Centennial-scale climate variability during the past 2000 years derived from lacustrine sediment on the western Tibetan Plateau

摘要

The Tibetan Plateau (TP) climate change has been suggested to be modulated by the Asian monsoon and the westerly jet at seasonal, decadal, millennial and glacial-interglacial scales, which demonstrated evident regional variation. However, due to the lack of high resolution climate records, how the climate changed and how the regional environment was influenced by the monsoon and the westerlies on the western Tibetan Plateau (WTP) during the late Holocene remains unclear. Here we present multiple palaeo-climatic proxy records in sediment core from Xiada Co in the WTP for the past 2000 years, based on the relative distribution of branched glycerol dialkyl glycerol tetraethers (brGDGTs), n-alkanoic acid average chain length (ACL) and percent aquatic inputs (Paq), XRF, total organic carbon (TOC) and inorganic carbon (TIC) concentration. The centennial-scale variation of the climate records captures well-known climatic events over the past 2000 years, for example, the cool-dry 'Little Ice Age' (LIA) and the warm-wet 'Medieval Warm Period' (MWP). Besides, the multi-proxy indicated a severe dry event during 350-250 cal yr BP and a cool-wet climate during the past 200 years. This study concludes that Xiada Co was mainly influenced by the Indian monsoon during the past 2000 years. In addition, the temperature variability appears to correspond to solar irradiance changes, suggesting a significant solar influence on temperature variability in the WTP. Our results suggest that the abrupt drought near 320 cal yr BP may be the key factor leading to the demise of the Guge Kingdom.