Researchers find arctic may have had less ice 6000-7000 years ago

I love field work. I think any climate scientist that basically becomes a data jockey should be forced to go out and examine real world measurement systems and weather stations once a year so that they don’t lose touch with the source of the data they study. That’s why I’m pleased to see that scientists at the Geological Survey of Norway (NGU ) did some good old fashioned field work to look at geologic residues of past climate.

What they found was intriguing. The arctic may have periodically been nearly ice free in recent geologic history, after the last ice age. It is clear from this that we don’t really know as much as some think they do about climatic and ice cycles of our planet.

From NGU:

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.

Greenland

BEACH RIDGE: The scientists believe that this beach ridge in North Greenland formed by wave activity about 6000-7000 years ago. This implies that there was more open sea in this region than there is today. (Click the picture for a larger image) Photo: Astrid Lyså, NGU

”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

Greenland

ICE COVER: Today, at the mouth of Independence Fjord in North Greenland, drift ice forms a continuous cover from the land. (Click for a larger image) Photo: Eiliv Larsen, 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.

Greenland

SETTLEMENT: Astrid Lyså in August 2007 in the ruined settlement left by the Independence I Culture in North Greenland. The first immigrants to these inhospitable regions succumbed to the elements nearly 4000 years ago, when the climate became colder again. (Click for a larger image) Photo: Eiliv Larsen, NGU

”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.

(hat tip to many commenters and emailers, too numerous to mention, but thanks to all)

Advertisements

  Subscribe  
newest oldest most voted
Notify of

Yeah, but THIS TIME, it’s OUR fault!!!!!!!!!!!!!!!
snark – off

”The climate in the northern regions has never been milder since the last Ice Age than it was about 6000-7000 years ago.”
And those who believe that the correlation between climate and solar activity is ‘obvious’ can compare with one reconstruction of solar activity [Usoskin et al.] at 4000-5000 BC:
http://upload.wikimedia.org/wikipedia/commons/thumb/2/27/Sunspots_11000_years.svg/800px-Sunspots_11000_years.svg.png
Low spots -> cold, remember.

Leon Brozyna

An interesting study, including the standard disclaimer:
“Changes that took place 6000-7000 years ago were controlled by other climatic forces than those which seem to dominate today,” Astrid Lyså believes.
Even good studies have to protect themselves from charges of going against the prevailing orthodoxy. Sad.

Jeff Alberts

Anthony, you know this doesn’t matter, only the trend over the last 30 years matters. :/

Patrick Henry

The study suggests that the Arctic Ocean may have been ice free 6,000 years ago, but we know that can’t be true. The Independent wrote this summer “Scientists warn….for the first time in human history, ice is on course to disappear entirely from the North Pole this year.
http://www.independent.co.uk/environment/climate-change/exclusive-no-ice-at-the-north-pole-855406.html
The Telegraph wrote The North Pole has become an island for the first time in human history
http://www.telegraph.co.uk/earth/main.jhtml?xml=/earth/2008/08/31/eaarctic131.xml
And respected scientists corroborated for National Geographic “We’re actually projecting this year that the North Pole may be free of ice for the first time [in history],” David Barber, of the University of Manitoba
http://news.nationalgeographic.com/news/2008/06/080620-north-pole.html

Hell_IS_Like_Newark

6k to 7k years ago the Sahara was wet and green. I think the only deserts that expanded during that time was in the western USA (per some article I read years back).
Yet the global warmers always show deserts expanding as a result of warming…..

Patrick Henry

Leif,
What is your point about sunspots? The graph you linked to showed very high sunspot activity 7,000 years ago.

PearlandAggie

Leif Svalgaard (16:07:17)
Leif, pardon my ignorance, but I’m missing your point. I haven’t seen a temperature reconstruction for that period of time, so I’m not getting what you’re driving at.

evanjones

Hmm. Didn’t Greenland have a heck of a lot less ice 1000 years ago?

