Study finds large variability in Arctic summer ice extent over last 10,000 years; less than half of current amounts for several thousand years
04 August 2011
A new study led by researchers from the Danish National Research Foundation for Geogenetics at the University of Copenhagen has determined that for the last 10,000 years, the extent of summer sea ice in the Arctic Ocean has varied widely. For several thousand years, there was much less sea ice in the Arctic Ocean than now—probably less than half, the researchers concluded. Their paper is published in the journal Science.
Our studies show that there have been large fluctuations in the amount of summer sea ice during the last 10,000 years. During the so-called Holocene Climate Optimum, from approximately 8000 to 5000 years ago, when the temperatures were somewhat warmer than today, there was significantly less sea ice in the Arctic Ocean, probably less than 50% of the summer 2007 coverage, which was absolutely lowest on record.
Our studies also show that when the ice disappears in one area, it may accumulate in another. We have discovered this by comparing our results with observations from northern Canada. While the amount of sea ice decreased in northern Greenland, it increased in Canada. This is probably due to changes in the prevailing wind systems. This factor has not been sufficiently taken into account when forecasting the imminent disappearance of sea ice in the Arctic Ocean.
—Svend Funder, team leader
Although sea ice comes and goes without leaving a record, the team developed a method by which it is possible to measure the variations in the ice several millennia back in time.
The results are based on driftwood gathered along the coast of northern Greenland, which scientists expect will be the final place summer ice will survive, if global temperatures continue to rise.
Driftwood is from the outset embedded in sea ice, said Funder, and reaches the north Greenland coast along with it. The amount of driftwood therefore indicates how much multiyear sea ice there was in the ocean back then.
After the expeditions had been completed, the team needed to study the wood they had collected: wood types had to be determined and it had to be carbon-14 dated. The driftwood originated near the great rivers of present-day North America and Siberia. The wood types were almost entirely spruce, which is widespread in the Boreal forest of North America, and larch, which is dominates the Siberian taiga. The different wood types therefore are evidence of changing travel routes and altered current and wind conditions in the ocean.
The team also examined the beach ridges along the coast. Today, perennial ice prevents any sort of beach from forming along the coasts of northern Greenland. But this had not always been the case. Behind the present shore long rows of beach ridges show that at one time waves could break onto the beach unhindered by sea ice. The beach ridges were mapped for 500 kilometers along the coast, and carbon-14 dating has shown that during the warm period from about 8000 until 4000 years ago, there was more open water and less coastal ice than today.
Our studies show that there are great natural variations in the amount of Arctic sea ice. The bad news is that there is a clear connection between temperature and the amount of sea ice. And there is no doubt that continued global warming will lead to a reduction in the amount of summer sea ice in the Arctic Ocean. The good news is that even with a reduction to less than 50% of the current amount of sea ice the ice will not reach a point of no return: a level where the ice no longer can regenerate itself even if the climate was to return to cooler temperatures. Finally, our studies show that the changes to a large degree are caused by the effect that temperature has on the prevailing wind systems. This has not been sufficiently taken into account when forecasting the imminent disappearance of the ice, as often portrayed in the media.
—Sven Funder
Resources
Svend Funder, Hugues Goosse, Hans Jepsen, Eigil Kaas, Kurt H. Kjær, Niels J. Korsgaard, Nicolaj K. Larsen, Hans Linderson, Astrid Lyså, Per Möller, Jesper Olsen, and Eske Willerslev (2011) A 10,000-Year Record of Arctic Ocean Sea-Ice Variability—View from the Beach. Science 333 (6043), 747-750. doi: 10.1126/science.1202760
Eeek! Yet ANOTHER peer reviewed study confirming natural variation. Cue the usual respondents.
Posted by: Reel$$ | 04 August 2011 at 09:34 PM
Atmospheric CO2 was a lot lower then than now.
Posted by: Engineer-Poet | 05 August 2011 at 09:21 AM
So um, EP finally confirms the fact that CO2 does NOT drive global warming! Thank you for finally seeing the light!
PS: Let Algore know. He's still confused.
Posted by: Reel$$ | 05 August 2011 at 02:30 PM
"Our studies show that there are great natural variations in the amount of Arctic sea ice. The bad news is that there is a clear connection between temperature and the amount of sea ice. And there is no doubt that continued global warming will lead to a reduction in the amount of summer sea ice in the Arctic Ocean."
Gee I don't see anything about Co2 in this report summary or anything about current conditions. The gist of it is to say the ice could comeback from greater than 50% reduction. Nothing about what drove it other than warm winds. Hello, that's what's melting the ice today. Warm winds from warmer temps up north driven by changing jet stream patterns driven by warmer oceans driven by absorption of warmer air caused by climate change from greater Co2.
Posted by: jeffa | 05 August 2011 at 03:33 PM
Typical Reel, claiming that an effect can only have one cause. Of course, if he admitted that the world is not as simple as his mind, he wouldn't be here.
