NCPA - National Center for Policy Analysis


October 29, 2007

Chinese researchers recently examined their ancient historic records, which go back farther in China than in any other society.  They found evidence of a warm period from the years 1 to about 240 AD (known as the Roman Warming); a cold period (the Dark Ages) from 240 to 800 AD; a warming (the Medieval Optimum) from 800 to 1400; and the Little Ice Age from 1400 to about 1920.

The Chinese records indicate the warm periods had fewer and milder storms, and fewer droughts and floods than the cold Dark Ages and the Little Ice Age.  This is not what we've been told to expect from the Modern Warming, says Dennis Avery, a senior fellow with the Heartland Institute.  China, during the Roman and Medieval periods, also had better crops and more prosperity than during the cold times.

The Chinese researchers also looked at modern proxy evidence of past temperatures:

  • The oxygen isotopes in ice cores yield an annual record of the air temperatures when the ice was laid down; the researchers looked at two ice cores from Tibet.
  • Trees respond to warmth and rainfall by growing more rapidly, and the Chinese researchers examined two tree ring records from China and one from nearby Japan.
  • They included analysis of pollen and organic matter in a deep peat bog on the edge of the Tibetan Plateau.
  • They examined sediment cores from two lake beds in Taiwan.

From this evidence, the Chinese researchers concluded China's warmest period during the past 2000 years occurred around 100 AD.  This aligns with Roman records of growing wine grapes in Britain during their occupation of that island in the first century--even though Britain was unable to grow wine grapes from 1300 to 1950 because of much colder temperatures.

Source: Dennis T. Avery, "Skeptics Help Us Search for Truth," Heartland Institute, October 24, 2007. 


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