Black carbon
{{#badges: Climate change}} Black carbon, also called soot, arises from such sources as diesel engine exhaust, burning biomass, and cooking fires. It is made up of tiny carbon particles that, unlike greenhouse gases which absorb infrared heat radiation, actually absorbs the sun's heat waves, making it considered a growing factor in global warming. It is also an important component of air pollution around the world.[1]
To test the effect of black carbon on warming, UI College of Engineering Professors Greg Carmichael and Karl Kammermeyer conducted a study comparing ground-level air samples at Cheju Island, South Korea, with "purer" air sampled at altitudes between 100 and 15,000 feet above the ground. They found that the amount of solar radiation absorbed increased as the black carbon to sulphate ratio rose. Also, black carbon plumes derived from fossil fuels were 100 percent more efficient at warming than were plumes arising from biomass burning: "These results had been indicated by theory but not verified by observations before this work. There is currently great interest in developing strategies to reduce black carbon as it offers the opportunity to reduce air pollution and global warming at the same time," Carmichael said. The authors suggest that climate mitigation policies should aim to reduce the ratio of black carbon to sulphate in emissions, as well as the total amount of black carbon released.[1]
A 2010 USAID study identified black carbon as the second or third largest contributor to the current anthropogenic global warming, surpassed only by carbon dioxide and methane. Black carbon, however, has a much shorter average atmospheric residence time than carbon dioxide. It has been found that one kg of black carbon heats the atmosphere 500 to 680 times more than one kg of carbon dioxide over a 100-year time frame and 1,500 to 2,200 times over a 20-year time frame.[2]
The report also considered black carbon an agent for faster melting of ice in the Himalayas: "Black carbon directly heats the surface on which it is deposited and accelerates the melting of the Arctic sea and land ice, glaciers and seasonal snow covers. As per 2006 data, China is a dominant emitter of black carbon from combustion, accounting for 61 percent of all Asian emissions, followed by India at 12 percent and Indonesia at 6 percent.[2]
In a paper published in May 2008 in Nature Geoscience, Carmichael and Ramanathan found that black carbon soot from diesel engine exhaust and cooking fires -- widely used in Asia -- may play a larger role than previously thought in global warming. They said that coal and cow dung-fueled cooking fires in China and India produce about one-third of black carbon; the rest is largely due to diesel exhaust in Europe and other regions relying on diesel transport. The largest source of black carbon is the burning of biomass, especially forests and grasslands.[1]
Resources
References
- ↑ Jump up to: 1.0 1.1 1.2 "Black Carbon Implicated in Global Warming" Science daily, July 30, 2010.
- ↑ Jump up to: 2.0 2.1 Ramesh Prasad Bhushal, "Black carbon, a major culprit for climate change: Study" The Himalayan Times, May 2, 2010.
