Clouds of pollution threaten glaciers, health

A dirty brown haze sometimes more than a mile thick is darkening skies not only over vast areas of Asia, but also in the Middle East, southern Africa and the Amazon Basin, changing weather patterns around the world and threatening health and food supplies, the U.N. reported Thursday.

The huge smog-like plumes, caused mainly by the burning of fossil fuels and firewood, are known as "atmospheric brown clouds."

When mixed with emissions of carbon dioxide and other gases blamed for warming the earth's atmosphere like a greenhouse, they are the newest threat to the global environment, according to a report commissioned by the U.N. Environment Program.

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One of the most serious problems, Ramanathan said, is retreat of the glaciers in the Himalaya and Hindu Kush and in Tibet. The glaciers feed most Asian rivers and "have serious implications for the water and food security of Asia," he said.

Monsoon rains over India and southeast Asia decreased between 5 and 7 percent overall since the 1950s, the report says, naming brown clouds and global warming as a possible cause. Likewise, they may have contributed to the melting of China's glaciers, which have shrunk 5 percent since the 1950s. The volume of China's nearly 47,000 glaciers has fallen by 3,000 square kilometers (1,158.31 square miles) in the past 25 years, according to the Chinese Academy of Sciences.

Soot winds up on the surface of the glaciers that feed the Ganges, Indus, Yangtze and Yellow rivers, which makes the glaciers absorb more sunlight and melt more quickly and also pollutes the rivers, the researchers say.

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