Soot's role in climate warming examined

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DENVER, Aug. 31 (UPI) -- Cutting soot emissions from diesel engines and other sources could be the fastest, most economical way to slow global warming, a U.S. scientist says.

Mark Z. Jacobson says reducing soot could slow melting of sea ice in the arctic, considered by many as a tipping point for Earth's climate, a point of no return. That's because the ice, which reflects sunlight and heat back into space, would, as it melts, expose darker water that absorbs heat and makes global warming worse, he said at a meeting of the American Chemical Society in Denver.

Jacobson says his calculations show controlling soot could reduce warming above parts of the Arctic Circle by almost 3 degrees Fahrenheit within 15 years, virtually erasing all of the warming that has occurred in the region during the last 100 years, a society release reported Wednesday.

"No other measure could have such an immediate effect," Jacobson said. "Soot emissions are second only to carbon dioxide [CO2] in promoting global warming, but its effects have been underestimated in previous climate models.

"Soot emissions account for about 17 percent of global warming, more than greenhouse gases like methane.

"Soot's contribution, however, could be reduced by 90 percent in 5-10 years with aggressive national and international policies."

Decreasing soot could have a rapid effect, Jacobson explained, because unlike carbon dioxide, which remains in the atmosphere for years, soot disappears within a few weeks.