Centennial-scale climatic changes in Central China during the Holocene climatic optimum

Abstract

Our knowledge about climatic changes at centennial-scale and their causes during the Holocene climatic optimum (HCO) remains poorly constrained. Here, we present δ18O and δ13C records from a precisely dated stalagmite (13.2 to 1.9 kyr BP) from Xiniu Cave, central China. The δ18O record shows a gradual weakening in the strength of the East Asian summer monsoon (EASM) from early to middle Holocene, corresponding with a decrease in Northern Hemisphere summer insolation (NHSI). A similar pattern is absent in our δ13C record, and is replaced by persistent centennial-scale oscillations throughout the Holocene. Variations of δ13C reflect changes in vegetation density, soil CO2 production, CO2 degassing, prior calcite precipitation (PCP), and cave ventilation, associated with temperature and rainfall variations at local scale. Based on the δ13C record, three dry/cold events at approximately 6.0, 8.2, and 10.5 kyr BP, can be identified during the HCO (11.1 ± 0.1 to 5.4 ± 0.1 kyr BP), coinciding with the well-known Holocene Bond events. The power spectrum analysis shows that the significant periodicity (843 yr) of the δ13C record within the HCO may be related to the North Atlantic-cycle. Therefore, we speculate that the centennial-scale climatic changes during the HCO probably resulted from cooling in the North Atlantic, and that the intensified and southward Westerly jet played a role in transmitting this signal from high latitudes to central China.