More aggressive action is required to reduce soot emissions in a bid to achieve climate policy goals such as those set forth in last December’s Copenhagen Accord, says a study.
The Princeton University researchers assessed the climatic contribution of ‘carbonaceous aerosols,’ fine particulates emitted into the air, known as soot.
Soot is a term that refers to the impure carbon particles produced by the incomplete combustion of organic matter and comes from diesel engines and coal combustion to biomass cook stoves, crop burning and wildfires.
Soot has complex effects on the global climate when airborne or deposited on snow. It has two main components: black carbon and organic carbon.
Black carbon is dark and absorbs radiation, thus warming the atmosphere; organic carbon is light coloured and reflective, so tends to have a cooling effect.
Their effects on climate are complicated, in part because they depend on how they are mixed with other particles in the atmosphere, and in part because both types of aerosols can cool the climate through their effects on cloud formation.
Black carbon also warms the Earth’s surface when it falls on snow or ice.
‘Because of uncertainties in these many effects and because of differences in whether and how these effects get incorporated into various models, past studies of soot’s contribution to global warming have ranged widely,’ said Robert Kopp, post-doctoral researcher jointly in Princeton’s Woodrow Wilson School of Public & International Affairs and its Department of Geosciences.
‘We took several key studies, put them all on a common footing, and assessed what emerged,’ Kopp said.
Using four sets of highly cited but disparate studies that span the range of past estimates, Kopp and Denise Mauzerall, associate professor of environmental engineering and international affairs at Princeton, attempted to reconcile and standardise the results into one, common global metric.
‘Unfortunately, most climate change mitigation scenarios used in policy contexts have focused exclusively on heat-trapping gases,’ Mauzerall said, according to a university release.
These findings were published online in the Proceedings of the National Academy of Sciences.
Source: Geoscientists call for reducing soot emissions - southkoreanews.net
Date: 26 June 2010