How Coupled Carbon Flows Reshape Urban Carbon Neutrality: Spatial Patterns and Differentiated Pathways Across Chinese Cities

Urban carbon neutrality is increasingly shaped by cross-regional interactions rather than a closed balance between local emissions and sequestration. From an open-system perspective, this study conceptualizes urban carbon neutrality as the outcome of interactions between embodied carbon transfer (ECT) and carbon sequestration service flows (CSSFs). Using panel data for 297 Chinese cities in 2012, 2017, and 2022, an integrated measurement framework is developed to examine spatiotemporal patterns, typological heterogeneity, and driving mechanisms. The results reveal significant disparities in emission responsibility and ecological support across city types. Ecological conservation-oriented cities act as major carbon sequestration providers, while industrial- and service-oriented cities face higher emission pressures and weaker local sequestration capacity. The joint effects of ECT and CSSF reshape urban carbon neutrality through responsibility reallocation and ecological support transfer, enhancing overall performance while intensifying inter-city differentiation. Spatial Durbin model results indicate that carbon neutrality is jointly influenced by socioeconomic development, energy structure, factor mobility, ecological conditions, and institutional regulation, with both local and spillover effects. These findings suggest that urban carbon neutrality is a relational process embedded in production–consumption linkages and ecosystem service networks, highlighting the need for differentiated governance pathways to support coordinated mitigation and ecological compensation.