As the global climate warms, glaciers are melting into lakes, raising the possibility for damaging floods. One such lake in the Himalayas, known as Imja, could dump water, mud and rocks for miles around if it flooded. "We need action, and hopefully within five years. I feel our time is shorter than what I thought before," said geographer Teiji Watanabe of Japan's Hokkaido University. Other glacier lakes have been drained, but applying that technique at Imja would be challenging, said Cesar Portocarrero of Peru's national water agency.