15 million people live under the threat of glacial floods

As glaciers melt and pour huge amounts of water into nearby lakes, 15 million people around the world live under the threat of a deadly flash flood, a new study finds.

More than half of those living in the shadow of the disaster called glacial lake outburst floods are in just four countries: India, Pakistan, Peru and China, according to a study published in Nature Communications. A second study, pending publication in a peer-reviewed journal, catalogs more than 150 glacial flood outbursts in history and recent times.

It’s a threat Americans and Europeans rarely think about, but 1 million people live just 6 miles (10 kilometers) from potentially volatile glacier-fed lakes, the study calculated.

One of the most devastating floods occurred in Peru in 1941 and killed between 1,800 and 6,000 people. A 2020 glacial lake flood in British Columbia, Canada caused a 330-foot-high tsunami of water, but no one was hurt. A 2017 glacial flood in Nepal triggered by a landslide was filmed by German mountaineers. Alaska’s Mendenhall Glacier has experienced small annual glacial floods in what the National Weather Service calls a “suicide basin” since 2011, according to study lead author Caroline Taylor, a researcher at the University of Newcastle in the UK.

Heavy rains and the flooding of a glacial lake combined in 2013 in India to kill thousands. A deadly 2021 flood in India, initially attributed to a glacial lake explosion, wasn’t caused by one, later studies found.

Scientists say so far it doesn’t appear that climate change has made those floods more frequent, but as glaciers shrink with warming, the amount of water in lakes increases, making them more dangerous in those rare situations where dams fail.

“In the past we’ve had flooding from glacial lake outbursts that killed many thousands in a single catastrophic flood event,” said study co-author Tom Robinson, a disaster risk scientist at the University of Canterbury in New York. Zeeland. “And with climate change the glaciers are melting, so these lakes are getting bigger, potentially becoming more unstable.”

Dan Shugar, a geoscientist at the University of Calgary who was not part of the two studies, said much of the threat simply depends on how many people live in an alluvial glacial zone.

“In a warming world, we definitely expect bigger and bigger glacial lakes,” Shugar said in an email. “But the threat these lakes could pose depends critically on where people live and what their vulnerabilities might be.”

Robinson said what’s different about his study is that he’s the first to look at climate, geography, population, vulnerability, and all of those factors to get “a good overview of where in the world the most dangerous places are.” for all 1,089 glacial basins.

Topping the list is the Khyber Pakhtunkhwa Basin in Pakistan, north of Islamabad.

“This is especially bad,” Robinson said. “A lot of people and they are very, very vulnerable” because they live in a valley under the lake.

The trouble is, scientists are focusing too much attention on Pakistan, India, China and the Himalayas, often called high-mountainous Asia, and somewhat ignoring the Andes, Robinson said. The second and third highest-risk basins are in Peru’s Santa Basin and Bolivia’s Beni Basin, the paper said.

After the deadly Andes flood in the 1940s, that region “was kind of a leader” in working on glacial flood outburst threats, but in the last decade or so, high-mountain Asia has taken the upper hand due to the ‘high population,’ said University of Dayton geology professor Umesh Haritashya, who was not part of the studies.

India tops the threat list not so much because of physical configuration but because of “huge numbers of people downstream.”

Three lake basins in the United States and Canada rank highest for threats, from the Pacific Northwest to Alaska, but they’re not as high as areas in Asia and the Andes with few people in the danger zone. They are found on Alaska’s Kenai Peninsula, distinct from the Mendenhall Glacier near Juneau, northeast of Washington, and in west-central British Columbia.

“This ranking is a good checklist for further research,” said Oliver Korup of the University of Potsdam in Germany, co-author of the glacial lake flood list.


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