A new study of the role played by pollution-filled 'brown clouds' over South Asia offers hope that the region may be able to stop some of the alarming retreat of Himalayan glaciers.
The glaciers provide a lifeline for billions of people by feeding the major rivers in the region, according to the United Nations Environment Programme.
The UNEP-supported analysis by researchers at Scripps Institution of Oceanography at the University of California, San Diego, found that the clouds containing soot, trace metals and other particles from a growing cadre of urban, industrial and agricultural sources enhance solar heating of the lower atmosphere by about 50 per cent.
The hope lies in reducing this pollution, which, combined with the heating effect of greenhouse gases, is enough to account for the retreat of Himalayan glaciers observed in the past half century, with serious implications for such famed rivers as the Yangtze, Ganges and Indus, the chief water supply for billions of people in China, India and other South Asian countries, the study noted.
"The main cause of climate change is the buildup of greenhouse gases from the burning of fossil fuels, but brown clouds, whose environmental and economic impacts are beginning to be unravelled by scientists, are complicating and in some cases aggravating their effects," UNEP Executive Director Achim Steiner said.
"The new findings should spur the international community to ever greater action, in particular at the next crucial climate change convention meeting in Indonesia this December.
"For it is likely that in curbing greenhouse gases we can tackle the twin challenges of climate change and brown clouds and in doing so reap wider benefits from reduced air pollution to improved agricultural yields," Steiner added.
The study, released by the UNEP, also appeared in the August 2 issue of Nature, the international weekly journal.
"The rapid melting of these glaciers, the third-largest ice mass on the planet, if it becomes widespread and continues for several more decades, will have unprecedented downstream effects on southern and eastern Asia," the study concluded.