Scientists from NASA analyzed satellite images and came to the conclusion that glaciers on average decreased by 5 km. for 50 years. The main reason for the change is global warming.
Most of the data comes from the Landsat satellite or similar devices that have shot the Earth from similar points for decades. However, other NASA satellites record changes, sometimes within one to two years.
Glacier images from 1972 to 2019 allowed glaciologist Mark Fanstust of the University of Alaska at Fairbanks to create six-second clips at time intervals showing changes in glacier shape.
“We now have detailed records that allow us to look at what happened to the glaciers,” the NASA statement said. When you watch these clips, you get an idea of how dynamic these systems are and how fragile the ice cover is.”
Glaciers react differently to global warming. For example, the Columbia Glacier in Alaska was stable for a long time and its size did not change. Its active melting began in the mid-1980s; Now its size has changed by 20 km. Meanwhile, the nearby Hubbard Glacier has moved just 5 km in the same 48 years. however, in 2019, the largest section of ice broke away from it.
Michalea King, a graduate student at Ohio State University, studied detailed satellite imagery to analyze the effects of global warming on 200 glaciers. She concluded that, during the observations, they decreased on average by 5 km.
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