On 17 January 2026, the Agreement on the Conservation and Sustainable Use of Marine Biological Diversity of Areas Beyond National Jurisdiction commonly known as the BBNJ Agreement—entered into force. The Agreement’s overarching objective is to ensure the conservation and sustainable use of marine biological diversity in areas beyond national jurisdiction (ABNJ), encompassing both the High Seas and the Area, as defined under UNCLOS. It does so by introducing novel approaches to ocean governance, including explicit recognition of the relevance of traditional knowledge of Indigenous Peoples and local communities, marking a notable evolution in international environmental law.

  The Agreement represents a major milestone in the governance of the global ocean commons. However, its effective implementation will depend heavily on cooperation among States Parties as well as with existing global, regional, subregional and sectoral bodies—such as Regional Fisheries Management Organizations (RFMOs)—whose mandates intersect with activities in ABNJ.

  This blogpost focuses on one of the Agreement’s most consequential innovations: the Environmental Impact Assessment (EIA) regime. It highlights the structure of the EIA framework and identifies key interpretative and operational challenges that may arise from the text of the BBNJ Agreement. 

1.       Environmental Impact Assessments

Environmental Impact Assessments (EIAs) constitute the operational nucleus of the BBNJ Agreement, operationalizing the provisions of UNCLOS on environmental impact assessment for areas beyond national jurisdiction [Art. 27(a)]. While UNCLOS obliges States to assess activities that may cause, in the words now incorporated into Article 28 of the BBNJ Agreement, “substantial pollution of or significant and harmful changes to the marine environment,” it nevertheless lacks a uniform procedural framework to guide how such assessments must be conducted. The BBNJ Agreement addresses this lacuna by introducing a codified, sequential process – screening, scoping, impact assessment, prevention and mitigation, monitoring, and reporting [Arts. 27–38], applicable both to activities conducted in areas beyond national jurisdiction [Art. 28(1)] and to those within national jurisdiction where a Party determines that the activity “may cause substantial pollution of or significant and harmful changes to the marine environment in areas beyond national jurisdiction” [Art. 28(2)]. Such proceduralization effectively elevates what was formerly a latent treaty obligation into a fully operationalized compliance architecture capable of guiding and constraining State conduct.

  The Agreement adopts a tiered threshold architecture that significantly expands the ambit of regulatory oversight. The trigger for initial review is deliberately precautionary: a Party with jurisdiction or control over a planned activity must conduct a screening whenever the activity ‘may have more than a minor or transitory effect on the marine environment, or the effects of the activity are unknown or poorly understood [Art. 30(1)]. This deliberately low threshold functions as a cautionary filter, capturing activities that might otherwise evade regulatory scrutiny. During screening, should the Party determine that it ‘has reasonable grounds for believing that the planned activity may cause substantial pollution of or significant and harmful changes to the marine environment,’ a full environmental impact assessment becomes mandatory [Art. 30(1)(b)]. Critically, even where a full EIA is not deemed necessary, the Party must make its determination publicly available and publish relevant information, including the description and initial analysis required under Article 30(1)(a), through the ‘Clearing-House Mechanism’ [Art. 31(1)(a)(i)]. Other Parties may register their views on the potential impacts with the determining Party and the Scientific and Technical Body within forty days of publication [Art. 31(1)(a)(ii)], and the Scientific and Technical Body may consider and evaluate the potential impacts and make recommendations to the determining Party [Art. 31(1)(a)(iv)–(v)].

  Where a full EIA is triggered, the subsequent scoping phase delineates the assessment’s substantive boundaries. This stage ensures that ‘key environmental and any associated impacts, such as economic, social, cultural and human health impacts, including potential cumulative impacts and impacts in areas within national jurisdiction, as well as alternatives to the planned activity, if any,’ are identified, with the scope ‘defined by using the best available science and scientific information and, where available, relevant traditional knowledge of Indigenous Peoples and local communities’ [Art. 31(1)(b)]. Crucially, the Agreement mandates the assessment of cumulative impacts and alternatives during both scoping [Art. 31(1)(b)] and the subsequent impact assessment and evaluation phase [Art. 31(1)(c)]. This requirement compels decision-makers to transcend project-specific myopia and systematically consider the aggregate stress placed on marine ecosystems over time, a significant advancement over traditional EIA practice.

  Transparency and public participation constitute the regime’s primary compliance drivers. Results must be compiled into a comprehensive EIA report containing, at a minimum, the elements specified in Article 33(2), including a description of the planned activity, baseline assessment, potential impacts, prevention and mitigation measures, uncertainties and gaps in knowledge, information on public consultation, consideration of alternatives, follow-up actions including an environmental management plan, and a non-technical summary, and published through the ‘Clearing-House Mechanism’ [Arts. 33(2), 33(5)]. The Agreement imposes robust consultation obligations: Parties must ensure ‘timely public notification of a planned activity, including by publication through the ‘Clearing-House Mechanism’ and through the secretariat, and planned and effective time-bound opportunities’ for participation by all States—’in particular adjacent coastal States and any other States adjacent to the activity when they are potentially most affected States’—and stakeholders throughout the EIA process, ‘including when identifying the scope of an environmental impact assessment under article 31, paragraph 1 (b), and when a draft environmental impact assessment report has been prepared under article 33, before a decision is made as to whether to authorize the activity’ [Art. 32(1)]. Parties are further obligated to consider and respond to or address substantive comments received during consultation, giving ‘particular regard to comments concerning potential impacts in areas within national jurisdiction’ and providing ‘written responses, as appropriate, specifically addressing such comments, including regarding any additional measures meant to address those potential impacts,’ with both comments and responses made public [Art. 32(5)].

