Science / Medicine : Leaf Fossils Tell of a Once-Warmer Antarctic

Fossilized tree leaves found near the South Pole indicate that the now frigid Antarctic was much warmer as recently as 3 million years ago, Ohio scientists reported last week. Under widely accepted theories, a permanent sheet of ice was thought to have covered most of Antarctica for the last 15 million years or more.

But based on the latest findings, it appears the Antarctic climate “has a much more dynamic and unstable record,” said Peter Webb of Ohio State University in Columbus, who led the team that found the leaves.

Webb and other researchers found the leaves from southern beech trees late last year about 250 miles from the South Pole near the head of Beardmore Glacier. Based on the find, Barrie McKelvey of the University of New England in Armidale, Australia, estimated that the region’s average temperature must have been 18 degrees to 27 degrees Fahrenheit higher than current levels.

The latest discovery, coupled with signs of similar warming in the Arctic during the same period, suggests that polar ice sheet has been “waxing and waning in response to an ever-changing climate, and in so doing has caused major changes in world sea level,” McKelvey said.