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.
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h/t to Ecotretas
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Vuk etc. says:
September 8, 2010 at 10:34 am
Enneagram says: September 8, 2010 at 9:55 am
………..
Ha, Ha!, that’s not the correct answer as you can have very small particles with a very high specific gravity floating on the ice, as a needle floating on a glass of water. It’s size!
In anyway those ice core analysis are as good as palm reading, phrenology or tea leaves readings, also like Mann’s dendrology.
R. Gates says:
September 8, 2010 at 11:59 am
Then we are in a “Holocene Pessimum” as you may well check very soon before Christmas.
R. Gates says: September 8, 2010 at 11:59 am
Furthermore, nothing in this study negates or refutes the notion that current warmth could be related to the 40% increase in CO2 since the 1700′s.
tosh !
Whilst there may be debate as to the causing of the warmer conditions 6,000/7,000 years ago, the one thing that there can be no debate upon is that those warmer conditions did not wipe out any major artic living species (eg., it did not kill off the polar bears). Further, there is no evidence that those warmer conditions were bad for man. Indeed, this is when civilisations began to flourish (viz, the beginning of the Egyptian empire).
That being the case, where is the problem if the world warms say 2degC? Species simply adapt (man included).
It’s sad the narwhals survived the extra iceburgs the warmer arctic produced 6,000 -7,000 years ago, only to have to go through it as a species all over again:
http://news.bbc.co.uk/earth/hi/earth_news/newsid_8972000/8972021.stm
Now that polar bears don’t seem so endanged, the warmist science studies speculators (and grant providers) are trying to rope in the narwhals as their pet of the month.
/sarc
@Smokey
From your “source” link
Wednesday, September 08, 2010
Street theater “education”
“The climate and renewable energy con is losing its luster – prompting anguish and desperation” Icecap Note: To see how desparate they have become – they are lying through their teeth as this SPPI story by Tom Nelson shows. This is what happens when prophecies fail.
By Paul Driessen
It’s been a rough few weeks for the “eco-progressive” fringe.
“Static jet streams induced near-record high temperatures in parts of the United States and Russia, but extreme cold pummeled Seattle, England and much of the Southern Hemisphere. Perhaps Al Gore, Michael Mann and Rajendra Pachauri can turn this hodgepodge into “catastrophic climate change,” but most folks understand it as Mother Nature and weather.”
No it hasn’t. Just a wet start to the Autumn (nothing unusual there) with some wind in a few places (nothing unusual there). Very odd to cite England.
Enneagram says:
September 8, 2010 at 12:35 pm
……..
Needle or coin floating on the water, surface tension, different physics principle here regardless of their study. Metal objects are highly conductive. Solar storms pump large electric currents into any metal object in the Arctic area, remember Canadian greed burn-out. This aircraft if it exist would be frequently heated by induced currents from magnetic storms, sinking ever deeper. BTW Magnetic storms penetrate the arctic lithosphere to depth of hundreds of km (ask Dr. S.).
Vuk etc. says:
Correction
Should be ‘Canadian grid burn-out.’
Vuk etc. says:
September 8, 2010 at 1:07 pm
There you are: That’s it, precisely!. Small particles are proportionally less subjected to gravity than to EM fields. It’s like politicians know, a matter of “spin”. It is usually found in chemistry that, for example, we can produce a copper carbonate of a low bulk density, where particles are electrically charge and repel among them, and another of high bulk density where that charge is presumably lower, apparent color also varies. However charge does not relates always inversely to diameter, there can be of a third kind: Of a high bulk density and smaller particle size. What takes us to gravity….
Vuk etc. says:
September 8, 2010 at 1:07 pm
BTW Magnetic storms penetrate the arctic lithosphere to depth of hundreds of km (ask Dr. S.).
Not to mention the brain!.I can understand it now!, just see the Z vector of magnetic field and find where some minds are becoming more confused. 🙂
Whilst not contemporary to the report concerning this period 6000 years ago, there is lots of evidence of warmer times in the Arctic without needing to resort to the evidence left by the Vikings.
