Black carbon from India contributing in melting of Himalayan glaciers - - India News Times

In a new research, scientists have found that airborne black carbon aerosols from India are a major contributor to the decline in snow and ice cover on the Himalayan glaciers. Lawrence Berkeley National Laboratory scientist Surabi Menon and colleagues carried out the research. "Our simulations showed greenhouse gases alone are not nearly enough to be responsible for the snow melt," said Menon, a physicist and staff scientist in Berkeley Lab's Environmental Energy Technologies Division. "Most of the change in snow and ice cover-about 90 percent-is from aerosols. Black carbon alone contributes at least 30 percent of this sum," she added. Menon and her collaborators used two sets of aerosol inventories by Indian researchers to run their simulations. The actual contribution of black carbon, emitted largely as a result of burning fossil fuels and biomass, may be even higher than 30 percent because the inventories report less black carbon than what has been measured by observations at several stations in India. Previous studies have shown that black carbon can have a powerful effect on local atmospheric temperature. "Black carbon can be very strong. A small amount of black carbon tends to be more potent than the same mass of sulfate or other aerosols," Menon said. "We may be underestimating the amount of black carbon by as much as a factor of four," she said. Unlike other aerosols, black carbon absorbs sunlight, similar to greenhouse gases. But unlike greenhouse gases, black carbon does not heat up the surface; it warms only the atmosphere. This warming is one of two ways in which black carbon melts snow and ice. The second effect results from the deposition of the black carbon on a white surface, which produces an albedo effect that accelerates melting. Put another way, dirty snow absorbs far more sunlight-and gets warmer faster-than pure white snow. Black carbon, which is caused by incomplete combustion, is especially prevalent in India and China. Satellite images clearly show that its levels there have climbed dramatically in the last few decades. According to Menon's data, black carbon emitted in India increased by 46 percent from 1990 to 2000 and by another 51 percent from 2000 to 2010. "Carbon dioxide stays in the atmosphere for 100 years, but black carbon doesn't stay in the atmosphere for more than a few weeks, so the effects of controlling black carbon are much faster", Menon said. "If you control black carbon now, you're going to see an immediate effect," she added.