In July 2023, the International Maritime Organization (IMO) resolved to reduce international shipping’s greenhouse gas emissions to net zero “by or around, i.e., close to” 2050. There is a long-running debate about whether the sector should decarbonize and how it could do so in a way that is equitable for states and the shipping industry. This Article is the first to normatively define shipping’s fair share of the overall climate mitigation burden using principles of international environmental law.

Methane is estimated to be responsible for one-third of the global rise in temperatures from greenhouse gases; it is shorter-lived but much more potent than carbon dioxide. The United States and the European Union (E.U.) launched the Global Methane Pledge at the 2021 United Nations Climate Change Conference (COP26). At COP28’s Global Methane Pledge Ministerial last December, new strategies were announced, including the E.U.’s first-ever adoption of methane regulations and a final rule by the U.S. Environmental Protection Agency to reduce methane from the oil and gas industry.