The melting ice fields have also caused a dramatic increase in the number and size of glacial lakes that now risk bursting and devastating mountain communities, delegates at the conference said.

"If temperatures continue to rise as it is, then there will be no snow and ice in the Himalayas in 50 years time," said Surendra Shrestha, the regional director for the United Nations Environment Programme (UNEP)

Glaciers in the Himalayas, a 2,400-kilometre (1,500-mile) range that sweeps through Pakistan, India, China, Nepal and Bhutan, provide headwaters for Asia's nine largest rivers, a lifeline for the 1.3 billion people who live downstream.

But temperatures in the region have been increasing by between 0.15 and 0.6 degrees Celsius (0.27 and 1.08 degrees Fahrenheit) per decade for the last 30 years.

In Nepal, the Imja Glacier just south of Mount Everest has been retreating at a rate of about 70 metres (230 feet) per year, with the water forming huge glacial lakes.

"There are studies showing that the surfaces of some of these lakes have increased by 150 to 200 percent and there is a danger that these lakes will burst," said Andreas Schild, the director general of the International Centre for Integrated Mountain Development, the host of Monday's conference.

In the 1950s about 12 glacial lakes were recorded in Nepal.

"When the inventory was done in 2000 there were 2,400 lakes in Nepal. Out of these, lakes that are about to burst are about 14," the UN's Shrestha told reporters.

"If we were to have a very small earthquake, all that water is going to come down. Because of the altitude, as it comes down it will pick up debris and speed, it's like a big bulldozer that wipes everything out," said Shrestha.