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.

The Aleutian Low (AL) is one of the major atmospheric systems that determines environmental conditions during winter in the North Pacific Ocean, with impacts that affect the climates of both Asia and North America from mid- to high latitudes. However, the multi-centennial and longer scale behavior of the AL during the Holocene is not fully understood. In this study, AL variability since 7.5 ka was examined by applying the principal component analysis technique to published δ18O data derived from sedimentary calcite, peat, ice, and speleothem from western North America. The extracted Principal Component 1 (PC1) represents a dramatic change from the mid- to late Holocene, and appears to reflect long-term intensified AL related to interactions between orbitally-driven southward shift of the Westerly Jet (WJ) over East Asia and the northwestern Pacific, and intensification of the El Niño–Southern Oscillation. In contrast, PC2 is characterized by multi-centennial to millennial-scale oscillations, with a spatial loading pattern that suggests PC2 reflects AL intensity and position shifts. These oscillations are contemporaneous with both WJ latitude and/or the meandering path shifts over East Asia and solar activity change, suggesting that a decrease/increase in solar irradiance is related to AL variability via interactions with the WJ.