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Heat destroys part of the ice shelf of Greenland



Satellite images
Satellite images

Much of the ice has broken off from the largest remaining ice shelf in the Arctic – 79N or Nioghalvfjerdsfjorden ̵

1; in northeastern Greenland.

The discarded section covers about 110 sq. Km; satellite images show that it shattered into very small pieces.

The loss is further evidence, scientists say, of rapid climate change in Greenland.

“The atmosphere in this region has warmed by about 3 ° C since 1980,” said Dr. Jenny Turton.

“In 2019 and 2020, he saw record summer temperatures,” a polar researcher at Friedrich-Alexander University in Germany told BBC News.

Nioghalvfjerdsfjorden is approximately 80 km long and 20 km wide and is the floating front end of the ice stream of Northeast Greenland – where it flows from the land into the ocean to become floating.

At its leading edge, the 79N glacier splits in two, with a small shoot facing directly north. This branch or tributary, called the Spalte Glacier, has now disintegrated.

The ice is attacked from above and below
The ice is attacked from above and below

The ice characteristic was already severely broken in 2019; the heat of this summer was its final removal. The Spalte Glacier has become a flotilla of icebergs.

Look closely at the satellite images and the higher air temperatures recorded in the region are evident from the large number of melting lakes sitting on top of the shelf ice.

The presence of such liquid water is often problematic for ice platforms. If it fills cracks, it can help open them. The water will push the cracks out, pushing them to the base of the shelf in a process known as hydro-destruction. This will weaken the ice shelf.

Oceanographers have also documented warmer sea temperatures, which means that shelf ice is almost certainly melting below.

“79N became the ‘largest remaining Arctic ice shelf’ very recently after the Peterman Glacier in northwestern Greenland lost a large area in 2010 and 2012,” explained Professor Jason Box of the Geological Survey of Denmark and Greenland (GEUS).

“What makes the 79N so important is the way it is attached to the inner ice sheet, which means that one day – if the climate warms as we expect – this region is likely to become one of the main centers of action. for the deforestation of Greenland. “

The trunk of the N79 is covered with melting ponds and streams
The trunk of the N79 is covered with melting ponds and streams

The ice flow of Northeast Greenland removes about 15% of the inner ice cover. The stream takes its ice down the N79 or glacial member just south, Zacharia Istrem. Zacharias has already lost most of his floating ice shelf.

Professor Box said the N79 could last longer because it was written right at its front end by some islands. This gives some stability. But, he added, the shelf continues to thin, albeit mostly further back in the trunk.

“This will probably lead to the disintegration of the N79 from the middle, which is something unique. But I guess it won’t happen for another 10 or 20 years. Who knows?” he told BBC News.

In July, another large structure on the Arctic ice shelf lost a significant area. This was the Milne ice shelf at the northern tip of the Canadian island of Ellesmere.

Eighty square kilometers were freed from Milne, leaving a still secure segment of only 106 square meters. Milne is the largest intact remnant of a wider shelf, covering 8,600 square kilometers in the early 20th century.

Greenland’s rapid melting rate was highlighted in a study last month that analyzed data from US-German Grace-FO satellites. These spacecraft are able to track changes in the ice mass by sensing changes in the attraction of local gravity. They essentially weigh the ice sheet.

The Grace mission found that 2019 was a record year, as the ice sheet dropped about 530 billion tons. This is enough molten water flowing from the land into the ocean to raise global sea levels by 1.5 mm.


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