Two and a half years ago, the Baker River in Chilean Patagonia suddenly tripled in size, causing a virtual river tsunami. In less than 48 hours, roads, bridges, and farms were severely damaged and dozens of livestock drowned. Residents were in disbelief. Jonathan Leidich, an American whose company regularly leads tourists on treks up to nearby glaciers, hiked to the Colonia Glacier at the eastern flank of the Northern Patagonian Ice Field and discovered the source of the mysterious flood: Lake Cachet 2 had vanished. This enormous, two-square-mile glacial lake had emptied its 200 million cubic meters of water in just a matter of hours. What happened? Glaciologists say it was yet another “glacial lake outburst flood,” or GLOF. An increasing rate of melting at the Colonia Glacier swelled the lake so much so that the resulting water pressure gradually forced the creation of a tunnel beneath the surface of the adjacent ice and drained the lake. Since Cachet 2 emptied in 2008, the lake has “disappeared” six more times.
Such GLOFs don’t necessarily arise because of climate change; indeed, some four decades ago a GLOF occurred on the Baker River. But a clear warming trend over the past decade has taken its toll on the world’s glaciers, and it is widely agreed that climate change is dramatically increasing the frequency and intensity of GLOFs. Last month, the United Nations Environment Programme (UNEP) released a report on mountain glaciers at the climate-change talks in Cancún, Mexico, stating that glaciers on Argentine and Chilean Patagonia are “losing mass faster and for longer than glaciers in other parts of the world.” “Accumulation of science shows us a clear general trend of melting glaciers linked to a warming climate,” said UNEP executive director Achim Steiner.
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In the Himalayan region of Nepal, China, Bhutan, India, and Pakistan, the International Centre for Integrated Mountain Development has identified 200 “potentially dangerous” glacial lakes. Moreover, scientists predict that several major rivers fed by the Himalayas, such as the storied Ganges River in India, are set to be affected by massive glacial floods in the years ahead and eventually, as the glaciers retreat, the site of serious water shortages for untold millions of people during dry seasons.
At Lake Cachet 2 in Chile, the 36-year-old Leidich says, “The lake is increasing in size, and the floods are getting worse.” Especially worrisome to Leidich and other residents is the combined effect these GLOFs may have together with a series of controversial large dams planned for the Baker River as part of a $5 billion HidroAysén project. The companies pushing the project, Italy’s Enel and Chile’s Colbun, hope to get the first of its Baker River dams readied by 2015. A GLOF-related accident at the dam could wipe out the 512-person Tortel, a small, tranquil village located at the mouth of the Baker River, where the river merges with the Pacific Ocean. Tortel is already issuing GLOF-evacuation orders for its people as the high-water mark of the Baker River hits new peaks with the GLOF events.
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http://www.newsweek.com/2011/01/01/lakes-disappearing-after-glacial-outburst-floods.html
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