Spatial relevance of synergistic effects between air pollutants and carbon dioxide emission reductions: A case study in the Bohai Rim region of China

Analyzing the spatial correlation of synergistic effect of reducing air pollutants and carbon dioxide (SERAC) between cities, which are spatial hubs characterized by dense populations, industries, and energy usage, provides a foundation for devising regional joint prevention and control policies tailored to local circumstances at this scale. The study analyzed 43 cities in the Bohai Rim region, assessing synergistic emission reduction effects from 2006 to 2020 using a coupled coordination model based on air pollutants (AP) and carbon dioxide (CO₂) emission trends. Social network analysis is employed to investigate the structural characteristics and robustness of the spatial correlation network and to unveil the position and significance of each city within the network. The study found that: (1) AP emission equivalent peaked in 2011, while the growth rate of CO₂ emission equivalent slowed down in the Bohai Rim region. (2) The low-value areas for the SERAC are spatially clustered in Beijing, Tianjin, and Tangshan, with 90% of the cities in a coordinated state. (3) The network showcasing the spatial correlation between the SERAC features both “local clustering” and “global correlation” coexisting, and its robustness needs improvement. (4) Membership within the plates is relatively stable. On this basis, it is proposed that the Bohai Rim region can enhance the SERAC by establishing a “lead-follow” inter-city mechanism, strengthen the stabilizing role of core entities, implement differentiated emission reduction measures in communities, and expand regional cooperation, ultimately reducing costs and increasing efficiency.