Decadal causes of the Wanli megadrought in northern China during the Ming Dynasty: Perspectives from the Pacific Ocean

Climate change has profound implications for the social stability and societal crisis. The prominent Wanli megadrought (1585–1590 CE) had a profound impact on northern China and might contribute to the collapse of the Ming Dynasty. Despite its historical significance, the underlying mechanisms of the Wanli megadrought remain unclear. This study combines reconstruction and CESM Last Millennium Ensemble (CESM-LME) simulation to investigate the decadal-scale evolution of the Wanli megadrought. The reconstructed summer precipitation over much of northern China reveals a decadal Wanli megadrought period during 1581 and 1592 CE. The simulation reasonably reproduces the Wanli megadrought and associated climate fluctuations preceding and succeeding it on a decadal timescale. During the Wanli megadrought, simulated summer precipitation decreased from the Yangtze River to northern China, accompanied by anomalous air subsidence and anomalous cyclones over Northeast Asia and the subtropical western North Pacific. These circulation anomalies during the Wanli megadrought were mainly driven by warming around the Maritime Continent and cooling over the rest tropical Pacific on a decadal timescale, as evidenced by proxy data and simulation. These sea surface temperature (SST) changes caused the weakening of the East Asian summer monsoon through their influences on Walker circulation and inducing the decadal Pacific–Japan-like Rossby wave train propagated northward. Additionally, the phase shift of the PDO-like SST pattern may also contribute to the Wanli megadrought, aligning with several reconstructions, though more SST evidence is needed. Perspectives from the Pacific SST variability would enhance our understanding of the Wanli megadrought on a decadal timescale. • The simulation reproduced the reconstructed Wanli megadrought on a decadal scale. • The decadal Wanli megadrought period was linked with the Pacific SST changes. • Maritime Continent SST anomaly caused PJ-like Rossby wave train northward.