Two Weeks, Countless Voices: Explaining the ICJ’s Unprecedented Hearings on Climate Obligations

The International Court of Justice (ICJ) is set to hold historic hearings from December 2 to December 13, 2024, addressing an advisory opinion request on states' obligations to protect the climate system. This request lodged by the United Nations General Assembly (GA) marks a significant milestone in international climate law and for the ICJ itself. 

It is undeniable that climate change has caused significant warming, with global surface temperatures rising by 1.1°C above pre-industrial levels between 2011 and 2020. While the goal set in Article 2(1)(a) of the 2015 Paris Agreement is to hold the increase in the global average temperature to well below 2°C above pre-industrial levels and of pursuing efforts to limit the temperature increase to 1.5°C above pre-industrial levels, currently a trajectory towards a temperature above 2°C is predicted. This increase, as outlined in the 2023 IPCC Synthesis Report, is largely attributed to unsustainable energy practices, land use, consumption patterns, and lifestyle choices that vary across regions, countries, and individuals. In 2020, it was reported that the cumulative historical GHG emissions of just 23 developed countries accounted for approximately half of all global GHG emissions, with more than 150 countries emitting the other half. These emissions have not only intensified global warming but have also exacerbated inequalities, as historical and ongoing contributions to greenhouse gas emissions are unevenly distributed worldwide (See the 2023 IPCC Synthesis Report, A2). 

The upcoming hearings on climate obligations are notable not only for their subject matter but also for the unprecedented level of participation. With ninety-one written statements submitted and over 100 states and entities preparing oral statements, the level of participation in these hearings underscores the global importance of the issue. To put this in perspective: In 1995, the ICJ conducted proceedings for an advisory opinion on the Legality of the Threat or Use of Nuclear Weapons, during which 22 oral statements were made. More recently, in February 2024, the ICJ held hearings on the Legal Consequences of Israel's Policies and Practices in the Occupied Palestinian Territory, including East Jerusalem, which saw an unprecedented level of participation, with no fewer than 50 oral statements—more than in any previous ICJ proceeding. The advisory opinion on climate obligations has attracted over twice the number of participants from the February 2024 hearings, setting a new record for ICJ proceedings. 

This blog post aims to provide essential context for understanding how this request for an advisory opinion on obligation of states in respect of climate change came before the ICJ, the procedural aspects surrounding advisory opinions, some of the key questions presented to the Court, and what to expect during the hearings.

The Path to the Advisory Opinion Request, and the Question put to the Court:

It is not the first time that the initiative to request an advisory opinion on climate change from the ICJ has come up. As Gerrard notes, a similar initiative was already initiated by Palau and the Marshall Islands in 2012, but failed to receive the necessary majority in the UN General Assembly (UNGA) mainly due to an opposition by the United States. However in 2019, 27 law students from 8 different small pacific islands developed the idea in their environmental law class to bring climate change, one of the world’s biggest problems, to the world’s highest court. What started with this small group of pacific island students emerged further into a global youth movement, the World’s Youth for Climate Justice. Indeed, the idea of an ICJ Climate Change advisory opinion received more and more support not only by Vanuatu’s government, but also by 132 other states sponsoring the UNGA request. 

Vanuatu’s prime minister introduced the resolution with the following words: 

It is the firm belief of the core group that we must use all the tools at our disposal to address the climate crisis and its threats to human, national and international security (…) Together, we will send a loud and clear message, not only around the world, but far into the future, that on this very day, the peoples of the United Nations, acting through their Governments, decided to set aside differences and work together to tackle the defining challenge of our times, climate change (…)  

And, indeed, on March 29, 2023, the GA adopted Resolution 77/276 by consensus, formally seeking an advisory opinion from the ICJ on climate obligations. The adoption of this decision was celebrated as ‘historic’ by numerous delegations, world mediaand non-governmental organisations.

