Canada’s last Arctic ice shelf collapses | Polarjournal

Canada’s last intact ice sheet has collapsed, losing a huge ice field of 79 square kilometers. The satellite image shows the broken off piece marked with a red outline. (Image: ESA / Copernicus Sentinenel-1)

Canada’s last intact ice sheet has collapsed, pushing a huge block of ice 79 square kilometers in size into the Arctic Ocean. The collapse, caused by climate change, resulted in the ice shelf losing more than 40 percent of its mass in less than 48 hours at the end of July 2020. The Milne Ice Shelf is located on the edge of Ellesmere Island, in the sparsely populated area of Nunavut.

The satellite images from the ESA satellite “Copernicus Sentinel-1” show the collapse of the Milne Ice Shelf and the 79 square kilometre ice island.

“Above normal air temperatures, offshore winds and open water in front of the ice shelf are all part of the recipe for ice shelf break up,” a Canadian Ice Service spokesman said.

“This was the largest remaining intact ice shelf, and it’s disintegrated, basically,” said Luke Copland, a glaciologist at the University of Ottawa. Experts have been observing the Milne Ice Shelf for some time to see how the ice shelf copes with the warming climate, often using satellite imagery. The Arctic has warmed twice as fast as the rest of the world in the past 30 years due to a phenomenon known as Arctic amplification. But 2020 has been particularly intense, with record temperatures north of the Arctic Circle, wildfires and the lowest level of polar sea ice in July in 40 years.

The collapsed Milne Ice Shelf is located on the edge of Ellesmere Island, in the sparsely populated northern Canadian region of Nunavut.

Scientists have long expected that shrinking Arctic sea ice cover will lead to a strong warming of Arctic air. Sea ice helps keep the Arctic atmosphere cold, as its white reflects much of the sun’s rays. It also physically isolates the land below.

With less sea ice, more dark, open water is exposed, which easily absorbs the sun’s energy in summer, warms the ocean and leads to even more melting. With less sea ice, there is also less insulation, so the heat of the ocean escapes and warms the atmosphere in autumn and winter.

This results in a runaway train effect that leads to temperatures that are well above the global average.

This summer has averaged 5 degrees Celsius above normal since 1990. All these factors have probably contributed to the Milne collapse and have threatened smaller ice sheets which can melt quickly due to their lack of mass.

A research camp with instruments to measure the flow of water through the ice shelf was lost when the shelf collapsed. “It is lucky we were not on the ice shelf when this happened,”researcher Derek Mueller of Carleton University in Ottawa said in a blog post.

Ellesmere also lost his two ice caps at St Patrick Bay this summer. Images taken by NASA in 2015 and 2020 show how the polar ice caps have disappeared in half a decade due to global warming. The caps in 2015 (left) and the same place on July 14, 2020 (right). (Photo: Ice Data Center)

Ellesmere lost his two ice caps at St. Patrick Bay in 2020.

‘We saw them going like someone with terminal cancer. It was just a matter of time,” said Mark Serreze, director of the National Snow and Ice Date Center. (NSIDC) in Boulder, Colorado. Serreze and other NSIDC scientists had published a 2017 study that predicted that the ice caps would likely disappear within five years. It was assumed that the ice caps formed several centuries ago.

The vanishing was confirmed last month when NASA satellite images of the region showed a complete lack of snow and ice, said Serreze, who studied the caps as a doctoral student on his first trip to the Arctic years ago.

Meanwhile, two more ice caps on Ellesmere, the Murray and Simmons ice caps are also taking off and are likely to disappear within 10 years, Serreze said.

Heiner Kubny, PolarJournal

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