Revisiting East Asian monsoon change during the Last Glacial Maximum using PMIP4 simulations

The Last Glacial Maximum (LGM; 21 000 years ago) East Asian monsoon was revisited using all available simulations performed by the latest generation of climate models participating in phase 4 of the Paleoclimate Modelling Intercomparison Project (PMIP4). With respect to the preindustrial period, all five models consistently showed a weakening of the East Asian monsoon by 1%-18% in winter and by 2%-32% in summer during that glacial period. Regionally, the LGM monsoon circulation was dominated by southerly wind anomalies in winter but northerly wind anomalies in summer over East Asia in AWI-ESM-1-1-LR, MIROC-ES2L, and MPI-ESM1-2-LR. In the two versions of CESM2, large regional differences existed in the LGM change in the East Asian monsoon, especially for summer. Such changes in the East Asian monsoon can be explained by the various geographical distributions of surface cooling and sea level pressure difference, mainly due to the large volume of ice sheets and lower atmospheric greenhouse gas concentrations during the LGM. The spread among the models and the uncertainty among the proxy data call for further simulation and reconstruction efforts to comprehend the change in the East Asian monsoon during the glacial period.