By Rob Jordan

Scientists have long known that black carbon, particles emitted into the atmosphere by burning diesel fuel, biomass and other solid fuels, contributes to global warming. Most previous estimates of the soot component’s heat-trapping power, however, have been off by a factor of almost three, according to a new study co-authored by Stanford Woods Institute Senior Fellow Mark Jacobson.

The study calls black soot the “second most important human emission in terms of its climate-forcing in the present-day atmosphere,” behind only carbon dioxide. Unlike carbon dioxide, which lingers in the atmosphere for decades, black carbon generally stays in the air for seven to 10 days. Therefore, controlling black carbon emissions is the fastest method of slowing Arctic sea ice loss and global warming. Such controls could also improve human health, according to Jacobson, who said that black carbon causes over a million premature deaths each year.

Jacobson expressed hope that the study will provide more momentum for including black carbon in climate change treaties and laws. “It has been ignored or passed over by most organizations involved in large treaties because of the dominant focus on greenhouse gases and the fear that focusing on black carbon will hurt legislation on greenhouse gases,” he said.

Methods of reducing black carbon include the use of particle traps on combustion devices and conversion to non-combusting technologies such as electric vehicles and heating technologies driven by electricity.

The comprehensive analysis uses climate models as well as field observations and measurements. It looks at a variety of factors such as solar heat absorbed by black carbon and effects of the particulate’s interaction with atmospheric chemicals, clouds and the earth’s surface. As such, the study’s results provide a meaningful baseline from which to improve future climate change estimates.