Flood/drought change of last millennium in the Yangtze Delta and its possible connections with Tibetan climatic changes

Flood/drought series during the past 1000 yrs in the Yangtze Delta, China, was reconstructed based on historical documents and local chronologies. Continuous wavelet transform was applied to detect the periodicity and variability of the flood/drought series. Research results indicate that: (1) Larger fluctuations of climatic changes in the Tibetan Plateau result in higher wavelet variance of flood/drought in the Yangtze Delta, for example, during 1400–1700, the proxy indicators indicate that the annual temperature in Tibet experienced larger variability and that this time interval exactly corresponds to the time when the higher and significant wavelet variance occurred; (2) Periods featured by colder temperature in the Tibetan Plateau usually correspond to periods characterized by higher wetness with higher probability of flood events; (3) Variability of heating features of the Tibetan Plateau exerted great influences on intensity and onset of Indian monsoon and south Asian summer monsoon, and these atmospheric activities are in direct connection with precipitation in Eastern China. Current global warming may alter the snow mass of Tibetan Plateau and then alters the heating features of Tibetan Plateau, which may in turn impact flood/drought conditions in the Yangtze Delta.