Regulating project-associated greenhouse gas emissions from deep-seabed mining: a climate-sensitive EIA framework for the International Seabed Authority

Deep-seabed mining (DSM) in the international seabed Area is often framed either as a necessary supply option for the clean-energy transition or as a potential threat to the ocean carbon sink. This Policy and Practice Review argues that neither framing should determine the regulatory design of DSM climate governance. Among the several climate-relevant dimensions of DSM, the one most amenable to regulation on the basis of present knowledge is project-associated greenhouse-gas (GHG) emissions generated by extraction, transport and, especially, downstream metallurgical processing of seabed minerals. The article asks a focused legal question: to what extent can the 2024 Advisory Opinion of the International Tribunal for the Law of the Sea (ITLOS) and the 2025 Advisory Opinion of the International Court of Justice (ICJ) be read as requiring the International Seabed Authority (ISA) to incorporate GHG-emissions assessment into its environmental regime for exploitation. It identifies a bounded governance gap: DSM-related emissions are not wholly covered by existing climate, shipping or domestic regimes, but the ISA’s exploitation-approval process, currently under negotiation, does not yet contain a coherent, mandatory and verifiable requirement to quantify, assess, disclose and mitigate project-associated GHG emissions through environmental impact assessment (EIA). Drawing on the two advisory opinions and on existing scholarship, the article shows that due diligence, the precautionary approach, EIA, and the duty to regulate private operators now provide a stronger legal basis for integrating climate considerations into DSM authorization, and that the entry into force of the BBNJ Agreement and the evolving International Maritime Organization (IMO) framework reinforce, but do not replace, the need for GHG-specific content within the ISA’s own environmental impact assessment rules. On that basis, and grounding each element in the literature and in existing ISA instruments, the article develops a climate-sensitive GHG-EIA component, a defined block of required content within the ISA’s EIA framework, comprising accounting boundaries, reporting metrics, independent verification, a mitigation hierarchy, and adaptive review triggers, designed to operationalize the ISA’s existing mandate rather than to convert the ISA into a general climate regulator.