The glacial lakes began to melt abruptly. They are unstable and dangerous by floods

In the largest-ever study of glacial lakes, researchers using NASA’s 30-year satellite data found that the volume of these lakes worldwide has increased by about 50% since 1990 as glaciers melt and retreat due to climate change. The results, published in the journal Nature Climate Change, will help researchers assess potential hazards to communities downstream of these often volatile lakes, and improve the accuracy of estimates of sea-level rise. This will improve scientists’ understanding of how glacial meltwater is transported to the oceans.

Glaciers are retreating on an almost global scale, and the new study is giving scientists a clearer picture of how much of this water has accumulated in the lakes.

We know that not all meltwater ends up in the oceans right away. But so far there has been no data to estimate how much is stored in lakes or groundwater. ” The study estimates that the current volumes of glacial lakes are about 37.4 cubic miles (156 cubic kilometers) of water, equivalent to about one-third the volume of Lake Erie.

Dan Sugar of the University of Calgary Canada, lead author of the article

Sugar and his collaborators from the governments and universities of Canada, the United States, and the United Kingdom, working on a grant from the NASA program in Alpine Asia, originally planned to use satellite images and other remote sensing data to study two dozen glacial lakes in Alpine Asia – a geographic region that includes the Tibetan Plateau and the surrounding mountain ranges, including the Himalayas.

“We wrote scripts in Google Earth Engine, an online platform for very large geospatial data analysis, to look only at high-altitude Asia, and then decided to look at all the glacial lakes in the world,” the scientists explain. “From there, we were able to plot a scale ratio to estimate the volume of glacial lakes in the world based on the area of ​​this large group of lakes.”

The team ultimately analyzed more than 250,000 scenes from the Landsat satellites, a joint NASA / US Geological Survey program. Ten years ago, it would have been impossible to process and analyze such a volume of data. The team looked at data at five-time steps starting in 1990 to study all of the world’s glacial regions except Antarctica and analyze how glacial lakes have changed over that period.

Sugar notes that while water from melting glaciers contributes relatively little to overall sea-level rise, it can have a large impact on mountain communities downstream of these glacial lakes.

In the largest-ever study of glacial lakes, researchers using 30-year satellite recordings found that the volume of these lakes worldwide has increased by about 50% since 1990.

Glacial lakes are unstable, they are often covered by ice or glacial deposits – moraine, which is composed of loose rocks and debris that are pushed out to the front and side of the glaciers. They can break through banks or dams, causing massive flooding downstream. These types of floods, caused by the outburst of glacial lakes, have caused thousands of deaths over the past century, as well as the destruction of villages, infrastructure, and livestock. In May 2020, flooding caused by the outburst of a glacial lake hit the Hunza Valley in Pakistan.

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