New study shows Arctic sea ice extent ~6000 years ago was much less than today

This is interesting, somehow the Earth managed to reduce a good portion of the Arctic Ice Cap during the Holocene Climate Optimum from approximately 10,000-6,000 years ago without the help of the industrial revolution, fossil fuels, or automobile emissions.

This new paper published in Quaternary Science Reviews finds Arctic sea ice extent and thickness was much less than present-day conditions and according to the authors,

“Arctic Ocean sea ice proxies generally suggest a reduction in sea ice during parts of the early and middle Holocene (∼6000–10,000 years Before the Present) compared to present day conditions.”

The authors show how  8 different proxy studies reveal extended periods lasting hundreds of years without perennial sea ice in the Arctic [ice-free conditions], and find solar insolation explains these changes. See figure 4 from the paper below.

The top graph shows simulated annual mean sea ice thickness [orange curve] was much less during the Holocene Climate Optimum ~13,000-6,000 years ago compared to the end of the 20th century at right side of graph. The bottom graph shows multiple proxies of sea ice with darker green indicating periods of less sea ice. Modern sea ice is at high levels in comparison to the rest of the Holocene.

Fig. 4.
Annual mean sea ice thickness for the three different simulations (Panel a) compared with results from published paleo-sea ice studies (Panel b). Black curve: constant surface albedo; red curve: dynamic surface albedo parameterization. The simulation implemented with a dynamic surface albedo parameterization was run from present time and backwards to address the importance of the initial state of the sea ice cover. The annual mean sea ice thickness from this simulation (orange curve) reveals a hysteresis of ∼1000 years. The annual mean insolation at 80°N shown with a stippled curve is based on the algorithm presented by Berger (1978). To compare the results from different paleo-sea ice studies a scale of sea ice concentration was inferred using the approach by Jakobsson et al. (2010). This scale must be considered as highly qualitative because none of the paleo-sea ice proxies provide absolute measures of past sea ice concentrations.

The paper:

Arctic Ocean perennial sea ice breakdown during the Early Holocene Insolation Maximum 

Christian Stranne, Martin Jakobsson, Göran Björk

Abstract

Arctic Ocean sea ice proxies generally suggest a reduction in sea ice during parts of the early and middle Holocene (∼6000–10,000 years Before the Present) compared to present day conditions. This sea ice minimum has been attributed to the northern hemisphere Early Holocene Insolation Maximum (EHIM) associated with Earth’s orbital cycles. Here we investigate the transient effect of insolation variations during the final part of the last glaciation and the Holocene by means of continuous climate simulations with the coupled atmosphere–sea ice–ocean column model CCAM. We show that the increased insolation during EHIM has the potential to push the Arctic Ocean sea ice cover into a regime dominated by seasonal ice, i.e. ice free summers. The strong sea ice thickness response is caused by the positive sea ice albedo feedback. Studies of the GRIP ice cores and high latitude North Atlantic sediment cores show that the Bølling–Allerød period (c. 12,700–14,700 years BP) was a climatically unstable period in the northern high latitudes and we speculate that this instability may be linked to dual stability modes of the Arctic sea ice cover characterized by e.g. transitions between periods with and without perennial sea ice cover.

http://www.sciencedirect.com/science/article/pii/S0277379113004162?np=y

h/t to The Hockey Schtick

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Box of Rocks

Now we need to send in the archaeologist to find the coal fired power plants and GMC Yukons….
That is going to be one big dig. But hey people will be employed!

There were a lot of interesting things going on 6000 years ago, I saved some in http://wermenh.com/climate/6000.html
Most of my savings were about glaciers around the world (hello Oetzi!), but I also have this:
2008 Oct 20: 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.”
This includes a ruined settlement left by the Independence I Culture in North Greenland abandoned at least 4,000 years ago.
Hey, the link still works, see http://www.ngu.no/sciencepub/eng/pages/Whatsup_20_10_08.html

cnxtim

We have never had to look any further than our Sun to see whichis the only force that matters when it comes to the Earths climate.
It is positively ludicrous to propose the a minute increase or decrease in CO2 can have any significant effect.,
Consequently one must accept the only logical explanation, That this preposterous hypothesis is all about political control,,and science be damned.

