Measurement of carbon emission efficiency and influencing factors of port clusters in the Bohai Rim region

With the implementation of the "2024-2025 Energy Conservation and Carbon Reduction Action Plan", the port industry, as a core component of the transportation system, faces urgent tasks in energy conservation and emission reduction. To enhance the carbon emission efficiency and competitiveness of regional port clusters, and to promote more sustainable development of port clusters in the Bohai Rim region, this study measures the carbon emission efficiency and dynamic efficiency of 14 major ports in the Bohai Rim from 2007 to 2022 using the unexpected output super-efficiency SBM-Malmquist model. A Tobit regression model is further constructed to analyze the influencing factors of port carbon emission efficiency. The results reveal an overall upward trend in carbon emission efficiency among Bohai Rim ports. The regional ranking of carbon emission efficiency has shifted from Shandong > Liaodong > Jingjinji to Jingjinji > Shandong > Liaodong, with the efficiency gap between Jingjinji and the Shandong and Liaodong Peninsula ports widening. Scientific innovation and ecological compensation are identified as primary drivers of port carbon emission efficiency improvement, while the level of openness, transport capacity, and industrial structure exert negative effects. Based on these findings, this paper proposes pathways for improving carbon emission efficiency and optimizing management in Bohai Rim port clusters.