In some parts of the world, large lakes are bounded by natural dams made of glacial ice. When the ice melts, the resulting surges of water are comparable in effect to the failure of human-made dams. Merzbacher Lake, in Kyrgyzstan, has completely emptied 39 times, following such events. An article in Geophysical Research Letters describes that lake in greater detail.
Significant past examples of such glacial lake outbursts occurred in Iceland, Alaska, Canada, and Bhutan. While relatively few areas are threatened by such events, they are demonstrative of the kind of change that is ongoing in the cryosphere.
Tsho Rolpa, a glacial lake in Nepal, seems to be due for such an event. It is 4580m above sea level and dammed by 150m of ice. The melting of the Trakarding Glacier is feeding the growth of the lake, which will eventually breach the ice wall in a highly dramatic manner. Local communities have been building raised watchtowers and shoring up embankments. Tsho Rolpa is one of 2,323 glacial lakes in the Nepalese Himalayas.
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