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An image of a narrowed Alaska glacier after 35 years

The Grand Plateau glacier lost large amounts of ice between 1984-2019, becoming thinner and narrower.

Satellite images of the Grand Plateau glacier in 1984 and 1994. Photo: NASA.

Data from NASA satellites show the change of the Grand Plateau glacier in Glacier Bay National Park, Alaska, the Earth Observatory reported on August 13. The image taken by Landsat 5 on September 7, 1984 and by the Landsat 8 satellite on September 17, 2019 show that a large amount of ice has disappeared.

Ice was shrinking before satellites took pictures. At its height during the Little Ice Age, the Grand Plateau stretched out onto the Pacific coast. After that, this glacier has recovered significantly. A moraine (a mass of rock that accumulates at the edge of a glacier) near the coast acts like a dam that holds water, creating a glacier edge lake. In the 2019 photo, the moraine clearly sticks out from the lake’s surface. It is the remnant of a glacier branch in the 1984 photo.

In 35 years, the flow of the glacier system has changed. In 1984, many tributaries poured into the lake in a southwest direction. By 2019, the glacier shrinks, causing some branches to change currents and flow northwest.

Not only shrinking, the Grand Plateau also becomes narrower and thinner. The protruding ledge in the center of the image looks larger due to reduced ice, increasing the exposed land area. The same phenomenon occurs in other areas along the glacier.

Another noteworthy change is the appearance of arcs – brown curves in the lower right part of the glacier in the 2019 photo. The rocks that fall into the glacier will initially be scattered. Over time, the seasonal glaciers’ acceleration has cornered them into arcs. Photo taken in 1984 does not have these arcs. Part of the reason may be that a few decades ago, this place had more or less snow cover or landslides.

“The frequency of landslides is a matter of concern. It is likely that this will happen more often as the climate continues to warm, causing the slopes to thaw and the ability to hold rocky soil,” says Christopher Shuman, who glacier research at the University of Maryland, said.

(According to Earth Observatory)

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