Graeme Rodaughan

Sorry Leon,
ANTI-AGW Rant Begins.
The “obvious conclusion” is that the laws of physics are unstable – they must have been different 6000 to 7000 years ago to allow the arctic ice to disappear without high levels of man-made CO2 – Golly.
Obviously the polar bears must have been decimated at the same time due to the reduced ice – I suspect that the members of the Independence I Culture probably ate all the easy to catch starving and drowning polar bears.
Of course once it got cold again, the bears would have proliferated and fattened up, becoming fierce and difficult to catch. Hence the subsequent retreat of the Independence I Culture from those inhospitable shores.
The fact that these scientists can’t (draw and) state the obvious conclusions that 20th century warming is not UNPrecendented and have to tip their hat at the AGW Mantra is no longer sad – it is pathetic cowardice of the first order.
Where’s their self respect.
ANTI-AGW Rant Ends.

Patrick Henry (17:15:38) :
What is your point about sunspots? The graph you linked to showed very high sunspot activity 7,000 years ago.
7000 years ago was 5000 BC …
PearlandAggie (17:19:54) :
I haven’t seen a temperature reconstruction for that period of time, so I’m not getting what you’re driving at.
The post has two data points:
4000-5000 BC: “The climate in the northern regions has never been milder since the last Ice Age than it was about 6000-7000 years ago”
2000 BC : “succumbed to the elements nearly 4000 years ago, when the climate became colder again”

John M

Patrick Henry (17:13:00) :
Come, come now, that’s only the “popular media” (you missed the recent WWF press release BTW). There’s nothing in the “peer reviewed literature”.
Tut tut tut
Harumph harumph harumph

Bruce Sanson

Leif, slightly off topic, but I would love to know if you perceive a variation in the earths received solar wind as its orbital inclination drops to zero?

Patrick Henry

Leif,
The article said “than it was about 6000-7000 years ago” In geology speak, the “about” easily covers anywhere from about 3000BC to 7000BC. The sunspot graph is probably also of similar imprecision. I don’t think your assertion carries much weight.

Richard Sharpe

Ahh, I see your point, Leif.
~7000 years ago, sunspot activity was low, but the arctic seems to have been warm, while ~4000 years ago sunspot activity was high, but the arctic was cold.
BTW, nice rifle she is carrying in that photo. I wonder if she kills polar bears should she need to? Maybe she is friends with Palin.

Raven

Leif,
Do you have any good links on solar isolation changes over the last 20000 years?

Edward Morgan

Leif, far be it for me to suggest but it was obviously warmer at the time these sea edges were made. If that means it was earlier than the researchers think or your sunspot data is wrong than that is where logic leads. All you do is dismiss I don’t think you can be so sure.
Can you answer me what differences to world temperature you feel fifty sunspots like a Dalton minimum versus an ‘averagish’ 50000 sunspot cycle would make to the climate? I know this isn’t accurate but it would give us some idea of where your coming from. You seem to feel that this thousand times difference is a pretty minor affair. We can all visualise the difference, so to go alongside that what do you say the temperature difference would be e.g Dalton’s 50 spots down ? degrees. Average 50000 spots up ? degrees. Ed.

David Vermette

Anybody know how accurate that chart of historical sunspots numbers is likely to be? This is all I could find on it:
11,000 Year Sunspot Number Reconstruction
Do we really have precise enough measurements about sunspot numbers, arctic ice levels, or temperatures from 6,000 – 7,000 years ago to be able to make any meaningful correlations?

SteveSadlov

Steve M had some rather interesting threads over a year ago, on the Quaternary and particularly Holocene history of the Northern shore of Greenland, and Ellesmere Island. Ice free conditions during the past million or even 10000 years can not be dis proven at this time.

Patrick Henry (17:15:38) :
What is your point about sunspots? The graph you linked to showed very high sunspot activity 7,000 years ago.
Patrick Henry (18:29:28) :
The article said “than it was about 6000-7000 years ago” In geology speak, the “about” easily covers anywhere from about 3000BC to 7000BC. The sunspot graph is probably also of similar imprecision. I don’t think your assertion carries much weight.
If so, neither does yours. It is more likely that you overlooked the 2000-year difference between BC and BP.
David Vermette (19:01:46) :
Do we really have precise enough measurements about sunspot numbers, arctic ice levels, or temperatures from 6,000 – 7,000 years ago to be able to make any meaningful correlations?
If the correlations support one’s pet theory then clearly the data is good. If not, then clearly the data is bad. The data is however not total garbage. It is unlikely that the timing is more than a thousand years off.

