Himalaya Ice-Melt Threat Monitored in Nepal

James Owen
for National Geographic News
March 10, 2006
The Khumbu Glacier on href="">Mount Everest has
retreated more than three miles (five kilometers) from the time when
Edmund Hillary and Tensing Norgay famously set out to conquer the
world's highest peak in 1953.

Scientists have documented a similar trend in glaciers throughout the Himalaya, the mountain range that houses Mount Everest.

The range, which spans several Asian nations, is known as the Water Tower of Asia, since billions of people depend on its life-bringing flows.

But scientists fear that these water supplies could eventually dry up as the glaciers melt due to global warming.

Researchers have therefore installed an automatic weather station on the Himalayan Ngozumpa Glacier, the longest in Nepal (see map).

The unmanned station will record data, such as solar radiation, humidity, air temperature, wind speed, air pressure, and precipitation.

Changes in water flow caused by glacial melting will also be measured in a river fed by the 16-mile-long (25-kilometer-long) glacier.

Previously, scientists monitoring these mountain glaciers had to climb the icy peaks or rely on satellite images.

WWF, the international conservation group, donated the equipment for this project to the Nepalese government's Department of Hydrology and Meteorology.

"Taking this glacier as a pilot site we can predict what the implications are of climate change in the glacier environment," said Sandeep Chamling Rai, climate change officer for WWF's Nepal Program.

Rai says there are not enough automatic weather stations in Nepal "to give a clear picture of what is going on in the Himalayan region."

He adds that another station is soon to be installed on Mount Everest's Khumbu Glacier.

Busted Lakes

Last year WWF released a report warning that Himalayan glaciers are currently receding at an average rate of 33 to 50 feet (10 to 15 meters) per year.

In India (see map) the Gangotri Glacier, the source of the Ganges (or Ganga) River, is retreating at a rate of 75 feet (23 meters) annually.

The report also noted that air temperatures in the region have risen by 1.8°F (1°C) since the 1970s—twice as much as average warming in other northern hemisphere countries over the same time period.

WWF says environmental impacts associated with faster melting glaciers include an increased risk of flooding and landslides.

At least 20 glacier lakes in Nepal have grown to the point where they could potentially burst, according to a 2001 survey by the United Nations Environment Program.

Formed by accumulated meltwater, the overfilled lakes could suddenly discharge massive volumes of water, known as glacial lake outburst flooding (GLOF).

Such flooding can cause loss of life and widespread damage to villages, roads, bridges, and farmland.

"GLOF is a major threat in Nepal as a result of climate change," Rai, of the WWF Nepal Program, said.

"We have been seeing this quite often, and we feel that there will be more in the near future. Lots of glacier lakes are expanding in size."

From Flood to Drought

Jennifer Morgan, director of WWF's Global Climate Change Program, says glacial melting will also increase the volume of water in rivers, causing widespread flooding.

"But in a few decades this situation will change, and the water level in rivers will decline," she added.

Over time, as the glaciers become smaller, seasonal melt will decrease and contribute less water to annual river flows.

For example, researchers at the National Institute of Hydrology in Roorkee, India, estimate that reduced glacier meltwater would cut July-through-September river flow of the Ganges by two-thirds.

This decline would leave 500 million people and 37 percent of India's irrigated land short of water.

Himalayan glaciers also feed six other of Asia's great rivers—Indus, Brahmaputra, Salween, Mekong, Yangtze, and Huang Ho—putting communities across this region at risk of water shortages.

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