Does trade protection undercut the green efficiency of the marine economy? A case study

The development of the marine economy is closely related to trade openness. But does trade openness promote sustainable development of the marine economy? To understand the impact of trade openness on marine economy sustainable, this study examines the impact of trade openness on the green efficiency of marine economy. To this end, the green efficiency of the marine economy of 11 coastal provincial regions of China is measured by the undesired super-efficiency SBM technique, to examine the impact of trade openness on green efficiency of marine economy using a panel vector autoregressive technique from a perspective of North-South regional differences. The results show (i) the overall green efficiency of marine economy in China's coastal areas needs to be improved, and a spatial distribution pattern is weak in the north and strong in the south; (ii) trade openness emerges as a positive factor contributing to the green efficiency of marine economy. It is evident that enhancing the level of trade openness is a pivotal pathway for promoting environmentally sustainable devel-opment in the maritime sector. Furthermore, it is noteworthy that the stimulatory effect of trade openness ex-hibits significant regional disparities, with its impact being notably stronger in the southern coastal areas compared to the northern ones; (iii) the development level of the marine economy and the structure of the marine industry exert negative influences on the green efficiency of marine economy; (iv) bidirectional causal relationships are observed between the green efficiency of marine economy and three crucial variables, namely, trade openness, marine economic development level, and marine industry structure. In light of the aforemen-tioned results, this study adopts a regional disparity perspective to offer practical recommendations for advancing the green development of marine economies in emerging nations such as China.