Baseline Preservation as a Response to Sea-Level Rise

Abstract

To combat the adverse effects of climate-change-driven sea-level rise, an increasing number of states have started preserving baselines. In this context, preservation means making baselines permanent despite changes to the coastline resulting from sea-level rise. In 2023, the International Law Commission’s Study Group on Sea-level rise in relation to international law released its Additional Paper on the impact of sea-level rise on the law of the sea. The Additional Paper focused on the states’ views concerning the possibility of preserving baselines irrespective of coastal changes caused by sea-level rise. However, the Additional Paper did not include a convincing methodological framing of the question of baseline preservation. This article frames this question as one of custom formation or treaty interpretation, arguing that neither framing would allow one to conclude that positive international law sanctions the preservation of baselines, but that there are viable solutions de lege ferenda to achieve it.