Firm heterogeneity in sources of changes in CO2 emissions from international container shipping

Container ships are the largest source of CO2 emissions in international shipping, and reducing their environmental impacts is crucial to reduce global CO2 emissions. However, the sources of changes in CO2 emissions are still unclear at the firm level, making it difficult to propose practical policies to stakeholders. In this study, we investigated firm heterogeneity in the sources of changes in CO2 emissions from international container shipping by a firm-level factor decomposition analysis. We estimated route-specific CO2 emissions during 2018-2020 for the top seven operating companies using comprehensive firm-level microdata. The results show that the combined annual CO2 emissions increased during 2018-2019, and transportation activity changes considerably contributed to the increase in CO2 emissions. The results during 2019-2020 show that changes in transportation networks had higher impacts in decreasing CO2 emissions than carbon intensity improvements; thus, establishing suitable regulations for network structures can effectively decarbonize container shipping.