Warming Planet May Cause Fewer High Clouds in Tropics, Allowing Heat to Escape into Space
"A technician at a Department of Energy site in Oklahoma launching a weather balloon to help scientists analyze clouds." Source of caption and photo: online version of the NYT article quoted and cited below.
(p. A1) Richard S. Lindzen, a professor of meteorology at the Massachusetts Institute of Technology, is the leading proponent of the view that clouds will save the day. His stature in the field -- he has been making seminal contributions to climate science since the 1960s -- has amplified his influence.
Dr. Lindzen says the earth is not especially sensitive to greenhouse gases because clouds will react to counter them, and he believes he has identified a specific mechanism. On a warming planet, he says, less coverage by high clouds in the tropics will allow more heat to escape to space, (p. A14) countering the temperature increase.
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Dr. Lindzen accepts the elementary tenets of climate science. He agrees that carbon dioxide is a greenhouse gas, calling people who dispute that point "nutty." He agrees that the level of it is rising because of human activity and that this should warm the climate.
But for more than a decade, Dr. Lindzen has said that when surface temperature increases, the columns of moist air rising in the tropics will rain out more of their moisture, leaving less available to be thrown off as ice, which forms the thin, high clouds known as cirrus. Just like greenhouse gases, these cirrus clouds act to reduce the cooling of the earth, and a decrease of them would counteract the increase of greenhouse gases.
Dr. Lindzen calls his mechanism the iris effect, after the iris of the eye, which opens at night to let in more light. In this case, the earth's "iris" of high clouds would be opening to let more heat escape.
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"If I'm right, we'll have saved money" by avoiding measures to limit emissions, Dr. Lindzen said in the interview. "If I'm wrong, we'll know it in 50 years and can do something."
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"You have politicians who are being told if they question this, they are anti-science," Dr. Lindzen said. "We are trying to tell them, no, questioning is never anti-science."
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(Note: the online version of the article is dated April 30, 2012.)