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.