Bobby Lane

Just an observation: Leif opens his mouth and he gets half a dozen questions in return. Not that this is a bad thing (it isn’t) and not that it doesn’t happen on plenty of other postings (it does), but I was just thinking…
Wouldn’t it be great if more scientists took the time to talk to the general public like Leif does here? I mean, I have learned a ton of stuff from this blog and the presence of various scientists, though particularly Leif since he posts the most I think. It is always important, I think, that the public understand the research and that scientists are able to explain it in a way the man on the street can understand without overdiluting or being untrue to their work. Anyway, totally OT, but I thought I would post it.

Bobby Lane

Leon Brozyna (16:14:02) : Even good studies have to protect themselves from charges of going against the prevailing orthodoxy. Sad.
That’s exactly what I thought when I first read it too. However, even as I endorse that line of thinking, I also wonder if the AGW propaganda (surely the greatest in the world!) doesn’t have a tight grip on her too. Remember, many scientists like Dr. Meier have said that “well, since we are not able to account for it naturally, it must be man-made CO2.” There seems to be a leve of dissonance involved in the work. And I wonder what reasoning she would give apart from AGW that would fit her definition of the climactic forces at work today. But I am also open to the line of thinking that says that statement may also be not just KMA but also to make sure the grant-funding spigot stays on so they can continue researching.

Edward Morgan (18:57:12) :
If that means it was earlier than the researchers think or your sunspot data is wrong than that is where logic leads. All you do is dismiss I don’t think you can be so sure.
If the correlations support one’s pet theory then clearly the data is good. If not, then clearly the data is bad. The data is however not total garbage. It is unlikely that the timing is more than a thousand years off.
And I’m not dismissing because I’m sure. What I’m saying is that in order for you to maintain the sunspot-climate link, you will now had to add the extra assumption that this particular data is bad. It is usually a sign of a weakness in a theory that one has to add further assumptions as new data becomes available.
Can you answer me what differences to world temperature you feel fifty sunspots like a Dalton minimum versus an ‘averagish’ 50,000 sunspot cycle would make to the climate?
First, a Dalton minimum cycle didn’t have but 50 spots, but more like 15,000. So, no factor of a thousand. Perhaps you meant the Maunder Minimum?
Second, TSI for a Dalton cycle was 1365.8, and for a modern cycle 1366.2. A difference of 0.03%. This, on its own, would cause a temperature difference of 0.03%/4 = 0.0075% of 300K = 0.02K.
And 0.03K for the Maunder Minimum.

Bobby Lane

I should say CMA not KMA, sorry.

Bobby Lane (19:30:21) :
Wouldn’t it be great if more scientists took the time to talk to the general public like Leif does here?
There has been some posts from Roy Spencer and Douglas Hoyt. A problem is that most scientists would be put off by the tone of some comments and feel that they have better thing to do than suffer the abuse. Most are not as thick-skinned as I am and are also too busy to take an interest. But it would be great.
Another problem is that if two such participating scientists were disagreeing on something, their exchanges would rapidly become technical and incomprehensible to the majority of the readers.

Bobby Lane (19:39:42) :
I should say CMA not KMA, sorry.
That’s OK, I don’t know the difference anyway 🙂

How are we measuring sunspots from 5,000 years ago? Is it, pardon the expression, “settled” science?

Pamela Gray

Right on about Leif. I was just wondering if I can get college credit. Is there a test? There have been times when I wanted to raise my hand and ask the teacher if I could go home now because my head hurts.

Did I just read it has a 68% UNcertainty?

Bill Marsh

But, but, I thought the WWF said that the Arctic hasn’t been this free of ice in a million years??

P Folkens

I’m not surprised at the article’s conclusion of an ice-free arctic 6kybp.
Rhodes Fairbridge had the same conclusion in the 1970s in his reconstruction of Late Holocene sea levels known as the Fairbridge Curve (sea level more than 2 meters higher than now 6kybp). Even the comment in the article that the Independence I Culture succumbed to cooling at 4000ybp is shown in the Fairbridge Curve. The first optimum of the interglacial lasted until around 2500BC (4500 ybp) according to Fairbridge and reached a maximum cool at 2300BC (4300 ybp). It warmed again by 3900 ybp (1900BC). Another independent paper recently showed similar results in Brazil (2 meters higher sea level around 6kybp).
Reference: Fairbridge, R.W., Science 191 (4225) 359-359 1976
When we get corroboration from several different and independent sources, the foundation for questioning the AGW modelers becomes stronger.