  The Agreement also addresses the notoriously fragmented landscape of ocean governance through its carefully calibrated relationship with existing relevant legal instruments and frameworks and relevant global, regional, subregional and sectoral bodies. Under Article 29(4), it is not necessary to conduct a screening or an environmental impact assessment of a planned activity in areas beyond national jurisdiction where the Party with jurisdiction or control determines that: (a) the potential impacts have been assessed in accordance with the requirements of other relevant legal instruments or frameworks or by relevant global, regional, subregional or sectoral bodies; and (b) either the assessment already undertaken is ‘equivalent to the one required under this Part’ and its results are taken into account [Art. 29(4)(b)(i)], or the resulting regulations or standards ‘were designed to prevent, mitigate or manage potential impacts below the threshold for environmental impact assessments under this Part, and they have been complied with’ [Art. 29(4)(b)(ii)]. This provision seeks to balance regulatory coherence with administrative efficiency, while ensuring that the Clearing-House Mechanism becomes a centralized repository for all high seas impact data—the Party concerned must still ensure that the environmental impact assessment report is published through the ‘Clearing-House Mechanism’ [Art. 29(5)], and unless the activity is subject to monitoring and review under the relevant instrument, framework or body, the Party must monitor the activity and ensure monitoring and review reports are published through the ‘Clearing-House Mechanism’ [Art. 29(6)].

  Decision-making authority ultimately remains with the flag or sponsoring State, reflecting a carefully negotiated compromise between international oversight and sovereign prerogative. The Agreement does not grant the Conference of the Parties veto power over individual projects; rather, the ‘Party under whose jurisdiction or control a planned activity falls shall be responsible for determining if it may proceed’ [Art. 34(1)]. However, this authority is circumscribed: a decision to authorize the planned activity ‘shall only be made when, taking into account mitigation or management measures, the Party has determined that it has made all reasonable efforts to ensure that the activity can be conducted in a manner consistent with the prevention of significant adverse impacts on the marine environment’ [Art. 34(2)]. While the Scientific and Technical Body may provide comments on draft EIA reports [Art. 33(4)] and may notify the authorizing Party and make recommendations where it considers that an authorized activity may have significant adverse impacts not foreseen in the EIA or arising from a breach of approval conditions [Arts. 37(3)–(4)], it lacks binding enforcement power—the authorizing Party is only obligated to ‘give consideration to’ such notifications and recommendations [Art. 37(4)(e)]. This ‘managerial’ approach relies on transparency, iterative dialogue, and peer pressure rather than supranational adjudication—a design choice that will inevitably test the limits of good faith compliance.

   Notwithstanding these advances, significant implementation challenges persist. The terms ‘minor or transitory’ [Art. 30(1)] and ‘equivalent’ [Art. 29(4)(b)(i)] remain undefined in the treaty text, leaving considerable room for divergent interpretation and raising the spectre of inconsistent application or strategic ‘forum shopping’ whereby Parties might route activities through less rigorous sectural bodies to circumvent BBNJ scrutiny. The Scientific and Technical Body is tasked with developing standards or guidelines on, inter alia, ‘the determination of whether the thresholds for the conduct of a screening or an environmental impact assessment under article 30 have been met or exceeded’ [Art. 38(1)(a)], but until such guidance is adopted by the Conference of the Parties, interpretive discretion will remain with individual Parties. Furthermore, the regime’s reliance on self-assessment creates inherent conflicts of interest, particularly where commercial sensitivities collide with transparency obligations—though the Agreement provides that ‘Parties shall not be required to disclose confidential or proprietary information’ but ‘the fact that confidential or proprietary information has been redacted shall be indicated in public documents’ [Art. 32(7)].

  Finally, the administrative burden of this procedural regime places disproportionate weight on developing States, making the Agreement’s capacity-building and technology transfer provisions under Part V—including the objective to ‘build and strengthen the capacity of Parties, particularly developing States Parties […] to prepare, conduct and evaluate environmental impact assessments and strategic environmental assessments’ [Art. 27(f)] not merely complementary but essential prerequisites for equitable and effective implementation.

   In sum, the BBNJ Agreement represents a paradigm shift in high seas environmental governance. By establishing clear procedural steps [Art. 31], a precautionary screening threshold [Art. 30], and a centralized transparency mechanism through the ‘Clearing-House Mechanism’—which serves as ‘a centralized platform to enable Parties to access, provide and disseminate information’ including on environmental impact assessments [Art. 51(3)(a)(iii)]—the treaty integrates scientific rigour with legal accountability in a manner unprecedented for areas beyond national jurisdiction. However, its ultimate effectiveness will hinge upon the good faith implementation by Parties [Art. 63], the rigorous and timely development of standards and guidelines by the Scientific and Technical Body [Art. 38]. Only through such concerted effort can EIAs fulfil their intended function as the procedural backbone of a sustainable management regime for the global ocean commons.