Kathmandu, April 6 -- In the spring of 2010, Pemba Gelje Sherpa crossed the dreaded Khumbu Icefall 14 times. The Icefall is the most treacherous part of the Khumbu glacier, fast-moving and ridden with crevasses and seracs. Each time Pemba, who was hired by an Everest expedition outfitter as a high-altitude climbing sherpa, walked on narrow ladders above the Icefall's many crevasses-some of them several metres deep and wide-he was carrying oxygen bottles, food, fuel and tents, all in the shadow of ice seracs, tall towers of ice that can collapse any time.

Pemba's job on the expedition was to set up the high camps for the Everest expedition that he worked for, above Everest Base Camp. Of the four high camps on Everest, the lowest, Camp 1, ...