Soot, a new variable, blamed in global warming

Black soot, generated by combustion of carbon-based materials and
emitted into the atmosphere, is making a significant contribution to
global warming, according to newly released research. Scientists from
the National Aeronautics and Space Administration say soot reduces the
reflectivity of snow and ice, creating a warming effect.

According to a press release Monday, soot on the snow and icefields of
the planet's higher latitudes means those regions absorb more of the
sun's energy than they otherwise would. The researchers at the
administration's Goddard Institute for Space Studies and Columbia
University's Earth Institute found that this effect had been
overlooked in previous studies of global warming, concluding that the
soot effect may account for as much as 25 percent of observed global
warming over the past century.

While soot on snow may be previously unrecognized in climate change
science, the researchers agree with the predominant view that carbon
dioxide and other greenhouse gases are the chief causes of global
warming.
Dr. James Hansen and Larissa Nazarenko, both of the Goddard
Institute, did the research.
"Black carbon reduces the amount of energy reflected by snow back into
space, thus heating the snow surface more than if there were no black
carbon," Hansen said.

Soot's increased absorption of solar energy is especially effective in
warming the world's climate. "This forcing is unusually effective,
causing twice as much global warming as a carbon-dioxide forcing of
the same magnitude," Hansen noted.

Hansen cautioned, although the role of soot in altering global climate
is substantial, it does not alter the fact greenhouse gases are the
primary cause of climate warming during the past century. Such gases
are expected to be the largest climate forcing for the rest of this
century.

The researchers found that observed warming in the Northern Hemisphere
was large in the winter and spring at middle and high latitudes. These
observations were consistent with the researchers' climate model
simulations, which showed some of the largest warming effects occurred
when there was heavy snow cover and sufficient sunlight.

In article <19faaec.0312240721.e9655db@posting.google.com>,
ilena@san.rr.com (Ilena) wrote:

Soot, a new variable, blamed in global warming



The title should be written, "Soot ***on snow***, a new variable blamed
in global warming". That is, "soot on snow" is just one other aspect of
environmental change brought about by the unrestrained discharge of
waste products from human activities into the atmosphere. India is a
major source of carbon contamination of the Indian Ocean which may be
affecting the frequency and intensity of seasonal rainfall.

Soot from jet engines is another important source of atmospheric air
pollution which is emitted with other pollutants like water vapor,in the
high troposphere and the low stratosphere where they have the potential
to both cool and warm the atmosphere. The result in either or both
cases is change, the effects of which are difficult to determine.

Jim Scanlon