JustAnotherPoster

Good, Decent well done science. Can’t fault it really. Suprised it got published as it doesn’t fit the its warmer than ever and were all going to die MEME.

Sooo disappointing….. “Our work points to the strong surface albedo feedback as the common denominator between the sea ice minimum before 6000 years ago and the present diminishing trend. However, at the same time as our simulations show the importance of the surface albedo feedback, there are likely two distinctly different underlying causes for the feedback to kick in: increased insolation (past) and increased GHG levels (present). We also speculate that climatically unstable periods such as the Bølling–Allerød period (c. 12,700–14,700 ”
If increased insolation caused reduced ice in the past, whi do they assume its GHG levels in the present.
ARGHHHHHHHH

hunter

Skeptics proven right again.
We have been questioning the validity of the AGW claim that Arctic sea ice is
1- at unprecedented low levels
2- dangerous to the climate when it is low
now we see this is the case.
Hyping AGW is lucrative, and popular, but that does make it correct.

Alan Robertson

cnxtim says:
March 24, 2014 at 5:17 am
We have never had to look any further than our Sun to see whichis the only force that matters when it comes to the Earths climate.
It is positively ludicrous to propose the a minute increase or decrease in CO2 can have any significant effect.,
Consequently one must accept the only logical explanation, That this preposterous hypothesis is all about political control,,and science be damned.
____________________________
Well, you are correct about the political part. Perhaps you could provide links to historical data which show the Sun’s link to climate and you’ll be right about that, too. Do any such studies hold under scrutiny? To say the Sun is the primary source of energy is one thing, but saying the Sun is the primary driver of Climate is another thing, unproven to date.

Steve Keohane

Yup, sea level was 2 meters higher 4-6000 years ago.

As Ric Werme says, this is old-hat, and I think now stuffed with a few new feathers by computer modellers. Norwegian real scientists found the north Greenland beach structures – showing evidence of wave action on a coastline where there is now ‘permanent’ ice, and carbon-dated it to the period 8000-6000BP (reviewed in my book Chill, 2009). For the same time-period, other real scientists in my home country of Somerset discovered that the lake-village dwellers ate Pelicans for breakfast (European birds now found only in Greece and the Danube delta)! Recent flooding may bring the lake-villages back, but it will take a lot of global warming to encourage the Pelicans to return. Greenpeace campaigners please note: this previous Arctic meltdown did not release methane hydrates that fried the planet.

beng

Notice these types of papers don’t go into fearmongering mode when talking about previous natural changes. It’s only when talking about similar changes that might happen now that the fearmongering emerges. What about the poor polar bears back then? The poor seals? The delicate Arctic ecosystem?

Alan Robertson

To cnxtim:
The radiative energy reaching the Earth from the Sun varies both cyclically and randomly, but so far, the changes don’t correlate to historical climate change. It may well be that the Sun, in concert with other forces we don’t yet understand, such as the Solar wind influence > cosmic radiation > cloud formation is a major factor in our changing climate. There is just too much going on that we don’t yet understand.

Gary

It’s 99% modeling results with a tiny bit of support from other studies using paleo data, some of which the authors say is contradictory. The only thing worthwhile coming from it is that models can cut both ways, which hardly supports the paper’s conclusion.

The truth is the hysteria of the ice caps is based upon such a miniscule window into the behavior of the ice caps that no logical conclusions can be drawn. Yet those seeking to advance their alarmist agenda still use it as some sort of absolute measuring stick.

Climate philosophy – about as `scientific` as say alchemy, astrology or reading palms. The corrupt Cult of Globaloneywarming just highlights the poverty of modern critical thinking. Truly a dark age in some ways.

