Astray in the Arctic, the city of ice

Last updated at 22:00 29 December 2006

An ice shelf the size of a city has broken away from the northern Canadian mainland, scientists have revealed.

They said the dramatic event is the latest evidence of how global warming is changing the face of the planet.

After floating out into the Arctic Ocean, the Ayles shelf has frozen into the winter sea ice ten miles from shore.

Believed to have been formed around 4,000 years ago, the shelf is ten miles long, three miles wide and 20 yards deep.

Until it broke away, it was one of six ice shelves on Ellesmere Island, Canada's most northern landmass, 500 miles from the North Pole. All six have shrunk to a tenth of the size they were in 1906.

"We're seeing incredible changes," said Warwick Vincent, of Laval University in Quebec.

"People talk of endangered animals - well, these are endangered landscape features and we're losing them." Professor Vincent, who studies aquatic ecosystems, said it was as if a cruise missile "had come down and hit the ice shelf".

Although the shelf broke off 16 months ago, scientists have only now worked out what happened using earthquake records and satellite images.

They are blaming the event on the hot summer of last year and high winds that helped expose the Ayles shelf to waves and open water. It is thought it will float off again in warmer weather.

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