A large shelf of ice has collapsed in an area of the Antarctic where scientists say warming is happening faster than the global average.

The British Antarctic Survey said the Antarctic Peninsula, which reaches up toward Chile and Argentina, has warmed 2.5 C since the late 1940s, much faster than the rest of the planet.

The portion of the Larsen B shelf 200 metres thick with a surface area of 3,250 square kilometres crumbled into small icebergs, said the Survey.

The shelf is now about 40 per cent as large as it was five years ago, scientists said.

Ice shelves are thick plates that float on the ocean surrounding Antarctica and are fed by the continent's glaciers.

Scientists at the National Snow and Ice Data Center at the University of Colorado first noticed the collapse on satellite images earlier this month.

They said the shelf disintegrated over a 35-day period beginning on Jan. 31.

"This breakup gave us the information we need to reassess the stability of ice shelves around the rest of the Antarctic continent," glaciologist Ted Scambos said in a statement.

David Vaughan of the British Antarctic Survey said about 500 billion tonnes of ice broke off the Antarctic Peninsula when Larsen B shattered.