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.
Himalayan glacier studies commence
By Navin Singh Khadka
Environment reporter, BBC News
After a long gap, scientists in Nepal have embarked on the first field studies of Himalayan glacial lakes, some of which are feared to be swelling dangerously due to global warming.
In May, they completed the field visit to the first location, a lake in the Everest region, in a series of studies.
They plan to conduct similar surveys of two other glacial lakes in the central and western part of the Nepalese Himalayas later in the year.
“We have started with Nepal, but we intend to extend studies to other Hindu Kush Himalayan countries,” says Arun Bhakta Shrestha, a climate change specialist with the International Centre for Integrated Mountain Development (ICIMOD), which is carrying out the research alongside a number of government agencies.
This video makes reference to the threat described in this post, with a specific example of glacial lakes in Bhutan which are located upriver of proposed new dam sites.
Glacial lakes threaten millions with flooding as planet heats up | Climate change | The Guardian
http://www.theguardian.com/environment/2021/may/02/glacial-lakes-threaten-millions-with-floods-as-planet-heats-up