Huaraz, Peru, Tries To Prepare For Outburst Flood; Glacial Lake Above City 34X Bigger Than Last Time

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Siphon pipes lead up the mountain to Laguna Palcacocha, a swollen glacial lake in the Andes mountain range in the Ancash Region of Peru on Wednesday, July 12, 2017. The siphons were installed to reduce the volume of the lake and to try and prevent a dam rupture but were damaged in the recent icefall and only two still work. Credit: Jabin Botsford/The Washington Post via Getty Images

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The flood would trigger a mass evacuation, threaten large parts of the city with destruction and wash away many residents’ livelihoods. In the longer term, Huaraz could lose part of its water supplies for drinking and farming. The study, published today in Nature Geoscience, found it more than 99 percent certain that human-caused warming is melting the Palcaraju Glacier and increasing the threat. Lake Palcacocha sits at 14,980 feet above sea level in the gleaming Cordillera Blanca mountain range. The Palcaraju Glacier towers another vertical mile above it, at about 20,000 feet. Huaraz is 5,000 vertical feet below the lake, near the mouth of a steep, 13-mile canyon. Since 1941, as the glacier has shrunk, the lake has grown 34 times in size.

An outburst from the lake that year killed about 1,800 people, and the rapid meltdown of the glacier makes it more likely than ever that the waves from a large rock, ice or mudslide falling into the lake will easily breach the barriers holding back the water.

The new study showed the 1941 flood was also linked with human-caused warming, making it one of the earliest identified impacts of climate change to take lives. There was a series of glacial outburst floods around the middle of the 20th century, which previous research identified as early responses to human-caused warming.

“The ongoing and frightening, deadly flood risk is indeed a consequence of human influence on the climate,” said University of Oxford climate researcher Rupert Stuart-Smith, co-author of the research. The results show, with greater than 99 percent probability, that human-caused global warming has caused Palcaraju Glacier’s retreat, the swelling of the lake and the imminent risk to Huaraz, he said.

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https://insideclimatenews.org/news/04022021/for-a-city-staring-down-the-barrel-of-a-climate-driven-flood-a-new-study-could-be-the-smoking-gun/