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Both external forcing and internal climate variability are playing significant roles in driving the East Asian summer monsoon (EASM) changes. However, dynamic linkages between these natural forcings and EASM on decadal timescales remain uncertain, partly due to the limited instrumental climate data. Here, we present a high-resolution EASM record over the past 200 years based on 2315 δ18O measurements from two annually laminated stalagmites (YX92 and YX120) in Yongxing Cave over the middle Yangtze River Valley (mid-YRV). Our records match well with the δ18O records from the nearby Heshang Cave, showing that EASM intensity in the mid-YRV varies at a dominant periodicity of ∼80 years. The multidecadal-scale oscillations in the EASM intensity are closely related to the ENSO-like states, supporting a notion that the ENSO dominantly modulates the EASM variability. Furthermore, the decadal oscillations in EASM and ENSO are synchronous with tropical volcanic eruptions during the solar minima, probably leading to the enhanced El Niño-like response, intensified EASM and strengthened ENSO-EASM coupling. Our findings imply that external forcings potentially contribute to the anomalies in ENSO and EASM during the ongoing global warming. • EASM changes at a dominant periodicity of ∼80 years over the past 200 years. • Multidecadal-scale oscillations in EASM intensity closely related to ENSO-like states. • Decadal oscillations in EASM and ENSO evolution synchronous with tropical volcanic eruptions during the solar minima. • Tropical volcanic eruptions likely enhanced the ENSO-EASM coupling. [ABSTRACT FROM AUTHOR]

• A composite high-resolution monsoon precipitation record over the mid-YRV. • Centennial-scale oscillations in EASM rainfall related to solar activity and ENSO. • An anti-phase relationship of monsoon rainfall between the mid-YRV and tropical WNP. • A new EAP index calculated as the difference between monsoon rainfall in the mid-YRV and WNP. • A strong correlation between the EAP and SOI index. Meteorological observations reveal an inverse relationship of summer monsoon rainfall between the tropical western North Pacific (WNP) and middle Yangtze River Valley (mid-YRV) on interannual and intraseasonal timescales. This seesaw-like pattern, named the East Asian-Pacific (EAP) pattern, is one of the major teleconnections that affect summer precipitation in the mid-YRV. However, due to the scarcity of long and continuous instrumental data, the behavior and mechanism of the EAP pattern on a long timescale are poorly understood. Here, we present a composite high-resolution summer monsoon rainfall record from 230 BC to 1810 AD, based on 1221 δ 18 O measurements and 22 230Th dates from two stalagmites (EB1 and EB5) in Shenqi Cave over the mid-YRV. Our new record shows that monsoon rainfall in the mid-YRV varies at a dominant periodicity of ∼100 years, probably linked to solar activity and ENSO variability. The multi-centennial fluctuations in the EB record, broadly consistent with the North Hemisphere temperature reconstruction, display strong similarities to two stalagmite δ 18 O records from nearby Heshang and Luoshui caves. To represent the integrated hydroclimate variations over the mid-YRV, we extracted the first principal component (PC1) of these three cave δ 18 O records by using the principal component analysis. We reveal a striking inverse relationship of wet/dry conditions between the mid-YRV and tropical WNP, suggesting that changes in the EAP pattern have an important impact on centennial-scale monsoon precipitation changes. Furthermore, we compile monsoon rainfall records from the mid-YRV and WNP to reconstruct a new EAP index. This EAP index exhibits a strong correlation with the ENSO proxy, confirming that the ENSO variability may play a key role in modulating the monsoon rainfall in the mid-YRV through the EAP teleconnection. [ABSTRACT FROM AUTHOR]

Observations and models suggest a latitudinal redistribution of precipitation as a result of ongoing global climatic warming. However, the dynamic link between temperature and regional precipitation in the course of natural climatic variability during the current interglacial period remains unclear, especially in the monsoon regions of China. Here we present a reconstruction of a ∼5 year-resolution summer monsoon rainfall record for the past 3200 years, based on 622 pairs of δ18O and δ13C and 29 230Th dates from a stalagmite (Wu37) from Wulu Cave in southern China. A close similarity between the δ18O and δ13C records on centennial to decadal timescales suggests that calcite δ18O is most likely a proxy associated with monsoon precipitation. The record reveals that the Little Ice Age (650 - 100 yr B.P.) was a relatively humid period, with two centennial-scale wet events, compared with the Medieval Warm Period (1050 - 650 yr B.P.). In contrast with previous observations in India and northern China, monsoon precipitation variations indicated by our record and other cave records nearby were inversely related to changes in Northern Hemisphere (NH) temperature over the past two millennia, in particular to variations in the thermal gradient between the Northern and Southern hemispheres. This suggests that NH temperature has an important influence on summer precipitation in southern China, via the interhemispheric thermal gradient and land-ocean thermal contrast. In addition, we find that variations of monsoon rainfall in southern China on multi-centennial to centennial timescales are inversely correlated with observed rainfall in the core monsoon region of India and in the northern fringe of the Asian summer monsoon region in China. This spatial pattern of rainfall variability can be interpreted as a result of the migration of the intertropical convergence zone that is likely dominated by the interhemispheric thermal gradient via cross-equatorial airflows. • Increase of monsoon precipitation in southern China (SC) since the LIA. • Anti-phase relationship between SC precipitation and NH temperature. • A negative correlation between precipitation in SC and India, northern China. • A direct control of NH temperature on the shifts of the ITCZ rainbelt. [ABSTRACT FROM AUTHOR]