Wang, N., Yao, T., Thompson, L.G., Henderson, K.A. and Davis, M.E. 2002. Evidence for cold events in the early Holocene from the Guliya ice core, Tibetean Plateau, China. Chinese Science Bulletin 47: 1422-1427.
What was done
The authors studied changes in ð18O and NO3- in an ice core retrieved from the Guliya Ice Cap (35°17'N, 81°29'E) on the Tibetan Plateau in China, comparing the results they obtained with ancillary data from Greenland and Antarctica.
What was learned
Two cold events -- a weak one around 9.6-9.2 thousand years ago (ka) and a strong one universally referred to as the "8.2 ka cold event" -- were identified in the Guliya ice core record. The authors report that these events occurred "nearly simultaneously with two ice-rafted episodes in the North Atlantic Ocean." They additionally report that both events occurred during periods of weakened solar activity.
What it means
Remarking that evidence for the 8.2 ka cold event "occurs in glacial and lacustrine deposits from different areas," the authors say this evidence "suggests that the influence of this cold event may have been global." They also say that "comprehensive analyses indicate that the weakening of solar insolation might have been the external cause of the '8.2 ka cold event'," and that "the cause of the cold event around 9.6-9.2 ka was also possibly related to the weaker solar activity." The authors thus conclude that all of these things considered together imply that "millennial-scale climatic cyclicity might exist in the Tibetan Plateau as well as in the North Atlantic."
We agree wholeheartedly with these conclusions, which comprise but one more solid piece of evidence for the reality of the solar-forced millennial-scale oscillation of global climate that has alternately brought the world the Roman Warm Period, the Dark Ages Cold Period, the Medieval Warm Period, the Little Ice Age and, most recently, the Modern Warm Period. CO2 has had absolutely nothing to do with the establishment or demise of any of these climatic interludes. That the air's CO2 content rose in tandem with the warming that produced the Modern Warm Period is purely coincidental.
Reviewed 2 April 2003