Ron (20:02:22) :
How are we measuring sunspots from 5,000 years ago? Is it, pardon the expression, “settled” science?
Pretty much settled, although there are always some calibration issues. It works like this: When there are many sunspots, interplanetary space is full of tangled magnetic fields. These ‘scatter’ cosmic rays out of the solar system, so that fewer hit the Earth. When a cosmic ray hits the atmosphere it transforms some carbon 12 to radioactive carbon 14 and nitrogen 14 and oxygen 16 to radioactive beryllium 10. The former is taken up by trees and can be measured in tree rings. The latter deposited in ice on Greenland and Antarctica. From these ‘proxies’ one can deduce the cosmic ray flux and from the sun’s magnetic field and from that the number of sunspots. Pretty involved, but it works reasonably well.

Well, either way about the sunspots, it’s a red herring for this discussion. The point was/is/should be, the poles were very warm before, and without AGW from man-made GHG. Unless we want to blame human intestinal methane production…? 😉

Patrick Henry

Leif,
You are the one who threw in the 5,000 BC sunspot graph and the unsupportable correlation vs. the vague time frame of the article. Did Johnny Hart measure the sunspots 5,000 years ago?

Patrick Henry

Normally when scientists adopt the wookie defense of “you wouldn’t understand it anyway” that means that they don’t understand it well enough to explain it.
‘Simplicity is the ultimate sophistication’.
Leonardo da Vinci

Michael J. Bentley

Leif,
First of all, I echo the accolades – Anthony does a good job of bringing in people who do science. You and others are patient with those of us who need our noses poked into the information. It’s kinda like the college classes I took that I liked. They were the grab the firehose, take a big drink, and don’t let go whatever you do types of classes. I didn’t always get the best grade, but the information I could put to use was awesome.
I do need to point out an inaccuracy. It’s not your thick hide that keeps you coming back but your Scandinavian stubborness.
Very seriously, thanks for your input, and that goes for the rest (or most of ya). I’m learning a bunch and enjoying the hell out of it.
and yes there is a test. It’s called life.
Mike

Patrick Henry (20:36:50) :
You are the one who threw in the 5,000 BC sunspot graph and the unsupportable correlation vs. the vague time frame of the article. Did Johnny Hart measure the sunspots 5,000 years ago?
You still seem confused about 5000 BC and 5000 years ago.
And Juerg Beer measured sunspots for 5000 BC.

Suzanne Morstad

Hey guys,
How about looking at the high angle of the tilt of the Earth’s axis at the time of the “Holocene Maximum”? (Around 8,000-4,000 YBP) It certainly plays a significant role both in the warmth of the northern hemisphere as well as the increased rainfall in the Sahara. Sunspots aren’t the whole story. During the Holocene Maximum Canadian forests extended north of the present day tundra line by about 300 miles (Bryson, 1965). Northern Hemisphere temperatures were estimated to be 3-5 degrees C warmer than present. The desert Southwest had increased monsoonal moisture as did the Middle East and Indus Valley. Sarnthein’s work back in 1978 showed that cold times are associated with increased desert while warm times show increased moisture and decreased desert. It took computer models to come up with the “Evidence” that deserts increase globally with increased warmth.
For a really interesting picture of the world of the Holocene Maximum check out Brian Fagan’s The Long Summer.
It’s nice to see research into the Holocene Maximum besides the Greenland Ice
cores.

Michael J. Bentley (20:56:13) :
but your Scandinavian stubbornness
Hmmm, so says also my non-Scandinavian wife…

mr.artday

‘Science News This Week’ for Oct.18/08 has an article about Lonnie Thompson complaining about melting glaciers dissappearing his data. He says the Quelcaya glacier in Peru has melted back uncovering a 5 kya+ wetland from which 50 species of plants were recovered. Neither Dr. Thompson or the author of the piece, Janet Raloff seem to notice that they have disagreed with WWF and other unimpeachable climatic authorities. How far back does the “hockey stick” handle reach? If the beach ridge on N. Greenland is now above present sea level, has the sea level dropped or Greenland rebounded or both. Since the earliest writing dates from about 5.5 kya, the statement ‘not in recorded history’ is not wrong, just misleading.

