Progressing sustainable development of "the Belt and Road countries": Estimating environmental efficiency based on the Super-slack-based measure model

The "Belt and Road" (B&R) initiative not only promotes international economic prosperity but also inflicts enormous pressure on natural resources and create severe environmental problems. Therefore, to achieve a sustainable development, B&R countries should analyse their environmental efficiency and improve such efficiency by adopting effective measures. This study estimates and compares the environmental efficiency of B&R and non-B&R countries from 1990 to 2014, analyses their environmental efficiency based on their income levels and geographical locations, and identifies some paths that these countries should take to achieve an optimal environmental efficiency. This paper applies the Super-slack-based measure model that considers undesirable outputs. The empirical results reveal that the current performance and future prospects of these B&R countries in terms of environmental efficiency are generally poor, with only 30% of these countries exceeding the optimal efficiency. Some significant differences have also been reported amongst these countries in terms of their industrial development at the geographical and income levels. These findings provide a valuable reference for B&R countries to identify unique strategies that can promote their environmental efficiency.