Atmospheric soot may not have nearly as much climate warming potential as previously thought.
Tiny carbon particles produced by biomass burning and incomplete combustion of fossil fuels absorb sunlight, warming the planet. Xuan Wang at the Massachusetts Institute of Technology in Cambridge and his colleagues used a refined chemical transport model, along with actual observations, to study black-carbon behaviour.
They found that previous simulations have substantially overestimated concentrations of soot in remote regions as well as its global lifetime, leading to higher estimates of its warming potential. The authors conclude that the direct warming effect of black carbon might be less than one-quarter of the previously reported value.
Policies aimed at reducing black-carbon emissions could have only a limited impact on mitigating climate warming, the team cautions.