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Mid-Holocene and Medieval Warm Period Temperatures in China
Reference
Ge, Q., Wang, S., Wen, X., Shen, C. and Hao, Z. 2007. Temperature and precipitation changes in China during the Holocene. Advances in Atmospheric Sciences 24: 1024-1036.

What was done
Noting it is widely believed that "increasing concentrations of greenhouse gases in the atmosphere are causing higher global atmospheric temperatures," and, therefore, that "paleoclimate data are essential for both checking the predictions of climate models and characterizing the natural variability of [earth's] climate system," the authors reviewed proxy temperature records of China that span the entire Holocene, while providing greatest emphasis on the last two millennia.

What was learned
The warmest period of the Holocene occurred between 9600 and 6200 years ago, during portions of which, in the words of Ge et al., temperatures "were about 1C-5C higher than the present in China." They also report that "during the past two millennia, a warming trend in the 20th century was clearly detected, but the warming magnitude was smaller than the maximum level of the Medieval Warm Period [our italics]," which they describe as having occurred between AD 900 and 1300. What is more, they say that "the modern warm period has [only] lasted 20 years from 1987 to 2006," and their annual mean temperature series of China since AD 1880 indicates that the country was actually warmer in the mid-1940s than it is today.

What it means
In light of the findings of the five researchers, it would appear that the climate-alarmist claim that the warming of the last decades of the 20th century was unprecedented, does not apply to China, for it was bested there by the warmth of the Middle Holocene of several thousand years ago, as well as the warmth of the Medieval Warm Period of a single thousand years ago (which Ge et al. attribute to elevated solar activity and lack of volcanic eruptions), and even the warmth of the mid-1940s of only half a century ago, which also cannot be ascribed to elevated atmospheric CO2. Consequently, their findings cast great doubt upon what we continually hear from the likes of Al Gore and James Hansen, i.e., that rising atmospheric CO2 concentrations are the greatest threat ever to be faced by the planet. Mountains of ever-accumulating real-world evidence from all around the world consistently demonstrate this claim to be false.

Reviewed 12 March 2008