Effect of high-speed rail network on carbon mitigation: Beggar-thy-neighbor or benefit-thy-neighbor

This study empirically investigates the impact of cities' roles and positions within the high-speed rail (HSR) network on carbon dioxide (CO 2 ) emissions in China. We also explore the distance range of spatial spillover effects and analyze the potential mechanisms. Empirical findings indicate that cities exhibiting higher betweenness centrality experience more substantial reductions in CO 2 emissions within the focal urban areas; however, this is accompanied by an increase in CO 2 emissions in adjacent cities. This pattern suggests the presence of a pronounced Beggar-Thy-Neighbor effect. Importantly, the overall total effect remains significantly negative, confirming that betweenness centrality provides a net environmental benefit in curbing aggregate CO 2 emissions. These findings are validated by robustness tests and endogeneity analysis. However, as spatial distance expands, the impact of betweenness centrality within the HSR network on CO 2 emissions gradually shifts from a Beggar-Thy-Neighbor effect to a Benefit-Thy-Neighbor effect characterized by synergistic emission reduction. Industrial agglomeration, industrial structure upgrading, and green technological innovation are identified as the main mechanisms through which betweenness centrality impacts CO 2 emissions.