Centennial-Scale Climatic Oscillations during the Dansgaard–Oeschger 14 Revealed by Stalagmite Isotopic Records from Shouyuangong Cave, Southern China

During the last glacial, Dansgaard–Oeschger (DO) events are mostly characterized by moderate and shorter fluctuations. Here, we present the three-year-resolution stalagmite isotopic record from Shouyuangong Cave (SYG), southern China, revealing a detailed history of Asian summer monsoon (ASM) and local environmental changes during the middle and late period of DO 14. During this period, the SYG1 δ18O is characterized by the persistence of centennial-scale oscillations. These centennial δ18O enrichment excursions are clearly mirrored in the δ13C signal. This correlation suggests that changes in soil CO2 production at this site are closely correlated with centennial-scale ASM variability. Furthermore, power spectrum analysis shows that δ18O and δ13C display the common periodicities consistent with solar activity cycles, implicating a control of solar activity on the ASM and soil humidity. Particularly, weak solar activity generally corresponds to weak ASM and a decline in soil CO2 production. One possible link between them is that external forcing controls the ASM intensity via the thermal contrast between the ocean and land. Subsequently, the balance of soil moisture co-varies with the hydrological responses. Finally, the soil CO2 production is further amplified by ecological effect.