Tom J

Well at least now we don’t have to worry about any emails being sent from Michael Mann to Phil Jones inquiring whether they can get one of the editors at Quaternary Science Reviews sacked.
Maybe.

Alan Robertson

Ferdinand (@StFerdinandIII) says:
March 24, 2014 at 5:52 am
__________________
Engelbeen, is that you?

Although generally preferring more direct data than model simulations, there are quite a number of studies showing the Holocene Climate Optimum had greater warmth than now, higher sea level, more arctic vegetation (fitting the warmth), etc. Some are listed within co2science.org
And naturally solar forcing was high then.
Variation in solar forcing at Earth, both from Milankovitch cycles and from variation in solar activity itself, is the prime driver of climate on most timescales, including through influence on cosmic rays (also affected by geomagnetic variation and movement around the galaxy):
As a Dergachev et al 2004 paper flatly notes, known data “proves that cosmic rays were the main factor affecting the weather and climate during tens of thousands of years.
References and far more are within my usual http://tinyurl.com/nbnh7hq link.
Such includes implicit debunking of various common Big Lies; for example, one common falsehood is that solar activity was flat during the 1970s->1990s warming, aided by rewriting ACRIM data with PMOD, but there were too many more independent neutron monitors to get those rewritten, so observe what a plot 2/3rds of the way down in the prior link shows.

Tom in Florida

re: cnxtim says: March 24, 2014 at 5:17 am
————————————————————————————————————————
Please do not confuse TSI and insolation. The chart shows higher insolation at 80 N because approx 10,000 years ago obliquity was 24 degrees and perihelion was at summer solstice. One would certainly expect less northern sea ice under those conditions which are a result of Earth’s orbit not changes in the Sun’s output.

It’s the wobble, precession of the axis. The Earth was closest to the sun in the Northern Hemisphere summer (July through September) during that period causing the insulation minimum. The sea ice extent and thickness should have been at a maximum in the Southern Hemisphere approximately 13000 to 8000 BP. We are now at perihelion in early January, therefore moderating NH winters. The asymmetrical distribution of continental crust complicates the matter.

Leo Geiger

I see this paper doesn’t get the “Claim:” characterization added to the blog post title. I guess someone likes some aspect of the paper. That’s interesting, since the conclusion comes from modelling:

The Arctic sea ice conditions are simulated from the later part of the last Glacial Maximum (17,000 years BP) and throughout the Holocene using the coupled atmosphere–sea ice–ocean column model CCAM (Stranne and Björk, 2011).

Climate models are OK now?
Later it is noted that the paleo-sea ice records don’t necessarily support ice free conditions found in the model, while they do support a reduction in ice extent:

Whether or not the summer sea ice disappeared in the Holocene over the entire Arctic Ocean is far from resolved from paleo-proxies, although the majority of published results seems to indicate a substantial decrease in the earlier and middle part of the Holocene (Fig. 4b).

But yes, they are arguing that it is possible the Arctic could have been ice free during some part of the period from 6000-12000 years ago based on their models. So do the authors of this paper think this means the current decline in Arctic sea ice has a natural cause? Nope. In their own words:

However, at the same time as our simulations show the importance of the surface albedo feedback, there are likely two distinctly different underlying causes for the feedback to kick in: increased insolation (past) and increased GHG levels (present).

Espen

Not very surprising. Hardangervidda in Norway was a forest back then.

