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Glacier Melting is Causing a Rapid Growth of Glacial Lakes

Aug. 31, 2020

lake palcacoha lake and glacier

Lake Palcacocha is a glacial lake in the Cordillera Blanca of Peru with an elevation of 4,566 meters, more than 15,000 feet. Palcacocha has the horrific reputation as the worst mass killer of people of all the glacial lakes in the world. It and nearby lakes in Peru have killed hundreds or thousands of people over multiple occasions. The worst event was in 1941, when a large ice avalanche into the lake triggered a sudden glacial lake outburst flood unleashed onto the city of Huaraz, killing at least 4,000. This lake evolved considerably between 2004, when Kargel first saw the lake, and 2016. The glaciers hanging onto the mountain have thinned and retreated, and the lake has grown right up to the steep headwall. Glacier retreat has been so extensive that the glacier barely connects with the lake.

Credit: Jeffrey Kargel (2016)

 

A worldwide study has shown that glacial lakes have grown by almost 50 percent since 1990 due to climate change and melting glaciers. 

These growing glacial lakes are often dammed by unstable glacial sediment or ice that can burst, causing sometimes deadly flooding downstream, according to Planetary Science Institute Senior Scientist Jeffrey Kargel, a co-author on the paper “The Rapid Growth of Glacial Lakes Since 1990” (https://www.nature.com/articles/s41558-020-0855-4) that appears in Nature Climate Change. Dan H. Shugar, of the University of Calgary Department of Geoscience, is lead author on the paper. Kargel is the principal investigator of the NASA Earth Science Division-funded project supporting this work. 

The authors  calculated the role of glacial lakes in temporarily storing glacial meltwater that otherwise would drain straight into the sea. However, that stabilizing effect on sea level rise is small. “The issue is 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 glacial lake outburst floods can be devastating,” Shugar said. “Fortunately, organizations like the United Nations are doing or facilitating a lot of monitoring work and some mitigation work where they’re lowering the lakes to try and decrease the risks." 

Kargel, who has led expeditions in the Himalaya to assess glacial lake hazards and to prepare for mitigation, agreed: “The widespread expansion of unstable glacial lakes represents a threat to communities and ecosystems.” 

Researchers ran their software in Google Earth Engine to analyze historic and recent images from NASA satellites to detect, map, and measure areas of all the glacial lakes on Earth, except for in Antarctica, between 1990 and 2018. 

“More than a quarter million Landsat images were used to map glacial lakes and track their growth – or shrinkage – from the 1990s to the 2010s. We analyzed the data by area, and then estimated their volumes using the average relationship between lake area and volume,“  Kargel said. “The team also analyzed the number of lakes and the lakes’ distribution and changes both globally and region-by-region. There was about a 48 percent increase in the lakes' total volume.” 

Another issue is fresh water availability. “Melting of glaciers and mountain snowpack is a part of the shifting global impacts of climate change on the loss of fresh water and altered behavior of rivers. For example, the mighty glacier-fed rivers of the Himalayan region, such as the Ganges and Indus and their tributaries, will gradually lose their glacier sources during this and next century,” Kargel said. “Some of the rivers in Asia will behave more like the Colorado River does today, where almost all the Ice Age glaciers have melted already and runoff today is mainly from melting snowpack and rainfall. The Colorado River in recent historical times dried to a trickle in the dry seasons. Scientists, water managers, and policy makers around the world are increasingly focused on these impacts of climate change on melting glaciers and snowpack because they affect millions of people’s health, safety, and livelihoods.” 

Visit https://www.youtube.com/watch?v=rvRCKgw2B8k to see a video showing glacial lake growth due to glacier melt. 

 

 

MEDIA CONTACT:

Alan Fischer

Public Information Officer

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fischer [at] psi.edu 

 

SCIENCE CONTACT:

Jeffrey Kargel

Senior Scientist

520-780-7759

jkargel [at] psi.edu

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