Obama Looking at Cooling Air to Fight Warming

The 65-year-old physicist is far from alone in taking geoengineering seriously. The National Academy of Sciences is making it the subject of the first workshop in its new climate challenges program for policymakers, scientists and the public. The British Parliament has also discussed the idea. At an international meeting of climate scientists last month in Copenhagen, 15 talks dealt with different aspects of geoengineering.

John Holdren talks about his role as President Obama's science adviser during an interview with The...

John Holdren talks about his role as President Obama's science adviser during an interview with The Associated Press, in Washington, yesterday. Tinkering with Earth's climate to chill runaway global warming — a radical idea once dismissed out of hand — is being discussed by the White House as a potential emergency option.

(J. Scott Applewhite/AP Photo)

The American Meteorological Society is crafting a policy statement that says "it is prudent to consider geoengineering's potential, to understand its limits and to avoid rash deployment."

Last week, Princeton scientist Robert Socolow told the National Academy that geoengineering should be an available option in case climate worsens dramatically.

Holdren, a 1981 winner of a MacArthur Foundation "genius" grant, outlined these possible geoengineering options:

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— Shooting sulfur particles (like those produced by power plants and volcanoes, for example) into the upper atmosphere, an idea that gained steam when it was proposed by Nobel laureate Paul Crutzen in 2006. It would be "basically mimicking the effect of volcanoes in screening out the incoming sunlight," Holdren said.

— Creating artificial "trees" — giant towers that suck carbon dioxide out of the air and store it.

The first approach would "try to produce a cooling effect to offset the heating effect of carbon dioxide and other greenhouse gases," Holdren said.

But he said there could be grave side effects. Studies suggest that might include eating away a large chunk of the ozone layer above the poles and causing the Mediterranean and the Mideast to be much drier.

And those are just the predicted problems. Scientists say they worry about side effects that they don't anticipate.

While the idea could strike some people as too risky, the Obama administration could get unusual support on the idea from groups that have often denied the harm of global warming in the past.