Trade-linked shipping CO2 emissions

The ambitious targets for shipping emissions reduction and challenges for mechanism design call for new approaches to encourage decarbonization. Here we build a compound model chain to deconstruct global international shipping emissions to fine-scale trade flows and propose trade-linked indicators to measure shipping emissions efficiency. International maritime trade in 2018 contributes 746.2 Tg to shipping emissions of CO2, of which 17.2% is contributed from ten out of thousands of trade flows at the country level. We argue that potential unfairness exists if allocating shipping emissions responsibility to bilateral traders due to external beneficiaries. However, a huge shipping emissions-reduction potential could be expected by optimizing international trade patterns, with a maximum reaching 38% of the current total. Our comprehensive modelling system can serve as a benchmark tool to support the construction of a systematic solution and joint effort from the shipping industry and global trade network to address climate change. More than 80% of trade by volume occurs via maritime shipping, with growing pressure to reduce associated GHG emissions. The top 10 single-direction trade pairs account for nearly 20% of emissions; optimizing trade patterns could reduce emissions by 38% of current totals.