Industrial green total factor productivity based on an MML index in the Yangtze River Economic Belt

The environmental problems caused by industrial development in the Yangtze River Economic Belt in China have become a bottleneck for urban economic development. Therefore, the measurement of the green efficiency of the urban industry in the Yangtze River Economic Belt can provide a reasonable basis for future industrial green development paths. Based on the DEA model, this study measures the industrial green total factor productivity of 108 cities in the YREB by combining the meta-frontier infrastructure framework and the Malmquist-Luenberger index. The results indicate the following: (1) The industrial green total factor productivity of cities in the Yangtze River Economic Belt declined at first and then increased from 2009 to 2016. The overall performance indicated that the structures of the technological efficiency change index and technological change index were unreasonable. The industrial green total factor productivity of midstream cities is the highest, and the difference between cities is influenced by economic development level, industrial base, transportation convenience, labor quality, and the government's emphasis on green development of industrialization. (2) Different regions have different decomposition efficiency to promote the improvement of ITFP. Considering regional heterogeneity, the industrial green total factor productivity in the middle and lower reaches of the region relies on the advantages of technical efficiency, whereas the upper reaches rely on the improvement of management efficiency. (3) The technology gap in the upper and lower reaches is small, and in the middle reaches is relatively large. Thus, according to the above empirical results, this study finally presents some policy suggestions for industrial green development in different cities of the Yangtze River Economic Belt.