DNA reveals Greenland's lush past

[Lt_Ripley]

DNA reveals Greenland's lush past

Scientists analysed the sediment-rich base of the ice cores

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.

Ice-locker

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.

SAMPLE SITES

Dye 3: 2km long ice core

Greenland Ice Core Project (GRIP): 3km long ice core

John Evans Glacier (JEG): Control site

Kap Kobenhavn: Previously youngest known Greenland forest

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.

Plant-life

The new results were obtained from the sediment rich bottom of ice cores.

The 2km long Dye 3 core was drilled in south-central Greenland, whilst the 3km-long Greenland Ice Core Project (GRIP) core was taken from the summit of the Greenland ice sheet.

Greenland heats up

Enlarge Image

Samples from other glaciers, such as the John Evans Glacier on Ellesmere island were used as a control, to verify the age of the samples and to confirm that the DNA was from plants that grew in southern Greenland, rather than from plant matter carried by wind or water from elsewhere in the world.

Although the ice contained only a handful of pollen grains and no fossils, the researchers were able to extract DNA form the organic matter held in the silt.

Comparisons with modern species show that the area was populated by diverse forests made up of alders, spruce, pine and members of the yew family.

Living in the trees and on the forest floor was a wide variety of insect life including beetles, flies, spiders, butterflies and moths.

The discovery pushes forward the date when the last forests were known to exist in Greenland by nearly two million years.

Previously, the youngest fossil evidence of a native forest in the region came from fossils found in the Kap Kobenhavn Formation in northern Greenland. There, the fossils date from around 2.4m years ago.

The study paves the way for scientists to probe beneath the ice in other parts of the world.

"Given that 10% of the Earth's terrestrial surface is covered by thick ice sheets, it could open up a world of new discoveries," said Dr Enrico Cappellini of the University of York.

http://news.bbc.co.uk/2/hi/science/nature/6276576.stm

[The Mule]

Good find Ripley, thanks!

[Shaftsbury]

An ice core to bedrock

will provide samples of each annual layer deposited originally as snow through t he last 200,000 years or more.

That is amazing, a 3000+ meter long ice core spanning over 200,000 years.

The data from this should clear up a few myths I'm sure.

Source: http://www.glaciology.gfy.ku.dk/ngrip/iskerner_eng.htm

[Fearisgood]

Interesting...

Living in the trees and on the forest floor was a wide variety of insect life including beetles, flies, spiders, butterflies and moths

Sounds like it was pretty habitable.

The discovery pushes forward the date when the last forests were known to exist in Greenland by nearly two million years.

I'm not sure how they measured the time of a 3km ice core. Radiometric dating or do they count the ice layers as yearly like in tree rings?

Do the layers in ice cores represent annual layers only, or is it possible that other non-precipitation variables such as snow dunes, large subseasonal storms and more melt or hoar frost layers create subannual oscillation? Oxygen isotope measurements in Greenland cores were only resolved down to about 300 meters or 1000 feet in the GISP2 core. How much of an effect does compression have? Doesn't compression affect the resolution the deeper you go?

Wiki: Ice cores

Dating is a difficult task. Five different dating methods have been used for Vostok cores, with differences such as 300 years at 100 m depth, 600yr at 200 m, 7000yr at 400 m, 5000yr at 800 m, 6000yr at 1600 m, and 5000yr at 1934 m.

Any non-google glaciologists here?

Has anybody heard of "Glacier girl"? 50 years after crashing July 15, 1942 on a remote ice cap in Greenland (no-one died) the wreck of one of the p-38 planes was recovered. The plane was covered in 80m (268 feet) of ice. Very interesting, they even restored the plane.

The plane was covered in 80 meters of ice in 50 years. That is +-1.6m ice per year. Snowfall near the coast is higher however, so that affects the rate of layering when compared to samples from ice cores. But looking at the photos of the recovery it looks like there are more than 50 layers...

Edited July 7, 2007 by Fearisgood

[The Carnivore]

So was Iceland ever covered in ice?

[Shaftsbury]

Interesting...

Sounds like it was pretty habitable.

I'm not sure how they measured the time of a 3km ice core. Radiometric dating or do they count the ice layers as yearly like in tree rings?

Do the layers in ice cores represent annual layers only, or is it possible that other non-precipitation variables such as snow dunes, large subseasonal storms and more melt or hoar frost layers create subannual oscillation?

"The data used for the main annual layer counting of the past 7900 years are the DYE-

3, GRIP and NGRIP stable isotope records."

Source 1: http://www.agu.org/pubs/crossref/2006/2005JD006921.shtml

Source 2: http://www.nbi.ku.dk/page25265.htm

It looks like they are using Isotope geochemistry to date the cores, then comparing the data from all the Greenland ice core projects.

Oxygen isotope measurements in Greenland cores were only resolved down to about 300 meters or 1000 feet in the GISP2 core. How much of an effect does compression have? Doesn't compression affect the resolution the deeper you go?

Wiki: Ice cores

I'm not sure where you got that bit, my source shows accurate measurements down to 2790 m. ?

"The climatic significance of the deeper part of the GISP2 ice core, below 2790 m depth and 110 kyr age, is a matter of considerable investigation and controversy.

The isotopic temperature records and electrical conductivity records of GISP2 and GRIP, so similar for ice <110 kyr in age, are very different in the lower part [ Grootes et al., 1993; Taylor et al., 1993a].

Ice in GISP2 below 2790 m depth is folded and tilted, and shows evidence of unconformities [ Gow et al., 1993]. The O of O in GISP2 above 2790 m matches almost perfectly with the Vostok record [ Sowers et al., 1993]; below that depth, it is far noisier and cannot be aligned with the smoothed Vostok signal [ Bender et al., 1994]."

Source 3: http://www.agu.org/revgeophys/mayews01/nod...000000000000000

But if anybody is seriously interested, here is a rather detailed article on the Greenland Ice Core Chronology 2005

(GICC05) project: http://www.gfy.ku.dk/~www-glac/papers/pdfs/219.pdf

edit* specified the (GICC05) project rather than a general project.

Edited July 9, 2007 by Shaftsbury

[Oxymoron]

Very Intersting. Maybe Greenlands name actually characterized What it ounce was, and the discovery of the land was not an accident by the Vikings. Does this prove an ancient civilazation that existed when Greenland was indeed green, and this map knowledge was passed to the Vikings. Is it a coincedence that the Vikings found America so easily or did they know it existed?

[Roj47]

Very Intersting. Maybe Greenlands name actually characterized What it ounce was,

Heh...., and these names follow suit...

Turkey - Populated by the bird when first discovered.

Hungary - inhabitant were always demanding food for families.

Russia - Everyone was in a hurry and ran round.

Chile - It is cold

Congo - People performed the dance of holding hips and kicking legs out....

heh...

[Essan]

So was Iceland ever covered in ice?

Well, it is now Much of the island is covered in an ice cap. Which, incidently lies outside the arctic circle!

I'll add my recomendation to the links Shaftsbury posted - and add that Richard Alley's book The 2 Mile Time Machine is well worth reading too

[Oxymoron]

Heh...., and these names follow suit...

Turkey - Populated by the bird when first discovered.

Hungary - inhabitant were always demanding food for families.

Russia - Everyone was in a hurry and ran round.

Chile - It is cold

Congo - People performed the dance of holding hips and kicking legs out....

heh...

Well in reality the vikings named the new lands based on their characteristics for example Vineland(N America),