Reference
Liu, Y., An, Z., Ma, H., Cai, Q., Liu, Z., Kutzbach, J.K., Shi, J., Song, H., Sun, J., Yi, L., Li, Q., Yang, Y. and Wang, L. 2006. Precipitation variation in the northeastern Tibetan Plateau recorded by the tree rings since 850 AD and its relevance to the Northern Hemisphere temperature. Science in China: Series D Earth Sciences 49: 408-420.
Description
The authors used three well-dated Sabina Przewalskii ring-width chronologies derived from a total of 77 trees growing in three locations near Dulan, China, on the northeastern Tibetan Plateau (36.0-36.3°N, 98.2-98.6°E), to reconstruct annual precipitation variations in that region over the period AD 850-2002, after which they compared the results with instrumental temperature data for the same region over the period of temporal overlap. This protocol produced a 40-year moving average that was so well correlated with seven temperature curves of the Northern Hemisphere that they concluded it "could be regarded as the millenary temperature curve for the northeastern Tibetan Plateau," and this curve revealed that a group of 40-year-averaged temperature proxies in the vicinity of AD 915 were definitely greater than the highest such average at the end of the 20th century, which comprised the next highest peak of the record.