Sea Level Rise and Implications for Maritime Security in Southeast Asia

<p dir="ltr">Clarity and predictability in maritime jurisdiction, grounded in UNCLOS, are essential for stable and secure oceans, yet Southeast Asia’s crowded coastlines, complex geography, and overlapping claims have long created uncertainty and tension—both among ASEAN states and with external actors. These unresolved boundaries already hinder cooperation on issues like piracy, IUU fishing, and ecosystem protection, and sea level rise now adds a further layer of complexity by physically altering coastlines and potentially shifting baselines and maritime zones. Although Southeast Asia is highly vulnerable to SLR, UNCLOS provides little guidance on how climate-driven coastal changes should affect maritime limits, prompting legal debates and efforts—led mainly by Pacific Island states—to secure baseline and boundary permanence. This article examines how SLR may affect maritime jurisdictional clarity and thus maritime security in Southeast Asia, analysing current state practices and emerging legal approaches before outlining implications and potential strategies for mitigating SLR-related challenges.</p>