A high-resolution stalagmite record of hydrological drought in northern China around 6.6 ka BP

The Holocene Climatic Optimum was punctuated by significant decadal-to centennial-scale climate variability, despite its overall warm and humid conditions. However, the spatiotemporal patterns and underlying dynamics of these fluctuations, particularly in the northern fringe of the East Asian Summer Monsoon in China, remain inadequately understood. Here, we present ∼2–5-year-resolution multi-proxy (δ 13 C, δ 18 O, and Mg/Ca) records from a stalagmite collected in Lianhua Cave, northern China, spanning 6.85 to 6.42 ka BP. Covariations among δ 18 O, δ 13 C, and Mg/Ca indicate a coupling between East Asian Summer Monsoon (EASM) intensity and regional hydrological changes. Our record captures a pronounced centennial-scale drought event centered at ∼6.6 ka BP, characterized by an asymmetric W-shaped structure with a duration of ∼130 years. Comparative analysis with other geological proxy records indicates that this event was broadly contemporaneous across a region from northern China to the Yangtze River Basin. Spectral analysis reveals significant periodicities of ∼60–120 years that are coherent with solar activity cycles, suggesting that the timing and structure of the event were potentially paced by solar activity. This external forcing likely required amplification through internal climate variability, such as the Atlantic Meridional Overturning Circulation and El Niño-Southern Oscillation. Furthermore, a cold-phase Atlantic Multidecadal Oscillation may have excited teleconnections within the Afro-Asian summer monsoon systems, thereby amplifying the Asian summer monsoon weakening and associated drought. This study provides new constraints for understanding the characteristics and mechanisms of megadrought events in northern China under a warm period background.