By David Shukman

Eureka High Arctic Weather Station, Canada



The researchers had to work fast in case the weather closed in

The scientists at work

Some 16km long and 5km wide (10x3 miles), Ayles Ice Island broke away from the Canadian Arctic coast in 2005, but has only recently been identified.

Researchers have now landed on the giant berg with a BBC team and planted a tracking beacon on its surface.

This will allow the island's progress to be monitored as currents push it around the Arctic Ocean.

The team wants to know why this Ice Island formed

Tracking the island

Its current location is about 600km (400 miles) from the North Pole, in what is one of the fastest warming regions on Earth.

We approached the island in a small plane. From the air, the vast expanse of white stood out as unusually smooth compared with the much rougher sea ice that forms and thaws with the changing seasons.

The island's surface was judged safe enough to land on - our plane was fitted with skis - and after a bumpy touchdown we ground to a halt, the first expedition of its kind.

Soon the scientists were at work - time was limited with the risk of the weather changing.

Recent satellite images show the island free of the coast

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Then he and Dr Luke Copland, of the University of Ottawa, carried out a series of measurements using a ground-penetrating radar.

They found that the average of thickness of the ice was 42-45m (138-148ft) - the equivalent of the height of a 10-storey building.

This was slightly thicker than expected.

One implication is that the island is may prove even more durable than predicted - the sheer weight of ice estimated at two billion tonnes may take longer to melt than initially thought.

From above, the island appears flat against the jagged sea ice

"This shows how climate change can trigger very sudden changes even on a massive scale - when the ice shelf broke away, the rupture registered with the force of a small earthquake," he said.

The records show that this region of the Arctic - the northern coast of Ellesmere Island - has lost 90% of its ice shelves in the past century.

Much of this occurred during the warmer period of the 1940s but then in the cooler decades that followed, some of the ice shelves showed signs of reforming.

According to Dr Mueller, "the difference now is that with the current rate of warming, those ice shelves are likely never to be reconstituted".

The BBC team sets up on Ayles Ice Island

Mission to Ice Island Your Arctic answers

Before we left, the scientists planted a satellite tracking beacon - because if the island continues to drift to the west, it could threaten the oil and gas installations off Alaska.

Click here to see the Canadian Ice Service website tracking the beacon's location.