Strange Rumblings in the Khumbu

Mountaineer and documentary film maker David Breashears has wryly referred to May as Everest Awareness Month. The world's highest peak was first summited by Sherpa Tenzing Norgay and Sir Edmund Hillary on May 29, 1953. These days, climbers on Everest and across the Himalayas are increasingly aware of rapid climate change in the region and the impact it has on their sport. As Ang Tsering Sherpa, president of the Nepal Mountaineering Association tells the BBC:

Climate change has made the weather conditions extremely unpredictable across the mountains. For example, in seasons when we don't normally expect any snowfall, we see heavy snowfalls. And in seasons when we expect heavy snowfalls, we have no snowfalls at all. We are worried.

Such unpredictable conditions can make an already risky venture all the more perilous, as in October 2005 when a massive avalanche on 6,981m-high Mount Ganguru took the lives of 18 expedition members. Ang Tsering Sherpa pointed to unseasonably heavy snowfall as the cause. "Normally we don't have snow in October."

The implications run far beyond mountaineering and expeditioning. Millions of people are sustained by glacial runoff from the Himalayas -- glaciers that are quickly disappearing.