Multi-phased Asian Hydroclimate Variability During Heinrich Stadial 5

Changes in Asian summer monsoon (ASM) circulation and effective precipitation (precipitation/evaporation, P/E) were reconstructed from stalagmite δ 18 O and trace element records from Wulu Cave in southern China, covering Chinese Interstadial (CIS) 13 to Heinrich Stadial (HS) 5. The timing of HS 5 in our record (48.5 ± 0.1 ka, 47.2 ± 0.1 ka) agrees well with spatially-separated cave records (48.7 ± 0.1 ka, 47.4 ± 0.2 ka). At the onset of HS 5, Asian hydroclimate changes are coeval with bipolar ice-core records, but lead the Greenland warming by 300 years at the termination or are synchronous with Greenland records via the atmospheric CH 4 constraint. During HS 5, the evolution of δ 18 O-based ASM, featuring four-phased variability, is less clear in element-inferred P/E variations. In contrast, the element records generally exhibit coherent variations among themselves, and are characterized by greater values in CIS 13 (stronger prior calcite precipitation (PCP) under seasonal drought conditions), followed by a rapid decline to a lower-than-average level (weaker PCP under relatively wetting conditions) during HS 5. This implicates an enhanced evaporation in the interstadial, but sufficient moisture availability during HS 5. The ASM weakening in mid-HS 5 is significantly stronger, in degree, than during Chinese Stadial (CS) 14, while the P/E variability in HS 5 is practically equivalent to that in CS 14. It suggests a pronounced sensitivity of ASM and an inertial effective precipitation response to HSs. Probably, the ocean–atmosphere interactions at low latitudes could favor the sustained moisture availability in southern China during HS 5. This at least implicates that the effective rainfall in southern China is less sensitive to climate perturbations during HS 5.