The World Wide Fund for Nature (WWF) said efforts by local and international agencies earlier this year reduced the risk of the brimming Thorthormi Tsho lake in the Himalayas flooding a valley.

"The story of Thorthormi lake is shaping up to be a story of successful adaptation to climate change," Tariq Aziz, who heads WWF's Living Himalayas Initiative, said in a statement.

"It is also a story of the risks that climate change is building for communities and the costs and complexities of successful adaptation work," he added.

A breach in the lake, perched at 4,428 metres (14,612 feet) above sea level, would be catastrophic, the environmental group warned.

"The prospect is frightening," WWF said, recalling a smaller glacial lake burst in the same region in 1994 that left 20 people dead and caused havoc.

The Bhutanese government with the help of the United Nations Development Programme, WWF, an Austrian agency and local volunteers partly drained the lake and lowered its level by 86 centimetres (2.80 feet).

The target is to lower Thorthormi's level by five metres in three years.

On December 7, world leaders will gather in Copenhagen for a United Nations climate conference that will work to frame a major new deal for tackling global warming and its impacts beyond 2012.

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