Temperature changes over the past 2000 yr in China and comparison with the Northern Hemisphere

We use principal component regression and partial least squares regression to separately reconstruct a composite series of temperature variations in China, and associated uncertainties, at a decadal resolution over the past 2000 yr. The reconstruction is developed using proxy temperature data with relatively high confidence levels from five regions across China, and using a temperature series from observations by the Chinese Meteorological Administration, covering the period from 1871 to 2000. Relative to the 1851-1950 climatology, our two reconstructions show four warm intervals during AD 1 AD 200, AD 551 AD 760, AD 951 AD 1320, and after AD 1921, and four cold intervals during AD 201 AD 350, AD 441 AD 530, AD 781 AD 950, and AD 1321 AD 1920. The temperatures during AD 981 AD 1100 and AD 1201 AD 1270 are comparable to those of the Present Warm Period, but have an uncertainty of +0.28 C to 0.42 C at the 95 % confidence interval. Temperature variations over China are typically in phase with those of the Northern Hemisphere (NH) after 1000, a period which covers the Medieval Climate Anomaly, the Little Ice Age, and the Present Warm Period. In contrast, a warm period in China during AD 541 AD 740 is not obviously seen in the NH