Thousands of glaciers in the Himalaya mountains are the source of water for nine major Asian rivers whose basins are home to 1.3 billion people, including Pakistan and parts of India and China.

The melting causes lakes to form at the base of glaciers, which may then break their banks and flood down the valleys. "When the glaciers recede there's a growing danger of glacial dams collapsing," Marton-Lefevre said. "The effect will be very dramatic."

"There's a lot of poor people living at the foot of the Himalaya," she said.

Marton-Lefevre said it could take decades to slow down the process of global warming, but hoped it would be possible.

There is now a greater commitment from businesses and governments to cutting emissions, as scientific studies, extreme weather and climate campaigning have all raised awareness of the problem. About 190 nations agreed in December in Bali, Indonesia, to launch negotiations on a new pact to fight global warming.

"I'm concerned about how difficult this road map is going to be, and then there are some recalcitrant countries, like the United States," Marton-Lefevre said.