Description: Highlights: • We compare proxy moisture records in Northeast Asia with the results from a transient simulation. • An east–west antiphasing of summer precipitation in Northeast Asia during the Holocene is found. • The East Asian summer monsoon circulation and mid-latitude westerlies caused the zonal precipitation contrast. Abstract: The East Asian summer monsoon (EASM) is a complex system that brings precipitation to East Asia showing considerable spatiotemporal variations. This study explored the zonal differences of summer precipitation in Northeast Asia at orbital timescales during the Holocene by comparing proxy records with simulation results. At orbital timescales, there was generally an east–west antiphasing of summer precipitation in Northeast Asia during the Holocene. Model–proxy comparison revealed that the driest interval occurred during the late Holocene in western Northeast Asia and during the early to middle Holocene in eastern Northeast Asia. Changes of summer precipitation in western Northeast Asia were mainly influenced by precession-driven EASM circulation. On the one hand, a weaker EASM circulation during the late Holocene weakened water vapor transport from the North Pacific Ocean to Northeast Asia, and on the other hand it was associated with anomalous downward motions in western Northeast Asia. Both factors were in favor of a reduction of summer precipitation in western Northeast Asia during the late Holocene. In contrast, anomalous downward motions prevailed in eastern Northeast Asia during the early to middle Holocene, which were probably related to stronger western Pacific subtropical high and weaker westerlies. The effect of the anomalous downward motions overwhelmed the enhanced water vapor transport, leading to a dry climate in this area from the early to middle Holocene. This study suggests that special care should be taken when discussing the meridional shift of the Holocene climatic optimum in the EASM region due to the zonal precipitation contrast.

Description: Identifying the relationships between moisture changes in arid central Asia and those in East Asia may help us understand the interplay between the westerlies and the Asian summer monsoon. We combined proxy moisture records with the results from a transient simulation forced by changes in orbital parameters to analyse their relationships during the Holocene (9.5–0 ka BP). The proxy records and simulation results generally agree with a relatively dry early Holocene, the wettest period in the middle Holocene, and a dry late Holocene in East Asia. These periods were not solely controlled by precession-driven East Asian summer monsoon variability, but were significantly influenced by precipitation during the other seasons and by evaporation. However, different proxy records show contrasting results for moisture changes in arid central Asia during the Holocene. To study this, we analysed the climatic signals of the competing proxy records by comparing these proxy records with simulation results. We found that speleothem δ18O was significantly influenced by water vapour sources and evaporation rather than by the amount of precipitation. Thus, the model data reveals a persistent wetting trend throughout the Holocene that was out-of-phase with the trend in East Asia. The wetting trend in arid central Asia was caused by precipitation that increased faster than evaporation during the Holocene. The enhanced water vapour input from South Asia and the Middle East was the main cause of the increase in precipitation in arid central Asia, which in turn gave rise to the intensification of evaporation.

Description: The East Asian winter monsoon (EAWM) is one of the most active components of the global climate system. Climate anomalies associated with the EAWM differ between extratropical and tropical regions due to the EAWM's meridional extent. Spatial differences in the EAWM variability on centennial and millennial time scales during the Holocene have not been well understood. This study describes Holocene spatiotemporal features of the EAWM based on comparisons of proxy records and climate simulations. The analysis specifically compared four proxy records located throughout China to assess the EAWM's spatial variability during the Holocene. These records indicate a stronger EAWM during the early Holocene than that during the late Holocene. The EAWM also shows a rapid, asynchronous decline from northwestern to southeastern China. The EAWM declined in northwestern China from 10 to 7.5 ka B.P., whereas the decline did not occur in southern China and the eastern Tibetan Plateau until 6–4.5 ka B.P. Coupled equilibrium and transient simulations of climate evolution during the Holocene indicate that the decline of the EAWM from 10 to 7.5 ka B.P. was probably caused by melting of Northern Hemisphere (NH) ice sheets and enhanced Atlantic meridional overturning circulation (AMOC). The decline of the EAWM from 6 to 4.5 ka B.P. over the eastern Tibetan Plateau and southern China is related to an abrupt increase in sea surface temperatures (SSTs) of the tropical western Indian Ocean. We therefore argue that the regional shift in EAWM intensity was probably related to a distinguishing response to high-latitude (NH ice sheets and AMOC) and low-latitude (tropical SSTs) forcings.