Like all ecosystems, the Arctic ice shelves experience ice growth and loss over time. However, the calving, or breaking off into the sea, of the Ayles ice shelf in August 2005, and the lack of new ice coming into the remaining five Canadian ice shelves, are the latest concerns the Canadian Arctic is facing.
“It’s an indicator of a trend we’ve seen over the last decade of increasingly warm temperatures globally,” said Laurie Weir, an ice analyst at the Canadian Ice Service in a telephone interview. She spotted the ice break a week after it occurred and contacted a University of Ottawa colleague, Luke Copland of the Laboratory for Cryospheric Research.
With additional data from NASA’s MODIS and ASTER imaging instruments and wind and temperature patterns leading up to the event, Copland and his colleagues spent a year piecing together the half-hour when the 87 square kilometres of ice were lost.
“That’s a little larger than the island of Manhattan,” Copland explained. His report has recently been submitted to Geophysical Research Letters, and the information on the break has been presented at a number of climate change conferences.
With the information gained about the Ayles ice break, the future of the five remaining Canadian ice shelves-dated at three to four thousand years old-isn’t promising.
“In 1900, there were 10,000 square kilometres [of ice]. Today’s there are about a thousand,” said Copland. The Ayles is the biggest single piece of ice to break off in the last 25 years, but this century has seen the continuous loss of 90 per cent of Canada’s sea ice.
“In a balanced climate, you would expect ice shelves to fracture off at regular periods naturally, because natural ice would form and push old ice off,” said Copland. “But the difference is we’re not getting the resupply of ice coming back from the ice shelves.”
“In particular, in the Ward Hunt ice shelf, situated further east of the Ayles ice shelf…pieces of this ice shelf have calved and moved out to the Arctic path,” said Weir.
In 2002, the Ward Hunt ice shelf cracked in half. To Copland, it looks doomed to break off entirely.
“Calving is a natural process, but it’s not being balanced,” said Copland. “None of [the shelves have] enough [ice] coming in to them.”
The ice shelves host unique, microscopic ecosystems in the brackish water beneath them. The floating shelves, typically attached to ice on the ground, trap a mixture of sea water and fresh water called an epishelf lake, which plays home to microbes like microalgae. The fracture and loss of the ice shelves have destroyed the environment that housed these unique species, and with it a part of the Arctic’s biodiversity.
The seven degree temperature increase in today’s Arctic has alert stations and ice scientists closely watching not only the Ayles ice shelf but the rest of Canada’s ice.
The gulf of the St. Lawrence river and the Great Lakes, according to Weir, usually receives ice in inlets, but has seen minimal ice this year. For transport routes that run through these bodies of water, nearly ice-free conditions make transport easier, albeit at the environment’s expense.
As for the former Ayles ice shelf, which has frozen into sea ice 50 km west of its original location since the summer of 2006, the threat of the new island colliding with oil platforms or shipping routes is minimal.
“If we continue to see the arctic pack melting, and with the general trend in the currents in the Arctic Ocean, we would expect that this ice island will move south westward, and potentially into the Beauford Sea area where there are oil [projects],” said Weir.
“We’re in period of a warming environment,” said Weir. “What’s up for debate is the cause. Some people would say man has induced this change, and others feel this is part of a regular cycle of climatic change. I would certainly say that the temperatures you’re seeing in Toronto are being reflected in the high Arctic.”
