Mass death alert as Himalayan glaciers thaw

By PETER POPHAM in New Delhi

The giant glaciers of the Himalayas are melting so quickly that within five years dozens of glacial lakes may burst their banks, killing tens of thousands of people in their path, a United Nations report warns.

Researchers from the UN's Environment Programme, which has been monitoring the glaciers for the past 15 years, are deeply alarmed by the speed with which many lakes are filling up as glaciers shrink because of global warming.

Raphstreng Tsho glacial lake in Bhutan, for example, was 1.6km long, 0.96km wide and 80m deep in 1986.

Nine years later it is 1.94km long, 1.13km wide and 107m deep.

Surendra Shrestha, from the programme's Early Warning Division, said: "Our findings indicate that 20 glacial lakes in Nepal and 24 in Bhutan have become potentially dangerous as a result of climate change.

"Any one of these could, unless urgent action is taken, burst its banks in five to 10 years with potentially catastrophic results for people and property hundreds of kilometres downstream.

"These are the ones we know about. Who knows how many others, elsewhere in the Himalayas and across the world are in a similar critical state?"

The Tsho Rolpa lake in the Dolakha district of Nepal covered an area of 0.23kmsup2 in the late 1950s.

But today, with the melting of a nearby glacier, it has swollen to six times the size.

Pradeep Mool, a remote sensing expert with the International Centre for Integrated Mountain Development said: "A flood from this lake could cause serious damage down to the village of Tribeni, which is 108km downstream, threatening about 10,000 human lives, thousands of livestock, agricultural land, bridges and other infrastructure."

The warnings add a new dimension to the understanding of the multiple environmental hazards posed by climate change.

Although the deaths of nearby residents and the destruction of homes and farms will be the most immediate effects of such Glacial Lake Outburst Floods, or Glofs, as they are known, these are by no means the only hazard.

Klaus Toepfer, executive director of UNEP, said: "It is not just the risk to human lives, agriculture and property that should worry us. Mountains are the world's water towers, feeding the rivers and lakes upon which all life depends.

"If the glaciers continue to retreat at the rates being seen in places like the Himalayas, then many rivers and freshwater systems could run dry, threatening drinking water supplies as well as fisheries and wildlife.

"We have now another compelling reason to act to reduce emissions of carbon dioxide and other greenhouse gases."

Glofs have occurred in the past - one from the Dig Tsho glacial lake in Nepal in August 1985 destroyed 14 bridges and damaged a nearby hydroelectric plant - but now they pose a far more serious menace, the researchers say.

Engineers at Tsho Rolpa engineers have installed a network of sensors and sirens to give people living downstream enough warning to escape the rising waters.

They are also trying to lower the lake's level by 30m, to postpone the disaster.

But to tackle all the problem lakes will cost an enormous sum, warns UNEP.

"Solving this problem is going to be costly because glacial lakes are situated in remote areas which are difficult to reach," said Shrestha.

Toepfer said: "Mountains were once considered indomitable, unchanging and impregnable. But we are learning they are as vulnerable as the world's oceans, grasslands and forests."

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