Meltdown shrinks Antarctica

An area of Antarctic ice the size of a small continent has been lost through warming of the local climate, new research by British scientists has shown.

Glaciologists David Vaughan and Chris Doake, at the British Antarctic Survey, say they cannot be certain whether global warming is behind the disintegration of the 8,000 sq kms of ice shelf.

But they warn in a paper published in the science journal Nature that if the Antarctic peninsula continues to grow warmer, more ice shelves will be threatened.

Five ice shelves on the peninsula had broken up as the local climate became 2.5C warmer over the last 50 years, say the scientists.

The "catastrophic effect" has changed the maps of Antarctica, cutting several islands off from the continent and giving birth to thousands of icebergs.

The destruction of the ice shelves was accurately predicted by an American geologist John Mercer in 1978.

But Vaughan and Doake disagree with Mercer's prediction that the retreat of the ice shelves would lead to a significant increase in world sea levels.

Ice shelves are enormous sheets of ice which extend into the sea. The largest cover areas similar to the size of Spain and are up to 1,800 metres thick.

In their paper the scientists say it is clear that ice shelves cannot survive periods of warming lasting more than a few decades.

They write: "We cannot determine whether the Antarctic peninsular warming can be ascribed to a global warming magnified by regional temperature/sea- ice feedback, or if this is a natural oscillation as a result of the same feedback.

"We offer no prediction that the warming will continue, but if it does, other ice shelves are threatened."

If the ice sheets do succumb to the effects of further warming, there could be a significant increase in iceberg hazards to shipping in the Southern Ocean.

Wildlife could benefit however. Antarctic animals like penguins and seals tend to thrive in areas where the ice is thin enough for rocky outcrops to be exposed.