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Global Warming Fills Glacial Lakes to Bursting GENEVA, Switzerland, April 19, 2002 (ENS) - At least 44 glacial lakes high in the Himalayas are filling so rapidly they could burst their banks in as little as five years, an international team of scientists has found. Scientists with the United Nations Environment Programme (UNEP) and the International Centre for Integrated Mountain Development (ICIMOD), and their colleagues from Nepal and Bhutan, are warning that the lakes could overflow, sending millions of gallons of deadly floodwaters swirling down valleys, putting at risk tens of thousands of lives.
The lakes are rapidly filling with icy water as rising temperatures in the high mountains accelerate the melting of glaciers and snowfields that feed them. Surendra Shrestha, regional coordinator in Asia for UNEP's Division of Early Warning and Assessment, said, "Our findings indicate that 20 glacial lakes in Nepal and 24 in Bhutan have become potentially dangerous as a result of climate change." The newly issued study began in 1999 and is based on topographic maps, aerial photographs and satellite images from Landsat, Spot and IRS spacecraft. The survey has identified 3,252 glaciers and 2,323 glacial lakes in Nepal and 677 glaciers and 2,674 glacial lakes in Bhutan. The data indicates that the glaciers in Bhutan are retreating at a rate of 30 to 40 metres (100 to 131 feet) a year. In some areas the retreat is even faster. The Tradkarding Glacier, which feeds the Tsho Rolpa glacial lake in Nepal's Rolwaling Valley, retreated 100 meters (328 feet) in some of the years within the last decade. Besides the 44 lakes identified as as dangerous, more glacial lakes, as yet unexplored, could also be filling rapidly. "These are the ones we know about," said Shrestha. "Who knows how many others, elsewhere in the Himalayas and across the world, are in a similar critical state?" Glacial Lake Outburst Floods are not a new phenomenon, but there is evidence that the frequency of such events has risen over the past three decades. In August 1985, a sudden outburst flood from the Dig Tsho glacial lake in Nepal destroyed 14 bridges and $1.5 million worth of damage was caused to the nearly completed Namche Small Hydropower Plant. Data collected from 49 climate monitoring stations in Nepal reveals a clear increase in temperature since the mid-1970s, with highest temperatures found at higher altitudes. On average, air temperatures here are one degree Celsius higher than in the 1970s rising by 0.06 degrees Celsius per year. People are at risk if any of the lakes overflows, and so are many millions of dollars worth of property, tourism facilities, trekking trails, roads, bridges and hydroelectric plants which are the economic life blood of many countries in the region.
The study was released as the Intergovernmental Panel on Climate Change (IPCC) convenes in closed session this week in Geneva. The panel of eminent climate scientists was jointly created by UNEP and the World Meteorological Organization to advise the United Nations and governments on global warming. Klaus Toepfer, executive director of UNEP, said, "Mountains were once considered indomitable, unchanging and impregnable. But we are learning that they are as vulnerable as the world's oceans, grasslands and forests to environmental threats and insensitive, unfettered, development." "The findings from our joint studies in the Himalayas, the roof of the world, reveals the extent of a new, and alarming, threat," Toepfer said. "It is not just the risk to human lives, agriculture and property that should worry us. Mountains are the world's water towers feeding the rivers and lakes upon which all life depends." "If the glaciers continue to retreat at the rates being seen in places like the Himalayas, then many rivers and freshwater systems could run dry, threatening drinking water supplies as well as fisheries and wildlife. We now have another compelling reason to act to reduce emissions of carbon dioxide and other greenhouse gases," said Toepfer. Pradeep Mool, a remote sensing expert with ICIMOD, said work is underway to lower the water levels of one critical glacial lake pinpointed by on the ground surveys and new satellite images. This is the Tsho Rolpa Lake that feeds the Rolwaling and Tama Koshi valleys in the Dolakha District of Nepal. The researchers have found that, as a result of the melting of a nearby glacier, the lake has grown six-fold, from an area of 0.23 square kilometres (56 acres) in the late 1950s to one of 1.4 square kilometres (346 acres) now. "A flood from this lake could cause serious damage down to the village of Tribeni, which is 108 kilometers (67 miles) downstream, threatening about 10,000 human lives, thousands of livestock, agricultural land, bridges and other infrastructure, " said Mool. A high tech communications network of sensors and sirens has been linked from the lake to villages at risk from floodwaters. Engineering work is underway to lower the water levels at Tsho Rolpa by 30 metres (98 feet). Experts say money is needed urgently to carry out similar work on scores of other glacial lakes if catastrophes are to be averted.
"Part of our work is to help the governments of Nepal and Bhutan find and focus on potentially dangerous lakes, develop early warning systems, be able to warn communities of an impending Glacial Lake Outburst Flood, and to carry out engineering works to reduce the threats," said Shrestha. "Some donor country governments are backing our efforts, but much more aid is needed," said Shrestha. "Solving this problem is going to be costly because glacial lakes are situated in remote areas which are difficult to reach." The findings will be published this year, the United Nations International Year of the Mountains. UN officials hope the year will highlight the fragility and threats to these vital ecosystems from global warming, unsustainable tourism, pollution and other impacts. It is also hoped that the year will galvanize governments, industry, non-governmental organizations and the public to act to protect the world's precious mountain ranges for future generations. Climate change and other environment and development issues, including those affecting mountains, will be at the heart of the World Summit on Sustainable Development, scheduled to take place in Johannesburg, South Africa from August 26 through September 4. Copyright Environment News Service (ENS) 2002. All rights reserved. |
River of meltwater rushes down a mountainside in Bhutan (Two photos courtesy Department of Geology and Mines, Royal Government of Bhutan)
Glacial lake, Bhutan 
Tsho Rolpa Lake (Photo credit unknown)