Since there is so much worry about the Arctic Sea Ice extent this time of year, it is always good to get some historical perspective. According to this study, our current low Arctic ice extents are not unprecedented.
From a press release of the Geological Survey of Norway:
Less ice in the Arctic Ocean 6000-7000 years ago
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 complete story follows.
”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).
Shore features
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.
Open sea
”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.
Inuit immigration
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.
===========================
h/t to Ecotretas
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Isn’t this old news? Have there been any follow-ups since this research or other studies done?
Does a warm August lead to a warm fall when we look at the temperatures? Checking at the top 5 warmest Augusts in Cleveland, the results are fairly consistant.
Less Arctic ice 6 – 7 millennia ago than today. And no temperature records broken on any continent for over 30 years. [source]
This article provides more evidence that what is being observed in the Arctic is regional climate variability. It has happened in the past, and it will happen again. Human activity has nothing measurable to do with any of it.
I posted the link above for the Geological Survey of Norway on Romm’s Climate Progress as well as Historic Variation in Arctic Ice and was quickly censored. It appeared fleetingly then was deleted.
I also refered to:
Weasel word alert:
‘“Changes that took place 6000-7000 years ago were controlled by other climatic forces than those which seem to dominate today,” Astrid Lyså believes.’
Weasel word aside, what evidence is there to support such a belief?
I came across this paper this time last year. Can’t remember now who posted the original link but I think it was a regular on WUWT. The poster also gave 2 other links:
Holocene sea-ice variations in Greenland: onshore evidence (from studies of driftwood): 1. Ole Bennike. Geological Survey of Denmark and Greenland, Oster Voldgade 10, DK-1350 Copenhagen K, Denmark
http://hol.sagepub.com/cgi/content/abstract/14/4/607
and http://www.apex.geo.su.se/images/stories/apex2009.pdf
The link which jimbo has just added to the Narwaal post is also worth repeating:
“Historic Variation in Arctic Ice” by Tony B
http://noconsensus.wordpress.com/2009/06/16/historic-variation-in-arctic-ice-tony-b/
“Changes that took place 6000-7000 years ago were controlled by other climatic forces than those which seem to dominate today,” Astrid Lyså believes.
Now why would she feel the need to go and say a completely unscientific thing like that, based on a mere belief? Can’t imagine.
”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.”
Here, let re-phrase and factually simplify that statement:
6000-7000 years ago, north of Greenland, there was more open water than there is today. The Arctic Ocean may have been completely ice free as the weather was more temperate than today.
I just posted to Climate Progress more contrary, peer reviewed papers concerning historic Arctic ice melt and don’t even see the words “your comment is awaiting moderation” whereas previously I did. Now I’m getting:
“Error 503 Service Unavailable
Service Unavailable”
This is how you know you are over the target. :o)
we have had dated to about 6000-7000 years ago …
What kind of dating? As from long, long ago, as WWII?:
World War II Airplanes Under the Ice
The Greenland Society of Atlanta has recently attempted to excavate a 10-foot diameter shaft in the Greenland ice pack to remove two B-17 Flying Fortresses and six P-38 Lightning fighters trapped under an estimated 250 feet of ice for almost 50 years (Bloomberg, 1989). Aside from the fascination with salvaging several vintage aircraft for parts and movie rights, the fact that these aircraft were buried so deeply in such a short time focuses attention on the time scales used to estimate the chronologies of ice.
http://www.icr.org/article/ice-cores-age-earth/
Post-normal-science again?
dp says:
September 8, 2010 at 9:37 am
Weasel word alert:
‘“Changes that took place 6000-7000 years ago were controlled by other climatic forces than those which seem to dominate today,” Astrid Lyså believes.’
=================================
Yeah I caught that, too. Gotta put in the obligatory circular reasoning AGW plug for funding, even if it is only a cryptic implication like this one.
Chris
Norfolk, VA, USA
Interesting, indeed. And it’s never inconvenient to learn something new. However, this particular article isn’t really new. I read something similar a couple of months ago. The seasonally ice-free Arctic ocean was probably a consequence of increased solar irradiance during the summer months due to a shift in the Milankovic cycles. And I would be very surprised if researchers of the NGU were ‘sceptical’ of the AGW, at least there’s no hint of that in the story.
