APP Document Black Soot
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Black soot, or black carbon, is generated from automobile traffic like diesel trucks and buses, industrial processes with inefficient combustion, outdoor fires, and household burning of fuels with incomplete combustion. Nearly 80% of black soot emissions come from developing countries. Black soot particles absorb sunlight and heat the atmosphere, modify cloud properties, and increase the albedo and heat absorption of snow and ice. Some studies have proposed that black soot may be the second most important greenhouse gas after CO2 and responsible for 25% of observed global warming over the past century.
APP Document Black Soot
- 1. (E7Q A ~~~Black Soot * Black carbon or soot is generated from o automobile traffic, primarily from diesel trucks and buses; o industrial processes with inefficient combustion; o outdoor forest fires and the burning of fields in the tropics; and o household burning of coal and biomass fuels. * Emissions are large in areas where cooking and heating are done with wood, field residue, cow dung and coal, at a low temperature that does not allow for complete combustion. o Nearly 80% of black soot emissions come from developing countries (Streets et al., Journalof Geophysical Research, December 2004) * The resulting soot particles o absorb sunlight directly, heating the atmosphere o indirectly affect climate through modifying cloud radiative properties (more black soot means smaller, more reflective clouds and cooling) o increase the albedo and heat absorption of snow and ice-covered surfaces * Black soot has been proposed as possibly the second most important greenhouse species after CO 2 (see below), though that view has been challenged within the scientific community. o According to one computer simulation by NASA scientist Jim Hansen, black soot may be responsible for 25% of observed global warming over the past century. 41 ~~~~Climate rordungs (Wm) 1850 - 20 + l b 01 A1 M o A F dd c d l Aerusk DUM Ctoud Cuter (02 (ZI14 Thp- 0$0,4 Carboo Mhn~e~b4)hB)I tmdlircdCi INtt a stralospheric dirty dnudx & .1 IA a oiw Oj) j _2 water uvapor (iodired vin snOW Cfrhet$) C 4~ ~Iarn) str~l'upheric '2 ~~~~~~oz-one -irpopvi Aerosok-l~ j4- ~Greenhouse Gawse -1 - Other Anthropntgeniic Foriavgs ----- J f4Naturul rfnrcingsH Source: NASA Press Release, January 2002, http://www.gsfc.nasa.gov/gsfc/eartlh/pictures/hansenOI0302/figure2m~gif