This civilisation linked below thrived in the Arctic over 2000 years ago during what we now know as the Roman warm optimum. First link is from ‘Time’ of 1941 which describes a great city in the Arctic
http://www.time.com/time/magazine/article/0,9171,765299,00.html
Here is the original report on which it is based
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1078291/pdf/pnas01626-0001.pdf
Doubtless there are other treasures waiting to be discovered.
Tonyb
“….In other words, the ice does indeed respond strongly to external forcing, as we’re seeing now.
walt”
Walt, if I may call you Walt, I think the point at issue is that the MSM and general public are under the impression it’s never happened before. As in ‘unprecedented’ and ‘polar bears facing extinction’ etc. By the way how did the polar bears survive the great melt 7000 years ago?
cheers David
As you wind the clock back towards the time of the Holocene optimum, summer insolation above 65N increases due to the Milankovich cycle (particularly the Earth’s obliquity, which increases as you go back in time). It would be surprising if the arctic wasn’t warmer then than it is now. Going forward in time, the obliquity is decreasing, which will lead to cooler summers – and gasp – more sea ice!
When you look at the Milankovic cycles, the arctic got about 60 W/m2 more solar irradiation during early holocene summers than today. The main reason has been the fact that arctic summer solstice still was close to perihel, while today, perihel is around winter solstice, on Jan 4. Perihel has coincided with arctic summer solstice about 10000 years ago, this was the time when the great ice shields of Northern America, of Europe and Sibiria disappeared. Then, there had been 80 W/m2 more solar irradiation during arctic summer than today. However, the Greenland ice shield had survived and it also did survive early holocene, as is obvious from the cores of the bore holes drilled into the Greenland ice.
Leif Svalgaard has told me a while ago that he had asked Gavin Schmidt to carry out a climate model calculation for the early holocene, say, for the time after the 8.2 K event, when all relevant parameters for the earth had become rather close to present days values. No time, has been the answer, if I recall Leif’s story correctly.
Actually, if a model calculation existed, which shows convincingly that on the one hand 60 W/m2 additional solar irradiation would not kill the Greenland ice shield, but 1 or 2 W/m2 more warming through CO2 greenhouse effect would do so – even the biggest sceptic would abjure his evil thoughts.
Included in the results of the model calculation had to be an answer to the problem why in present days a series of positive feedbacks such as permafrost thawing and consecutive methane release should occur, while for reasons unknown to me they have not occurred in early holocene.
To be more serious, there exist model calculations for the CLIMAP project, which covers the time of the maximum ice extend 20000 years ago (see wikipedia). In fact, according to wikipedia, the model results disagree severly with the geological data. Thus it was concluded that there must exist problems with the geological data.
About 6000 years ago buffalo hunting on the Western Canadian plains came to a complete halt and lasted for about 1000 years. The reason a shortage of grass for the Plains Buffalo. No grass means a warm, dry climate. I’m not trying to say this is related to the Arctic ice pack but it does give some food for thought.
Walt Meier says: September 8, 2010 at 10:15 am “…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.”
Correlation does not prove causation, Dr. M. The presence of a forcing does not prove that it is the origin of an effect, even if it precedes the latter. Also, you don’t mention it, but is it not clear from the record that absence of summer sea ice must not involve a climate tipping point?
Penguin optimum was when it was warmer, we know when it cools, they die and migrate closer to the equator. It’s not like they like living in cold.
Werner Weber
There are plenty of model integrations with 6ka orbital parameters, which are rather similar to those at 8ka. See PMIP 2
Remember that the increased early Holocene insolation was only in the high latitudes during summer. The global annual insolation changed little.
D.C. says:
September 8, 2010 at 2:13 pm
Do you have a reference for that? I may add a non-ice section to
http://wermenh.com/climate/6000.html
I haven’t read all the comments, so, if its been said already, it bears repeating anyway. We’ve had less ice in the arctic in the last 30-70 years.
http://www.csp.navy.mil/asl/Timeline.htm ……… and, of course, http://wattsupwiththat.com/2009/04/26/ice-at-the-north-pole-in-1958-not-so-thick/
See the open water?
