Scientists say soot a key factor in warming
Soot from diesel engines, coal-fired power plants and burning wood is a bigger cause of global warming than previously thought, and is the major cause of the rapid melting of the Arctic's sea ice, Stanford climate experts say.Flashback: South Asia Brown Cloud Is Homemade: Scientific American Podcast
In a report to be published Thursday in the Journal of Geophysical Research, Jacobson noted that soot particles - both black and brown carbon - come not only from burning fossil fuels in industry and transportation, but also from the immense quantities of wood and dung that are burned for heating and cooking throughout the developing world.
Controlling soot may be the only way to significantly slow Arctic warming over the next two decades, Jacobson said.
"We have to start taking its effects into account in planning mitigation efforts, and the sooner we start making changes, the better," he said.
James Hansen, a leading climate expert at NASA's Goddard Institute for Space Studies and an outspoken advocate of strong political action to combat global warming, agrees that soot is a major factor in the rapid melting of Arctic sea ice.
In an e-mail to The Chronicle, Hansen referred to soot particles as "dirty aerosols," saying that the melting of ice in the Arctic and worldwide is "usually attributed solely to global warming," and that the role of soot has not been adequately acknowledged.
The cloud contains black particles called carbonaceous aerosols—basically carbon soot. The team used radiocarbon analysis to figure out what parts of the soot come from biomass and what comes from fossil fuels. Biomass typically comes from burning forests for agriculture or burning wood in stoves. And fossil fuel particulates come from sources such as diesel engines or burning coal.
The investigators were surprised to discover that a large percentage of the soot, from almost half to two-thirds, comes from burning biomass like wood and dung for cooking and heat, rather than from coal power plants.