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
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
"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
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
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.