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Climate Models Really Don’t Know Clouds At All
The first reliable analysis of cloud behavior over past decades suggests—but falls short of proving—that clouds are strongly amplifying global warming. If that’s true, then almost all climate models have got it wrong. On page 460, climate researchers consider the two best, long-term records of cloud behavior over a rectangle of ocean that nearly spans the subtropics between Hawaii and Mexico. In a warming episode that started around 1976, ship-based data showed that cloud cover—especially low-altitude cloud layers—decreased in the study area as ocean temperatures rose and atmospheric pressure fell. One interpretation, the researchers say, is that the warming ocean was transferring heat to the overlying atmosphere, thinning out the low-lying clouds to let in more sunlight that further warmed the ocean. That’s a positive or amplifying feedback. During a cooling event in the late 1990s, both data sets recorded just the opposite changes—exactly what would happen if the same amplifying process were operating in reverse.
CRN comment: I ‘like’ the alarmist terminology – negative feedback is described as ‘an amplifying process operating in reverse.’ This sounds rather like Richard Lindzen’s proposed ‘Iris Effect.’
Clouds Appear to Be Big, Bad Player in Global Warming
Richard A. Kerr
Science 24 July 2009:
Vol. 325. no. 5939, p. 376
DOI: 10.1126/science.325_376
Roy Spencer: ‘New Study in Science Magazine: Proof of Positive Cloud Feedback?’