As glaciers melt and pour massive amounts of water into nearby lakes, 15 million people across the globe live under the threat of a sudden and deadly outburst 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 Tuesday in Nature Communications. A second study, awaiting publication in a peer-reviewed journal, catalogs more than 150 glacial flood outbursts in history and recent times, the AP reports. It's a threat Americans and Europeans rarely think about, but 1 million people live within just 6 miles of potentially unstable glacial-fed lakes, the study calculated.
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 outburst flood in British Columbia, Canada, caused a tsunami of water about 330 feet high, but no one was hurt. A 2017 glacial outburst flood in Nepal, triggered by a landslide, was captured on video by German climbers. Alaska’s Mendenhall glacier has had annual small glacial outburst floods in what the National Weather Service calls "suicide basin" since 2011, according to study lead author Caroline Taylor, a researcher at Newcastle University in the United Kingdom. Heavy rains and a glacial lake outburst flood combined in 2013 in India to kill thousands of people.
Scientists say so far it doesn’t seem like climate change has made the floods more frequent, but as glaciers shrink with warming, the amount of water in the lakes grows, making them more dangerous in those rare situations when dams burst. "We had glacier lake outburst floods in the past that have killed many, many thousands of people in a single catastrophic flooding event," said study co-author Tom Robinson, a disaster risk scientist at the University of Canterbury in New Zealand. "And with climate change glaciers are melting so these lakes are getting bigger, potentially getting more unstable."
Robinson said the study is the first to look at the climate, geography, population, and vulnerability to get "a good overview of where in the world is the most dangerous places'' for all 1,089 glacial basins. At the top of the list is Khyber Pakhtunkhwa basin in Pakistan, north of Islamabad. "That’s particularly bad,” Robinson said. "Lots of people and they’re very, very vulnerable" because they live in a valley below the lake. But scientists are focusing too much attention on the Pakistan, India, China, and the Himalayas, often called High Mountain 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.
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