Loss of Manhattan-sized Arctic ice shelf is 'sign of things to come'

An ice shelf almost the size of Manhattan has broken off from an island in the Canadian Arctic, researchers revealed today, warning that the near-record loss of polar ice cover this summer was an indicator of the changes global warming would inflict on mankind.
The region’s ice shelf has lost 83 square miles this summer, the second-biggest retreat of ice cover in the Arctic Ocean since satellite measurements began 30 years ago, Martin Jeffries of the US National Science Foundation and University of Alaska Fairbanks, said.
But unlike retreats in the last century, the current warming of the climate means the ice shelves will not reform.
“These changes are irreversible under the present climate and indicate that the environmental conditions that have kept these ice shelves in balance for thousands of years are no longer present,” said Derek Mueller, an Arctic ice shelf specialist at Trent University in Ontario.

The 4,500-year-old Markham Ice Shelf separated from Ellesmere Island in early August and the 19-square-mile shelf is now adrift in the Arctic Ocean, Mr Mueller said.
“The Markham Ice Shelf was a big surprise because it suddenly disappeared. We went under a cloud for a bit during our research and, when the weather cleared up, all of a sudden there was no more ice shelf. It was a shocking event that underscores the rapidity of changes taking place in the Arctic,” he explained.
Two large sections of ice have also detached from the Serson Ice Shelf, shrinking it by 47 square miles - or 60 per cent. The Ward Hunt Ice Shelf, which lost 8 square miles earlier in the summer, has also continued to break up.
Mr Mueller said that a further 8 square miles had since broken off the shelf - which at around 155 square miles and 40-metres-thick is the largest remaining in the Arctic.
In all, the Arctic ice shelves have lost an area more than three times the size of Manhattan Island this summer – 23 percent of their total mass - the researchers said. The loss is more than 10 times initial predictions, they added.
Warwick Vincent, director of Laval University’s Centre for Northern Studies and a researcher in the program ArcticNet, said extensive cracks in the Ward Hunt shelf meant that it would continue to disintegrate.
“Clearly the long-term viability of that ice shelf is now actually short-term,” he said.
Formed by accumulating snow and freezing meltwater, ice shelves are large platforms of thick, ancient sea ice that float on the ocean’s surface but are connected to land.
During the last century, when ice shelves would break off, thick sea ice would eventually reform in their place and eventually over time, compression, continuous movement in the ocean and icy temperatures would help to create another ice shelf.
“But today, warmer temperatures and a changing climate means there’s no hope for regrowth. A scary scenario,” Mr Mueller said.
The latest developments come on the heels of unusual cracks in a northern Greenland glacier and the rapid melting of a southern Greenland glacier. At the other end of the globe, a 160-square-mile chunk of an Antarctic ice shelf disintegrated earlier this year.
Ellesmere Island was once entirely ringed by a single enormous ice shelf of around 3,500 square miles, which began to break up in the early 1900s. All that is left today are the four much smaller shelves that together cover little more than 299 square miles.

The coast of the island has warmed an average of two degrees Celsius in the last 50 years, said Luke Copland, director of Ottawa University’s cryospheric research lab.
In winter, temperatures are now five degrees warmer, making it more difficult for ice lost in summer to recover in winter.
“It’s part of global warming. When we warm up the planet it gets concentrated close to he poles,” Mr Copland said.
Mr Vincent said the developments in the Arctic were an early indicator of the “very substantial changes” that global warming will eventually impose on all mankind. Climate change is forecast to generate more destructive extreme weather such as hurricanes, cyclones and floods.
“Climate models indicate that the greatest changes, the most severe changes, will happen earliest in the highest northern latitudes,” he said.
“This will be the starting point for more substantial changes throughout the rest of the planet.... Our indicators are showing us exactly what the climate models predict,” he said.
The peak temperature the team recorded was 19.7 degrees Celsius, far above the average of 7.7 degrees.
Mr Vincent said he had no doubt that global warming was caused in part by human activity.
“I think we’re at a point where it is not stoppable but it can be slowed down. And if you think about the magnitude of effects on our society, then we really need to buy ourselves more time to get ready for some very substantial changes that are ahead,” he said.