Variable Phase Relationship Between Monsoon and Temperature in East Asia During Termination II Revealed by Oxygen and Clumped Isotopes of a Northern Chinese Stalagmite

Termination II (T-II) is a natural reference for evaluating the potential effect of substantial ice sheets melting on monsoon and temperature changes caused by global warming. However, the phase relationship of East Asian summer monsoon (EASM) and temperature during T-II remains enigmatic due to the lack of paleotemperature proxies. Here, we provide high-resolution mean annual atmospheric temperature (MAAT) estimates during T-II in northern China using speleothem clumped isotopes. Compared with present, the maximum MAAT at the last interglacial was 1.8 +/- 1.5 degrees C higher, and the minimum MAAT at the penultimate glaciation was 6.8 +/- 1.3 degrees C lower. EASM and temperature decoupled during the first 2100 years of the record and coupled onwards. This variable phase relationship is plausibly modified by the strength of the cold anomaly in North Atlantic triggered by collapse of ice sheets. When the cold anomaly exceeds a boundary condition, it could not only weaken EASM but also lower temperature.

Automated summary

This study investigates the changes in mean annual atmospheric temperature (MAAT) during T-II in northern China using speleothem clumped isotopes. The results indicate that the highest MAAT during the last interglacial period was higher compared to present, while the lowest MAAT during the penultimate glaciation was lower. The phase relationship between the East Asian summer monsoon (EASM) and temperature varied during the record, potentially influenced by the strength of the cold anomaly triggered by the collapse of ice sheets in the North Atlantic.