Evolutionary Characteristics of the Spatial Correlation Network of County-Level CO2 Emissions Driven by the “Dual Cores”: A Case Study of the Chengdu–Chongqing Twin-City Economic Circle

Cross-regional collaborative governance is one of the key issues in implementing the “Dual Carbon” strategy. The Chengdu–Chongqing Economic Circle (CCEC), characterized by a dual-core driven spatial pattern, provides an ideal context for investigating CO2 emission linkage mechanisms. Integrating nighttime light and land use data, this paper constructed a county-level CO2 emission dataset from 2000 to 2020. A dual-core deconstructed standard deviational ellipse, a modified gravity model, and social network analysis were utilized to assess spatial trajectories and network evolution. Total CO2 emissions stabilized following an initial increase, exhibiting core-periphery differentiation and spatial convergence of the dual-core centers of gravity. A fully connected network emerged with decreased hierarchy and increased efficiency. The structure evolved into a hierarchical system dominated by manufacturing cores and transit hubs. Driven by secondary industry agglomeration, spillover sources shifted to manufacturing zones (e.g., Longquanyi, Yubei). Central-axis nodes (e.g., Jianyang, Chuanshan) acted as intermediary hubs for cross-regional CO2 transfers. Regional industrial restructuring introduces spatial environmental cost transfer risks. Differentiated mitigation requires low-carbon technological innovation in core manufacturing nodes, regulated green entry thresholds for intermediary hubs, and network flow-based cross-regional ecological compensation mechanisms.