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[1] Recent studies indicated that the spatial pattern and temporal variability of summer rainfall over eastern China are well correlated with the Pacific Decadal Oscillation (PDO). Here we used a data set of the drought/flood index (a proxy of summer rainfall) since 1470 AD to reconstruct the annual PDO index. The reconstruction indicates that the PDO is a robust feature of North Pacific climate variability throughout the study period, however, the major modes of oscillation providing the basic PDO regime timescale have not been persistent over the last 530 years. The quasi-centennial (75 -115-yr) and pentadecadal (50 -70-yr) oscillations dominated the periods before and after 1850, respectively. Our analysis suggest that solar forcing fluctuation on quasi-centennial time scale (Gleissberg cycle) could be the pace-maker of the PDO before 1850, and the PDO behavior after 1850 could be due, in part, to the global warming.

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