6000-7000 thousand years it’s a very long time, did the GWRs were already preaching around Global Warming?. Can’t believe it….the great,great, great,great grandfather of Al Baby !
Here’s some more:
Not much new here. There have been several studies indicating low ice conditions during the Holocene maximum. I referenced one in a post I did earlier this summer:
http://wattsupwiththat.com/2010/07/14/nsidcs-dr-walt-meier-part-2/
This indicates that the Arctic sea ice is quite fragile and it doesn’t take a large increase in temperatures for it to melt completely during summer – temperatures not much higher than where we’ve been in recent years.
In other words, the ice does indeed respond strongly to external forcing, as we’re seeing now.
walt
You know what tundra is? Frozen peat. You know what peat is? Dead trees and bushes. Since the peat goes right up to the Arctic Ocean, trees must have grown there in the past. Trees don’t fare well in ice year round. And the oil under the tundra? Guess.
If you research the history of the polar bear, a species that is only about 250,000 years old, you realize they were brown bears who wandered north when the forest grew near the Arctic ocean, searching for food. They turned white to hunt seals. It’s called Evolution.
So the discovery of the Holocene Optimum is not really new, just what Paleoclimatologists have known since …
Welcome to the Early Holocene Thermal Maximum! Summer insolation was substantially higher in the Arctic in the early Holocene because of changes in the Earth’s orbit (Milankovitch cycles and all that).
I can just imagine how shocked people might have been if our modern technical society had developed during the fading years of the last ice-age. Just picture the ‘save the ice’ campaigns to stop anthropogenic global melting.
Enneagram says: September 8, 2010 at 9:55 am
………..
An object with specific weight higher than that of ice will slowly sink further down.
Was there AGW some millenniums ago? Doesn’t seem so, and the Romans only appeared afterward…
Wait, mammoths had gone also.
Might it be Atlantis?
Just kidding, of course. I just love these History & Geology lessons. Hansen et al. must get back to there school chairs fast! And while it has been warming since the Little Ice Age, AGW and the hockey stick are of course buried when we look back just these few millenniums…
Ecotretas
If only this kind of data would sink in with the alarmists. We could see a press release like.
“Arctic Ice at 30 year minimum, yawn.”
“Models fail to hindcast prior warming periods. IPCC declares them unsuitable for policy direction”
Anthony, I have been looking for a peer-reviewed paper on this study ever since that press release was issued. No sign of it yet. If they haven’t been able to get it published, we should be asking ourselves, why not?
If we can’t see the details of the study, everything said in this PR piece should be taken with a grain of salt.
I have come across no other evidence that the Arctic was ice-free in this region during the Holocene, particularly “all the way to the North Pole” [why do they say this? based on what evidence?]. This area is historically where the very thickest and most stable ice is found.
Even if their interpretation of the ridges is correct, could these ridges not have formed during intense September storms over a week or two when winds briefly drove ice away from shore? There was a period about that time (ca. 7000-8000 years ago) when the ice dam holding back the last of the Laurentide Ice Sheet meltwater (around Hudson Bay) broke through. I’m sure sea ice conditions shifted briefly around that time, but surely that would not have constituted “normal” arctic conditions by anyone’s stretch of the imagination.
More data to falsify ‘the Earth is warming, we’re all going to die!’, mantra from the likes of Hansen et al. Perhaps they live in an alternative universe which operates on different laws of physics? This is a good illustration of how by picking a suitable base period as ‘normal’, it is easy to show a false warming or cooling trend.
In the mean time, weather/climate continues to oscillate up and down, just as it always has. Mankind needs to be prepared for whatever threat this brings.
This is the same era when the Sahara became wet and hospitable. So what happened? Was everywhere warm, or did all the worldwide weather bands all just move north a bit – so the ITCZ ended up over the Sahara, and N European weather ended up over Greenland?
.
Climate progress is posting a complaint regarding censorship at Digg.com Now any reference to this finding will and must be censored by climate progress.
Pot is calling the kettle black.