Glacial Lakes

Charles Clover

The Telegraph, London

Calgary Herald
Wednesday, April 17, 2002

Lakes forming in the Himalayas and other mountain ranges because of global warming threaten the lives of tens of thousands of people, UN scientists warned Tuesday.

The lakes are being created - many where none existed in living memory - as glaciers retreat and high-altitude snowfields melt in response to a one-degree rise in temperatures over 25 years.

The study of lakes in Nepal and Bhutan, released by United Nations scientists in London, found that 44 were filling so rapidly that they were in danger of bursting within five to 10 years, sending millions of litres of water into populated valleys. There are 2,323 glacial lakes in Nepal alone.

There were no records of glacial lake "outburst floods" until one in Tibet in 1954, which flowed 50 kilometres into China. They were assumed to be events that occurred once in 500 years, but since the mid-1950S there have been others, the largest causing vast damage 110 kilometres away.

Surundra Shrestha, regional coordinator in Asia for the UN Environment Program's early warning study, said: "Our findings indicate that 20 glacial lakes in Nepal and 24 in Bhutan have become potentially dangerous through climate change."

"If we go to a geological time scale, this is a crisis. The ice has never been retreating at this rate," he added.

Work is underway to reduce the levels of only one of the critical lakes pinpointed by ground surveys and satellite images - the Tsho Rolpa lake, feeding the Rolwaling and Tama Koshi valleys of Nepal. It has grown from 0.23 square kilometres in the late 1950S to 1.4 square kilometres.

Pradeep Mool, a remote sensing expert with the International Centre for Integrated Mountain Development, based in Nepal, said: "A flood from this lake could cause serious damage down to the village of Tribeni, which is 67 miles (107 kilometres) downstream, threatening about 10,000 i lives, thousands of livestock, agricultural land, bridges and other infrastructure."