Ellesmere Island (Jan 08/07) - Pretend for a minute the island of Manhattan was mobile and made of ice.

Fifty kilometres west of the northern tip of Ellesmere Island is just such a chunk of ice. It used to be the Ayles Ice Shelf, but now, at 66 square kilometres, it's one of the world's largest icebergs.

The enormous mass of ice broke off from Ellesmere 16 months ago, to the alarm of scientists with the Canadian Ice Service and other researchers. Media picked up the story only recently, making headlines around the world. Ice shelves float on water but are connected to land.

A NASA satellite image taken in late 2006 of where the Ayles Ice Shelf used to be. The area has since been filled in with sea ice. - image courtesy of Luke Copland/Laboratory for Cryospheric Research

But what truly stunned scientists is how quickly the massive collapse happened.

"When it actually broke apart this thing took less than an hour to completely break off the land," said Luke Copland, director of the Global Ice Lab and an assistant professor of geography at the University of Ottawa.

The northern tip of Ellesmere Island is the only part of Canada that is (or was) cold enough to form ice shelves. Ayles was one of six remaining shelves in Canada, which have collectively lost 90 per cent of their area in the past century.

Still, Copland said it's hard to make a concrete connection between the collapse of Ayles and climate change.

But "it fits into a very clear trend that we've seen on northern Ellesmere."

Trudy Wohlleben, a sea ice forecaster with the Canadian Ice Service, said it's clear the climate is changing, though this incident doesn't reveal anything about whether humans are behind the shift.

"There has definitely been, over the last several decades, a negative trend in the sea ice concentrations in the Canadian Arctic," she said. "There's no doubt about that."

Sea ice in the Canadian Arctic has declined by 15 per cent between 1969 and 2001, Wohlleben said.

The huge frozen island formerly comprising the ice shelf is forecast to slowly drift south to the Beaufort Sea, and then west past Alaska and Siberia over the next 10 to 20 years, Copland said. If the island lasts long enough, it would eventually wind up in the North Atlantic between Greenland and Spitzbergen.

That path into the Beaufort Sea has raised concerns about shipping routes and oil and gas production.

Sunny Munroe, a spokeswoman with the Northern Transportation Company (NTCL), said the company will likely keep tabs on the ice island. But she added that it likely won't pose a threat to barging operations since most of the company's vessels operate in shallow water close to shore.

Icebergs on Canada's Atlantic coast are regularly towed away from shipping lanes and infrastructure Wohlleben said.

"Given the size of (this ice island) I think it would be a really difficult thing to do," she said. "Even with some of the icebergs getting a tow rope around it is no small feat." The Canadian Ice Service launched last week a page on its Web site where visitors can check the location of what was once the Ayles ice shelf.