Temperature variability in North-Central China during the past 231 years based on multiple proxies

Several temperature-sensitive paleoclimate proxies, including tree rings, stalagmites, and historical documents, were employed to derive regional temperature signals for the period 1779-1985 via principal component analysis (PCA). The PCA series was significantly correlated with gridded temperature datasets for Northeast China, the Korean Peninsula, and part of Japan. Based on statistical correlation between the PCA series and observed temperature records, we regionally reconstructed May-August temperature variations for 1779 to 2009. The reconstruction explained 53.4% of the variance in observed summer temperature during the instrumental period. Intervals with persistent decadal warm and cold periods in the past 231 years were detected. The results suggest that, of the past 231 years, the past half century suffered unprecedented warming in North-Central China, which may be related to increasing human activities since the Anthropocene epoch.