Spatial patterns and mechanisms of the temperature response in East Asia to mid-Piacenzian warming

The mid-Piacenzian (3.264–3.025 Ma) is regarded as being the most recent warm period with atmospheric CO₂ levels comparable to those of the present-day, thus reconstruction of corresponding climate change provides a good reference for our understanding the current and future global warming. In this study, we undertook climate reconstructions for East Asia using the modern analogue technique, based on fossil pollen records. The results show significant spatial variations in paleoclimate, with a warmer zone in the northwest and a colder zone in the eastern monsoonal regional. To better understand the data–model discrepancies, particularly with respect to the overall warming trend indicated by the simulations, we decomposed the physical processes in the simulation based on the surface energy budget equation. Our findings suggest that the cooling effects of cloud radiative forcing, non-surface albedo feedbacks induced by clear-sky shortwave radiation, and latent heat flux contributed to the cooling trend in the eastern zone. In contrast, the warming observed in the northwestern zone was driven primarily by increased clear-sky downward longwave radiation. These results highlight the complex responses of different regions to climatic change and the key role of cloud and radiation processes in controlling regional climate.