As glaciers melt, millions in danger zone of deadly floods: Study

WASHINGTON — As glaciers melt and dump massive amounts of water into nearby lakes, 15 million people globally are living under the threat of a sudden and deadly flood, a new study finds. .

According to a study in the journal Nature Communications on Tuesday, more than half of people live in the shadow of a disaster known as glacial lake flood outbreaks in just four countries: India, Pakistan, Peru and China . A second study, pending publication in a peer-reviewed journal, lists more than 150 recent and historical ice flood outbreaks.

It’s a threat Americans and Europeans rarely think about, but 1 million people live within a radius of just 6 miles (10 km) of potentially unstable glacier-fed lakes, the study calculates. maths.

One of the more devastating floods was in Peru in 1941 and it killed between 1,800 and 6,000 people. A 2020 glacial lake outbreak flood in British Columbia, Canada, caused a tsunami of water about 330 feet high, but no one was injured. A 2017 icy flood in Nepal, caused by landslides, was captured on video by German climbers. According to the study’s lead author Caroline Taylor, a researcher at the University of Newcastle in the United Kingdom, Alaska’s Mendenhall Glacier has had small glacial floods every year in what the National Weather Service calls “suicide basin” since 2011.

Heavy rains and flash floods in an glacial lake combined in 2013 in India, killing thousands of people. Subsequent studies discovered the deadly 2021 floods in India were initially attributed to the explosion of the glacial lake rather than to a single person.

So far, scientists say, it doesn’t seem like climate change will make flooding more frequent, but as glaciers shrink due to warming, the amount of water in the lakes increases, making them more dangerous. more dangerous in rare situations when smashing.

Study co-author Tom Robinson, a disaster risk scientist at the University of Canterbury in New Zealand, said: “We’ve seen flash floods in glacial lakes before. killed thousands of people in just one catastrophic flood. “And with climate change, the glaciers are melting so these lakes are getting bigger, potentially becoming more unstable.”

Dan Shugar, a geologist at the University of Calgary who was not involved in the two studies, said much of the threat simply depends on how many people live in the ice floodplain.

“In a warming world, we certainly expect more and more large glacial lakes,” Shugar said in an email. “But the threat these lakes can pose seriously depends on where people live and how vulnerable they are.”

What’s different about his study, Robinson said, is that it’s the first to look at climate, geography, population, vulnerability and all of these factors to get an “overview of the landscape.” where in the world is the most dangerous’ for all 1,089 glacier basins. .

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

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

The trouble is that scientists are focusing too much on Pakistan, India, China and the Himalayas, commonly known as High Mountain Asia, and partly ignoring the Andes, Robinson said. The paper said the second and third highest risk basins are in Peru’s Santa Basin and Bolivia’s Beni Basin.

After the deadly floods of the Andes in the 1940s, that region “lead” in addressing the threat of glacial outbreaks, but in the last decade or so the Asian highlands have dominated That’s because of the large population, says Dayton College of Geosciences. Professor Umesh Haritashya, who was not involved in the study.

India ranks high on the list of threats not because of the physical setup but because of “a large number of people downstream”.

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

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

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