C4MIP-based projections of moisture convergence and extreme precipitation risks in East Asia

As climate change accelerates, extreme precipitation is becoming more frequent and intense across East Asia, underscoring the need for improved understanding of evolving hydrological regimes. While most future projections have relied on CMIP6 models, the Coupled Climate Carbon Cycle Model Intercomparison Project (C4MIP) integrates terrestrial–oceanic carbon cycle feedback including nitrogen deposition and biogeochemical processes to enhance the reliability of climate projection. Despite these advancements, C4MIP has been underutilized in hydrological assessments for East Asia. In this study, we analyze multi-model ensembles from C4MIP to evaluate patterns of vertically integrated moisture flux convergence (VIMFC). Our results demonstrate that C4MIP offers improved skill in capturing both seasonal and annual VIMFC patterns, particularly during periods of pronounced convergence or divergence. Under the SSP5–8.5- bgc scenario, projections indicate intensified moisture convergence and an elevated risk of extreme precipitation over southeastern China and North Korea. These findings provide a diagnostic evaluation of C4MIP's hydrological performance and offer valuable insights for future regional climate projections and adaptation strategies. • C4MIP offers slight improvement on CMIP6 in simulating VIMFC across East Asia. • VIMFC’ role in summer rainfall has weakened through intensified moisture divergence. • Extreme precipitation risk is projected to rise, especially in SE China and Korea.