Compiled by UNEP's Polar Research Centre GRID-Arendal and experts from research centers in Asia, Europe, Latin America and North America, the report says the larger glaciers may take centuries to disappear but many low-lying, smaller glaciers, which are often crucial water sources in dry lands, are melting much faster.
Glacial melt will change the lives of millions as over half of the world's population lives in watersheds of major rivers originating in mountains with glaciers and snow.
The valley of Chitral has always looked to the glaciers of Tirich Mir for water. Rising above 25,000 feet, Tirich Mir is the highest mountain in the Hindu Kush range. (Photo by Amina Tariq)
Glaciers in Argentina and Chile, followed by those in Alaska and its coastal mountain ranges, have been losing mass faster and for longer than glaciers in other parts of the world, finds the report, "High Mountain Glaciers and Climate Change - Challenges to Human Livelihoods and Adaptation."
The third fastest rate of loss is among glaciers in the northwest United States and southwest Canada.
Melting more slowly are glaciers in the high mountains of Asia, including the Hindu Kush region of the Himalayas, the Arctic and the Andes.
Europe's glaciers had been growing since the mid-1970s, but they began to lose mass around the year 2000, the report shows.
"These alarming findings on melting glaciers underline the importance of combating climate change globally. It sends a strong message to us as politicians and climate negotiators in Cancun," said Norway's Minister of the Environment and International Development Erik Solheim.
The red circles indicate floods from 2008-2010 in the Hindu Kush region and downstream. (Map courtesy UNEP Grid Arendal)
Solheim announced today that Norway will fully fund, with more than US$12 million, the five-year Hindu-Kush-Himalayas Climate Impact Adaptation and Assessment Programme from 2011.
"People in the Himalayas must prepare for a tough and unpredictable future. They need our committed support," said Solheim. "Therefore, Norway will fully fund the brand new five-year program. We see this program as a potent mix of solid climate science, promising intra-regional cooperation and concrete adaptation projects on the ground."
The initiative will be carried out by the Centre for International Climate and Environmental Research, the International Centre for Integrated Mountain Development and UNEP-Grid Arendal.
Overall, the trend is shrinking glaciers, but greater precipitation in some places has increased the mass and the size of glaciers in western Norway, New Zealand's South Island and parts of the Tierra del Fuego in South America.
"Accumulation of science shows us a clear general trend of melting glaciers linked to a warming climate and perhaps other impacts, such as the deposit of soot, reducing the reflection of heat back into space," UNEP Executive Director Achim Steiner said today.
"This report underlines a global trend, observed over many decades now in some parts of the globe, which has short and long-term implications for considerable numbers of people in terms of water supplies and vulnerability," he said.
In Argentina's Glaciers National Park are the glaciated peaks of Mt. Fitzroy. (Photo by Trey Ratcliff)
In dry regions of Central Asia, Chile, Argentina and Peru, where there is little rainfall and precipitation, receding glaciers will have much more impact on the seasonal water availability than in Europe or in parts of Asia, where monsoon rains play a much more prominent role in the water cycle, the report finds.
Some areas are experiencing contradictory effects, according to the report. In smaller areas of Asia's Karakoram range, for example, advancing glaciers have crept over areas that have been free of ice for 50 years. But in Asia's Tianshan and Himalayan mountain ranges, glaciers are receding, and some are shrinking rapidly, causing glacial lakes to burst.
"Without doubt the main driving force behind the rapid melting of Himalayan glaciers and formation of the catastrophic Glacial Lake Outburst Floods is warming due to climate change," said Madhav Karki, deputy director general of the International Centre for Integrated Mountain Development.
"The risk to lives and livelihoods in the fragile Hindu Kush Himalayan region is high and getting higher," said Dr. Karki, expressing thanks to the Norwegian government for its funding of the new adaptation program. "Immediate action by the global community on launching long-term adaptation and resilience-building programs is urgently needed."
Bridge destroyed in a glacial lake outburst flood in Iceland, under the Vatnajokull glacier, 1996. (Photo by Marco Franchino)
In the last 40 years, Glacial Lake Outburst Floods, often called GLOFs, have been increasing, not only in China, Nepal and Bhutan, but also more recently in Patagonia and the Andes.
Five major GLOFs took place in April, October and December 2008 and again in March and September 2009 in the Northern Patagonia Icefield in Chile. On each occasion, the Cachet 2 Lake, dammed by the Colonia Glacier, released around 200 million tonnes of water into the Colonia River. The lake has since rapidly refilled, suggesting high risk of further GLOFs.
There has been a near doubling in the frequency of GLOFs in the Yarkant region of Karakoram, China since 1959, attributed to the warming climate.
In the Lunana region of Bhutan on October 7, 1994, the glacial lake Luggye Tsho burst. The ensuing GLOF, which contained an estimated 18 million cubic meters of water, debris and trees, swept downstream killing more than 20 people, and travelled over 204 kilometers.
"When glaciers disappear, people, livestock, birds and animals will be forced to move," says one of the report's editors, Christian Nellemann of the UNEP/GRID-Arendal research center in Norway. "But ironically, a lot of people die in deserts also from drowning, when increasingly unpredictable rains cause flash floods."
"The impact of floods was brought into sharp relief in Pakistan in August 2010. As of November 2010, over six million people were still being affected by this disaster, with many displaced and housing, livelihoods, crops and livestock lost," said Steiner in his introduction to the report.
Ice cave on the shrunken Pastouri glacier at 5,000 meters in Peru's Cordillera Blanca (Photo by Alfredo Remy)
Siphoning off the water from overflowing lakes is one adaptive action, successfully carried out at lakes in Peru's Cordillera Blanca. Similar projects have been carried out in the Tsho and Thorthormi Glaciers in Nepal and Bhutan but the cost and technical challenges in remote locations can be high.
The report recommends:
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