Abstract

This study investigates how the international shipping sector can fairly and effectively reduce greenhouse gas (GHG) emissions in Areas Beyond National Jurisdiction (ABNJ) by integrating the principle of Common But Differentiated Responsibilities (CBDR) into International Maritime Organization (IMO) regulations. Current IMO instruments, such as MARPOL Annex VI, employ uniform obligations via the No More Favourable Treatment (NMFT) principle; however, this approach insufficiently addresses disparities in technological and economic capacity between developed and developing states and complicates enforcement for ships registered under Flags of Convenience (FOC). By comparatively analyzing major international environmental law instruments—including the UNFCCC and the Paris Agreement—this paper diagnoses gaps and conflicts between the NMFT paradigm and the CBDR principle within the IMO context. Legal and institutional reform proposals are presented to embed differentiated responsibilities, technical and financial support mechanisms, and improved enforcement for GHG emission reduction from ships operating in ABNJ. Integrating the CBDR principle into IMO regulatory frameworks is argued as essential to enhance regulatory legitimacy and to achieve both equity and effective decarbonization of the global shipping sector in compliance with 2050 climate neutrality goals.