The GA request reads as follows:

Having particular regard to the Charter of the United Nations, the International Covenant on Civil and Political Rights, the International Covenant on Economic, Social and Cultural Rights, the United Nations Framework Convention on Climate Change, the Paris Agreement, the United Nations Convention on the Law of the Sea, the duty of due diligence, the rights recognized in the Universal Declaration of Human Rights, the principle of prevention of significant harm to the environment and the duty to protect and preserve the marine environment,

(a) What are the obligations of States under international law to ensure the protection of the climate system and other parts of the environment from anthropogenic emissions of greenhouse gases for States and for present and future generations;

(b) What are the legal consequences under these obligations for States where they, by their acts and omissions, have caused significant harm to the climate system and other parts of the environment, with respect to:

(i) States, including, in particular, small island developing States, which due to their geographical circumstances and level of development, are injured or specially affected by or are particularly vulnerable to the adverse effects of climate change?

(ii) Peoples and individuals of the present and future generations affected by the adverse effects of climate change? 

Broadly, the GA request aims to clarify: Firstly, what are the obligations of states under international law to protect the climate system and environment from human-caused greenhouse gas emissions? And, secondly, what are the legal consequences for states whose actions or omissions have caused significant harm to the climate system?

These overarching questions give rise to a number of significant legal and practical issues, many of which will be addressed by states during the ICJ hearings. One key concern is the existential threat faced by small island developing states, whose sovereignty and survival are jeopardized by rising sea levels and warming seas. For these nations, the implications of climate change go beyond environmental harm to question the very continuity of their statehood.

Another important issue stems from the GA request's call for the Court to consider future generations. This raises complex questions about the extent to which states have legal obligations toward unborn entities and how such considerations might influence the interpretation of existing obligations for present actors.

The principle of ‘common but differentiated responsibilities and respective capabilities’ will also likely feature prominently in the hearings. This principle acknowledges the greater responsibility of developed countries, given their historical contributions to greenhouse gas emissions, to mitigate emissions and provide financial or technological support to developing countries. The GA request reflects this dual focus on mitigation and adaptation, emphasizing the need to prevent further harm and address the impacts of climate change. Low-income countries, despite their minimal contributions, require substantial financial support to implement effective adaptation strategies.

It is important to note that the GA request references a wide range of potential legal frameworks to guide the Court in determining states’ obligations. However, certain states argue that the climate change treaties should be the primary, if not the sole, source of legal obligations. This issue will be explored in greater detail later in this blog post.

The ICJ’s Advisory Jurisdiction

The ICJ’s authority to issue advisory opinions is derived from Article 65, paragraph 1 of its Statute, allowing it to address questions referred by authorized UN organs. Article 96 of the UN Charter provides the General Assembly and the Security Council with the right to request advisory opinions on any legal matter. This advisory function enables the ICJ to clarify principles of international law, even in the absence of a contentious dispute, and to actively support the work of the United Nations.

In its 2019 advisory opinion on the Legal Consequences of the Separation of the Chagos Archipelago from Mauritius, the Court emphasized that responding to advisory requests constitutes ‘participation in the activities of the [United Nations] Organization, and, in principle, should not be refused’ (para. 65).

The questions posed in the GA request on climate obligations have been noted for their broad scope, addressing the complex and universally impactful nature of climate change. However, the ICJ has a strong tradition of engaging with broad or intricate questions. In its Western Sahara advisory opinion, the Court clarified that ‘questions framed in terms of law and rais[ing] problems of international law…are by their very nature susceptible of a reply based on law’ (para. 15). This perspective highlights the ICJ’s readiness to address complex issues of international law, provided they are legal in nature. 

The fact that the Court has jurisdiction does not mean, however, that it is obliged to exercise it. Indeed, the Court has discretionary power to decline to give an advisory opinion. Still, in the 2010 advisory opinion on Kosovo's Declaration of Independence, the Court highlighted that any refusal must take into account its role as both a principal UN organ and a judicial body (para. 30), which accordingly requires ‘compelling reasons’ to justify a refusal to address requests for advisory opinions. This standard underscores that the ICJ would only decline a request if providing an opinion would compromise its essential judicial character or undermine its institutional integrity.

The Broad Scope of the Climate Change Request

In considering the advisory opinion request on climate obligations, the ICJ faces a question not only of jurisdiction but also of how to navigate the extensive range of legal sources referenced in the preamble. The GA request is structured in a way that emphasizes multiple potential sources of law, which could guide the Court in determining states’ obligations. A similar issue of broad legal interpretation arose in the 1996 GA request for an advisory opinion on the Legality of the Threat or Use of Nuclear Weapons. In that case, the Court observed that it needed to ‘decide, after consideration of the great corpus of international law norms available to it, what might be the relevant applicable law’ (para. 23). 

