Climatic Changes During the Last Two Millennia on the Southern Tibetan Plateau Based on Lake Sediment and Its Forcing Mechanisms

Abstract

Based on the high resolution precipitation/moisture series over the Southern Tibetan Plateau in the past two millennia, the spatiotemporal pattern of drought-wet change over the Southern Tibetan Plateau are discussed by regional comparison and integrated analysis. The characteristics and mechanisms of climate change during the two typical periods, i.e. the Medieval Climate Anomaly (MCA, AD 600-1400) and the Little Ice Age (LIA, AD 1400-1900), are discussed emphatically. The results show that climate over the Southern Tibetan Plateau has changed significantly in the past two thousand years. It changed from wet to dry in AD 1-600, keeping dry in AD 600-1400, and then wet after AD 1400. The LIA and MCA climate conditions on the Southern Tibetan Plateau were found to be generally similar to those in the south-eastern and Northwestern Tibetan Plateau areas, but anti-phase with those in the Southwestern and Eastern Tibetan Plateau areas. The variation of dry and wet climate over the Southern Tibetan Plateau in the past two thousand years may be related to the intensity changes of Indian monsoon and westerlies, the seasonal movement of westerly jet over the Tibetan Plateau, and the intensity changes of evapotranspiration.