Allocating carbon emissions from crude oil tanker shipping: Full voyage lifecycle perspective

This study introduces a full voyage lifecycle framework that links maritime CO₂ emissions to international trade flows through First-In-First-Out (FIFO) cargo tracking. By analysing AIS trajectories of 2,491 crude oil tankers in 2020, we quantified total shipping emissions at approximately 108 million tonnes of CO₂, of which ballast voyages accounted for nearly 40 %. Distinct from conventional allocation methods (flag-state registration, fuel sales, or simplistic port-to-port voyages), our approach significantly enhances allocation equity: the trade-normalized Gini coefficient decreases from 0.232 under traditional voyage-based methods to 0.151 with back-allocation. Sensitivity analyses confirm robust policy flexibility, demonstrating minimal changes in national emission responsibility rankings when varying the exporter–importer allocation factor (α = 0.25–0.75). This framework provides a practical foundation for integrating shipping emissions into emerging carbon pricing mechanisms, harmonizing maritime carbon accountability with global trade, and supporting equitable international climate governance.