All Necessary Measures: Climate Law for International Shipping

International shipping is one of the largest sources of climate pollution. The conventional view is that, despite some ambiguities in the climate treaties, international law only requires states to implement global rules adopted by the International Maritime Organization. This overlooks the important and timely question of whether other sources of law oblige states to do more. This Article argues that customary environmental principles, human rights law, and the UN Convention on the Law of the Sea mandate that states take all necessary measures to prevent and reduce shipping’s climate risks. The measures that are necessary are dynamic and differential, and they include support for ambitious and effective global rules and unilateral actions. Because shipping is a well-quantified sector, emissions data is readily available and there are various options for legal accountability.