LAKES forming in the Himalayas and other mountain ranges because of global warming threaten the lives of tens of thousands of people, scientists warned yesterday.
They are being created - mostly 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 gallons of water into populated valleys.
There were no records of glacial lake "outburst floods" until one in Tibet in 1954, which flowed 30 miles 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 70 miles away.
Surundra Shrestha, regional co-ordinator in Asia for the UN Environment Programme'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."
Work is under way 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 now.
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 downstream, threatening about 10,000 lives, thousands of livestock, agricultural land, bridges and other infrastructure."
A network of sensors has been connected to the lake, giving people at least an hour's notice of flood. Engineering is under way to lower water levels by 30 metres, though the work is hampered by the altitude.