Date published: 2007/07/06
The BBC says:
Armies of insects once crawled through lush forests in a region of Greenland now covered by more than 2000m of ice.
DNA extracted from ice cores show that moths and butterflies were living in forests of spruce and pine in the area between 450,000 and 800,000 years ago.
Writing in the journal Science, the researchers say they believe the DNAs are the oldest pure samples obtained.
The ice cores also suggest that the ice sheet is more resistant to warming than previously thought, the scientists say.
"We have shown for the first time that southern Greenland, which is currently hidden under more than 2km of ice, was once very different to the Greenland we see today," said Professor Eske Willerslev from the University of Copenhagen and one of the authors of the paper.
"What we've learned is that this part of the world was significantly warmer than most people thought," said Professor Martin Sharp from the University of Alberta and a co-author of the paper.
The ancient boreal forests were thought to cover southern Greenland during a period of increased global temperatures, known as an interglacial.
Temperatures at the time were probably between 10C in summer and -17C in winter.
When the temperatures dropped again 450,000 years ago, the forests and their inhabitants were covered by the advancing ice, effectively freezing them in time.
Studies suggest that even during the last interglacial (116,000-130,000 years ago), when temperatures were thought to be 5C warmer than today, the ice persevered, keeping the delicate samples entombed and free from contamination and decay.
At the time the ice is estimated to have been between 1,000 and 1,500m thick.
"If our data is correct, then this means that the southern Greenland ice cap is more stable than previously thought," said Professor Willerslev. "This may have implications for how the ice sheets respond to global warming."
Research by Australian scientists has suggested that a 3C rise in global temperatures would be enough to trigger the melting of the Greenland ice sheet.
In 2006, research conducted by researchers at Nasa suggested that the rate of melting of the giant ice sheet had tripled since 2004.
While in February 2006, researchers found that Greenland's glaciers were moving much faster than before, meaning that more of its ice was entering the sea.
And in 1996, Greenland was losing about 100 cubic km per year in mass from its ice sheet; by 2005, this had increased to about 220 cubic km.
A complete melt of the ice sheet would cause a global sea level rise of about 7m; but the current picture indicates that while some regions are thinning, others are apparently getting thicker.
Although the results are interesting, this is only one very limited study and, in spite of their claims, does not really have that much relevance to what is happening to Greenland today.
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