Foreign Relations & International Law

Climate Change Advisory Opinion Requests: Risk and Reward

Melissa Stewart
Friday, March 24, 2023, 11:47 AM

States facing an existential threat from climate change ask international tribunals to weigh in on the obligations of states before it is too late.

International Court of Justice in the Hague. (United Nations Photo,; CC BY-NC-ND 2.0,

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On March 29, the U.N. General Assembly will consider a draft resolution on a “Request for an advisory opinion of the International Court of Justice (ICJ) on the obligations of States in respect of climate change.” The Republic of Vanuatu, along with a “Core Group” of states, has been spearheading the effort to bring the resolution to fruition over the past several years. The draft resolution has 105 co-sponsors (more than half the U.N. member states) and is all but guaranteed to pass. 

Advisory opinions are not legally binding, including on the parties that request them. But they are “authoritative statements of law” with “legal effect” that influence state behavior in consequential areas such as when states believe they have the authority to use nuclear weapons. This particular advisory opinion has enormous potential to influence how states view their obligations under international law and, as phrased in the draft resolution, the potential “consequences” if they “have caused significant harm to the climate system.” 

The potential ICJ advisory opinion is proceeding in parallel with two other advisory opinion efforts in international fora—one at the Inter-American Court of Human Rights and the other at the International Tribunal for the Law of the Sea—to clarify the obligations of states in the context of climate change. The ICJ opinion is the most high-profile effort, but all have the potential to contribute to the development of international law and influence states’ behavior in terms of how they approach negotiations at the Conference of the Parties of the U.N. Framework Convention on Climate Change and interpret their obligations to protect the environment and ensure the promotion of human rights. 

There is inherent risk in the three advisory opinion efforts, both individually and collectively. There is the risk that one or more of the tribunals will not clarify the obligations of states or will articulate them in such a way that hinders progress on addressing climate change. There is also the risk that the three tribunals will issue decisions that offer contradictory interpretations of the law, thus creating confusion. For states that are facing an existential threat due to climate change, these risks seem to be outweighed by the potential reward that a strong statement by an international tribunal will lead to more urgent action to avoid the most dire consequences of climate change before it is too late. 

Climate Change and Security

Climate change has been described as a threat in and of itself, as well as a “threat multiplier” for global security. The impacts of a changing climate are becoming increasingly frequent and severe and thus will exacerbate existing security risks. Rising sea levels are expected to displace hundreds of millions of people by the end of the century, either internally or across borders, and are threatening the territorial integrity of nations. Observers have already identified strong connections between migration in the context of climate change and the rise of far-right nationalistic political parties. What’s more, extreme weather and disputes over scarce resources as a result of climate change can destabilize regions and lead to armed conflict

The U.N. Security Council has held debates on the “Maintenance of International Peace and Security: Climate and Security,” and “Threats to International Peace and Security: Sea-Level Rise.” While some states disagree about the extent to which the Security Council should address climate change, there is increasing recognition by other states of the connection between climate change and threats to national security and international peace and security. 

History and Context of the Current Advisory Opinion Efforts

In the words of Vanuatu’s Prime Minister Alatoi Ishmael Kalsakau, “Global warming is our enroute to Armageddon.” 

Vanuatu is not the first Pacific Island nation to consider turning to the ICJ to clarify the obligations of states with respect to climate change. In 2011, Palau, along with the Marshall Islands, announced that it intended to seek an advisory opinion from the ICJ on climate change. At that time, the question under consideration was narrowly focused on the obligations of states to ensure “that activities under its jurisdiction or control that emit greenhouse gases do not cause, or substantially contribute to, serious damage to another State or States.” This effort faced opposition from powerful states such as the United States and never made it to the floor of the General Assembly.

The legal questions in the current draft resolution are far more expansive. The resolution asks the ICJ to clarify the obligations of states to “ensure the protection of the climate system” and the environment from the emission of greenhouse gases “for present and future generations.” It also asks what the legal consequences are under these obligations for states that,“by their acts and omissions, have caused significant harm to the climate system and other parts of the environment.” The second question focuses specifically on states that “are injured or specially affected by or are particularly vulnerable to the adverse effects of climate change” as well as “present and future generations affected by the adverse effects of climate change.” 

As evidenced by the language of the draft resolution, small island developing states that are particularly vulnerable to the impacts of climate change are of specific concern. Four of these states—Tuvalu, Kiribati, the Maldives, and the Marshall Islands—are at risk of losing their entire territory due to rising sea levels. While Vanuatu is not at risk of losing its entire territory, if sea levels rise by one meter—which may happen as soon as the end of this century—it could lose up to 75 percent of the landmass of certain low-lying islands within its territory. Prior to submergence, significant portions of the territory of low-lying island states will likely become uninhabitable due to erosion, frequent flooding, and salinization of the groundwater. As I argue in a forthcoming article in the Stanford Journal of International Law, the loss of habitable territory will have drastic implications for the populations at risk of displacement as well as the traditional conception of statehood under international law, which is commonly understood to possess a territory, permanent population, and a government with “a sufficient degree of independence in international relations.” The extinction of a state due to physical causes is entirely unprecedented in history and international law, and the implications for preserving the continuity of a state in the absence of habitable territory are unclear.

