Key contentions at the Hearings on the ICJ Advisory Opinion on climate change
By Danilo B. Garrido Alves and Efstathios-Effraim Giannidakis
Published on 3 January 2025
Between 3 and 13 December, over 100 States and international organisations appeared before the International Court of Justice (some of which—such as Barbados, Sierra Leone, the Cook Islands, Micronesia, Nepal, the Dominican Republic, Samoa, and Uruguay—for the first time in history) to present their views on the two questions posed by the UN General Assembly, on the obligations of States in relation to climate change and the legal consequences for violations of those obligations. Although the majority of the participants seemed to agree that climate change poses an existential threat to humanity, there has been significant divergence on the positions regarding, inter alia, the applicable law, the existence of an obligation to prevent climate change or to repair for harm caused by it, questions of causation and attribution, the impact of historic emissions regarding state responsibility and the importance of best available science.
Due to space constraints, this blogpost focuses on only two of the central debates that took place during the ICJ hearings. Other key points of contention that should be highlighted include whether there are obligations and legal consequences in relation to historic emissions (and, if so, from which point in time those obligations arise); whether the principle of prevention of transboundary harm applies beyond bilateral or border relations between States, and can be global in scope; whether the framework of the law of State responsibility should be used to address the legal consequences for breached of primary climate obligations; and whether the right to a clean, healthy and sustainable environment is now part of customary international law (or, at least, whether it can be derived from rights enshrined in the human rights treaties). For the purposes of this blogpost, suffice it to say that the divide on those issues follow similar lines to the ones addressed below: high-emitting States seeking to limit their obligations to the maximum, and low-emitting States arguing for robust obligations and legal consequences arising from their breach.
Applicable law on the obligations of States relating to climate change
One of the key points of contention between States was on the scope of international law norms that were relevant to the proceedings, especially in relation to the obligations of States ‘to ensure the protection of the climate system and other parts of the environment’. As put by Samoa, the contention on applicable law concerned whether the UNFCCC, Paris Agreement and Kyoto Protocol (together, the ‘three climate treaties’) were either the only source of obligations (lex specialis argument) or the primary sources of obligations for States in relation to anthropogenic GHG emissions causing climate change. Alternatively, the question was whether other sources of international law were also applicable or just as important. With some exceptions, the idea that the three climate treaties were lex specialis or the primary source of obligations for States was mostly championed by high emitting and Global North States, while the position that other sources of law are also applicable was defended by most Global South States.
The United States, Saudi Arabia and China, among others, defended that the three climate treaties ‘should be considered the legal basis for regulation and lex specialis in the area of combating climate change’. They added that ‘to impose any obligations or consequences that go beyond or conflict with those contained in the specialized treaty régime on climate change would risk undermining the integrity of this régime and impair future progress in international efforts to protect the climate system’. The crux of this argument is that specialised rules prevail over general rules, and thus the three climate treaties should be the main or only source of obligations in relation to climate change. The Nordic countries supplemented this argument by stating that, as the latest instrument on climate change (lex posterior), the Paris Agreement should ‘take precedence’ over other norms of international law.
However, this line of argument is not persuasive, as articulated by most delegations of low emitting and developing countries. For example, Kenya called out ‘attempts by some Participants to smuggle the lex specialis argument through the back door, by arguing that customary law obligations of prevention do not apply or, if they do apply, their content must be determined exclusively by reference to the UNFCCC and the Paris Agreement’. States cannot conclude treaties implicitly to contract out of well-established customary norms, like the obligation to prevent transboundary harm. This is the case especially for treaties that do not create obligations that are incompatible with customary norms. Customary and treaty law apply simultaneously, as has been long clarified by the ICJ in Nicaragua, and should be interpreted in the most compatible way with each other, as required by the principle of systemic integration enshrined in Art. 31 (3)(c) VCLT. As such, the better interpretation is that, as put by Papua New Guinea, ‘the legal obligations governing climate change arise under the entire corpus of international law’, including—but not limited to—those mentioned in the chapeau of the questions posed by the General Assembly to the Court.
Causation between State conduct and climate harm
Another argument that was raised during the proceedings, primarily by States from the Global North, concerned the causal nexus required to attribute harm resulting from climate change to particular States. Australia invoked evidentiary hurdles and challenges regarding causation. It contended that the current regime does not allow injured States to claim reparation for harm suffered due to climate change and that, in any case, ‘challenges raised by causation are complex and cannot be resolved in the abstract, and for all possible cases, in these advisory proceedings’. Meanwhile, Nordic countries, in their joint oral submissions, cited lack of scientific agreement on attribution methodologies. The United States argued that impacted States may claim reparations as a result of specific events, such as hurricanes, only where they can establish a direct and certain link between internationally wrongful conduct and said events. The USA also argued that the IPCC’s findings would provide little guidance, as they relate to ‘the totality of anthropogenic greenhouse gas emissions’ and ‘do not draw any conclusions about a subset of internationally wrongful emissions and their effect on climate-related events’.
Other States attempted to rebut such arguments, highlighting that both international law and scientific scholarship provide useful guidance in establishing the causal nexus between States’ conduct and climate change. Côte d’Ivoire and Samoa, among others, have underlined that scientific evidence may demonstrate the causal link between emissions from certain states and climate change. Seychelles underlined the role of best available science, in particular the IPCC’s findings, in determining the measurable share of each high-emitting State for an injury that is ‘inherently divisible and attributable to each wrongdoer accordingly’. Brazil also mentioned that there is science-based methodology to enable States to quantify their national historical responsibility to global warming. Adding to these arguments, Costa Rica maintained that under the rules governing state responsibility—as they currently stand—both current and historic emissions are to be accounted for. Reflecting on the Court’s jurisprudence, Antigua and Barbuda affirmed that scientific uncertainty does not automatically preclude the existence of a duty to make reparation, and asked that the Court confirms its previous position that ‘the causal nexus required may vary depending on the primary rule violated and the nature and extent of the injury’. Belize stated that both the obligation in question and the context may point to different causal methodologies, while underlining that ‘the fact that a given harm has multiple causes does not mean that a State’s obligation to take measures to avert that harm is somehow disapplied or even attenuated’.
Conclusion
The two points of contention addressed in this blogpost serve as a rough proxy for the other contentious issues raised during the Hearings and on which side of the argument States fell. Indeed, rare were the occasions where high-emitting and low-emitting States agreed; and even when certain States from those groups seemed to agree on an issue, such as the obligation to cooperate, their positions again diverged upon closer analysis. Switzerland, for instance, addressed the importance of cooperation to address climate change, but did not address financial and technical assistance, which was a key part of this obligation for the Bahamas, Ecuador and Guatemala, nor debt relief, as submitted by developing States like Ghana and Sierra Leone.
Despite the great degree of divergence in the positions of Participants, the authors believe that the Opinion of the Court might still be robust and give clear guidance on obligations and legal consequences. This is so not only due to the quality of the arguments presented by low-emitting States (which, in our view, are more convincing than the ones by high-emitting States) and the unprecedented participation of Global South States in the proceedings, but also due to the commendable decision by ITLOS in the Advisory Opinion on the marine environment earlier this year. If the questions posed by four Judges to all Participants could be of any indication of the Court’s leaning, a progressive decision might just be the culmination of what started as a university project in the Pacific and is already a landmark for climate justice.