Palaeoclimate simulation of 21 ka for the Tibetan Plateau and Eastern Asia

Abstract.

A modelling experiment with changes in vegetation types at the Last Glacial Maximum (21 ka BP) is performed by using an AGCM coupled with a simplified simple biosphere model (AGCM+SSiB). The results show that the decrease in temperature is large in Tibet and Eastern Asia at 21 ka. The amplitudes of the decrease vary with seasons and locations. Annual mean temperature decreases between 13 °C and 2 °C. Summer and annual precipitation in eastern China at 21 ka is only about 50% of that at present; while little more or unchanged precipitation appears in northwest, west and southwest of China. The effective precipitation (P–E) shows much drier conditions in eastern and southeastern China than today. A comparison with geological evidences of lake-status and pollen-based vegetation shows that this simulation is in broad scale agreement with the geological records. The changes by using palaeo-vegetation data to prescribe land surface show improved signals in the 21 ka climate simulations in East Asia. This result encourages us to study the potential causes, feedbacks and mechanisms of palaeoclimate changes using the AGCM+SSiB modelling approach continuously.