Spatial spillover mechanisms of renewable resources industry agglomeration on urban “pollution control and carbon reduction”

Whether renewable resources industry agglomeration (RRIA) can break low-end lock-in remains a gap. This study identifies the mechanisms by which RRIA affects pollution control and carbon reduction in Chinese cities. RRIA generates local and spillover effects, but threshold tests show phased differences: carbon reduction has a single threshold (0.65), while pollution control has dual thresholds with synergy only above 1.05. Industrial upgrading (IU) promotes spillovers, whereas green technological innovation (GTI) produces a siphoning effect. Since 2010, policy-driven industrial chain reorganization has shifted cities from negative externalities to positive marginal effects, yet reliance on exogenous policies limits sustained endogenous GTI and IU. Regionally, the Northeast is constrained by GTI lock-in, the Central gains synergy through IU and GTI diffusion, the East reduces carbon through GTI but faces pollution challenges, and the West shows weak local governance with rising surrounding emissions. Policies should enhance endogenous GTI diffusion and coordinated industrial governance.