Special Report: Fight against Global Warming

    LOS ANGELES, March 25 (Xinhua) -- A new study by some U.S. scientists has found that black carbon plays a major role in global warming.

    Black carbon, a form of particulate air pollution most often produced from biomass burning, cooking with solid fuels and diesel exhaust, has a warming effect in the atmosphere three to four times greater than prevailing estimates, according to the study conducted by scientists at Scripps Institution of Oceanography at the University of California in San Diego (UCSD) and the University of Iowa.

    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 UCSD said in a press release on Tuesday.

    "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 UCSD atmospheric scientist V. 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."

    In the study, researchers integrated observed data from satellites, aircraft and surface instruments about the warming effect of black carbon and found that its forcing, or warming effect in the atmosphere, is about 0.9 watts per meter squared.

    That compares with estimates of between 0.2 to 0.4 watts per meter squared that were agreed upon as a consensus estimate in a report released last year by the Intergovernmental Panel on Climate Change (IPCC), a UN-sponsored agency that periodically synthesizes the body of climate change research.

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

    Elimination of black carbon, a contributor to global warming and a public health hazard, offers a nearly instant return on investment, the researchers said.

    Black carbon particles only remain airborne for weeks at most compared with carbon dioxide, which remains in the atmosphere for more than a century. In addition, technology that could substantially reduce black carbon emissions already exists in the form of commercially available products.

    The study will be published in the upcoming issue of the journal Nature Geoscience.