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The Little Medieval Warm Period in Northeastern China
Reference
Ku, T.L. and Li, H.C. 1998. Speleothems as high-resolution paleoenvironment archives: Records from northeastern China. Proceedings of the Indian Academy of Science (Earth and Planetary Science) 107: 321-330.

Background
Under the heading of Little Medieval Warm Period in our Subject Index, we have archived reviews of a number of papers that document the existence of a significant period of elevated air temperatures at a number of locations around the world that immediately preceded the Little Ice Age. We here describe another such study, based on data obtained by Ku and Li from Shihua Cave near Beijing, China.

What was done
Working with the top 2 cm of a 20-cm-long stalagmite that was collected in November of 1995, the authors obtained annually-resolved δ18O data covering the past five centuries.

What was learned
Based on their analyses of these and other pertinent data, Ku and Li determined that fluctuations of the δ18O data over periods of less than ten years "reflect changes in precipitation, whereas on coarser time scales (>50 years), the stalagmite δ18O records temperature variations." This finding, in turn, led them to conclude that "the period AD 1620-1900 was cold and periods 1520-1620 and 1900-1994 were warm." And in comparing their graphical representations of these two warm periods, it appears that the earlier period -- which we have dubbed the "Little Medieval Warm Period" -- was probably just a tad warmer than it was over the last two decades of the 20th century, which climate alarmists typically claim was the warmest period of the last two millennia.

What it means
Accumulating evidence from around the world seems to indicate that in addition to the primary Medieval Warm Period, the "Little" Medieval Warm Period -- which occurred just before the earth slipped into the Little Ice Age -- may also have experienced air temperatures that were warmer than those of the Current Warm Period.

Reviewed 25 March 2009