R. Gates,
Forget that study. The main point of the post was:
Now please read and comment on the following papers and studies:
http://www.agu.org/pubs/crossref/2010/2009PA001817.shtml
http://hol.sagepub.com/content/12/1/49.abstract
http://www.jstor.org/stable/1550979
http://www.sciencemag.org/cgi/content/abstract/278/5341/1257
http://agwobserver.wordpress.com/2009/08/29/papers-on-1500-year-climatic-cycle/
richard telford says:
September 8, 2010 at 10:30 am
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).
The uncertainties in paleoclimate reconstruction remain a live topic. Why did the warming from a significant increase in high latitude precession–driven solar forcing take thousands of years to work its way into lower latitudes?
Just browsing through the abstracts in front of the paywalls you find Ritchie et al. (1983):
‘According to the Milankovitch theory of global climatic change, maximum summer solar radiation at high latitudes of the Northern Hemisphere occurred at 10,000 yr BP. […] In particular, [Milankovitch theory] predicts summer solstice radiation greater by 9−10%.’
And:
‘Paradoxically, however, the large volume of fossil pollen and other evidence from North America indicates a maximum of Holocene warmth at 7,000−6,000 yr (ref. 5), and a recent review of the evidence from New England suggests that the warming began at 9,000 and ended at 5,000 yr, but also stresses the difficulties of interpretation in terms of climate change.’
http://www.nature.com/nature/journal/v305/n5930/abs/305126a0.html
Others agree:
‘Our data thus suggest that optimal summer warmth did not occur in Iceland until 8 kcal. yr BP at the earliest, possibly lasting until 6.7 kcal. yr BP.’
Caseldine et al. (2006)
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VBC-4KGG1X1-1&_user=10&_coverDate=09%2F30%2F2006&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1455101905&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=a32d7357dbcbf9795202aecc4194fa08&searchtype=a
A multi-author PARCS (Paleoenvironmental Arctic Sciences) study concurs:
‘[T]he warming was time-transgressive across the western Arctic.’
And suggests an explanation:
‘Alaska and northwest Canada experienced the HTM between ca 11 and 9 ka, about 4000 yr prior to the HTM in northeast Canada. The delayed warming in Quebec and Labrador was linked to the residual Laurentide Ice Sheet, which chilled the region through its impact on surface energy balance and ocean circulation.’
And they warn:
‘Unlike the HTM, however, future warming will not be counterbalanced by the cooling effect of a residual North American ice sheet.’
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VBC-4BRKMKW-2&_user=10&_coverDate=03%2F31%2F2004&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1455094113&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=b40fcbab47fbc5b06af3c46cd998b9a6&searchtype=a
Food for thought.
jorgekafkazar says:
September 8, 2010 at 2:17 pm
“Also, you don’t mention it, but is it not clear from the record that absence of summer sea ice must not involve a climate tipping point?”
I would also be curious what Dr Meier’s response to this question would be. This is perhaps the most important aspect of this article. And just so I am the first(?) Holocenegate! 😉
Vince Causey says:
September 8, 2010 at 1:57 pm
“Going forward in time, the obliquity is decreasing, which will lead to cooler summers – and gasp – more sea ice!”
_____
What is should be clear to anyone who has studied the last few hundred thousand years of Milankovitch cycles when looking at at temperatures/CO2/interglacial is that the present era is unlike anything that we’ve seen during at least the past 400,000 years and probably much longer. We are seeing Arctic temperatures now approach those seen duirng the Holocene Optimum, and I think you can well reason that if the ice melted then, as is quite possible, it will melt now, as we see happening. Walt Meier’s point about the sensitivity of the ice is exactly to this point. But even more importantly, the melting 6,000 or 7,000 years ago was caused most likely from Milankovitch cycles, whereas the most likely mechanism today is the 40% higher CO2 we have now than we had during that period of the Holocene. Morevoer, the warmth we are seeing now is far more global than the warmth during the Holocene, which is one more indication of the differences in the effects from the insolation and Milankovitch cycles versus global CO2 forcing.
James Sexton says:
September 8, 2010 at 3:19 pm
I haven’t read all the comments, so, if its been said already, it bears repeating anyway. We’ve had less ice in the arctic in the last 30-70 years.
http://www.csp.navy.mil/asl/Timeline.htm ……… and, of course, http://wattsupwiththat.com/2009/04/26/ice-at-the-north-pole-in-1958-not-so-thick/
See the open water?
Plenty more open water there today James!