its open knowledge?
Holocene climatic optimum
‘Of 140 sites across the western Arctic, there is clear evidence for warmer-than-present conditions at 120 sites. At 16 sites where quantitative estimates have been obtained, local HTM temperatures were on average 1.6±0.8 °C higher than present. Northwestern North America had peak warmth first, from 11,000 to 9,000 years ago, while the Laurentide ice sheet still chilled the continent. Northeastern North America experienced peak warming 4,000 years later. Along the Arctic Coastal Plain in Alaska, there are indications of summer temperatures 2–3 °C warmer than present.[5] Research indicates that the Arctic had substantially less sea ice during this period compared to present.’
“The Hans Tausen Iskappe (ice cap) in Peary Land (northern Greenland) was drilled in 1977 with a new deep drill to 325 m. The ice core contained distinct melt layers all the way to bedrock indicating that Hans Tausen Iskappe contains no ice from the last glaciation; i.e., the world’s northernmost ice cap melted away during the post-glacial climatic optimum and was rebuilt when the climate got colder some 4000 years ago.”
http://en.wikipedia.org/wiki/Holocene_climatic_optimum
better take a snapshot of that before the co2ers realise there is a wiki page they forgot to
‘improve’.
if the co2ers contextualised the warming within icce age cycles no one would take any notice of them which is why they have to sex it up so the press [who don’t care either way- they love sensation] have a headline.

Pamela Gray

Tom, thank you. Our Earth wibbles, wobbles, whirls, and varies its own intrinsic atmosphere and oceans in a fluidly dynamic dance around the ever present Sun. And I am unimpressed with these “discoveries” being marched out in front of us in order to proclaim that this has been the past but has now ceased to exist as the prime behavior of Earth, overtaken as it is by the breath of man.
Idiots.

ddpalmer

So then Polar Bears as a species only emerged within the last 6,000 years? Because we know current ice conditions are driving them to extinction, so the ice conditions in the paper would have killed them all off. Meaning the current species must postdate those lower ice conditions.

JimS

The skeptics may be right. It’s worse than we thought.

Jim Bo

Someone please translate the following for the science challenged and what, if any, import it has in reference to CAGW?…

However, at the same time as our simulations show the importance of the surface albedo feedback, there are likely two distinctly different underlying causes for the feedback to kick in: increased insolation (past) and increased GHG levels (present).

Ulric Lyons

“This is interesting, somehow the Earth managed to reduce a good portion of the Arctic Ice Cap during the Holocene Climate Optimum from approximately 10,000-6,000 years ago without the help of the industrial revolution, fossil fuels, or automobile emissions.”
Between 4800 and 4400 years ago was one of the warmest periods in the Temperate Zone during the Holocene, this was when there was a rapid expansion in city building worldwide, much like the past few centuries. While in the Arctic this was one the coldest periods: http://snag.gy/BztF1.jpg

a bear is a bear . other bears don’t need ice to live. seals still have to go somewhere so the bears will follow them. biggest threat to polar bear is man who shoots them if they get too close.

Bruce Cobb

@Jim,
1) Trenberth’s “arctic death spiral” was in effect then, and is today, but for a completely different, manmade reason. Total nonsense, of course.

Magma

It seems in their rush to applaud this mainstream refereed climate science paper, people have skipped over the part about mean annual insolation in the Arctic being 5 W/m^2 higher in the Early Holocene than today (for entirely understood reasons), or that the authors are comparing modeled and proxy-derived Early Holocence Arctic ice cover to modern pre-industrial ice cover.
That the paper shows Arctic climate is extremely sensitive to external forcings.also seems to have escaped the celebrators’ notice, as does the fact that Earth is nowhere near a Northern Hemisphere insolation maximum but the ice is melting anyway.
That’s OK. Own goals still count.

ulric -nice contextualising pic.
i think if people still looking for eloquent images [a previous thread] showing global temps and where we are then yours sums it up.

tommoriarty

Arctic sea ice extent less 6000 years ago than today?
Who would have thunk it?
See…
http://climatesanity.wordpress.com/2008/10/15/dont-panic-the-arctic-has-survived-warmer-temperatures-in-the-past/

joe

Yet The warmist bless the marcott 10,000 study as gospel.

John F. Hultquist

Jim Bo says:
March 24, 2014 at 6:44 am
Someone please translate . . .

They are saying ‘We don’t have a clue and hope you won’t notice if we throw in some big words’.
In addition, someone needs a course in writing. The phrase “ for the feedback to kick in” violates the rule to omit needless words, or in today’s lingo KISS. Why do they, given increased insolation, need a feedback or, if there was a feedback, why do they need increased insolation? Some reviewers call this “lazy writing.”

