Economic development, openness, and the impact of industrial co-agglomeration on urban carbon efficiency: An empirical study of threshold effects

This study employs panel data from 283 Chinese cities spanning 2001 to 2019 to examine the impact of industrial co-agglomeration on urban Carbon Total Factor Productivity (CTFP) via ordinary panel regression analysis. Subsequently, panel threshold regression analysis is applied to explore whether its impact on urban CTFP varies across different levels of economic development and openness. The results indicate that the co-agglomeration of manufacturing and service industries (CAMS) significantly enhances urban CTFP. Further analysis shows that the positive effect of industrial co-agglomeration on CTFP is more pronounced at lower economic development levels, but may diminish or even reverse as economic development level increases. Additionally, the study finds that its positive impact is strengthened at low to moderate openness levels, yet this effect weakens under high openness. These findings highlight the need to account for the moderating effects of economic development and openness when examining the impacts of industrial co-agglomeration on urban carbon efficiency, providing empirical evidence for urban low-carbon development policies.