Guest post by by Michael A. Lewis, Ph.D.
In my work as an archaeologist in Alaska, I spent a good swat of my time hiking through forests along the Yukon River, scrambling over piles of driftwood along the northwest coast and pulling roof beams and house posts out of 2,000 year-old dwelling sites on St. Lawrence Island.
The object of my quest? Tree rings.
From hundreds of core samples and cross-section “cookies,” I developed a regional tree ring climate chronology that I compared with archaeological records of human population movements across the Bering Strait over the past 2,500 years. One thing stood out clearly in both independent data sets:
About a thousand years ago, a remarkable change occurred among all Arctic peoples from Siberia to Greenland in a period of less than 200 years. People moved long distances. New technologies supplanted old. Ground slate harpoon blades replaced chipped stone. The sea mammal hunting Thule people of Northern Canada completely replaced the land based Dorset culture that had been in place for thousands of years. The Inuit language spread from Northwestern Alaska to Greenland, the greatest areal extent of any language on earth. Whale hunters migrated across northern Canada, following whales across the ice-free Arctic Ocean.
The tree ring record reflected these cultural changes. Across the Bering Strait and into Interior Alaska, increasing temperatures and changing precipitation patterns were recorded in tree rings from Siberia to Fort Yukon around 1,000 BP.
Something was afoot and my further research revealed the Alaskan signature of the Medieval Warming Period (MWP) that had been experienced across North America, Iceland, Greenland and Europe.
So you can imagine my surprise to see the infamous Hockey Stick graph appear in the 2001 IPCC Report, completely missing the MWP that I knew from multiple independent data sets, as well as the subsequent Little Ice Age that brought to an end the European occupation of Greenland. Later IPCC reports and subsequent media hype increased my discomfort with the concepts of Anthropogenic Global Warming and the insistence that presently observed climate change is driven primarily by human greenhouse gas emissions.
Archaeologists are “hard” scientists, driven by data, uniformitarianism, and a deep time perspective on human and natural history. My research demonstrated that humans had reacted to complex climate variation from Lake Baikal to Greenland over the past 100,000 years, climate variations that occurred in the complete absence of human greenhouse gas emissions. I see no reason to accept the automatic assumption that observed rising CO2 levels are solely the result of human emissions, or that the observed increase is significant with respect to the geological record of CO2 and temperature fluctuations.
It makes much more sense to me to view the present dynamic climatic situation in light of historical and geological records, particularly those of the past 2,000 years, for which we have independent data sets to confirm our findings. Dr. Syun-Ichi Akasofu has presented this perspective with remarkable clarity in his paper, On the recovery from the Little Ice Age, Natural Science, Vol.2, No.11, 1211-1224 (2010) http://www.scirp.org/journal/NS/
From this perspective, observed climate fluctuation is viewed as a continuation of natural geological and physical processes, in this case, recovery from the Little Ice Age.
This is not to say that human emissions do not contribute to climate fluctuation. However, we cannot understand the extent of human contributions until we fully understand the ongoing natural forces that have shaped the Earth’s climate for millennia before humans appeared on the scene.
Oh, and about smoking… in those days of yore in the wilds of Alaska, I used to smoke a pipe to wile away the lonely hours in tents and log cabins across the Arctic landscape. As my work shifted from field to laboratory, I gradually eschewed the fragrant clouds of tobacco smoke, until the day I realized I no longer enjoyed smoking.
I’m still working on the Global Warming part.
One minor quibble Doctor Lewis.
The LIA brought an end to European occupation of Greenland NOT Iceland.
Excellent post with a nice touch of wry humour as an ending.
Having read some (translated) first-hand accounts of the Viking occupation of Greenland and realised the parallel of the epic voyages of discovery carried out in the same period by Polynesian explorers of the Pacific Ocean, which could only have occurred during an extended period of warmish weather, the infamous Hockey Stick graph which attempted to deny the existence of the MWP as a global event irritated me intensely when I became aware of it.
“…completely missing the MWP that I knew from multiple independent data sets, as well as the subsequent Little Ice Age that brought to an end the European occupation of Iceland.”
Dr. Lewis, did you mean Greenland instead of Iceland?
Eyeing the chart, it looks to me like the trend is down.
amazing doesnt begin to describe the way some so called scientists have managed to ignore or smooth out… so much past historical proof that its a Cycle! and co2 isnt the cause of much if anything.
as I sit shivering in an Aussie summer cold wave.. the only warmth I am generating is Rage! at the liars and idiots pushing the warmist agenda.
