Contrasting Responses of Monsoon Rainfall and Speleothem Oxygen Isotope Between Northeast Asia and North China During the Early‐Mid Holocene

Abstract A critical gap in East Asian summer monsoon research is the lack of speleothem records from its northeasternmost fringe, hindering tests of orbital‐scale monsoon variability at higher latitudes. Our new records from the Russian Far East, spanning 9–5 ka BP, fill this spatial gap and reveal a synchronous δ 18 O negative excursion and intensified monsoon precipitation between 8 and 9 ka BP, contrasting with trends in North China. We suggest this difference may stem from changes in Northern Hemisphere summer insolation (NHSI) over the Holocene. The NHSI decrease since early Holocene weakens southwesterly winds and the Western Pacific Subtropical High, shifting the westerly jet and rainbelt southward. This causes reduced (increased) precipitation in North China (Northeast Asia), as well as reduced (increased) contribution of Pacific Ocean moisture to North China (Northeast Asia), resulting in δ 18 O increase (decrease) in North China (Northeast Asia).