The preamble of the current climate change request mentions an array of legal sources, including the Charter of the United Nations, the International Covenant on Civil and Political Rights (ICCPR), the International Covenant on Economic, Social and Cultural Rights (ICESCR), the United Nations Framework Convention on Climate Change (UNFCCC), the Paris Agreement, the United Nations Convention on the Law of the Sea (UNCLOS), and general principles such as due diligence. The central question for the ICJ, therefore, is to determine which of these regimes and principles create binding obligations for states to protect the climate system and environment from anthropogenic greenhouse gas emissions, and what the content of those obligations might be.

A key debate centers on whether the Court should apply the interpretative principle lex specialis derogat legi generali (specific law overrides general law) and the doctrine of self-contained regimes, thereby focusing primarily on climate change-specific treaties, or whether it should also consider a broader body of international law. Some states argue that the primary sources of obligations are the specialized treaties within the UN climate change framework, specifically the UNFCCC, the Kyoto Protocol and its Doha Amendment, and the Paris Agreement—collectively referred to as the ‘Climate Change Treaties.’ These treaties form the agreed framework by which states have committed to addressing harm to the climate system caused by greenhouse gas emissions and to mitigating future risks.

The main instrument in the Climate Change Treaties, and likely the one that will be most discussed during the ICJ hearings, is the 2015 Paris Agreement. This agreement is the central source of obligations for its state parties with regard to the mitigation of climate change, especially when observing the lex specialis principle. The overarching objective of the Agreement is, as mentioned above, to hold ‘the increase in the global average temperature to well below 2 degree Celsius above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5 degrees Celsius […]’ (the Paris Agreement, Article 2(a)). This goal is collective, creating a global commitment to limit the temperature increase, without creating any specific, individual obligation for State parties (Ghaleigh, 2021). This temperature goal is operationalized to an extent by Article 4(1), which envisions a global peaking of greenhouse gas emissions as soon as possible, followed by rapid reductions thereafter to achieve a balance in the “second half of this century”. However, the temperature goal, as well as the further elaboration in Article 4, do not lay out any specific action based commitments, and represent an obligation of result. It does not lay out any specific time frame, or a methodology for actually achieving the goal of stopping net-greenhouse gas emissions. 

In order to find more specific, actionable obligations in the Agreement, one must turn to the system of Nationally Determined Contributions (NDCs) laid out in Article 4(2-19). These NDCs are action plans in which states describe and develop their policies to contribute to achieving the objective of article 2, the temperature goal. They are the crux of the mitigation obligations of the Paris Agreement, as they are the primary mechanism whereby states’ develop their contributions. They are plans where states lay out their self-developed emission reduction commitments; in other words, where states lay out how they will develop their economy to emit less greenhouse gasses. The NDCs must be submitted every 5 years, beginning in 2020 (Article 4(9)). One central element designed to further dynamism is the ratchet mechanism. This mechanism is an obligation which pushes State parties to ensure that their NDCs become more ambitious over time, representing deeper cuts to emissions every 5 years. 

What can be said to be lacking from the Paris Agreement, however, is a substantive obligation to actually protect the climate system. There is an aspiration, to keep the global average temperature increase to well below 2 degrees Celsius and ideally 1.5, as well as procedural obligations to submit climate action plans in the form of NDCs, but the treaty remains silent on what happens if or when the climate system collapses. Furthermore, although there is a compliance mechanism in the agreement, espoused in Article 15, it is largely facilitative and not punitive, such as in mechanisms in the Agreements’ predecessor, the Kyoto Protocol. This protocol was the primary source of obligations for State parties in the pre-Paris era, containing so called top-down emission reduction commitments at the international level, as well as a compliance mechanism which had a facilitative and an enforcement branch. This enforcement branch had the responsibility of determining consequences for Parties’ breaches of their commitments, and there was even the possibility of imposing sanctions upon parties in such a case. The drafters of the Paris Agreement took a very different route, instead focusing on facilitation and participation of as many states as possible in the regime. 