Did you mean end of occupation of Greenland in stead of Iceland?
Typo alert!
“that brought to an end the European occupation of Iceland.” — Do you mean Greenland?
Tallbloke – Not only that , but notice how much longer the cold periods last , at least for the last five thousand years or so .
Shouldn’t that be “European occupation of Greenland.” not Iceland?
Just eye-balling the graph, I’d say there’s a distinct warm period from 5,000 BC to 2,600 BC, an intermediate period between 2,600 BC to 400 AD, followed by a cooler period from 400 AD to 2,000 AD. It appears the area from which the tree rings have been gathered has experienced a distinct cooling trend over the past 7,000 years. I’ve seen this same trend in other interglacials until the temperature drop-off into another ice age.
An interesting piece of info which slots in well with the Viking Greenlander complaints of an influx of Inuit competing for resources.
Anomalies from what?
The only problem with doing this sort of analysis is that it deals with only a single place. The Roman Warming Period shows up on this graph as a highly negative anomaly. I will assume that the area he measured was quite cool. However, archeological evidence in Europe shows a much warmer summer at the same period.
Greenland surely?
“So you can imagine my surprise to see the infamous Hockey Stick graph appear in the 2001 IPCC Report, completely missing the MWP that I knew from multiple independent data sets, as well as the subsequent Little Ice Age that brought to an end the European occupation of Iceland. “
typo ‘aerial’ should be ‘areal’?
And how often!
I had the same reaction to Gore’s presentation of the “hockey-Stick’ graph. After seeing temperature reconstructions since 1960, in archeological contexts, it was as if someone was rewriting history. Even the IPCC’s AR1 graph looked ‘normal’ in the context of history, see here: http://i39.tinypic.com/bgemm9.jpg
tallbloke says:
December 27, 2010 at 6:19 am
The scary thing about that graph is how quickly it can swing from warm to cold.
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and how close it matches what little we know about the PDO
A pipe is also good at keeping mosquitos away, but you don’t need to worry about that in the lab.
I would guess too that through a century or two of warmer weather in the north, Scandinavian populations expand dramatically. And when climate gets cold and stays cold, they head south looking for plunder and eventually new places to live.
Paragraph 6: “..Little Ice Age that brought to an end the European occupation of Iceland.”
Should be Greenland.
“My research demonstrated that humans had reacted to complex climate variation from Lake Baikal to Greenland over the past 100,000 years, climate variations that occurred in the complete absence of human greenhouse gas emissions. ”
Where have you published your results? I would enjoy reading more about your research.
Natural Science, Vol.2, No.11, 1211-1224 (2010) http://www.scirp.org/journal/NS/“
A quick googling of “Scientific Research Publishing” who publish this journal suggests that this journal is suspect — that they republish articles without permission and list people on the editorial boards without getting their permission. It would be nice to have an additional reference to a more established journal.
Another source suggests:
This is different from your conclusion “my further research revealed the Alaskan signature of the Medieval Warming Period (MWP) that had been experienced across North America, Iceland, Greenland and Europe.”
What specifically in your research shows that these published papers are wrong and your conclusions are right?
Also, what region is covered by the graph you show? Where were those tree rings collected and how was proxy tree ring data converted to temperatures? Furthermore, I don’t see much of a MWP in the graph. There is a slight warming around 1000, but a larger warming around 1500 at the start of the Little Ice Age.
And, of course, a much larger warming in modern times.
Variation on Greenland vs Iceland. I’ve read a few papers regarding the climate effects on Greenland, but can anyone recommend reading regarding population pressures or changes on Iceland during the same interval? I imagine it must have been quite a harsh place during the LIA. Strange how humanity seems to thrive during warm climate intervals, and suffers during cold ones.
(that last bit is /sarc btw)
Is the most recent warm spike dendro or instrumental? Given the well documented “divergence” – dendro decline vs instrumental rise since 1960, I would guess it is instrumental. Should the last spike be corrected?
tallbloke says:
December 27, 2010 at 6:19 am
The scary thing about that graph is how quickly it can swing from warm to cold.
More scary: How sea waves could freeze in less than the blink of an eye. The following images are from Antarctica:
http://www.scribd.com/doc/32858301/Frozen-Wave