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.
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.
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
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.
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)
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?
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?
But, but, I thought the WWF said that the Arctic hasn’t been this free of ice in a million years??
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…? 😉
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?
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
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.
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…
‘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.
“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.
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.
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.
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.