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The Medieval Warm Period and Little Ice Age in Tropical South China
Reference
Chu, G., Liu, J., Sun, Q., Lu, H., Gu, Z., Wang, W. and Liu, T. 2002. The 'Mediaeval Warm Period' drought recorded in Lake Huguangyan, tropical South China. The Holocene 12: 511-516.

What was done
The authors studied the geochemistry of dated sediments recovered from seven cores taken from three locations in Lake Huguangyan (219'N, 11017'E) on the low-lying Leizhou Peninsula in the tropical region of South China to infer its climatic history over the past 1400 years, assisted by additional information relative to the presence of snow, sleet, frost and frozen rivers over the past 1000 years obtained from historical documents.

What was learned
The authors report that "cold winter events over the past 1000 years in tropical South China are concentrated in three time intervals during the Little Ice Age at c. AD 1480-1550, 1670-1730 and 1830-1900," noting further that this distribution of cold events agrees well with results obtained from phenological studies (flowing seasons of peach, apricot, clove, etc.), which depict cold intervals at AD 1470-1520, 1620-1720 and 1840-1890 (Chu, 1973). They additionally report that "recent publications based on the phenological phenomena, distribution patterns of subtropical plants and cold events (Wang and Gong, 2000; Man, 1998; Wu and Dang, 1998; Zhang, 1994) argue for a warm period from the beginning of the tenth century AD to the late thirteenth century AD," as their own data also suggest.

Floods were found to be quite commonplace during the Little Ice Age, i.e., from about AD 1400-1900, while two major dry periods were dated to AD 670-760 and AD 880-1260 in the Medieval Warm Period. The authors also note that "local historical chronicles support these data, suggesting that the climate of tropical South China was dry during the 'Mediaeval Warm Period' and wet during the 'Little Ice Age'."

What it means
The results of this study are just one more example of the almost embarrassingly obvious fact that data from all around the globe demonstrate the reality of the millennial-scale climatic oscillation that has brought the planet the Medieval Warm Period, the Little Ice Age and now the Modern Warm Period, along with earlier named and unnamed climatic intervals of like nature, totally independent of changes in the air's CO2 concentration.

References
Chu, K.C. 1973. A preliminary study on the climatic fluctuations during the last 5000 years in China. Scientia Sinica 16: 226-256.

Man, M.Z. 1998. Climate in Tang Dynasty of China: discussion for its evidence. Quaternary Sciences 1: 20-30.

Wang, S.W. and Gong, D.Y. 2000. The temperature of several typical periods during the Holocene in China. The Advance in Nature Science 10: 325-332.

Wu, H.Q. and Dang, A.R. 1998. Fluctuation and characteristics of climate change in temperature of Sui-Tang times in China. Quaternary Sciences 1: 31-38.

Zhang, D.E. 1994. Evidence for the existence of the Medieval Warm Period in China. Climatic Change 26: 287-297.


Reviewed 13 November 2002