Alan Robertson

Magma says:
March 24, 2014 at 7:11 am
___________________
Your tirade might have been better without employing logical fallacies. It would have been more interesting if you would have given us what you think are the external forcings influencing Arctic sea ice melt. Even better, why is Antarctic ice at such great extent at Perihelion in Southern Hemisphere Summer?

“other real scientists in my home country of Somerset discovered that the lake-village dwellers ate Pelicans for breakfast (European birds now found only in Greece and the Danube delta)!”
Just for the record, Louisiana and the rest of the Gulf Coast are lousy with those things.

The only important thing here is the detection of a period of seasonal ice cover in the Arctic during the Holocene Climate Optimum, which was much warmer than today. There is no need for the postulated “dual stability modes”. When it is cold enough the ice stays around all year; when is is warm enough it doesn’t. Also, I notice the obligitory nod to AGW in the summary of the paper. During the HCO it was increased insolation, now it’s global warming causing the move to seasonal ice. There is no science here, just unsubstantiated speculation as to the cause. I am underwhelmed.

Coach Springer

Study = Observation + Spin. Observation = Proxies indicate much less ice in the past. Spin = Much more ice today means CO2 catastrophe possibly imminent, assuming no summer ice is a catastrophe contrary to hundreds of years of that condition without catastrophe.
I’m going to go with polar bears became extinct 6,000 years ago, but re-evolved. But won’t be able to again because man-made CO2 or something. (/s)

who believes models
REPLY: Not all models are worthless, just like not all Mosher drive-by comments are worthless – Anthony

Bob Kutz

Well, Magma, the point remains; we have been told arctic ice is a tipping point feedback.
As for the notion that the ice was thinner in the past because of higher insolation, we have been told repeatedly the insolation is a presumed constant, the sun does not vary enough to effect our climate and that current warming is unprecedented, as evidenced by arctic (and hysterically, antarctic) sea ice decline.
To now make the claim that the lower sea ice in the distant past was caused by the sun and scientists knew this all along is disingenuous at best, completely fraudulent at worst.
You simply cannot have a scientific theory which is confirmed by every single line of evidence, regardless of the direction that evidence takes, and still call it science.
Even if catastrophic anthropogenic global warming were true, the evidence would still be mixed. For a perfect example of why that is, look no further than the “simple” law of gravity. Go release a helium filled balloon into the air and reconcile it to 9.8 m/s^2. Now go to the top of a building and release it on a windy day. Now consider Mars. Simple right?
Simple laws do not play well with massive chaotic systems. Our models are horribly flawed on their best day, and the “scientists” who are clearly living in the world of advocacy rather than science, keep having to explain why their predictions are completely unskillful.
Still think CO2 science is “simple” or “settled”? Okay then; you fail the basic scientific skepticism test. Go away and let the adults handle this.

What they may be overlooking is the refill of the Mediterranean Sea, Red Sea and Persian Gulf for example which took place about the time they Are looking at. That would have changed all the dynamics of the Atlantic. Conveyor Belt with warmer waters. See Johnson, Secrets of the Med Sea.
Lot of Dynamics here that Are being over looked. ICE Age studies a must.
Paul

joe

One of the positive feedbacks that will drastically increase the warming is the release of methane currently frozen in the tundra of the north. That is supposed to be a really bad thing that will create a massive spiral of warming.
My question for the high priests of AGW is
1) Why did the methane not get released during the Holcene period to cause unprecedented warming
2) Since it apparently did not get released, does the methane have some form of internal mechanism that is able to differentiate between co2 warming on other forms of warming that it knows not to release unless it is co2 caused warming and
3) if the methane did get released during the holcene warming – then who put it back in the ground to get re-released.

