Variability of the East Asian summer monsoon rainfall over Korea during the Early to Mid-Holocene and its links to global climate changes

Abstract Understanding the spatiotemporal variability of global summer monsoons and the factors controlling them is essential for testing and predicting their future changes under the anticipated global warming. Here, we reconstructed a series of East Asian summer monsoon (EASM) patterns over South Korea. Based on radiocarbon dates, grain size, carbon/sulfur (C/S) ratios, and high-resolution X-ray fluorescence core scanning (XRF-CS) data (e.g., Ti/Al and Zr/Al ratios) from a paleo-bay site in Hadong area, southern Korea, we investigated the multi-decadal- to centennial-scale variation in the terrestrial element inputs as a proxy for the EASM rainfall during the period from 8600 to 7800 cal yr BP and compared previous results from the Buan area, western coast of Korea, to test possible synchronous local-scale hydroclimate change. We also explored global teleconnections among EASM over Korea, the Indian summer monsoon (ISM), and the movement of the Intertropical Convergence Zone (ITCZ). We found that the EASM variability was positively correlated with that of the ISM through latitudinal shifts of the ITCZ. High-latitude cooling climates, including the 8.2 ka cooling event, were also directly connected to the weakened EASM via the intensified winter monsoon and southward shift of the westerly jet position over the Tibetan Plateau. To predict future changes in summer rainfall, synchronized changes in the global summer precipitation should be considered in terms of ITCZ and high-latitude climate change, including westerly jet shifts over Asian regions.