Specific Obligations for Climate Change and Ocean Acidification Mitigation

Can the new advisory opinion interpreting the United Nations Convention on the Law of the Sea (UNCLOS) move us beyond the lethargy of unmet climate change policy needs? The International Tribunal for the Law of the Sea (the Tribunal, ITLOS) established the gravity of this question by stating that “climate change represents an existential threat and raises human rights concerns” (para. 66). The advisory opinion identified a number of specific State climate change obligations under UNCLOS in response to the request of the Commission of Small Island States (COSIS).

The Tribunal acted both boldly and conservatively by interpreting UNCLOS as an independent source of international legally binding obligations to address climate change and ocean acidification. When States become parties to UNCLOS, they agree to protect and preserve the marine environment, and they also make the more specific commitment to prevent, reduce, and control pollution of the marine environment. By accepting the COSIS request, ITLOS boldly advanced the international law of climate change to take full account of its harmful impacts on the marine environment.

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ITLOS further found that, while global and regional cooperation on climate change are necessary, it is not enough to simply “participat[e] in the global efforts to address the problems of climate change. States are required to take all necessary measures, including individual actions as appropriate” (paras 202, 294-321). It stated that “articles 213 and 222 of the Convention should be interpreted as imposing an obligation to adopt laws and regulations and to take measures necessary to implement, among others, rules and standards set out in climate change treaties and other relevant instruments” (para. 286). States with capacity must provide technical assistance to others (paras 322-339).

Under UNCLOS and customary international law, all States have duties to undertake environmental assessment, to monitor their activities, and to report the results. The ITLOS advisory opinion noted that this supports States in complying with their obligations under articles 192 and 194 of UNCLOS, and “is an essential part of a comprehensive environmental management system” (para. 353). It says that the duty applies to land-based activities as well as those at sea (para. 360). ITLOS also provided more specificity about the contents of environmental assessments than has been the case in the past, addressing points of particular relevance for climate change and ocean acidification, such as analysis of cumulative impacts and socio-economic impacts (paras 340-367). It notes that the Agreement on Biodiversity Beyond National Jurisdiction contains detailed provisions on environmental impact assessment procedures, including monitoring (para. 366).

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Standard for Performance of Specific Obligations

The advisory opinion concluded that the performance standard for taking all measures necessary to mitigate GHG emissions is due diligence, following its prior decisions in the Area Advisory Opinion and the IUU Fishing Advisory Opinion (paras 233, 234). The Tribunal observed that some participants identified certain obligations as requiring “States to adopt all measures necessary to ensure that certain events will not occur”, unlike the due diligence obligations analyzed in the Area Advisory Opinion (para. 255).

Some submissions described due diligence as merely requiring that a State take measures toward a particular outcome; others rejected a sharp distinction between obligations of conduct and obligations of result in this context. Judge Jesus, in his Declaration, found that while article 194, paragraph 2 “is an obligation that requires measures of due diligence, this obligation also imposes the achievement of results,” based on its description of the result to be obtained; however he would not apply paragraph 2 to anthropogenic GHGs (Jesus, paras 12, 16).

The Tribunal stated that article 194, paragraph 2, and other obligations “are formulated in such a way as to prescribe not only the required conduct of States but also the intended objective or result of such conduct”. (para. 238, emphasis added) It concluded, nonetheless, that articles 192 and 194 impose obligations of conduct (paras 441(c), (d)). However,  it said that due diligence is variable and subject to the following factors that make it a demanding standard:

• Article 192 requires “measures as far-reaching and efficacious as possible to prevent or reduce the deleterious effects of climate change and ocean acidification on the marine environment. The standard of due diligence under article 192 is … stringent given the high risks of serious and irreversible harm to the marine environment” (para. 399).

Cymie Payne, Verfassungsblog, 4 June 2024. Article.

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