Environmental Engineering Reference
In-Depth Information
Table 9.5
Combustion sources of black carbon
Source
Percentage
Open biomass (cooking and forest fi res)
42
Residential biofuel
18
Road transport (cars and trucks)
14
Nonroad transport (planes and ships)
10
Industry and power generation
10
Residential, coal and other
6
Source: Worldwatch Institute (2009).
dioxide in changing global air temperatures.
50 This may not be true in
Greenland because the island has little anthropogenic pollution.
Soot, or black carbon, is responsible for 18 percent of global warming,
second only to carbon dioxide as a greenhouse pollutant. In the Alps,
soot particles reduced the refl ecting power of the snow by 10 to 20
percent. Soot is the aerosol most responsible for the haze in rapidly
developing and heavily coal-burning countries such as China and India,
and it may be reducing the refl ecting ability of snow in the Himalayas
as it does in the Alps. In addition to its effect as individual particles, the
soot covers some of the sulfate aerosol particles, changing them from
refl ectors of sunlight into dark-colored absorbers of the long-wave radia-
tion emitted from earth's surface.
Soot has a very short life in the atmosphere, settling back to the
ground in a few days or weeks, so reducing its abundance would have
a rapid effect on global warming compared to a reduction in greenhouse
gases. NASA's study shows that the “strongest leverage” on reducing
global warming would be achieved by reducing emissions from domestic
fuel burning in developing countries, particularly in Asia, and by reduc-
ing surface transport emissions in North America, especially from diesel
engines. California, commonly a national leader in environmental
matters, enacted measures in December 2008 to force diesel-burning
trucks to fi t fi lters to reduce diesel soot emissions by 85 percent. 51
In December 2009 the Environmental Protection Agency formally
declared that carbon dioxide and other greenhouse gases were a threat
to human health and welfare. The declaration empowers the agency
to regulate these emissions and gives President Obama an important
tool if Congress fails to pass legislation to reduce global warming
emissions.
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