Anthropogenic forcing has impacted precipitation variability in the North China Monsoon Marginal Region

The Asian Summer Monsoon (ASM) is a crucial driver of precipitation, sustaining ecological balance and socio-economic development in North China. However, the extent to which climate change has influenced this monsoonal system, leading to detectable and attributable modifications in precipitation regimes, remains unclear. Here, we present a robust annual precipitation reconstruction spanning 1770-2020, derived from tree-ring stable oxygen isotope data and a simple linear regression model in the North China Monsoon Marginal Region (NCMMR). Reconstructed precipitation and independent hydroclimatic records reveal a pronounced drying trend across the NCMMR since the 1950s. Multiple linear regression (MLR) modelling, water vapor transport analyses using ensemble means from the Community Earth System Model-Last Millennium Ensemble, and correlation analysis indicate that precipitation variability in the NCMMR is modulated by the Indian Ocean Dipole, El Niño-Southern Oscillation, Atlantic Multidecadal Oscillation, and Interdecadal Pacific Oscillation. Nevertheless, fingerprint analysis suggests that the observed precipitation decline since the 1950s is strongly associated with greenhouse gas concentrations, albeit partially offset by the effects of anthropogenic aerosol emissions and internal variability. The impact of greenhouse gas forcing on precipitation variability is expected to intensify in the coming decades.