LGM lake records from China and an analysis of climate dynamics using a modelling approach

Abstract

Lake-geological studies in China have reported that there were much higher lake levels and much fresher water than today at the last glacial maximum (LGM) in western China. A compilation of lake data in this study showed LGM conditions much drier than today in eastern China but somewhat wetter in western China. These E–W differential patterns of climate conditions were completely different from the modern dry-wet conditions with a N–S differential distribution. In this study palaeoclimate simulations by an AGCM coupled with land surface process model were used to explore the possible mechanisms of LGM climate in China. The results confirmed that the dry conditions in eastern China resulted from less summer precipitation due to the Pacific Subtropical High occupying eastern China and the decline in the summer monsoon. The wet conditions in western China were produced by a decrease in evaporation due to a low temperature on land surface at the LGM and increase in precipitation. Two experiments of the palaeoclimate simulations with different land surface of modern and palaeo-vegetations have been designed to test the discrepancies of simulated LGM climate with in precipitation and P–E fields. The results suggested that the feedback from the Asian land surface within the climate system would amplify and modify external forcing, leading to marked climate changes in China.