Climate and ecology changes during the last deglaciation revealed by stalagmite from Shima Cave, central China

Abstract

We reconstructed high-resolution paleoclimate records with 24 230Th/U dates, 706 sets of stable isotope values (δ18O and δ13C) from a stalagmite from Shima Cave, Hunan Province, central China. The stalagmite grew during the last deglaciation from 19.7 to 13.3 ka, with a 1500-year hiatus during Heinrich Stadial 1. We interpret stalagmite δ18O as the East Asian summer monsoon (EASM) intensity, while δ13C as terrestrial CO2 related with biomass production and local hydrogeochemical processes. Long-term trend and millennial-scale changes in δ18O record are absent in the δ13C record, possibly due to the low biomass production and small vegetation changes in central China across the studied period, which is contrast to an obvious recovery of the biomass in northern China during the Bølling-Allerød period. Besides, high frequency of δ13C record displays quasi periods of 30–50 years, which are consistent with typical periodicities of the Pacific Decadal Oscillation (PDO). Furthermore, comparison of our δ18O record with measures of solar variability shows clear evidence for solar forcing on the EASM on the centennial timescale, which could possibly be mediated by the Atlantic Meridional Overturning Circulation and El Niño/Southern Oscillation/PDO. Therefore, we suggest that monsoonal climate and ecological changes during the last deglaciation could have been modulated by solar activity and sea surface temperature variability in both the Atlantic and the Pacific Ocean.