The Canadian Arctic’s last fully intact ice shelf has collapsed, losing almost half of its area—larger than the borough of Manhattan—in just two days, scientists say.
Milne Ice Shelf is located off the northern coast of Ellesmere Island in the Qikiqtaaluk Region of Nunavut, a northern Canadian territory home to some 40,000 people, mostly Inuit. Canadian Ice Services said above normal temperatures, offshore winds, and open water in front of the ice shelf caused the calving event over July 30-31.
The ice shelf lost 43 percent of its area or about 80 square kilometers, Reuters reported. The entire borough of Manhattan has an area of about 60 square kilometers.
One large ice island initially split off the 4,000-year old shelf, but then continued to break up this week into two pieces of 55 square kilometres and 24 square kilometres each, as well as into several smaller icebergs, said Adrienne White, an ice analyst with Canadian Ice Services who discovered the event.
The resulting islands, up to 80 metres thick, “pose a huge hazard for shipping activity,” White told VICE News. The agency said it will continue to monitor the ice islands to ensure they don’t pose a risk to oil rigs and ships if they drift south.
This summer the Arctic has battled a heatwave, with record-breaking temperatures scorching polar regions from Canada to Russia. July on the east Siberian coast was 6 C warmer than the long-term average in May and June, and the central Arctic has recorded days that are up to 10 C warmer than average, according to the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research. Northern forest fires have also ravaged Siberia’s Arctic, and sea ice extent in the region hit a historic low last month.
“This drastic decline in ice shelves is clearly related to climate change,” Luke Copland, a glaciologist at the University of Ottawa, said in a statement.
Sea ice extent, which measures how much of the ocean’s surface area is covered by ice, is partially to blame for the ice shelf falling apart, White said. Typically, Arctic sea ice, which builds and wanes depending on the season, buttresses up against ice shelves, sheltering them from winds and waves. But the diminished sea ice exposes ice shelves like Milne to open water and offshore winds that can contribute to their collapse.
Existing fractures and record-warming summer temperatures also played a part.
“We didn’t necessarily expect this one to go because we thought it was the most stable,” White said. “We’ve been seeing these ancient large features break up since 2005, which tells us that our climate is changing.”
Several ecosystems depend on the features that are gradually being destroyed, said Derek Mueller, a professor in the Department of Geography and Environmental Studies at Carleton University. That includes Canada’s last remaining epishelf lake, a layer of fresh water created by meltwater dammed by the ice shelf that floats directly on top of the ocean.
The epishelf lake “may well have disappeared as a result of this collapse,” Mueller said.
Algae, scallops, sea anemones, and other creatures that live on and in the ice, as well as in the epishelf lake, are also at risk. “You think of an ice shelf as just a piece of ice, but actually three separate ecosystems depend on that for survival and now they are breaking apart,” he said.
Canadian ice shelves “are almost certainly going to disappear within the next several decades,” Mueller said. He warned their collapse is a “window into the future”—in part because it foreshadows what could eventually happen in Antarctica, where ice shelves make up about 40 percent of the continent’s coast and are bigger and more important for sea-level rise.
“All sorts of warning signs are going off this year. It's incredible. Ice caps are disappearing. We are transitioning here into a totally different climate,” he said.
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