High- and low- latitude forcing on hydroclimate variability in southern China over the last two millennia

Knowledge of centennial-scale hydroclimate variability and underlying forcing mechanisms in southern China over the last two millennia remains limited. This study presents multiproxy results of the grain size, elemental ratios (Zr/Rb, and Rb/Sr), total organic carbon (TOC), total nitrogen (TN) and C/N ratios, together with high-precision 137Cs/210Pb and accelerator mass spectrometry (AMS) 14C ages of a sediment core from Lake Baxian, which is a small closed lake in Guangxi Province, southern China. Based on these high-resolution data, the hydroclimate change over the last two millennia is clearly revealed. Relatively high values of the mean grain size, Zr/Rb, TOC and TN, along with low values of Rb/Sr and C/N ratios during the Dark Ages Cold Period (DACP, 500–900 CE) and Little Ice Age (LIA, 1400–1850 CE), indicate a relatively wet climate during these intervals. Conversely, low values of the mean grain size, Zr/Rb, TOC and TN, along with high Rb/Sr ratios during the Roman Warm Period (RWP, 50–400 CE) and Medieval Climate Anomaly (MCA, 1000–1300 CE), suggest relatively dry conditions during these intervals. During the Current Warm Period (CWP, 1850-present), the values of the mean grain size and Zr/Rb increase abruptly and Rb/Sr ratios exhibit large fluctuations, which might be attributed to the impact of human activities. The general pattern of the reconstructed hydroclimate variations in this study is broadly consistent with the North Atlantic ice-rafted detritus and Indo-Pacific Warm Pool (IPWP) records, indicating that the hydroclimate variability on the centennial-scale in southern China has been controlled by both high- and low- latitude forcings over the last two millennia.