06 July 2007

Green Land

800 years or so ago Greenland was rather more temperate than it is now. For over 400 years there were Viking settlements which only died out with the onset of a mini ice age during the 15th Century. It seems, however, that it was rather warmer in even earlier times. If it had not been warmer then it would not have been possible to retrieve the world's oldest existing DNA samples from under a mile-deep icecap.

In a report in today’s Independent, sediments from the bottom of a 2km (1.2 mile) ice core provided direct evidence that Greenland was covered in a dense forest less than a million years ago. Scientists have extracted fragments of DNA estimated at 450,000-900,000 years old from a rich variety of organisms. "We have shown for the first time that southern Greenland, which is hidden under 2km of ice, was once very different to the Greenland we see today. Back then, it was inhabited by a diverse array of conifer trees and insects," said Professor Eske Willerslev of the University of Copenhagen, who led the research team. "We have found grain, pine, yew and alder. These correspond to the landscapes we find in eastern Canada and in Swedish forests today... we can also ascertain the climate since each species has its own temperature requirements. The yew trees reveal that the temperature during the winter could not have been lower than minus 17C and the presence of other trees shows that summer temperatures were at least 10C," he said.

The study shows that the Greenland ice cap has existed continuously, in some form or other, for longer than previously supposed. Given that the last organisms to live there have been shown to be so ancient. This appears to. The study suggests the ice cap has been in place for at least 450,000 years.

Professor Willerslev said the findings indicate the ice sheet may be more stable than was thought; disproving the theory that Greenland had been ice-free around 125,000 years ago when the global climate was about 5C warmer than it is today. "This may have implications for how the ice sheets respond to global warming. We know that, in the last interglacial, sea levels rose by 5-6m, but this must have come from other sources, such as the Antarctic ice. I would anticipate that, as the earth warms from man-made climate change, these sources would still contribute to a rise in sea levels,"

Martin Sharp, a glaciologist at the University of Alberta gave this view:”These findings allow us to make a more accurate environmental reconstruction of the time period from which these samples were taken. We've learnt that this part of the world was significantly warmer than most people thought... It could mean our current warming is the result of natural processes and human influences. We may be heading for bigger temperature increases than we thought."

Again fascinating stuff which appears to turn previous theories about Greenland on its head but as the scientists indicate, it does not provide ammunition for those who believe global warming is either a myth or simply a natural process.

5 comments:

Roland Dodds said...

I figure I had best buy a large plot of land on the island now; once global warming kicks in I will have nothing but beautiful green pastures to enjoy.

jams o donnell said...

Not a bad idea. Imagine what California will be like!

elasticwaistbandlady said...

I saw a gorgeous hot pink parka online at Hanna Andersson. Given Houston's climate, I couldn't justify the expense, but if a mini Ice Age is on its way, I need to be prepared!

jams o donnell said...

I wouldn't hold your breath... On the other hand it could be an instant sauna!

CreditStudent said...

Nice notice!
It was really interesting to read your post. I’d like to be at the Earth couple thousand years ago. You know, it’s should be great to see our planet in the past.