Evaluating the low-carbon efficiency of Chinese coastal ports in the context of dual carbon goals

In order to explore effective strategies for achieving the “dual carbon” goal by balancing energy conservation and emission reduction with the development of coastal ports, the carbon emission efficiency of major coastal ports in China from 2013 to 2023 is analyzed using a three-stage data envelopment analysis (DEA) model. Kernel density, Markov matrix, and Dagum Gini coefficient are used to explore the temporal and spatial evolution characteristics of coastal ports considering carbon emissions. The findings indicate that, in the first stage, the super-efficiency DEA model reveals a fluctuating upward trend in the average carbon emission efficiency. However, most ports—except Shenzhen and Haikou—fail to reach the efficient frontier. In the second stage, stochastic frontier analysis (SFA) is employed to account for environmental factors, such as hinterland GDP, and to minimize the influence of external factors and random errors on efficiency. In the third stage, adjusted input-output values are used to re-evaluate port efficiency, resulting in more accurate efficiency scores. While the efficiency scores show improvements compared to the first-stage results, the rankings of the ports by efficiency remain largely unchanged. Aside from Shenzhen, Haikou, and Qingdao, which have achieved efficient production, most ports have not yet attained optimal carbon emission efficiency, suggesting substantial room for improvement. The analysis using kernel density and the Dagum Gini coefficient highlights dynamic changes in resource allocation, development balance, and competitive cooperation among port clusters, thereby revealing regional development imbalances. Based on these findings, corresponding optimization strategies are proposed from aspects such as technological innovation, resource integration, and policy guidance to promote the coordinated development of carbon emission reduction and port development, providing a theoretical basis and practical reference for coastal ports to achieve the “dual carbon” goal.