Melting Glaciers Are Filling Unstable Lakes. And They’re Growing.

Nearly freezing and often an otherworldly shade of blue, glacial lakes form as glaciers melt and retreat. These lakes are a source of drinking and irrigation water for many communities. But they can turn deadly in an instant when the rocks that hold them in place shift and send torrents of water coursing downstream.
Now, researchers have compiled the first global database of glacial lakes and found that they increased in volume by nearly 50 percent over the last few decades. That growth, largely fueled by climate change, means that such floods will likely strike more frequently in the future, the team concluded in a paper published Monday in Nature Climate Change.
Dan Shugar, a geomorphologist at the University of Calgary, and his colleagues have decided to do a global census of glacial lakes.
The researchers collected more than 250,000 Landsat images of the Earth’s surface and fed that satellite imagery into Google Earth Engine, a platform for analyzing large Earth science data sets, to assemble the most complete glacial lake inventory to date.
Dr. Shugar and his collaborators measured how the number and size of glacial lakes evolved from 1990 through 2018. The team found that the number of lakes increased to over 14,300 from roughly 9,400, an uptick of more than 50 percent. The volume of water in the lakes also tended to swell over time, with an increase of about 50 percent.
All this growth is troubling, Dr. Shugar and his research team members suggest, because glacial lakes, by their very nature, can pose significant danger to downstream communities.

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