Melting snow and ice is making glacier lakes larger

4 September 2020

Glacial lakes increased in volume by nearly a half between 1990 and 2018. The reason: warming weather.

A team of scientists has reached this conclusion after conducting the largest-ever study of its kind by examining nearly 255,000 satellite images compiled by NASA over three decades. “[G]lobal glacier lake volume increased by around 48%, to 156.5 km3, between 1990 and 2018,” the experts note in a newly published study.

“Over the study period, lake numbers and total area increased by 53 and 51%, respectively. Median lake size has increased 3%; however, the 95th percentile has increased by around 9%,” they elucidate. “Currently, glacial lakes hold about 0.43 mm of sea level equivalent. As glaciers continue to retreat and feed glacial lakes, the implications for glacial lake outburst floods and water resources are of considerable societal and ecological importance.”

Water in lakes formed by melting glaciers lakes isn’t a major contributor to the rise in sea levels worldwide. However, the larger these volatile lakes get in the face of disappearing glaciers, the more likely it is that communities downstream will face flash floods, landslides and other calamities as a result.

“This is an issue for many parts of the world where people live downstream from these hazardous lakes, mostly in the Andes and in places like Bhutan and Nepal, where these floods can be devastating,” observes Dan Shugar, an expert at the University of Calgary in Canada who was lead author of the paper.

“Fortunately, organizations like the United Nations are facilitating a lot of monitoring and some mitigation work where they’re lowering the lakes to try and decrease the risks,” Shugar says. “In North America, the risks posed by a glacial lake outburst flood are lower. We don’t have much in the way of infrastructure or communities that are downstream, but we’re not immune to it.”

At present, glacial lakes hold a total volume of around 156 cubic kilometers of water, which is equivalent to a third of the volume in Lake Erie in the United States, the scientists estimate. “We have known that not all meltwater is making it into the oceans immediately. But until now there were no data to estimate how much was being stored in lakes or groundwater,” Shugar notes.

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