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Arctic Ice Sheet Nearly Size of Manhattan Breaks Off


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Canadian Arctic Ice Sheet Nearly Size of Manhattan Breaks Off

By Adam Satariano

Sept. 3 (Bloomberg) -- A 19-square-mile (50 kilometers) ice shelf attached to an island in Canada's northern arctic for thousands of years has broken from land, another sign of the effect of global warming, scientists said

Nearly the size of Manhattan, the 4,500-year-old Markham Ice Shelf separated from Ellesmere Island in early August and is now floating in the Arctic Ocean, said Luke Copeland, director of the Laboratory for Cryospheric Research at the University of Ottawa.

Copeland and fellow researchers were watching the ice shelf, which is about as tall as a 10-story building, using satellite imagery when cloud cover blocked the region for five days. When visibility returned, the mass was gone.

``It was a complete shock,'' Copeland said in an interview. ``Five days later it was completely gone. That's what was really amazing is that we lose it all in such a short period of time, within just a few days.''

The loss comes after last week's announcement by the National Snow and Ice Data Center that Arctic sea ice, which melts partially during each polar summer, had shrunk more this year than any other year except 2007. The Greenland Ice Sheet also has been losing mass, according to the conservation group WWF.

In January, the National Aeronautics and Space Administration said net loss of ice mass in Antarctica increased to 196 billion metric tons in 2006 from 112 metric tons a decade earlier.

`Broader Picture'

``It's part of the broader picture that things are changing very, very quickly,'' Copeland said.

The United Nations Intergovernmental Panel on Climate Change last year said temperatures in the Arctic are increasing at almost twice the global rate. The warmer weather is melting ice in the sea and in Greenland, which contains enough water to raise global sea levels by 7 meters (23 feet).

To have a chance of containing the average worldwide increase in temperature to 2 degrees Celsius (3.6 degrees Fahrenheit) would require cutting global greenhouse gas emissions by 50 to 85 percent by 2050, according to the UN panel.

Ice shelves, which attach to land and float on the ocean's surface, form through the accumulation of snow and freezing water.

The Markham Ice Shelf's separation was part of the 23 percent ice shelf loss seen in the Canadian arctic since July, leaving about 700 square kilometers remaining, Copeland said.

The researchers also documented the loss of two large sections of the Serson Ice Shelf, reducing its size by 47 square miles (122 kilometers), or 60 percent, while the Ward Hunt Ice Shelf lost 8 square miles (22 kilometers), Copeland said.


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Has this happened before with ice sheets of this size? Oh, the data only goes back to 1972, hmmm, then I would surmise probably so, right after the ice age! :poke:

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