Tree remains offer clues to past climate

A shrinking glacier in northern Sweden has revealed remains of trees believed to be at least 7,000 years old, a team from the Swedish Research Council reports.

The researchers say the remains of the trees – found beneath the Karsa Glacier, west of Abisko, Lapland – are evidence that the past century has been the warmest for at least seven thousand years.

“If the area hadn’t been covered by a glacier all these thousands of years, these tree remnants would never have made it,” said project leader Leif Kullman.

“The finds yield information indicating that the 20th Century was probably the warmest century in 7,000 years.

“The fact that the climate is so unique during the last century means that we must question whether this could be 100% the result of natural mechanisms,” said Professor Kullman.

Carbon dating shows that pines and birches grew on the site of the glacier during parts of or perhaps the entire period between 11,800 and 7,000 years ago.

The team examined parts of birch and pine trunks in four locations that had been uncovered as the glacier in the Lapland mountains retreated.

The researchers added that the remnants were very well preserved in most cases, but were degrading rapidly as they came in contact with air and water.

The team says that the oldest tree, a pine, lived and died on the site of the Karsa glacier about 12,000 years ago.

The location of the pine is 400-450 metres above today’s tree-line.

Professor Kullman said the discovery placed the thawing of ice at the end of the latest ice age in an entirely new perspective.

“Previous research indicated that Lapland was covered with ice at this time,” he said.

“These findings show that the ice melted and life returned much earlier than we previously thought.”

The researchers are now continuing their examination of glaciers in northern Lapland and Vosterbotten (West Bothnia).

This ongoing research is part of a larger project that comprises glaciers throughout the entire range of mountains in Sweden.

Source: Swedish Research Council press release

Date: 04/12/2008

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