Yak is still the main source of energy and food for villagers in Tibet. Greenpeace are in the area to study and document the deterioration of glaciers on Everest and the environmental implications of glacier melt. The Rongbuk Glaciers are one of the prime sources of water feeding into the major rivers of China and India. Glaciers in the Himalaya are receding faster than in any other part of the world as a result of global warming.