Sharp reduction in black carbon emission can be a lifesaver
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Paris, France: Sharply reducing the amount of black carbon - commonly known as soot - in the atmosphere could help slow global warming and buy precious time in the long-term fight against climate change, according to a study released in the British journal, Nature Geoscience.
Curbing soot emissions could be a lifesaver.
Each year, more than 400,000 deaths among women and children in India alone, and 1.6 million worldwide, are attributed to smoke inhalation during indoor cooking using biofuels such as wood or dung, one of the primary sources of black carbon, according to the World Health Organisation. Reviewing dozens of recent scientific studies, two researchers in the United States calculated that black carbon is the second largest contributor to global warming after carbon dioxide, a by-product of burning fossil fuels. In addition, the eight million metric tonnes of soot released into the atmosphere every year have created a number of “hot spots” around the world, contributing significantly to rising temperatures. 35% black carbon output from China, India The plains of South Asia along the Ganges River and continental East Asia are both such hotspots, in part because up to 35% of global black carbon output comes from China and India. Emissions in China alone doubled between 2000 and 2006, according to the study, published in 2006. Fine black soot settling on snow and ice - and thus trapping more of the sun’s radioactive force - have also accelerated the melting of glaciers in the Himalayas and ice cover in the Arctic, two regions that have been hit especially hard by climate change in recent decades. “A major focus on decreasing black carbon emissions offers an opportunity to mitigate effects of global warming trends in the short term,” the authors conclude. While the presence of black carbon, sometimes in the form of great plumes several kilometres high called atmospheric brown clouds, has been known to scientists for some time, their impact on warming has been hard to assess. Direct measurement requires multiple aircraft flying over the same domain at different altitudes for an extensive period at the same time. Cut back soot output Significantly cutting back on black carbon emissions is not only possible, but would yield rapid benefits, say the authors, Veerabhadran Ramanathan of the Scripps Institute in San Diego, California, and Greg Carmichael of the University of Iowa. Forty percent of soot comes from the same sources as greenhouses gases, notably the burning of coal and oil, and will only be reduced as quickly or slowly as economies become less carbon intensive. Remaining 60% of black carbon in the atmosphere comes from the more easily altered practices of burning biofuels and forests, the authors say. Also, cutting back soot output would have an almost immediate effect. In South Asia, air pollution often forms a brownish haze. Ramanathan's previous research has indicated that the warming effects of this smog appear to be accelerating the melt of Himalayan glaciers that provide billions of people throughout Asia with drinking water. Unlike carbon dioxide, which lingers in the atmosphere for 100 years after it is released, black carbon has an atmospheric life cycle of approximately one week. “Providing alternative energy-efficient and smoke-free cookers, and introducing transferring technology for reducing soot emissions from coal combustion in small industries could have major impacts” on reducing soot’s role in global warming, they conclude. Such measures would result in a 70-80% reduction in heating caused by black carbon in South Asia, and a 20-40% cut in China, according to the study. The authors caution, however, that soot reduction can only help delay unprecedented climate change, which is due primarily to CO2 emissions. Ramanathan said that an observation program for which he is currently seeking corporate sponsorship could dramatically illustrate the benefits. Known as Project Surya, the proposed venture would provide some 20,000 rural Indian households with smoke-free cookers and equipped to transmit data. At the same time, a team of researchers led by Ramanathan would observe air pollution levels in the region to measure the effect of the cookers. Source: Mint and Environment News Service |
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