Jacobson's study will be published this week in Journal of Geophysical Research (Atmospheres).
It is the magnitude of soot's contribution, combined with the fact that it lingers in the atmosphere for only a few weeks before being washed out, that leads to the conclusion that a reduction in soot output would start slowing the pace of global warming almost immediately.
Greenhouse gases, in contrast, typically persist in the atmosphere for decades some up to a century or more creating a considerable time lag between when emissions are cut and when the results become apparent.
Jacobson found that eliminating soot produced by the burning of fossil fuel and solid biofuel could reduce warming above parts of the Arctic Circle in the next fifteen years by up to 1.7 degrees Celsius. For perspective, net warming in the Arctic has been at least 2.5 degrees Celsius over the last century and is expected to warm significantly more in the future if nothing is done.
The most immediate, effective and low-cost way to reduce soot emissions is to put particle traps on vehicles, diesel trucks, buses, and construction equipment. Particle traps filter out soot particles from exhaust fumes.
Soot could be further reduced by converting vehicles to run on clean, renewable electric power.
Jacobson found that although fossil fuel soot contributed more to global warming, biofuel-derived soot caused about eight times the number of deaths as fossil fuel soot. Providing electricity to rural developing areas, thereby reducing usage of solid biofuels for home heating and cooking, would have major health benefits, he said.
Soot from fossil fuels contains more black carbon than soot produced by burning biofuels, which is why there is a difference in impact.
Black carbon is highly efficient at absorbing solar radiation in the atmosphere, just like a black shirt on a sunn
|Contact: Louis Bergeron|