"Controlling soot may be the only method of significantly slowing Arctic warming within the next two decades," said Jacobson, a professor of civil and environmental engineering and director of Stanford's Atmosphere/Energy Program.
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 fuels and solid biofuels could reduce warming above parts of the Arctic Circle in the next 15 years by up to 1.7 degrees Celsius. For perspective, net warming in the Arctic has been at least 2.5 degrees Celsius during the last century and is expected to warm significantly more in the future if nothing is done.
He also found that soot emissions kill more than 1.5 million people prematurely worldwide each year and afflict millions more with respiratory illness, cardiovascular disease and asthma, mostly in the developing world, where biofuels are used for home heating and cooking.