Warming Triggers Alarming Retreat Of Himalayan Glaciers

Warming Triggers Alarming Retreat of Himalayan Glaciers


Glacial runoff in the Himalayas is the largest source of freshwater for northern India, and provides more than half the water to its most important river, the Ganges.

Glacial runoff also is the source of the headwaters for the Indus River in Pakistan, the Brahmaputra that flows through Bangladesh, the Mekong that descends through Southeast Asia, the Irrawaddy in Burma, and the Yellow and Yangtze rivers of China.

Scientists say 1.3 billion people reside in areas affected by glacial retreat, either in flood-prone areas or in locales that rely on year-round supplies of fresh water from glaciers rather than from the monsoon rainfall of only three or four months.

The retreating glaciers are occurring across an area that's the largest high-altitude land mass on the planet, bordered by the Himalayas to the south, the Tian Shan range to the north, and the Pamirs and the Karakorum mountains to the west.

Throughout the area, experts say, dwindling glaciers may lead to unstable mountainsides, greater sedimentation in rivers and disrupted irrigation systems, in addition to threatening water supplies to large populations.

China issued its first ever report on climate change in late December, saying average temperatures will rise two to three degrees Fahrenheit by 2020 and up to 6.4 degrees by the end of the century, unleashing more frequent "extreme weather events."

Scientists say glacial retreat will bring a feast-or-famine cycle to the Himalayas.

In the near term, accelerated glacial melting will bring a bonanza of water flow, perhaps even intense flooding, with great impact on biodiversity.

"The flooding events will scour the species that live in the river areas," said Dr. Lara Hansen, chief scientist for the global climate change program at the World Wildlife Fund. High-altitude plants and animals that are highly dependent on the glacial melt during the non-rainy season also will be affected, she added.

As climate change intensifies, she said, humans growing desperate for year-round water are likely to pay less attention to the needs of protecting biodiversity.

Small villages in Nepal, Bhutan, India and Pakistan that rely on glacier-fed water "are already feeling the pinch of this," Kulkarni said.

Far from the highest peaks in Tibet, large lakes fed by glacial runoff are rising by as much as 30 feet, experts said, submerging new areas and displacing some nomads. Experts say permafrost, or perennially frozen ground, is also beginning to melt.

"Sometimes when we camp out, we see water seeping up from the tent floor," said Bendo, a senior engineer with Remote Sensing Application Research Center of the Tibet Autonomous Region, who goes by only one name.

The Himalayas, with 17 percent glacial cover, have far more extensive glaciers than other ranges, such as the Alps, which have only a 2 percent cap of glacier and icepack.

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Photo Slideshow/The Roof Of The World Is Melting