Changes in SST regulate hydroclimatic patterns in the monsoon marginal zone, northern China

The influence of recent global warming on the intensity, timing, and extent of the East Asian summer monsoon (EASM) remains not fully understood. Here we reconstruct an EASM precipitation history of the past ~ 500 years based on sedimentary multi-proxy indices from Lake Daihai, northern China. We find low EASM precipitation between ~ AD 1517 and ~ 1850, with three sharply weakened intervals, which were broadly concurrent with the Chinese dynastic and cultural transitions. The EASM intensified after ~ AD 1850, changing from cold-dry to warm-wet conditions, with greater multidecadal variability. These features match well with the coeval sea surface temperature (SST) records over the North Pacific and North Atlantic Oceans, suggesting that changes in global SSTs could have forced changes in EASM intensity and modulated regional hydroclimate on these timescales. We propose that the increased interhemispheric temperature gradients associated with the recent global warming might push northward the western Pacific Subtropical High (WPSH), the westerlies, and the monsoon front. Meanwhile, the multi-decadal warming in the North Atlantic may also strengthen the westerlies and the EASM. These multiple factors could have collectively led to higher precipitation in the converging zone of the westerlies and the WPSH since ~ AD 1850.