Black carbon: Big player in global warming

SAN DIEGO, March 25 (UPI) -- A U.S. study suggests black carbon produced by diesel exhaust, biomass burning and solid fuel cooking contributes more to global warming than thought.

University of California-San Diego researchers have found black carbon pollution has a warming effect in the atmosphere three to four times greater than prevailing estimates.

Scripps Institution of Oceanography atmospheric scientist Veerabhadran Ramanathan and University of Iowa chemical engineer Greg Carmichael have found soot and other forms of black carbon could have as much as 60 percent of the current global warming effect of carbon dioxide -- more than that of any greenhouse gas besides CO2.

The researchers also noted, however, mitigation would have immediate societal benefits in addition to the long-term effect of reducing greenhouse gas emissions.

"Observationally based studies such as ours are converging on the same large magnitude of black carbon heating as modeling studies from Stanford, Caltech and NASA," said Ramanathan. "We now have to examine if black carbon is also having a large role in the retreat of arctic sea ice and Himalayan glaciers as suggested by recent studies."

The researchers' findings appear online in the journal Nature Geoscience.