We have evidence that arctic sea ice can come back from a large reduction... in the atmospheric conditions prevailing 5000 years ago. Those conditions no longer exist.
Posted by: Engineer-Poet | 06 August 2011 at 09:33 AM
Climate scientists don't have a problem with there being "natural variation" in the climate. In fact, it shows how strong the case for AGW is. It shows the climate is sensitive to "forcing." Furthermore scientists have never said CO2 was the only such force acting on the climate. For example, during this Holocene Climate Optimum period(which was NOT a period of *global* warming BTW - just a period of northern hemisphere summer warming) the forcing is known to have been a change in the Earth's orbit and axial tilt (which was 24° at the time); http://www.ncdc.noaa.gov/paleo/globalwarming/holocene.html
It's been calculated that these changes would have provided 8% more solar radiation (+40W/m²) to the Northern Hemisphere in summer.
The thing is, all the forces that we know of that drive the climate also have known, quantifiable, effects(+&-) which can be added up... and the numbers for the current global warming doesn't add up UNLESS you include the effects of CO2.
Posted by: ai_vin | 06 August 2011 at 09:40 AM
Denial takes many forms -especially now amongst those clinging to the old and dead school of AGW. Evidence mounts day after day, not only the public and givernment have rejected AGW outright - science has also.
ai_vin acknowledges "all the forces we know of that drive climate also have known quantifiable effects..."
True but the value of many forces are largely unknown still, (cloud cover, carbon black, PDO, solar, volcanic, albedo, aerosols, precipitation, etc.) since there is little data to quantify. Thus the contribution of man-made CO2 sinks further down the list of real forcings affecting global temps.
Study the Breakthrough document gentlemen - it is your guide forward. Your comments would be interesting:
http://thebreakthrough.org/blog/2011/07/climate_pragmatism_innovation.shtml
Posted by: Reel$$ | 06 August 2011 at 10:53 AM
Actually, I have always seen myself as a Bright Green so there's little in Nordhaus and Shellenberger's work I don't agree with...but what's your point?
You're saying "that CO2 does NOT drive global warming" and that's the issue I have with you. I do not have an issue with your advocacy of technology(EVs, distributed power, etc) that would reduce our emissions.
So please show us where Nordhaus and Shellenberger say anything about CO2 not being the cause of AGW because up until now all I've seen says they are only arguing that the public debate and politicking surrounding climate change have failed to work. [No surprize there, what with all the nitwits in the public and public office.] Where do they argue against the science of AGW like you do?
Posted by: ai_vin | 06 August 2011 at 01:06 PM
True but the value of many forces are largely unknown still, (cloud cover, carbon black, PDO, solar, volcanic, albedo, aerosols, precipitation, etc.) since there is little data to quantify.
Actually Reel, of the things you've listed, their current values ARE largely known - which is all we need to show CO2 is currently the major driver of climate change. It's their future values that's the big unknown.
Posted by: ai_vin | 06 August 2011 at 01:16 PM
ai_ I think it fair to say the authors suggest the failure of government and public to act to cap CO2 suggests the "science" is unconvincing. In fact the excessively small number of alarmist scientists responsible for publishing the "consensus" view - are the cause of the failure:
http://blogs.forbes.com/williampentland/2011/07/31/climate-sins-and-the-high-priests-of-peer-review/#comment-1350
It is this high handed, elliptical condescension typified by the hateful expression "denier" that has galvanized the public against AGW and its proponents. Keep in mind that until the Renaissance "science" (aka Church) rejected the heliocentric model and propagated the flat earth myth. They also sought to suppress publishing and reading (familiar?) by controlling Gutenberg's presses. Hence the revolt of Martin Luther and the Reformation.
Breakthrough acknowledges much of this by approaching "climate" without mentioning climate. An idea we have long supported in the form of "Energy Independence." This allows a graceful retreat from the CO2/AGW claim without apology. So, for AGW believers emission reduction is achieved. For skeptics, energy independence addresses economic, security and political issues.
As far as believing we have accurate data in the myriad table of natural and man-made forcings on climate - highly doubtful. The complexity of a system of variables as large and STILL unknown as this - defies the best GCMs and programmers. So climate remains mysterious for a while - all the more opportunity for future scientists to disentangle.
Posted by: Reel$$ | 06 August 2011 at 02:14 PM
There was "high-handed, elliptical condescension" from the tobacco denialists (orchestrated by the George C. Marshall Institute via its paid PhD propagandists), until the evidence hidden by the Tobacco Institute came to light and it was revealed that the tobacco industry knew all along that its product was both addictive and the cause of many deadly diseases.
