This study is being listed as proof by some of the usual alarmist types that the issue of cloud feedback is settled. Before accepting that, read this from the summary in the June 24th issue of Science by Richard A. Kerr:
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.
Here’s the press release. I’ve looked at a few news writeups on it, and the caution listed in Science about it not being proven seems to be off the reporting radar. We’ll need further studies on a global scale, and not just one patch of ocean, before the question can be fully answered. – Anthony
This image shows unique cloud patterns over the Pacific Ocean of the coast of Baja California, an area of great interest to Amy Clement and Robert Burgman of the University of Miami and Joel Norris of Scripps Oceanography, as they study the role of low-level clouds in climate change. Credit: NASA
From Physorg.com
The role of clouds in climate change has been a major question for decades. As the earth warms under increasing greenhouse gases, it is not known whether clouds will dissipate, letting in more of the sun’s heat energy and making the earth warm even faster, or whether cloud cover will increase, blocking the Sun’s rays and actually slowing down global warming.
In a study published in the July 24 issue of Science, researchers Amy Clement and Robert Burgman from the University of Miami’s Rosenstiel School of Marine and Atmospheric Science and Joel Norris from Scripps Institution of Oceanography at UC San Diego begin to unravel this mystery. Using observational data collected over the last 50 years and complex climate models, the team has established that low-level stratiform clouds appear to dissipate as the ocean warms, indicating that changes in these clouds may enhance the warming of the planet. Read the rest of this entry »
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