CO2 Science: An Eighteen-Hundred-Year Climate Record from China.
Another point of great interest about the Zhang et al. record is that it "correlates with solar variability, Northern Hemisphere and Chinese temperature, Alpine glacial retreat, and Chinese cultural changes." And since none of the last four phenomena can influence the first one, it stands to reason that solar variability is what has driven the variations in every other factor mentioned. In fact, in a commentary that accompanies Zhang et al.'s article, Kerr (2008) states that the Zhang et al. record is described by other researchers as "amazing," "fabulous," and "phenomenal," and that it "provides the strongest evidence yet for a link among sun, climate, and culture." In addition, we note that it provides equally strong evidence for at least the Northern-Hemispheric-extent of the Medieval Warm Period and its greater and more persistent warmth than that of the Current Warm Period.