Zeroing in on soot

Published: Saturday 31 March 2001

soot may be responsible for as much as 30 per cent of global warming, according to a study done by the researchers of Stanford University, Calfornia. Soot is emitted from fireplaces, diesel engines and jet engines. "Soot or black carbon may be responsible for 15-30 per cent of global warming, yet it is not even considered in any of the discussions about combating global warming," said Mark Jacobson, an assistant professor of civil and environmental engineering at the university who lead the study team. Until now, experts on global warming have placed most of the emphasis on reducing carbon dioxide and other greenhouse gases.

Jacobson's team found that carbon dioxide and soot cause global warming in different ways. While carbon dioxide absorbs the Earth's infrared radiation, soot absorbs solar radiation directly, adding to global warming. Tests revealed that soot also interfered with the reflectivity of aerosols or organic particles thereby reducing their cooling effect considerably. "Besides its impact on global warming soot is also bad for heath," claims Jacobson. Exposure to soot particles has been associated with respiratory illnesses and cancer.

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