It is one of the biggest in Antarctica and, for the past century, the massive Wilkins ice shelf appeared to have escaped the ravages of global warming.

But now, enormous cracks have appeared in this floating ice platform the size of an American city. Scientists say it is breaking apart at an unprecedented rate after warmer temperatures weakened it.

A thin strip of ice is all that now prevents the Wilkins shelf from disintegrating and breaking away from the landmass of the Antarctic peninsula, scientists said yesterday. The peninsula is the fastest-warming region in the Antarctic and has seen some of the largest temperature rises on earth – 0.5C per decade – which is why the Wilkins ice shelf is on the verge of disappearing completely, said one of the scientists.

Observers at the British Antarctic Survey (BAS) in Cambridge and the US National Snow and Ice Data Centre in Colorado said they were astonished to discover just how fast the ice shelf was breaking apart since the first cracks were seen in February.

“Wilkins is the largest ice shelf yet on the Antarctic peninsula to be threatened, said David Vaughan of the BAS. “I didn’t expect to see things happen this quickly. The ice shelf is hanging by a thread – we’ll know in the next few days or weeks what its fate will be.”

Professor Vaughan was a member of a BAS team that predicted in 1993 that the Wilkins Shelf could collapse within 30 years, if the pace of global warming continued.

“Wilkins is the largest ice shelf on the Antarctic Peninsula yet to be threatened,” he said. “I didn’t expect to see things happen this quickly. We predicted it would happen, but it’s happened twice as fast as we predicted.”