Sunday, February 03, 2008

Saving the Himalayas

The upper Himalayas in Nepal and Bhutan are sprinkled with lakes formed by retreating glaciers. As the temperature rises, due to global warming,the lakes are getting bigger while the glaciers are receding. The consequences could be catastrophic.

In 1985 a natural earthen dam holding back the waters of Dig Tsho lake near Mt Everest burst. In four hours the entire lake, about ten million cubic meters of water, had gushed out drowning a hydro power dam and washing away scores of bridges and roads downstream.

The International Center for Integrated Mountain Development (ICIMOD) in Katmandu estimates that 15 glacial lakes have burst in recent years or an average of one every two to five years. It figures another 20 or so are candidates for GLOF – Glacial Lake Outburst Flooding.

The one that everyone is watching is Tsho Rolpa, northeast of Katmandu. A mere pond 50 years ago, the lake has grown to be 3.5 kilometers long and 500 meters wide, according to the last survey.

The Nepalese Ministry of Environment, Science and Technology estimates that if the moraine holding back the water did burst, it would release something like 100 million cubic meters of water. Within minutes the flood would engulf a village 10 kilometers downstream where a few hundred Nepalese tend yaks and sheep.

For more than 30 years scientists at Nagoya University in Japan have been surveying Nepal’s glaciers in cooperation with the Nepalese government. Their latest mission took place late last year. The main purpose of that mission, said Koji Fujita, associate professor of glaciology, was to establish a basis for satellite mapping.

This recognizes that traditional survey methods, such as aerial surveys or even ground mapping are not up to the task. There are simply too many lakes – some 2,323 to be exact – and more than 3,000 glaciers to keep track of. And with the warming climate, they are constantly growing.

This time, given global warming’s higher profile as a public concern, the Asahi Shimbun, one of Japan’s leading newspapers, sent a reporting team and an aerial surveillance aircraft to Nepal along with the scientists. The team flew to northeast Nepal to view lakes close to Mt Everest.

They found, among other things, that Inja Tsho lake, located not far from Everest, had expanded to about 2 kilometers in length and 600 meters in width since 2002 when the Nagoya University team last surveyed the lake.

The reporters also met with Nepal’s Prime Minister Prasad Koirala, who urged Japan to do more to help prevent glacial lake flooding in the Himalaya, by forming a joint GLOF institute with Nepal.

Draining lakes as they expand is one obvious though expensive and uncertain solution. With funds from the World Bank, “the Nepalese government began a difficult draining of Tsho Rolpa lake, but they succeeded in lowering the lake level by only three meters. This is not enough to prevent GLOF,” Fujita said.

Another solution would be a warming system, sort of like that is used for tsunamis. The trouble is that the triggering events are unpredictable and the consequences develop rapidly. The Dig Tsho flood was triggered by an avalanche that created a tidal wave that overpowered the moraine causing the dam to burst.

Such efforts were also hampered by Nepal’s deadly communist insurgency. In the 1990s Nagoya University teams visited Nepal on average twice a year, but the visits diminished during the early 2000s, the years before a truce with the government was negotiated.

Reporters from the Asahi Shimbun walked along the river originating from Tsho Rolpa said that all of the solar panels that the government had installed to power warning devices were gone. “Local people said that the communists took them; others said that the locals did,” Fujita said.

Just how much the growth of glacial lakes in Nepal is a direct consequence of global warming is difficult to say with precision, Fujita noted cautiously. Many lakes began expanding in the 1950s, before people thought in such terms.

Accurate instruments to monitor temperatures in the higher elevations (3,000 meters plus) have only been in place for the past 10 years. The Chinese have had weather monitoring station on the Tibetan Plateau for far longer, and they report a general warming trend. The consensus seems to be that temperatures are rising about six tenths of one percent of a degree of Centigrade per decade.

Fujita pointed out that the problem of GLOF in the Himalayas is exacerbated by local weather patterns. It makes a difference, he points out, whether precipitation falls on glaciers as rain or snow. A covering of snow, tends to reflect sunlight and inhibit melting in winter while restoring some of the bulk lost to summer melting.

The glaciers in Alaska and Greenland, though receding, benefit from a more normal winter-summer cycle of snow and rain. In Nepal the Indian monsoon reigns, bringing more rain and less snow, especially as temperatures rise. "That's why the Himalayan glaciers are so sensitive to global warming,” Fujita said.

While not mentioning the GLOF problem directly, Prime Minister Yasuo Fukuda made global warming the subject of his speech in late January to the World Economic Forum in Davos, Switzerland. He plans to make it the centerpiece at the G8 summit this summer, which Japan is hosting in Hokkaido.

He set forth an initiative to curb greenhouse emissions including country-by-country carbon dioxide emission reductions. He also proposed that Japan provide $10 billion in financial assistance to help developing countries, namely China and India, to promote emission curtailment in a way that is compatible with economic growth.


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