Himalayan lakes 'expanding dangerously'

Lakes that have been forming near Mount Everest could threaten settlements downstream if they overflow.

Ponds on the surface of the Khumbu glacier in the Himalayas have expanded and joined together to form larger bodies of water.

Climbers need to cross the glacier, including the treacherous Khumbu Icefall, to climb the mighty peak.

The accelerated meltdown of glaciers in the region is causing concern against a backdrop of rising global temperatures.

Scientists say the warning is the first of its kind for Khumbu, although other glaciers in the Himalayas have seen an increase in the number of lakes formed.

Such newly formed glacial lakes can overflow causing flooding, and with it loss of life and damage downstream.

This is the first scientific team to visit the region after the devastating earthquake last April.

"A decade or so ago, there were individual ponds on the Khumbu glacier but in the past five years or so they have begun to get larger and join up," said Ann Rowan, who led the field study team from the universities of Sheffield and Leeds.

Dr Rowan's team has been studying the behaviour of debris-covered glaciers, focusing on Khumbu.

"Particularly, on the left hand side of the lower reaches of the glacier, there is a series of about seven or eight large ponds that are now starting to link and form a big chain," she told the BBC.

"There is water flowing from the upper part of the glacier through the series of these ponds and that is going to encourage them to join up.

"At present, the glacier appears to be disintegrating, and may form a few large and potentially hazardous lakes on the glacier surface."

Dr Rowan's team has studied satellite images of the Khumbu glacier dating back 15 years and has also conducted three ground surveys since 2009.

The scientists found that parts of the lower region of the debris-covered glacier have been shrinking because of loss of ice underneath. This has allowed the formation and expansion of water bodies.

The Dig Tsho glacial lake in the Khumbu valley burst in 1985, destroying a hydropower plant and other infrastructure downstream.

According to the United Nations Environment Programme (Unep), there have been at least 35 events of glacial lake outbursts in Nepal, Pakistan, Bhutan and China over the past century.