Tibetan glacial shrink to cut water supply by 2050

Timothy Gardner, Reuters 16 Jan 09;

NEW YORK (Reuters) - Nearly 2 billion people in Asia, from coastal city dwellers to yak-herding nomads, will begin suffering water shortages in coming decades as global warming shrinks glaciers on the Tibetan Plateau, experts said.

The plateau has more than 45,000 glaciers that build up during the snowy season and then drain to the major rivers in Asia, including the Yangtze, Yellow, Brahmanputra and Mekong.

Temperatures in the plateau, which some scientists call the "Third Pole" for its massive glacial ice sheets, are rising twice as fast as other parts of the world, said Lonnie Thompson, a glaciologist at Ohio State University, who has collected ice cores from glaciers around the world for decades.

As glaciers melt at faster rates from the higher temperatures, a false sense of security about water supplies has developed across Asia, Thompson said on Friday.

If melting continues at current levels, two-thirds of the plateau's glaciers will likely be gone by 2050, he said at a meeting on climate change at the Asia Society in Manhattan.

Well before then, a threshold will have been hit in which people who depend on the water will start to start to see supplies dwindle.

"The scary thing is that a lot of structures, cities and lifestyles that have been developed in the region over the last 100 years were based on an abundance of water," Thompson said,

Nearly 2 billion people in China, India, Pakistan, Bangladesh and Bhutan would be hit by water shortages as the rivers slow, Geoff Dabelko, director of the environment and security program at the Woodrow Wilson International Center for Scholars in Washington, said by telephone.

Nomads in the Himalayas are at risk as deserts have already encroached on grasslands for yaks, on which they depend for most of their food, said Michael Zhao, a filmmaker who has worked in the region.

Shortages could also hit coastal cities in eastern China that would be affected by rising seas from the melt.

At worst, the shortages could lead to new wars in the region over scarce resources, Robert Barnett, a professor of Tibetan studies at Columbia University, said at the meeting.

Dams to contain the melted water can help in certain cases, but are generally a poor solution because they often face opposition from local residents and people in countries and regions downstream from the structures, Thompson said.

A global agreement to cut greenhouse gases emitted by smokestacks and tailpipes as well as the burning of forests could eventually help slow the melting, the experts said.

(Reporting by Timothy Gardner; Editing by Peter Cooney)