P Folkens (20:12:34) :
according to Fairbridge and reached a maximum cool at 2300BC (4300 ybp).
Right when there were supposed to be a maximum of sunspots in the 11,000-year reconstruction opposite of the ‘obvious’ correlation of many spots = warm. Or is this another case of bad data [because it contradicts the sunspot-climate connection]?

Thanks for the explanation, Dr. Leif! Your explanation is clear enough so that even *I* can understand it. I can’t verify it, but I understand what you are saying. Thank you.
Can you tell me what a confidence level of 68% UNcertainty in the data means?
Is that the same as a 32% confidence level?
Maybe I’m mixing up a couple of different data sets, but if one only has 32% confidence level, is that as to the magnitude of the sunspots, or the time correlation or both or what?
Then again, as I mentioned before, it’s kind of a hijack of the thread’s point which is that it seems to have been warm in the recent past without significant human causation.
Thanks!

May I point out to the website http://www.climate4you.com/ of Prof. Humlum, and there to the chapter climate and history, where he gives a Greenland temperature diagram derived from ice core analysis:http://www.climate4you.com/images/SummitAndCulture.gif from a Science paper by Dahl-Jensen el al of 1998.
It was indeed much warmer then. But still, glaciers did exist in Greenland then. So, even the sea level rise must have been moderate.
Does the present research by NGU give any sea level estimates?

Ron (21:40:00) :
Thank you.
You are welcome.
Can you tell me what a confidence level of 68% UNcertainty in the data means? Is that the same as a 32% confidence level?
I’m not sure what the context or data sets are. For a ‘normal’ distribution of data, 68% will lie within one standard deviation of the mean and 32% outside. But closer than that without the specific example I can’t come.

Werner Weber (21:41:35) :
May I point out to the website http://www.climate4you.com/ of Prof. Humlum, and there to the chapter climate and history, where he gives a Greenland temperature diagram derived from ice core analysis.
It was indeed much warmer then.

So, more data confirming warm = low sunspots back then.

Patrick Henry (20:47:36) :
Normally when scientists adopt the wookie defense of “you wouldn’t understand it anyway” that means that they don’t understand it well enough to explain it.
Hmmm, contrast with:
Ron (21:40:00) :
Thanks for the explanation, Dr. Leif! Your explanation is clear enough so that even *I* can understand it. I can’t verify it, but I understand what you are saying. Thank you.

crosspatch

“It’s nice to see research into the Holocene Maximum”
Yes, or as I have learned to call it, the Holocene Optimum. It is as if modern climate science wants to hide the existence of this period from people, just as they seem to want to avoid talking about the MWP.

Patrick Henry

Leif,
I think you are the confused one. Your off the cuff comparison of the NGU date WAG vs. the Be10 graph produces completely different conclusions depending on the registration of the graphs. Shift them by 500 years and you reach a completely different conclusion.
Carbon dating is not accurate within 1,000 years for a “6,000 year old” sample. (Stonehenge’s age was just demoted 1,000 years this summer.) Tree ring dating is problematic because there are no living trees that old. Be10 concentrations are affected by climate, weather and changes in the earth’s magnetic field which also impact cosmic rays. The NGU age estimate was clearly a WAG. It could easily be off by a couple of thousand years.
You were attempting to draw a conclusion based on alignment of two data sets, both with error bars too great to have any significance. Shift the NGU age estimates by a small amount and your conclusion reverses polarity.

Richard

So how did the polar bears survive? Oh i forgot its only man made climate change that kills them, natural changes are good for them.

crosspatch

Polar bears are basically brown bears that selected white fur because it enabled them to catch more seals than brown fur does. Anything that helps an animal eat better will get selected in over time. If all the ice melts, the advantage of white fur goes away and animals with darker fur will probably survive better and white fur would be selected out.
I wouldn’t be surprised if “polar bears” disappeared along with practically all other white coated animals (rabbits, owls, etc) during the last interglacial which was considerably warmer than this one has been, and then got selected back in during the last ice age. Remember that ice ages tend to last 10 times longer than interglacials (about 100K years for glacial periods, roughly 10K years for interglacials) so there is more time to select in a white coat than there is to select it out.
My guess is that polar bears will probably survive this interglacial as we know them. This interglacial has been longer but cooler than ones in the past.