Besides the Climate Change Treaties, UNCLOS is often referenced for marine environmental protection. However, some view it as not establishing distinct obligations beyond those found in the climate change framework. In fact, it is likely that during the ICJ hearings, some states will argue that the Court should address only the obligations under the Climate Change Treaties — and accordingly , with respect to the second question, the lack of legal consequences under the Law of State Responsibility for not mitigating climate change. In contrast, other states — particularly those from the Global South—argue that not only are the climate change treaties and distinct treaties such as the UNCLOS, ICCPR and ICESCR relevant, but most importantly general rules of international law also impose obligations to protect the climate system from human-caused emissions. These include the principle of prevention, the no-harm principle, and the duty to cooperate. Although these principles and obligations are incorporated into various multilateral environmental agreements, they also stand independently and may impose enforceable legal consequences if states fail to observe them.

It is important to note that the Court will be able to draw on the case law of other international bodies. For instance, in May 2024, the International Tribunal for the Law of the Sea (ITLOS) rendered its own advisory opinion, providing strong views on States’ obligations under the UNCLOS to prevent, reduce and control GHG emissions. It highlighted that in addition to the state obligation of the Paris agreement, UNCLOS stipulates distinct obligations for states in relation to the law of the sea and the Paris agreement is not lex specialis in this regard. Other important findings were made in relation to the impact of science on the development of law and the content and scope of due diligence obligations (see here for a detailed analysis).

Human rights bodies have also addressed issues relevant to the GA’s questions. In Teitiota v. New Zealand (2020), the UN Human Rights Committee acknowledged that climate change can trigger obligations under the International Covenant on Civil and Political Rights, particularly for individuals in small island states facing severe life-threatening conditions. The Committee emphasized that without robust efforts, the effects of climate change could violate individuals' rights to life and freedom from inhuman treatment, thereby invoking non-refoulement obligations. It further noted that the risk of an entire country becoming uninhabitable due to submersion may render living conditions incompatible with the right to life with dignity, even before total submersion occurs. 

A key issue regarding the relevance of human rights to states' obligations on climate change and its global effects is the question of extraterritorial jurisdiction. In this respect, the Committee on the Rights of the Child (CRC) held in Sacchi et al. v. Argentina, Brazil, France, Germany and Turkey that states with effective control over carbon emissions can be held responsible for their transboundary effects. Citing the Inter-American Court of Human Rights’ (IACtHR) advisory opinion on Environment and Human Rights, the CRC stated that when emissions cause harm across borders, children affected fall under the jurisdiction of the emitting state if a causal link exists and the state controls the emission sources. However, other states, in particular the European States, may instead prefer to refer the European Court of Human Rights' decision in Agostinho et al. v. Portugal and 32 Other States, which rejected these approaches to extraterritorial jurisdiction, finding they could not be grounded in the European Convention on Human Rights. According to this view, a state's obligations concerning climate change arise only in relation to individuals within its territory. 

While it is widely accepted that climate change affects human rights, the ICJ hearings are likely to reveal a key divide: some states will argue there are no international human rights obligations to mitigate GHG emissions, while others will focus on states' obligations under international human rights law in their analysis of the Court's questions. It will be interesting to see where the majority lies and whether geopolitical factors, including geographical, political, and economic considerations, help explain these differing strategies.

Conclusion

In this blog post we have highlighted some of the issues that will be debated during the ICJ hearings on states' obligations concerning climate change. Many more legal questions are on the agenda, including the legal consequences of states' failure to fulfill their obligations and how harm caused by climate change can be attributed to certain states. Interestingly, another advisory opinion request is pending before the IACtHR, seeking to clarify state obligations concerning the climate emergency within the framework of international human rights law. The IACtHR is expected to issue its opinion in early 2025, likely before the ICJ, and may be aiming to have a persuasive impact on the ICJ's deliberations—much like ITLOS in its own climate-related proceedings. As mentioned above, the hearings in The Hague will span two full weeks—an unprecedented duration for the Court. Never before has the ICJ - nor any other courts - been approached by so many states and entities. This reflects the urgency of climate change as a global legal and ethical issue.