Sea-Level Rise and the Limits of Rebus Sic Stantibus in Maritime Boundary Treaties

Abstract

Sea-level rise, driven by thermal expansion and polar ice-sheet melting, is progressively reshaping the coastal geography upon which the international law of the sea is built. As baselines shift landward and low-lying islands face submersion, the stability of existing maritime boundary treaties comes under increasing pressure. This article examines whether the doctrine of rebus sic stantibus, codified in Article 62 of the Vienna Convention on the Law of Treaties (VCLT), can be invoked to terminate or modify maritime boundary treaties in response to sea-level rise. After surveying the debate between the ambulatory and fixed baseline theories, and analyzing the institutional framework of Article 62 and its boundary treaty exception, this article tests sea-level rise against each constituent element of the doctrine. It concludes that in the vast majority of cases, sea-level rise fails to satisfy the cumulative requirements of Article 62, and that the pursuit of treaty stability through baseline fixation, bilateral arrangements, and multilateral norm-building represents a more viable and legally sound path forward.