Mike Tremblay

Magma says:
March 24, 2014 at 7:11 am
Alan Robertson says:
March 24, 2014 at 7:18 am
——————————————–
Magma is correct. This paper is disappointing in that, although it shows that the AGW assertions that Arctic sea ice cover is at unprecedented lows are wrong, it uses current GCMs to verify what the paleoproxies are already showing. The necessity of verifying the validity of proxies which were established as valid nearly forty years ago is pointless, especially using models which we know have have been shown to be consistently wrong. This paper seems more to be an exercise in showing that the models are valid because they correspond with what the proxies are showing.

Mike Tremblay

Bob Kutz says:
March 24, 2014 at 8:09 am
—————————————-
Bob, your response to Magma is unwarranted. The paleo evidence has been examined for nearly 40 years – since 1978 at least as referenced in the paper. That Climate Science has refused to recognize the validity of the proxies, or been ignorant of the previous studies, is what is being shown by this paper. They continue to use current GCMs as if they were not broken, and compare them to valid proxies, in order to make the point that their hypothesis is still correct and the models are valid. At the same time they refuse to recognize the evidence that, in the past, CO2 levels followed warming, not the other way around, so, IMO, their hypothesis about CO2 forcing is wrong and this is the basis of what is wrong with the models.

Alan Robertson

Mike Tremblay says:
March 24, 2014 at 8:42 am
Magma says:
March 24, 2014 at 7:11 am
Alan Robertson says:
March 24, 2014 at 7:18 am
——————————————–
Magma is correct… This paper seems more to be an exercise in showing that the models are valid because they correspond with what the proxies are showing.
_______________________
Howdy Mike,
I agree with your assessment of this paper. Perhaps I misinterpreted what Magma was saying. Maybe he’ll come back and clarify his remarks.

Gary Pearse

“speculate that this instability may be linked to dual stability modes of the Arctic sea ice cover characterized by e.g. transitions between periods with and without perennial sea ice cover.”
Oh Lord, bring them back to earth. I wonder if they have looked at a paper that has direct OBSERVATIONS of the lack of sea ice during the Holocene Climate Optimum!! Yes observations. How is this possible:
http://wattsupwiththat.com/2010/09/08/inconvenient-ice-study-less-ice-in-the-arctic-ocean-6000-7000-years-ago/
This study shows what you can do on a modest budget. They studied the beaches on the north coast of Greenland which these days is perennially bound in ice – even with our “alarming” summer extents and thicknesses that are to doom the planet. It is a classic. They looked at the raised beaches – higher sea levels (not much crustal rebound on Greenland), the plow marks made by ancient broken ice pack pushed onshore by wind, the beach itself which requires a good stretch of ocean with wind to build them and….wait for it… driftwood and other organic material that can be dated. Elegant and refreshing.

Adrian Metcalfe

Reporting this research here is just another dog whistle to those for whom the political implications of AGW mean it can’t be true. Either that or they’re too stupid to understand that just because the Polar ice cap melted 6000 years ago when it was closer to the sun means it can’t also melt now because of the effect of greenhouse gases.

Duster

jamesibbotson says:
March 24, 2014 at 5:37 am

If increased insolation caused reduced ice in the past, whi do they assume its GHG levels in the present.

The graph is the explanation. According to that, the present annual mean insolation north of 80 degrees is lower than it was 16,000 years ago.

Alan Robertson

Adrian Metcalfe says:
March 24, 2014 at 9:24 am
Reporting this research here is just another dog whistle to those for whom the political implications of AGW mean it can’t be true. Either that or they’re too stupid to understand that just because the Polar ice cap melted 6000 years ago when it was closer to the sun means it can’t also melt now because of the effect of greenhouse gases.
____________________
Why don’t you smarten us up? When do you predict the Polar Ice caps will melt? How about those predictions about Arctic ice melt? Were you one of the smarter- than- everyone- else guys telling us that the Arctic would be ice free by 2013? Does Antarctic sea ice increase count?

jamesibbotson says:
March 24, 2014 at 5:37 am
If increased insolation caused reduced ice in the past, whi do they assume its GHG levels in the present.
ARGHHHHHHHH
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Funding concerns, I am sure.