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article imageCanada's last fully intact ice shelf has collapsed due to warming

By Karen Graham     Aug 7, 2020 in Environment
The Milne Ice Shelf is at the fringe of Ellesmere Island in the northern Canadian territory of Nunavut. It was the last fully intact ice shelf in Canada, until Sunday - when it collapsed, losing 40 percent of its area.
“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,” the Canadian Ice Service said on Twitter when it announced the loss on Sunday.
“Entire cities are that size. These are big pieces of ice,” said Luke Copland, a glaciologist at the University of Ottawa who was part of the research team studying the Milne Ice Shelf. “This was the largest remaining intact ice shelf, and it’s disintegrated, basically,” Copland said, per Reuters.
To put the ice shelf's size in perspective, Manhattan Island in New York covers about 60 square kilometers. When the Milne ice shelf collapsed, the shelf's area shrank by about 80 square kilometers.
Laurence Smith  chair of geography at University of California  Los Angeles  deploys an autonomous d...
Laurence Smith, chair of geography at University of California, Los Angeles, deploys an autonomous drift boat equipped with several sensors in a meltwater river on the surface of the Greenland ice sheet on July 19, 2015.
NASA Goddard Space Flight Center from Greenbelt, MD,
Arctic amplification process
"Since the mid-20th Century, average global temperatures have warmed about 0.6°C (1.1°F), but the warming has not occurred equally everywhere. Temperatures have increased about twice as fast in the Arctic as in the mid-latitudes, a phenomenon known as Arctic amplification," according to NASA.
Sea ice helps to keep the Arctic atmosphere cold. Its whiteness reflects much of the Sun's energy back to space, insulating the Arctic atmosphere from the underlying Arctic Ocean. However, with less sea ice, more dark open water is exposed, which readily absorbs the Sun's energy in summer, heating the ocean and leading to even more melt.
There is growing recognition that this process could thaw permafrost and release the carbon stored in these soils back to the atmosphere, further accelerating climate warming. And as The Guardian points out, Arctic polar sea ice hit its lowest extent for July in 40 years, while record heat and wildfires have scorched Siberian Russia.
Summer in the Canadian Arctic this year in particular has been 5 degrees Celsius above the 30-year average, Copland said. Rising temperatures are threatening smaller ice caps because they don't have the bulk to withstand the heat as well as glaciers. But with rising temperatures, melting ice caps and glaciers expose more bedrock that in turn absorbs the heat, creating even more melting.
“The very small ones, we’re losing them dramatically,” Copeland said, citing researchers’ reviews of satellite imagery. “You feel like you’re on a sinking island chasing these features, and these are large features. It’s not as if it’s a little tiny patch of ice you find in your garden.”
The last epishelf lake in the Northern Hemisphere is gone
Epishelf lakes form where meltwater runoff from land is trapped in a fiord or bay behind a floating ice shelf. The Milne ice shelf basically acted as a dam, holding back the freshwater of the epishelf lake. With the collapse of the ice shelf on Sunday, the last epishelf lake in the Northern Hemisphere was lost.
Eureka Weather Station  seen in the distance  on Ellesmere Island in Canada’s Nunavut province  ab...
Eureka Weather Station, seen in the distance, on Ellesmere Island in Canada’s Nunavut province, about 690 miles from the North Pole. Image taken October 2004.
NASA
Until recently, a number of epishelf lakes existed along the northern coast of Ellesmere Island, however, thinning and break up of ice shelves due to climate warming has resulted in the widespread loss of these lakes.
A research camp, including instruments for measuring water flow through the ice shelf, was lost when the shelf collapsed. “It is lucky we were not on the ice shelf when this happened,” said researcher Derek Mueller of Carleton University in Ottawa, in an Aug. 2 blog post, according to Global News.
The two St. Patrick Bay ice caps on Ellesmere were also lost this summer. “We saw them going, like someone with terminal cancer. It was only a matter of time,” said Mark Serreze, director of the National Snow and Ice Data Center (NSIDC) in Boulder, Colorado.
More about Milne ice shelf, Ellesmere island, canadian arctic, Manhattan, Global warming
 
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