Different responses of precipitation patterns to the East Asian summer monsoon weakening: The 7.2 and 8.2 ka events

The 8.2 ka abrupt cooling event has been extensively studied, whereas the 7.2 ka event and their comparations rarely mentioned. Here, we present a high resolution (similar to 4 years) and precisely dated (+/- 25 years) speleothem multi-proxy record from Zhangjia Cave (northern margin of Sichuan basin, China) spanning the 7.2 and 8.2 ka events within the transition of early to middle Holocene. The speleothem delta O-18 mainly reflects the dynamic facets of the East Asian summer monsoon (EASM) system, while its delta C-13 and trace elements ratios serve as an indicator of local hydrological conditions. Our results reveal intense dry conditions in southwest China during the 7.2 ka event, despite the 7.2 event was characterized by a relatively stronger monsoon compared to the 8.2 ka event. Furthermore, the hydrological conditions during the 7.2 ka event and the middle Holocene appear to exhibit "north flood and south drought" pattern when compared to different paleoclimate records in EASM domains, while it can be summarized as "spatially consistent drought" in the 8.2 ka event. These different hydrological conditions are a response to the weakening of the EASM, a phenomenon also observed in modern climatic observations and empirical simulations, which underpins our understanding that the speleothem delta O-18 variations are mainly dynamical manifestations of the EASM system, likely different with its thermodynamical appearances.