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Geologist says Marcott's CO2 thesis failed

By Dennis T. Avery
web posted March 25, 2013

Geologist Don Easterbrook has commented on a new computer study that claims "current global temperatures of the past decade . . . are warmer than during 75 percent of the Holocene temperature history." Easterbrook says the Marcott paper is "totally at odds with the Greenland ice core data, the ‘gold standard' of paleoclimate research, as attested by hundreds of real-world studies of past global temperature proxies."

The Greenland ice layers say there have been 20 different centuries-long periods since the last Ice Age when the earth has been as warm or warmer than the Medieval Warming—which was warmer than today. All those past centuries of warm weather were thus warmer than our current temperatures.

  • At least six of these previous warm periods were as warm as the Medieval Warming Period.
  • Nine were 0.5 degree C warmer than the Medieval Warming.
  • Two warm periods were 1 degree C warmer then the Medieval.
  • Three warm periods were 1.5 degrees C warmer than the Medieval

Each of these twenty warm periods was matched by commensurate coolings, in the semi-erratic Dansgaard-Oeschger cycles that last 1,500 years (plus or minus 500). Until that phenomena  was discovered in the Greenland ice cores in 1984, we'd thought of the Little Ice Age and the Medieval Warming as events, not parts of a very old cycle. The "researchers" like Marcott who believe in man-made warming have never told their computers about this widely documented "natural variability" in the earth's climate history.  

And yes, the Medieval Warming was global. My book, Unstoppable Global Warming Every 1500 Years documented numerous Southern Hemisphere Medieval Warming proxies: Peruvian fossil pollen, South African cave stalagmites, New Zealand glacier melting and Antarctic lake sediments—to cite a few among many.    

The Marcott paper attempts to make us believe something has gone dramatically wrong with the earth's climate because of human-emitted CO2. However, Phil Jones, the man-made warming guru from Britain's University of East Anglia, was interviewed by the BBC's Roger Harrabin in 2010. He told the BBC that the 1975–98 warming was not statistically different from the previous two warm spurts.  Jones then stated that the previous warming spurts from 1860–1880 and 1910–1940 were not caused by human activity, but he has said that the warming spurt from 1975–98 was man-made.

This should immediately have raised a key science question: If the warming trend that started in 1850 was not caused by human activity, what did cause that dramatic reversal of the planet's 550-year cooling? Jones seems to indicate that this modern warming was due to the D-O cycle. If  the "man-made" temperature spurt from 1975–98 was not statistically different from the two earlier recent warmings,  how can we say with "90 percent confidence" that it was man-made? 

Only then do we get to the puzzling recent non-warming. That's easy. The thermometer record has trended upward and downward in 30-year spurts. This is just the heavy hand of the 60-year (30 and 30) Pacific Decadal Oscillation, reflecting temperatures in the earth's largest heat sink. The modelers agree, this is "natural variability" and another part of our wonderful global heating and cooling cycle. While the modern warming indicates a gradual warming will take place over the next couple of hundred years the temperature within that reality will spurt up and down thirty years at a stretch.
Let me get this straight. We don't know why the Little Ice Age ended unless it was the Dansgaard-Oeschger cycle. We all agree the temperatures warmed from 1860–1880 and 1910–1940 because of the PDO cycle. It did not warm in a pattern statistically different in 1975–98. Still, we know for virtually certain that 1975–98 was due to CO2.

Thus our concern for the public and our grandchildren forces us to tax people trillions of dollars, and consign them to the mercies of hugely expensive and highly erratic energy sources that won't keep the lights on in the hospitals or the food in our freezers cold. The Third World will be forbidden to burn coal, their only potential source of modern economic growth. We will never ever use the nuclear power that the Greens hate even though it emits no CO2.

Now I understand. But I wonder why no one is worried that each "warm" period" is progressively cooler. How long before our sun wears out? Worry about that before you worry about the blessings of the Modern Warming. ESR

Dennis T. Avery, a senior fellow for the Hudson Institute in Washington, D.C., is an environmental economist. He was formerly a senior analyst for the Department of State. He is co-author, with S. Fred Singer, of Unstoppable Global Warming Every 1500 Years. Readers may write to him at PO Box 202 Churchville, VA 2442; email to cgfi@mgwnet.com. Visit our website at www. cgfi.org





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