Research on the Nonlinear Relationship between Industrial Agglomeration and Urban Green Development: The Intermediary Role of Industrial Structure Upgrading

Whether industrial agglomeration (IA) can effectively improve green development efficiency (GDE) is crucial for both the smooth realization of China’s dual carbon goals and the country’s future green development. This paper evaluated the GDE and the IA of 283 cities in China by constructing an improved data envelopment analysis model and a location entropy model. The nonlinear effect of IA on GDE was investigated empirically using the recently created spatial statistical model and mediating effect model. The results showed that (1) China’s overall GDE shows a good upward trend, while IA shows a slight downward trend. The differences between cities are very obvious. High-GDE cities are concentrated in coastal areas, and their average annual growth rate (AAGR) is low or even negative. Low-GDE cities are concentrated mainly in inland areas, with high AAGR. (2) There is a strong nonlinear U-shaped correlation between IA and GDE. (3) Influence factors such as economic development level (GDP) will promote GDE improvement, while influence factors such as energy structure will inhibit GDE improvement. (4) Industrial structure upgrading plays a major intermediary role between IA and GDE. Therefore, this paper proposes corresponding policy implications for how IA can promote green development.