2010-08-31 11:38:00Is anyone game to tackle the clouds feedback argument?
James Wight

jameswight@southernphone.com...
58.105.164.221

In a recent comment, KR made this suggestion:

"I've been seeing the skeptic argument that 'the clouds are a huge negative feedback' for some time; from the Lindzen 'iris' effect to JoNova's web site, etc. This is essentially a "It won't happen" argument regarding AGW. Should we have a topic to discuss that here on SkepticalScience?"

I don't know enough about the subject to write a rebuttal - anybody else want to have a go?

2010-08-31 12:53:34I think we have a volunteer
John Cook

john@skepticalscience...
124.186.162.78

You know when they ask for a volunteer and everyone else steps backwards and there's one guy left standing out in front? James, you're that guy :-)

Seriously though, if noone does jump forward, perhaps everyone could paste useful resources on this topic - links to peer-reviewed papers, other blog posts, etc.

2010-08-31 12:58:04Comment
Robert Way

robert_way19@hotmail...
142.162.188.138
Roy Spencer just got a paper through review and published in GRL i think which aims to show that the cloud feedbacks are negative and that models have predicted wrongly by saying positive...
2010-08-31 17:36:16
Ari Jokimäki

arijmaki@yahoo...
192.100.112.202

Ok, since John asked for it, here goes:

Papers on cloud feedback:

http://agwobserver.wordpress.com/2009/10/26/papers-on-cloud-feedback-observations/

Papers on global cloud cover:

http://agwobserver.wordpress.com/2009/09/10/papers-on-global-cloud-cover-trends/

Huang & Ramaswamy (2008):

http://www.people.fas.harvard.edu/~yhuang/research/2008GL034859.pdf

Basically the situation here is that global cloud cover measurements show either positive cloud feedback or no feedback. To get a positive cloud feedback, you need to decrease low level clouds and/or increase high level clouds. There are some measurements of low level cloud cover decrease but most of that comes from ISCCP cloud data, which I don't think is trustworthy:

http://agwobserver.wordpress.com/2010/01/20/isccp-problems/

I haven't seen a single paper suggesting a long term increase in low level clouds which would be indicative of negative cloud feedback (low level cloud increase = more sunlight reflecting clouds). We just have some suspicious evidence of long term decrease in low level clouds. Some studies have found zero long term trends. One rather new study is the Clement et al. (2009) who correct for the ISCCP problem, use also other cloud data, and find positive cloud feedback. That's only regional study, though.

Curiously enough, I have seen same people arguing for the "it's clouds" argument (low level cloud cover has decreased in ISCCP data which then means that clouds have caused global warming) and then for the infrared iris (when it warms, cloud cover increases so more sunlight is reflected). Papers on Infrared iris:

http://agwobserver.wordpress.com/2009/11/13/papers-on-the-iris-hypothesis-of-lindzen/

On Lindzen & Choi:

http://agwobserver.wordpress.com/2009/12/05/comments-on-lindzen-choi-2009/

On Spencer & others:

http://agwobserver.wordpress.com/2010/04/22/on-quick-feedback-determinations/

To me it seems that negative cloud feedback can pretty much be ruled out based on the observations. Also, the papers suggesting negative feedback seem to be either badly flawed or(/and) using methods not suited to climate feedback analysis.

2010-09-01 01:03:34
doug_bostrom

dbostrom@clearwire...
184.77.83.151

Interesting to look at the rate of publications on this. G-Scholar restricted to closely related domains and excluding cites shows 43,500 hits on "cloud feedback," w/14,700 since 2005, 8980 in the past 2 years. 

So pretty intense ongoing scrutiny but nothing has apparently been revealed that is so earth-shaking as to appear simultaneously on such places as WUWT and in the popular scientific media.

I dropped a request on RealClimate a month or so ago for a general update on this matter but RC is a fickle oracle, no way of telling if they'll revisit the topic.  

2010-09-07 06:28:24
doug_bostrom

dbostrom@clearwire...
184.77.83.151

Fresh general discussion of cloudiness of cloud feedback here:

 http://e360.yale.edu/feature/the_effect_of_clouds_on_climate_a_key_mystery_for_researchers/2313/