Spatiotemporal patterns and influencing factors of green development efficiency in China's urban agglomerations

Urban agglomeration is an important means of collaborative regional development, and a critical organizational form for cities when their industrialization and urbanization develop to a certain stage. The green development of urban agglomerations is important for achieving coordinated, high-quality regional development. In light of this, this study established an input–output index system that considers technological innovation and environmental quality. Then, we used a super-efficiency epsilon-based measure model that included undesirable output to evaluate the green development efficiency of seven urban agglomerations in China: Beijing–Tianjin–Hebei, the Yangtze River Delta, the Pearl River Delta, Chengdu–Chongqing, the Yangtze River Midstream, the Guanzhong Plain, and the Central Plain. The spatiotemporal variability of the green development efficiency of each urban agglomeration was analyzed using kernel density estimation, the coefficient of variation, and the Theil index. Finally, a spatial econometric model was established to explore the factors affecting the green development efficiency of different agglomerations. The findings improve our understanding of the spatiotemporal patterns of green development in urban agglomerations, which can support the formulation of suitable strategies for collaborative regional green development.