Stalagmite multi-proxy records of weak Asian summer monsoon interval during Termination III as an analogue to Termination I

Multi-proxy analysis of abrupt climate change during Ice Age Termination III (T-III) is necessary to understand Asian summer monsoon (ASM) characteristics and mechanisms. We present ²³⁰Th dates and δ¹⁸O, δ¹³C, with equilibrium diameter, carbonate deposition amount and lithological characteristics from an annually laminated stalagmite (No. YXB) in Yongxing Cave, central China. Our multi-proxy records span 243.90 to 239.20 ka before present, falling within T-III/Marine Isotope Stage 7e. The changes in δ¹⁸O, equilibrium diameter, carbonate deposition amount, and lithological characteristics suggest a weak ASM interval during T III. By comparing these results with records from Ice Age Termination I (T-I), we find that the weakened ASM event during T-III is similar to the Younger Dryas (YD) event in terms of duration and structure. This result suggests that the YD-like event could be an inherent feature of glacial-interglacial climate cycles in the middle and late Pleistocene. The YXB δ¹³C sequence, without YD-like events, is broadly similar to the δ¹⁸O record on orbital timescale, indicating that variations in local vegetation could be driven by rising CO₂ during ice age terminations.