Soot is No. 2 global-warming culprit, study finds
From diesel engines to cow-dung cook fires, soot from inefficiently burned fuel has supplanted methane as the second most significant global-warming agent that humans are pumping into the air, according to an exhaustive review of more than a decade's worth of research on black-carbon soot emissions.
Carbon dioxide from burning fossil fuel and from land-use changes remains in the No. 1 spot. But the direct effect of soot on air temperatures, as well as its indirect effect on ice and snow melt and on cloud formation and persistence, are knocking at the door.
Given the uncertainties in the estimates, black-carbon soot may even outpace CO2's warming effect, according to the 232-page study published today in the Journal of Geophysical Research–Atmospheres.