Canada’s last fully intact ice shelf collapsed, losing more than 40% of its area in just two days at the end of July, researchers said last week.
The Milne Ice Shelf is at the fringe of Ellesmere Island, in the sparsely populated northern Canadian territory of Nunavut.
“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.
“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.
The shelf’s area shrank by about 80 square kilometres. By comparison, the island of Manhattan in New York covers roughly 60 square kilometres.
“This was the largest remaining intact ice shelf, and it’s disintegrated, basically,” Copland said.
The Arctic has been warming at twice the global rate for the last 30 years, due to a process known as Arctic amplification. But this year, temperatures in the polar region have been intense. The polar sea ice hit its lowest extent for July in 40 years. 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, and this has has threatened smaller ice caps to melt quickly. As a glacier disappears, more bedrock is exposed, which then heats up and accelerates the melting process.
The ice shelf collapse on Ellesmere Island also meant the loss of the northern hemisphere’s last known epishelf lake, a geographic feature in which a body of freshwater is dammed by the ice shelf and floats atop ocean water.
A research camp, including instruments for measuring water flow through the ice shelf, was lost when the shelf collapsed.
Meanwhile, another two ice caps on Ellesmere – called Murray and Simmons – are also diminishing and are likely to disappear within 10 years.