earth’s radiation budget
From the comments:
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David Wright says:
Oh, WOW!
What a killer punch, a perfect one-two with Spencer-Braswell. And just in time for inclusion in IPPC5. These two papers are going to seriously rattle a few cages in the Warmista camp, where the wagons are no doubt being circled right now. To mix in another metaphor, I doubt that all this evidence is going to cause any Team member to come out with their hands up just yet; but I’ll bet that one or two of them are starting to think about it.
Messed up title. Negative cooling would mean positive heating.
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Bart Verheggen says:
Anthony,
Could you please point out where in this paper it is mentioned that “clouds have large negative-*feedback* cooling effect on Earth’s radiation budget”?
I may be wrong, but I think you’re confusing two issues:
- the net effect of clouds on climate
- the net feedback of clouds on a change in climate
The paper, as I read it with a first quick overview, addresses the first, whereas you interpret it as if it addresses the second.
They are two distinctly different issues. The second (clouds as feedback) is about how cloud cover and properties might change in response to a warming or cooling of the climate: Will the net cloud radiative effect become more or less negative.
The net radiative effect of clouds on climate has long been known to be negative (i.e. cooling). See e.g this quote from the paper: “The overall global net cloud radiative effect is one
of cooling as documented previously (Ramanathan et al., 1989).” That can be verified in any textbook on the subject and most introductions of papers on this topic.
See also http://ourchangingclimate.wordpress.com/2009/04/16/aerosols-clouds-and-climate/
REPLY: Thanks, I can see where you’re coming from, but I saw things differently. See the update I posted at the end of the article. – Anthony
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Roy W. Spencer says:
Bart is correct. This paper is not about cloud feedback…it is about the average effect of clouds on the climate system, which the IPCC, Trenberth, Dessler, et al. will all agree is a cooling effect. It is an update of the early estimates from ERBE many years ago.
Feedback is instead how clouds will change in response to a temperature *change* from the average climate state.
Now, it might well be that since the average effect of clouds on the climate system in response to radiative heating by the sun is to cool the Earth, then a small increment in radiative heating (e.g. from more CO2) will ALSO result in clouds having a further increment in cooling. That’s basically what Monckton has been claiming, and he might well be correct. Lindzen pointed this out also in his 1990 BAMS paper.
I just wanted to point out that the IPCC view is that this paper is not about cloud feedback….even though it might be about cloud feedback. ;)
REPLY: Thanks Roy for the clarification. The question of whether clouds act as feedback, forcing, or both is one that will occupy us as a while. My interpretation is as both, they act as a forcing (albedo) and as a feedback via the water vapor cycle, see Willis: Further Evidence for my Thunderstorm Thermostat Hypothesis
See the update I’ve posted.
– Anthony
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Bill Illis says:
This was actually already known, it just wasn’t widely known or promoted by the pro-AGW scientists for obvious reasons.
The climate models project that this -21 W/m2 (might be as high as -30 W/m2) and project that it will turn into -20 W/m2 in a doubling scenario. So it is projected as a net +1.0 W/m2 feedback, about half of the feedbacks shown by the IPCC in its most recent report.
This is an illogical result in that more clouds (also predicted) should be even more negative rather than less negative. Having this feedback be +2 W/m2 or -2 W/m2 will be a make or break feature in the global warming debate and, hence, the spirited response to Spencer and Braswell from Trenberth, Dessler and the Team.
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Criminogenic, were not in a permanent ice age for 2 reasons:
1. if CERN is correct, then the cloud cover varies by intensity of the sun’s activity
2. cooler = less evaporation = less available water vapor for creating clouds.
Thus, in clouds, we have a self-regulating system with the absolute setting determined by the input of the sun, the relative setting determined by water vapor availability.
So to net this all out, we have three recent peer-reviewed papers making the twofold case that (1) at the climate level cloud cover tends to reduce temps, (2) and as clouds are a more powerful actor than greenhouse gases, the temps will not go runaway-hot due to increased greenhouse gasses, CO2 in particular.
Is that right?
If the Earth gets warmer, then ocean evaporation increases, producing more clouds. Condensation of water vapor into rain releases heat into the upper atmosphere, where it is more easily radiated away into space.
As oceans get even warmer, they are more able to sustain hurricanes, which are POWERFUL mechanisms for transferring heat energy from ocean surfaces to the upper atmosphere.
If anything, global warming would have been beneficial. Warmer times equal more evaporation, more rain, and longer growing seasons for crops. Global cooling means shorter growing seasons, less rain (drought), and famine.
Whenever you see warming in history, prosperity follows. Cooling - generally famine and fall of civilizations.
That said, I’m surprised it took so long to figure out the role of clouds. It’s pretty much common sense.
That would seem to be self-limiting too. I heard Joe Bastardi explain that when the atmosphere warms up significantly it creates a shearing effect at high altitudes that keeps tropical storms from gaining the strength to become hurricanes. The climate systems of the earth are pretty well balanced.
Note: this topic is from 9/20/2011.Thanks Ernest_at_the_Beach.
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"I really don't know clouds at all." - Joni Mitchell (couldn't resist!)
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