The Climate Change And Environment Response To East Asian Summer Monsoon Over The Last 21ka Based On TraCE-21ka

The comparative analysis of deposition records and paleoclimate simulation can effectively reveal the mechanism of past climate change.However,relevant research on the East Asian monsoon region has yet to be deepened.Here based on the results of modern observations and paleoclimate reconstructions,the capability of Tra CE-21 ka simulation to reproduce the climatic characteristics of modern East Asia and the evolution of paleomonsoon have been evaluated,and their differences and similarities are also compared and analyzed.On this basis,we explore the delayed environmental response to the East Asian summer monsoon over northern China during the early-to-late Holocene and provide a novel mechanism.At the same time,the possibility mismatched evolution of paleoclimate simulation and deposition records induced conduct research on the sensitivity of surface environment processes to climate change since the Last Glacial Maximum.Finally,based on the CLM4 simulation,plant transition from grass to tree in the early-to-late Holocene is analyzed to realize the purpose of understanding the environment response to climate change.The results show that:1)The Tra CE-21 ka can reasonably simulate the large-scale of spatial distribution pattern of modern East Asia climate,but there is a false value center in the Qinghai-Tibet Plateau under the premise of coarse resolution.It also has the ability to reproduce the orbital scale of monsoon evolution,but campared with the record its amplitude is small.2)Conventional hypotheses of synchronously evolution between EASM and northern China environment is not always evident truth over the past 21 ka.Here we show that the East Asian summer monsoon and precipitation tends to peak in the early Holocene,while environmentall moisture tends to peak in the mid Holocene.In addition to the impact of high-altitude ice sheet retreat on local precipitation,the delayed environmental response is caused by the reduction of transpiration during the plant transition from grass to tree and the subsequent impact on soil moisture in the early Holocene.And in the late Holocene,the rainfall caused by the decrease in solar radiation was large enough to dominate the local hydrological balance,and occur a strong response to north China environment.3)Now reconstruction and simulation are not always well matched.One of the possible reason is the regional differences in the sensitivity of surface environmental factors response to climate evolution.Along the direction of increasing climatic spatial gradient,it is more credible for the temporal and spatial slopes of transfer function as a high-sensitivity area from the North Africa to the northern China,and the climatic elements of reconstruction can be closer to the reality.4)Based on the sensitivity experiments of CLM4 coupled land-vegetation with atmospheric forcing of Tra CE-21 ka simulation indicate that,the early-Holocene plant transition from grass to tree attributes to the the narrowing of intra-seasonal temperature threshold under the driving of orbit.This is of great significance for the prediction of environmental response to climate sensitivity under the climate change in the future.