ITLOS delivers unanimous advisory opinion on obligations of UNCLOS Parties to confront climate change

ITLOS delivers unanimous advisory opinion on obligations of UNCLOS Parties to confront climate change

On 21 May 2024, the International Tribunal for the Law of the Sea (the “ITLOS”) delivered its advisory opinion on the obligations of State Parties to the UN Convention on the Law of the Sea (“UNCLOS” or the “Convention”) concerning climate change. The opinion addressed two interconnected questions: (a) the specific obligations of UNCLOS Parties to prevent, reduce and control pollution of the marine environment caused by greenhouse gas (“GHG”) emissions; and (b) the  specific obligations of UNCLOS Parties to protect and preserve the marine environment in relation to climate change impacts, including ocean warming, sea level rise, and ocean acidification.

On the first question, in focusing on the ocean as a natural carbon sink, the ITLOS concluded that GHG emissions constitute “pollution of the marine environment”, and thus trigger State obligations under UNCLOS. The ITLOS observed that Parties’ obligations with respect to pollution from GHG emissions are not discharged by participation in climate change instruments such as the UN Framework Convention on Climate Change and the Paris Agreement.  Rather, UNCLOS Parties are “required to take all necessary measures”, including individual actions as appropriate, to prevent, reduce and control marine pollution from GHG emissions, as well as endeavour to harmonise their policies in that regard. Such necessary measures must be balanced with other rights, including navigational rights, while various factors must be considered in an “objective assessment”. Among the factors to consider in an objective assessment, the ITLOS noted the importance of science, other international rules and standards relating to climate change, and the capabilities of the State concerned. Underscoring that science is a particularly relevant factor, the ITLOS attached significant weight to reports of the Intergovernmental Panel on Climate Change. In the absence of scientific certainty, the ITLOS underscored that the precautionary approach must be applied.

The ITLOS observed that the obligation to combat pollution under Article 194 of UNCLOS is a best-efforts obligation of conduct, subject to a “due diligence” standard. Due diligence, in turn, “requires a State to put in place a national system, including legislation, administrative procedures and an enforcement mechanism necessary to regulate the activities in question, and to exercise adequate vigilance to make such a system function efficiently, with a view to achieving the intended objective”. The ITLOS emphasised that due diligence “should not be understood as an obligation which depends largely on the discretion of a State or necessarily requires a lesser degree of effort to achieve the intended result”. Rather, the due diligence must be “determined objectively”, considering relevant factors and circumstances, while the obligation may be a demanding one. As regards pollution from GHG emissions, the ITLOS opined that the standard of due diligence must be stringent, given the high risks of serious and irreversible harm to the marine environment. In recognising the obligation of UNCLOS Parties to confront transboundary pollution from GHG emissions, the ITLOS acknowledged the inherent challenge in establishing causation.

The ITLOS also outlined the Parties’ obligation to legislate, implement and enforce rules in the context of GHG emissions. In particular, UNCLOS Parties must give due consideration, in good faith, to international norms under climate change instruments; States Parties must also cooperate in good faith, either directly or through competent international organisations. This obligation, per the ITLOS, must be assessed “by reference to the efforts made by States to formulate and elaborate international rules, standards and recommended practices and procedures”, and requires an “ongoing effort” to develop regulations in light of evolving scientific knowledge. In the context of the prevention, reduction, and control of pollution of the marine environment, the ITLOS highlighted the obligation of UNCLOS Parties to provide appropriate technical assistance to developing countries (particularly those vulnerable to the adverse effects of climate change), including when acting through other competent international organisations of which assisting States are members.

The ITLOS added that UNCLOS Parties must monitor the risks or effects of marine environment pollution, publish reports, and conduct environmental impact assessments (“EIAs”). A State’s discretion in deciding whether to conduct an EIA (a requirement of customary international law) was limited by the requirement to determine whether an activity under the State’s jurisdiction or control “may cause substantial pollution of or significant and harmful changes to the marine environment”. Such evaluation is an “objective determination based on facts and scientific knowledge” and needs to consider potential pollution and changes and consider the cumulative impact of activities. However, a State’s margin of discretion may be restricted by the precautionary approach.

On the second question, the ITLOS observed that the obligation under Article 192 of UNCLOS (to protect and preserve the marine environment) can be invoked to combat any form of environmental degradation, including the impacts of climate change (such as ocean warming, sea level rise, and ocean acidification). For the ITLOS, the term “preservation” included “restoration”, meaning that the obligation encompasses restoring degraded marine habitats and ecosystems. Also, UNCLOS Parties must take conservation measures, including adaptation and resilience-building, to protect and preserve the marine environment, as well as maintain living resources at risk from overexploitation within exclusive economic zones and the high-seas. That the obligation also requires that States ensure compliance by non-State actors under their jurisdiction or control.

Lastly, the ITLOS noted the increased implementation of “area-based management tools”, including marine protected areas (“MPAs”), within and beyond national jurisdiction. MPAs are supported in regional treaties and collaborative arrangements, including the recent UN Agreement on the conservation and sustainable use of marine biological diversity of areas beyond national jurisdiction. At the same time, the ITLOS noted that UNCLOS Parties may adopt more rigorous measures to protect and preserve the marine environment, so long as such measures were consistent with the Convention and other rules of international law.

The full text of the ITLOS’ advisory opinion is available here.

The respective declarations from Judges Jesus, Pawlak, Kulyk, Kittichaisaree and Infante Cassi are available here.

COSIS’ request for advisory opinion on 12 December 2022 is available here.