Cut Soot to Slow Global Warming: Stanford Study

A reduction in soot output would start slowing the pace of global warming almost immediately given the magnitude of soot's contribution and the fact that it lingers in the atmosphere for only a few weeks before being washed out, says a new Stanford study.

According to author of the study, Mark Z Jacobson, director of Stanford's atmopshere/Energy program, the quickest and best way to slow the rapid melting of Arctic sea ice is to reduce soot emissions from the burning of fossil fuel, wood and dung.

His analysis shows that soot is second only to carbon dioxide in contributing to global warming. But, he said, climate models to date have mischaracterized the effects of soot in the atmosphere.

Because of that, soot's contribution to global warming has been ignored in national and international global warming policy legislation, he said.

"Controlling soot may be the only method of significantly slowing Arctic warming within the next two decades," says Jacobson in a report in Stanford News, "We have to start taking its effects into account in planning our mitigation efforts, and the sooner we start making changes, the better."

To reach his conclusions, Jacobson used an intricate computer model of global climate, air pollution and weather that he developed over the last 20 years that includes atmospheric processes not incorporated in previous models.

He examined the effects of soot – black and brown particles that absorb solar radiation – from two types of sources. He analyzed the impacts of soot from fossil fuels – diesel, coal, gasoline, jet fuel – and from solid biofuels, such as wood, manure, dung and other biomass used for home heating and cooking in many locations. He also focused in detail on the effects of soot on heating clouds, snow and ice.

What he found was that the combination of both types of soot is the second-leading cause of global warming after carbon dioxide. That ranks the effects of soot ahead of methane, an important greenhouse gas.

Jacobson's study will be published this week in Journal of Geophysical Research–Atmospheres.

For full report: Best hope for saving Arctic sea ice is cutting soot emissions, says Stanford researcher