[Spatiotemporal Evolution Pattern and Influencing Factors of Synergistic Effect of Urban Pollution Reduction and Carbon Reduction in China].

Environmental pollution and carbon emissions predominantly stem from fossil fuel consumption， sharing common sources and processes. This inherent co-production relationship establishes a scientific foundation for implementing coordinated governance to enhance the Synergistic Effect of Pollution Reduction and Carbon Reduction （SEPCR）， thereby accelerating socio-economic green transition. However， existing literature lacks comprehensive assessments of SEPCR at the urban level in China and seldom examines its influencing factors from a spatiotemporal heterogeneity perspective. To address this gap， this study comprehensively uses the SBM-DEA model with unexpected outputs and coupling coordination model to measure the SEPCR of cities in China. The spatial Markov chain and data visualization methods are used to analyze the spatiotemporal evolution pattern of SEPCR in Chinese cities from 2004 to 2022. The spatiotemporal geographic weighted regression model （GTWR）， kernel density curve， and map visualization methods are used to investigate the spatiotemporal heterogeneity of factors influencing the SEPCR. The study revealed that： ① The overall SEPCR was on the rise， with a fluctuating decline prior to 2014 before entering a rapid growth period. ② The SEPCR exhibited strong stability， with a gradual evolution process. SEPCR levels of neighboring cities were positively correlated with the upward transfer probability of the city， while negatively correlated with the downward transfer probability of the city. ③ The SEPCR showed a spatial differentiation pattern of northeast>east>west>central regions， with high-value clusters concentrating in eastern coastal and northeastern regions， while central and western regions were generally stable and emerging progress. Low-value areas centered in Shanxi Province showed spatial convergence. ④ The regression results of GTWR indicate that industrial structure， energy efficiency， and technological innovation had a promoting effect on the SEPCR， while population expansion， economic development， and energy structure mainly exhibited an inhibitory effect. Each influencing factor demonstrated significant spatiotemporal heterogeneity.