Climate denialism is the same as tobacco denialism, right down to the involvement of GMI and some of the same individuals. Climate science has observational data like Galileo, and a model like Isaac Newton; the denialists have... denial and obfuscation. And in the case of Reel, a bunch of fake "alternatives" to fossil fuels (LENR/LANR and "hydrinos") without a single nod to the biggest real one, nuclear power. Both the denial movement and Reel are transparent frauds.
Posted by: Engineer-Poet | 06 August 2011 at 05:26 PM
As a bit of an aside, Reel's mention of the flat earth myth reminded me of something Isaac Asimov wrote.
The short version is here;
http://chem.tufts.edu/AnswersInScience/RelativityofWrong.htm
And the full version is here;
http://hermiene.net/essays-trans/relativity_of_wrong.html
Posted by: ai_vin | 07 August 2011 at 08:26 AM
Thanks for the article ai_... I had forgotten the term "oblateness" and its support for a relative flat earth. Remember too that sailors looking across the Atlantic ocean so only a flat horizon - and the number of people who knew of Eratosthenes were a handful.
EP's previous dialog indicates a severe schism and cognitive dissonance as when he accused Reel of working both for and against the coal industry. There is no conspiracy by tobacco to undermine climate scientists EP! Address your paranoia.
Unfortunately climate "science" which claims the consensus of all major scientific institutions - represents the "Church" of consensus with the handful of climate "priests" its guardians. Copernicus, Galileo, Luther, Bruno - were all declared heretics opposed to the church teachings. As are scientists today who oppose the climate "consensus."
EP well knows that I support a wide portfolio of alternative energy resources inclusive of certain types of classical nuclear - should they be economical. LANR and Randall Mills' work with "hydrinos" are two expressions of well-documented excess heat phenomena.
The stridency of your tone suggests you mean none of what you claim and in fact desire the opposite. Schism indeed!!
BTW, were a fraud actually transparent, only the blind would find it threatening.
Posted by: Reel$$ | 07 August 2011 at 10:59 AM
EP: would you care to amend your bet to the confirmation of "hydrinos?" I shall bet that Dr. Mills has identified a new (to us) form of Hydrogen with energy states lower than the presently accepted ground state.
Posted by: Reel$$ | 08 August 2011 at 01:46 PM
Reel's... issues with reading (or maybe honesty) come to the fore again. If I ever accused you of working against the coal industry, post a link. Working for gas is not the same. Delusional thinking is your stock in trade, as in this example:
No, you 1D10T. It's the George C. Marshall institute which has paid PhD's to create fake science against both real tobacco health data and real climate science. The paymasters behind GMI were different for the two cases, but at least one GMI worker was involved with both efforts.Then let's see a working device yielding useful energy. It took less than 3 years to go from the first chain reaction to a full-scale industry using nuclear reactors to make streams of plutonium good for many weapons a year. If hydrinos are real, why haven't we seen even a single device of useful scale (e.g. 3 kWth or more) provided for independent testing?
I see the collapse of Rossi (his dissociation with the shell company in Greece) has left you scrambling for a fallback position. Had you accepted my bet, I'd be collecting now.
There are certainly lower energy states of hydrogen than H2; H2O is one of them. I just dispute that they can be used to yield useful energy by means unknown to modern physics. I'm not aware of any statements by Mills regarding plans to enter production or other acts which would constitute unambiguous proof that hydrinos can supplant fossil fuels and/or nuclear power, so I see nothing to bet on.
Posted by: Engineer-Poet | 08 August 2011 at 05:01 PM
Hah, EP falls for the simplest of deceptions! His conspiracy claim centers around: "The paymasters behind GMI were different for the two cases, but at least one GMI worker was involved with both efforts."
So tell us EP, WHO are these paymasters? And though it takes two or more to form a conspiracy, WHO is the worker involved??? I'm sure the Tattler and Star would be very interested!
And, you refuse to accept MY bet that Mills has discovered an entirely new form of H, with energy states lower than presently accepted ground state? You've got the physics "consensus" on your side!
Mills has published a design for a chemical energy system (multi-cell thermally coupled reactor) utilizing the hydrino effect at a cost of about $1,380/kW installed. Competitive with CCGT as fuel costs are <$0.001/kWh at zero CO2 emission.
BTW Rossi et al, says his 1MW plant will be built in the USA, not Greece.
Posted by: Reel$$ | 09 August 2011 at 12:36 PM
EP opines on hydrinos: I just dispute that they can be used to yield useful energy by means unknown to modern physics.
Which in EP's world of semantic sleight of hand means he agrees the Blacklight hydrino effect does exactly what Dr. Mills says it does.
THAT, Algore, is shared reality.
Posted by: Reel$$ | 10 August 2011 at 09:00 PM
The names involved in both the tobacco-denial effort and the climate-denial effort are Frederick Seitz and Fred Singer.
A reporter went to the address of Rossi's putative US partner. It was a condominium that was for sale.
If you're such a believer in Rossi, take my bet.
Posted by: Engineer-Poet | 12 August 2011 at 05:59 AM