By Phoebe Okowa, Professor of Public International Law, Queen Mary University of London, and member of the UN International Law Commission, and Sean O’Reilly, Barrister, Plowman Chambers Hong Kong
The much anticipated hearings in the advisory opinion on States’ obligations with respect to climate change concluded last December, and the International Court of Justice (ICJ) is expected to give its judgment sometime this year. Regardless of what one expects the ultimate outcome to be, it is without doubt that the advisory proceedings have captured the attention of the international community.
This was made especially clear by the fact that over 90 States and international organizations had filed written submissions to the Court. Despite the diverse participation, there was a surprising degree of unity regarding the applicable legal rules and how they were to apply in the context of climate change. However, there were still numerous areas of substantive disagreement which saw rich debate among participants.
These problem areas mirrored the divisions between States frequently seen at annual UN climate change conferences, with the majority of industrialized developed States adopting an interpretation of the law that would effectively shield them from responsibility for historical greenhouse gas (GHG) emissions. For example, in the arguments put forward by the UK, not only was the Paris Agreement on climate change a complete answer to the questions put to the Court (albeit not as a lex specialis), but that the customary duty of prevention did not apply to the subject matter of climate change at all.
The position of developed States, therefore, was to downgrade the significance of customary international law and entirely evade the questions of compensation for loss and damage and historical responsibility. This was opposed by developing States who placed the focus squarely on the problem of historical responsibility, given that many developing States had little to no agency during the Industrial Revolution and would be prejudiced by what was, effectively, rigid adherence to the principle of inter-temporal law.
What compounded these divisions of politics and policy was making sense of the multiplicity of legal rules that could impose obligations on States with respect to their GHG emissions. This was further exacerbated by the breadth of the legal questions put to the Court, which asked it to consider obligations from across the entire corpus of international law, with particular regard to the UN Charter, the International Covenant on Civil and Political Rights (ICCPR), the International Covenant on Economic, Social and Cultural Rights (ICESCR), the UN Convention on Law of the Sea (UNCLOS), the Universal Declaration of Human Rights (UDHR), and the UNFCCC and Paris Agreement, as well as principles of international environmental law such as the duty of due diligence and duty to prevent significant transboundary harm. Yet the breadth of the questions put by the UN General Assembly (UNGA) did not prevent industrialized States from cherry picking legal sources and focusing only on putting forward anodyne interpretations of the UNFCCC and Paris Agreement.
This “systemic” challenge in concretizing what may be called “international climate change law,” therefore, has two dimensions, with the approach to each of these two dimensions strongly influenced by the political factors mentioned above. The first concern is establishing the linkage between customary international law rules, as well as human rights law, with the UNFCCC and Paris Agreement – what can be termed the “UN climate change regime”. The second is then ensuring internal consistency within the UN climate change regime itself. Below we share some observations on both of these dimensions and how they were explored across the written submissions by States.
The first challenge was the extent to which customary international law and human rights law informed treaty obligations within the UN climate regime. The answer put forward by industrialized States, was that the UN climate regime constituted lex specialis, such that other rules of international law were excluded. On the other hand, the majority of States relied on the principle of systemic integration and argued that those legal rules could inform the interpretation of provisions in the UN climate regime.
The lex specialis argument was problematic, however, as there were no specific provisions in the existing instruments to support the thesis that these obligations were intended to apply to the exclusion of others nor any clear intention, to displace the application of other international legal rules, such as customary international law. The lex specialis thesis was also at odds with the rules on treaty interpretation in the Vienna Convention on the Law of Treaties, which in Article 31(3)(c) provides that treaties have to be interpreted within and in light of other applicable rules of general international law. As it happens, the proponents of the Paris Agreement as lex specialis were unable to present any convincing evidence that its normative regime was intended to apply to exclusion of all others.
The next question was how systemic integration was to function in the context of the UN climate regime, and what its precise impact on the broader UNFCCC treaty framework would be. The implications of this are wider than they appear given the breadth of the UNFCCC and Paris Agreement’s scope, including not just the reporting, monitoring, and reduction of GHG emissions, but also finance and investment to developing States along with technology transfer.
Accordingly, applying systemic integration could support progressive interpretations of their provisions on climate finance, adaptation assistance, as well as the core GHG mitigation obligations. One important implication was the impact of customary international law, particularly the duty to undertake due diligence, on the fulfilment of the Paris Agreement’s temperature targets of 1.5°C and 2°C.
The received wisdom was that the temperature targets are simply hortatory goals with little or no legal effect, and there were States who stressed that view before the Court. However, if the UN climate regime’s provisions have to be read in light of the duty of due diligence, which takes into account the current scientific consensus that warming must be limited to 1.5°C to avert a climate catastrophe, then States parties to the UN climate regime are under even stronger obligations to take measures to reduce their GHG emissions in line with 1.5°C pathways. For the majority of States that would require a rapid reduction towards net-zero emissions by the middle of the century.
Within the UN climate regime itself, there was also considerable argument as to the meaning and scope of certain key terms and concepts, which on the face of it appeared broad and open-ended. Chief among them were the obligations under Articles 2 and 4 of the Paris Agreement, concerning progress towards the temperature targets and the publication of nationally determined contributions (NDCs). Were these obligations hortatory or did they require the adoption of certain concrete steps towards their realization? To what extent and in what ways did these also entail some degree of international oversight over what on the face of it appeared to be unilaterally determined obligations? These arguments turned heavily on the text of those two provisions, as well as the systemic integration points mentioned above.
Another important zone of ambiguity was the meaning of common but differentiated responsibilities (CBDR) both as a concept within international environmental law and as recognized in the Paris Agreement (whose broad formulation explicitly includes a recognition of States’ respective capabilities and national circumstances). CBDR was a crucial argument for developing States, who stressed that the UN climate regime would not be able to work without a differentiated approach. Yet at the same time, CBDR would work against the UN climate regime’s object and purpose if it became a cover for downgrading a State’s highest possible ambition.
One way around this dilemma could be to rely again on systemic integration and draw from another successful climate change treaty, the Montreal Protocol. One interesting aspect of its implementation of the CBDR principle was that developing States were not exempt from obligations to phase out ozone-depleting substances, but were given additional time to comply. If this approach to CBDR were adopted for the Paris Agreement, this would mean that the temperature targets could not be ignored by reason of lack of capacity, though developing States could benefit from longer timelines in reaching net zero.
There was considerable support for the argument especially among the many participants from the Global South, that CBDR concretized obligations of technology transfer to developing countries as a logical step in the realization of mitigation and adaptation measures. Many also went as far as advocating for debt relief as a practical measure for giving effect to the question of differentiation, allowing States that are frequently forced to make the choice between mitigation and servicing of debts to prioritize mitigation and adaptation measures.
The Court’s approach to its advisory opinion, as well as the particular areas it may choose to address or expand upon, remain to be seen. It speaks volumes that legal teams from over 90 participants still could not cover, let alone do justice to, all aspects of international law that concern the problem of climate change. Even so, systemic integration was at the forefront of many of the arguments and, it is hoped, may become a tool for the Court to strengthen and enhance the international law of climate change.
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This Guest Article is part of a project that seeks to raise awareness and build momentum and knowledge around the ICJ advisory opinion on obligations of States in respect of climate change and to promote a better understanding of the implications of the advisory opinion among sustainable development decision makers.
