Hydroclimate changes in southwestern China from Dark Age Cold Period to Medieval Climate Anomaly and their global teleconnections

Hydrological reconstructions in the Asian monsoon region during the Common Era have shown prominent regional discrepancies while at the same time being remotely correlated. However, the regional characteristics of hydrological climate change in southwestern China and their dynamics are still poorly understood. Here, we reconstruct a hydroclimatic record from AD670 to AD1310 using a high-resolution stalagmite oxygen isotope record from Riyue Cave, Guizhou Province, southwestern China. The stalagmite δ¹⁸O record shows a good agreement with hydrological reconstructions from cave and lake sediments in southern China during the overlapped period, indicating a monsoon precipitation increase during the late Dark Age Cold Period (DACP) and a monsoon precipitation decrease during the Medieval Climate Anomaly (MCA). Geological and historical records from the monsoonal region of China display a dipolar rainfall pattern in southern China and northern China, with a “wet north and dry south” pattern during the MCA and a “wet south and dry north” pattern during the DACP. Meanwhile, a rapid DACP-MCA transition at approximately AD960 ± 30 was detected in Riyue record, which is widely observed in other climatic reconstructions in the mid- to low-latitude regions, indicating a fast global reorganization of atmospheric circulation within decades. Comparison shows that the rainfall pattern in the monsoonal region of China should be dominantly modulated by temperature changes in the Northern Hemisphere and China which could influence the temperature gradients and the position of the Intertropical Convergence Zone, and secondly the internal variabilities such as El Niño Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD). Changes in temperature, ENSO and IOD could also cause the rapid transition from the DACP to the MCA.