More precise accounting of marine carbon emission efficiency: Based on input-output analysis and considering marine carbon sinks

As China continues to develop its marine resources, marine carbon emissions and their efficiency have become a focal point and risk of growing concern within both economic and environmental systems. However, due to the complexity of marine economic systems and the unique nature of marine carbon sink functions, existing research in this area remains limited and incomplete. We took 11 coastal provinces and regions in China as the research object, conducted carbon sink accounting and marine economic input-output analysis to precisely calculate marine carbon emissions (MCE) in China's coastal areas, and further analyzed marine carbon emission efficiency using the super-efficiency slacks-based measurement (SBM) model. The results show that the total MCE is decreasing year by year, with the tertiary sector replacing the secondary sector as the largest emission source. However, there is significant regional disparity in development, and the carbon sink function is showing a declining trend. A combined analysis of MCE and MCEE reveals that the two dangerous emission patterns—high-carbon-low-efficiency and low-carbon-low-efficiency—are primarily concentrated in the Bohai Rim region. The main causes of this phenomenon include industrial overcapacity, outdated industrial models, insufficient technological updates, lagging ecological protection, and inadequate resource endowments. Based on the endowments and limitations of different regions, we recommend promoting the sustainable development of China's marine carbon emissions through regional task division, setting MCEE red lines, and fully leveraging the regulatory roles of technology markets and carbon trading markets.