Less ice in the Arctic Ocean 6000-7000 years ago

Oct 20, 2008

Recent mapping of a number of raised beach ridges on the north coast of Greenland suggests that the ice cover in the Arctic Ocean was greatly reduced some 6000-7000 years ago. The Arctic Ocean may have been periodically ice free.

”The climate in the northern regions has never been milder since the last Ice Age than it was about 6000-7000 years ago. We still don’t know whether the Arctic Ocean was completely ice free, but there was more open water in the area north of Greenland than there is today,” says Astrid Lyså, a geologist and researcher at the Geological Survey of Norway (NGU).

Together with her NGU colleague, Eiliv Larsen, she has worked on the north coast of Greenland with a group of scientists from the University of Copenhagen, mapping sea-level changes and studying a number of shore features. She has also collected samples of driftwood that originated from Siberia or Alaska and had these dated, and has collected shells and microfossils from shore sediments.

”The architecture of a sandy shore depends partly on whether wave activity or pack ice has influenced its formation. Beach ridges, which are generally distinct, very long, broad features running parallel to the shoreline, form when there is wave activity and occasional storms. This requires periodically open water,” Astrid Lyså tells me.

Pack-ice ridges which form when drift ice is pressed onto the seashore piling up shore sediments that lie in its path, have a completely different character. They are generally shorter, narrower and more irregular in shape.

”The beach ridges which we have had dated to about 6000-7000 years ago were shaped by wave activity,” says Astrid Lyså. They are located at the mouth of Independence Fjord in North Greenland, on an open, flat plain facing directly onto the Arctic Ocean. Today, drift ice forms a continuous cover from the land here.
Astrid Lyså says that such old beach formations require that the sea all the way to the North Pole was periodically ice free for a long time.

”This stands in sharp contrast to the present-day situation where only ridges piled up by pack ice are being formed,” she says.

However, the scientists are very careful about drawing parallels with the present-day trend in the Arctic Ocean where the cover of sea ice seems to be decreasing.

"Changes that took place 6000-7000 years ago were controlled by other climatic forces than those which seem to dominate today,” Astrid Lyså believes.

The mapping at 82 degrees North took place in summer 2007 as part of the LongTerm project, a sub-project of the major International Polar Year project, SciencePub. The scientists also studied ruined settlements dating from the first Inuit immigration to these desolate coasts.

The first people from Alaska and Canada, called the Independence I Culture, travelled north-east as far as they could go on land as long ago as 4000-4500 years ago. The scientists have found out that drift ice had formed on the sea again in this period, which was essential for the Inuit in connection with their hunting. No beach ridges have been formed since then.

”Seals and driftwood were absolutely vital if they were to survive. They needed seals for food and clothing, and driftwood for fuel when the temperature crept towards minus 50 degrees. For us, it is inconceivable and extremely impressive,” says Eiliv Larsen, the NGU scientist and geologist.

Source: NGU

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User comments : 15

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jeffsaunders
4.2 / 5 (6) Oct 20, 2008
we need a mapping project like google earth with 100 year increments so we can travel back in time.
Velanarris
3.6 / 5 (13) Oct 20, 2008
Where's the almighty AGW concensus group to downrank this article into oblivion?

mikiwud
3.1 / 5 (8) Oct 21, 2008
Velanarris,
some have tried.Told you about argueing with idiots.
Velanarris
4.4 / 5 (7) Oct 21, 2008
Velanarris,
some have tried.Told you about argueing with idiots.
Well I just think it's funny, they were real quick to start handing out 1's but they're certainly not ready to comment on content.
deatopmg
4.5 / 5 (8) Oct 21, 2008
How did the kangaroos and polar bears survive? (in reference to recent falling sky physorg articles)
drel
4.4 / 5 (7) Oct 21, 2008
""Changes that took place 6000-7000 years ago were controlled by other climatic forces than those which seem to dominate today," Astrid Lysa believes."

What were the "...other climatic forces..."? Inappropriate to say that today's forces are different if we don't know what were the forces back then. Or do they just choose for some reason not to explain them in this write-up?
gmurphy
1.1 / 5 (7) Oct 22, 2008
Climate has and always will change. As the article states the climate change responsible for the ancient ice free artic is different from the human caused climate change we observe today.
Velanarris
4.1 / 5 (7) Oct 22, 2008
Climate has and always will change. As the article states the climate change responsible for the ancient ice free artic is different from the human caused climate change we observe today.
And how exactly is it different?
GrayMouser
4.3 / 5 (8) Oct 22, 2008
Climate has and always will change. As the article states the climate change responsible for the ancient ice free artic is different from the human caused climate change we observe today.
And how exactly is it different?


Because there weren't any reporters present?
MikeB
4 / 5 (6) Oct 22, 2008
"Changes that took place 6000-7000 years ago were controlled by other climatic forces than those which seem to dominate today,%u201D Astrid Lyså believes.

Perhaps her use of the word "seem" indicates some skepticism on her part.
out7x
4 / 5 (8) Oct 23, 2008
Where was Al Gore when we needed him, 6000 yrs ago?
Quantum_Conundrum
4 / 5 (5) Oct 24, 2008
LoL.

This Little Ice Age = Epic Phail for AGW alarmists.
MikeB
5 / 5 (2) Oct 26, 2008
"Where was Al Gore when we needed him, 6000 yrs ago?"

Too bad we can't send him back there.
Duude
2.7 / 5 (3) Oct 26, 2008
This article just goes to show you that there are plenty of climactic changes not influenced at all by the industrial revolution. Who can say that sun spot activity didn't affect the polar caps 7000 years ago. Who can say that sun spot activity isn't affecting the polar caps now? Who can say that underwater volcanic activity isn't filling the atmosphere with methane now or then?
BrianH
not rated yet Nov 18, 2008
That time was right smack in the middle of the 11,000 year interglacial period which is now ending.

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