Himalayan glaciers are among the fastest retreating glaciers globally due to the effects of global warming, and this will eventually result in water shortages for hundreds of millions of people who rely on glacier-dependent rivers in China, India and Nepal, warns WWF, the global conservation organization.

A new WWF report, An Overview of Glaciers, Glacier Retreat and Subsequent Impacts in Nepal, India and China, reveals the rate of retreat of Himalayan glaciers accelerating as global warming increases. The report states that glaciers in the region now are receding at an average rate of more than 40 feet per year.

“The rapid melting of Himalayan glaciers will first increase the volume of water in rivers, causing widespread flooding,” says Jennifer Morgan, director of WWF's Global Climate Change Programme. “But in a few decades this situation will change and the water level in rivers will decline, meaning massive economic and environmental problems for people in western China, Nepal and northern India.”

Himalayan glaciers feed into seven of Asia's greatest rivers (the Ganges, Indus, Brahmaputra, Salween, Mekong, Yangtze and Huange He), ensuring a year-round water supply to hundreds of millions of people in the Indian subcontinent and China. As glacier water flows dwindle, the energy potential of hydroelectric power will decrease causing problems for industry, while reduced irrigation means lower crop production.

The report shows that three of Nepal's snow-fed rivers have shown declining trends in discharge. In China, the report notes, the Qinhai Plateau's wetlands have seen declining lake water levels, lake shrinkage, the absence of water flow in rivers and streams, and the degradation of swamp wetlands. In India, the Gangotri glacier, which supports one of India's largest river basins, is receding at an average rate of 75 feet per year.