A vast Antarctic ice shelf is in danger of collapsing after the ice bridge that pinned it to land shattered over the weekend.
The Wilkins ice shelf would be the largest slab of ice to be lost by Antarctica in recent times, in what researchers say is a sign of how global warming is reshaping the map of Antarctica.
The shelf, almost half the size of Wales, is the tenth to break away or shrink to a fraction of its original size in the past 50 years.
David Vaughan of the British Antarctic Survey (BAS) said that warmer conditions in the Antarctic Peninsula caused the ice bridge to melt and that it is likely to be linked to global warming. Temperatures in the peninsula have risen 3 degrees Celsius (5.4 degrees Fahrenheit) in 50 years.
"The ice shelves that have retreated over the last few decades are the ones we would have expected to retreat because of atmospheric climate change in Antarctica," he said. "We are beginning to connect that to global changes."
He said that he was amazed by the speed of the breakup of the ice bridge and the retreat of the ice shelf. "This one was a very extensive ice shelf until the 1990s when it started retreating."
In the 1990s it measured 6,200 square miles (16,000 square km), since when it is thought to have retreated by at least half.
If the remaining ice breaks up it will be the biggest collapse on record, dwarfing the break up of the 770 square miles of the Larsen B shelf in 2002.