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

Glaciers are retreating on an almost global scale, and new research is giving scientists a clearer picture of

how much of this water was accumulated in the lakes.

We know that not all melt water immediately entersoceans. 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 staff from governments andUniversities in Canada, the United States and the United Kingdom, working on a NASA grant in Alpine Asia, originally planned to use satellite imagery and other remote sensing data to study two dozen glacial lakes in Alpine Asia, a geographic region that includes the Tibetan Plateau and surrounding mountain ranges, including the Himalayas ...

“We wrote scripts in Google Earth Engine,an online platform for very large analysis of geospatial data 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 more250,000 scenes from 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 although water from melting glacierscontributes relatively little to overall sea level rise, it could have a large impact on mountain communities downstream of these glacial lakes.

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

Glacial lakes are unstable, they are often blockedice or glacial deposits - moraine, which are composed of loose rocks and debris, which are pushed to the front and side of the glaciers. They can break through banks or dams, causing massive flooding downstream. These types of flooding, 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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