The current ICJAO Campaign, as it has been called, is in part the culmination of grassroots advocacy efforts spearheaded by the Pacific Islands Students Fighting Climate Change. It is building on interest cultivated by the previous effort led by Palau and the Marshall Islands and continued through the work of academics and activists. Ultimately, it was up to states to take the initiative forward, as the ICJ’s advisory jurisdiction is limited to requests from the General Assembly, the Security Council, or organs of the United Nations and specialized agencies that have been authorized by the General Assembly to request advisory opinions. Vanuatu has built a broad coalition of states from various geographic regions for its “Core Group” and has consulted with a range of member states on the precise wording of the definition over a period of several years. This, along with securing 105 U.N. member state co-sponsors, should help ensure that the resolution is adopted and the request is submitted to the court. 

The ICJ advisory opinion effort is proceeding in parallel with two other advisory opinion requests to international tribunals. A request for an advisory opinion from the International Tribunal for the Law of the Sea (ITLOS) was submitted by the Commission of Small Island States on Climate Change and International Law (COSIS) on Dec. 12, 2022. The request asks the tribunal to issue an advisory opinion on the obligations of state parties to the U.N. Convention on the Law of the Sea (UNCLOS) “to prevent, reduce and control pollution of the marine environment” and “to protect and preserve the marine environment” from the impacts of climate change. The case has been added to the court’s registry, and the tribunal has invited COSIS, states parties to UNCLOS, and certain international organizations—such as the United Nations, the U.N. Framework Convention on Climate Change, and the International Union for Conservation of Nature (IUCN)—to submit written statements by June 2023. Though it is not a state party to UNCLOS, the United States submitted a written statement “in its capacity as a Member State of the United Nations” in the only advisory opinion decided by the full tribunal to date. Given the potential reach of an ITLOS advisory opinion on climate change, it seems likely the United States will do the same here.

Less than a month after the ITLOS request, the foreign ministers of Chile and Colombia jointly requested an advisory opinion from the Inter-American Court of Human Rights (IACtHR). The request asks the court to clarify the obligations of states to respond to the climate emergency within the framework of international human rights law. The expansive request also outlines six questions for the court to clarify both substantive and procedural obligations of states, including the duty to prevent the adverse impacts of climate change, the obligation of states to cooperate to confront the adverse effects of climate change, and the obligation of states to protect the human rights of present and future generations. If the IACtHR decides to take up the request, it may choose to modify or narrow the scope of the questions presented to the court. Previous IACtHR decisions have been expansive in the interpretation of the rights contained in the Inter-American Convention on Human Rights. The influence of an advisory opinion could extend beyond the Inter-American system, including to claims brought by individuals from small island developing states. This was the case for the IACtHR advisory opinion on the environment and human rights, which was cited by the Committee on the Rights of the Child in Sacchi et al v. Argentina (a communication brought by nationals of, inter alia, the Marshall Islands and Palau) and the Human Rights Council in Teitiota v. New Zealand (a complaint brought by a citizen of Kiribati).

Considerations and Potential Concerns With the Advisory Opinion Requests

While counsel to Vanuatu recently expressed optimism that an opinion by the ICJ would not hinder progress on addressing the challenges of climate change through the progressive development of the law, others have expressed skepticism. There is a risk that the tribunal will come back with a vaguely worded answer or that it will not outline clear and strong obligations for states to protect the environment and those that could be or have been harmed by the adverse effects of climate change. This risk may be compounded if the question that is presented allows for too much “wiggle room” in how the court decides to interpret the question. 

Even if the question is clear and precisely worded, the court does not always reach a conclusion that advances the law in the ways that advocates might expect. For example, in the advisory opinion on the Legality of the Threat or Use of Nuclear Weapons, the court was unable to come to a definitive conclusion on the lawfulness of the threat or use of nuclear weapons in all circumstances, such as “when the very survival of a State” was at stake. This sort of equivocation on the legal consequences for states that have caused significant harm to the environment by the principal judicial organ of the United Nations could make it more difficult to hold states accountable for damage caused by their past and future emissions. Furthermore, it is unclear if or in what way the court will address the issue of attribution as it is mentioned not explicitly in the question but, rather, indirectly through the inclusion of the phrase “significant harm.” 

The Nuclear Weapons case also provides a cautionary tale of potential unintended consequences of advisory opinions and how they shape state behavior. Russia’s Military Doctrine as well as its State Policy on Nuclear Deterrence include language that “reserves the right” for Russia to use nuclear weapons “if the very existence of the state is in jeopardy.” Similar language has been used by Russian President Vladimir Putin, most recently during a speech announcing the suspension of Russia’s participation in the New START treaty in which he stated, “We are talking about the existence of our country.” Observers have argued that this language “effectively invok[es]” the language of the Nuclear Weapons advisory opinion.

Alternatively, an opinion may help establish “a common language” to facilitate more ambitious commitments from states in future climate negotiations. If the court goes beyond simply articulating that states have a duty to cooperate, as is the hope expressed by counsel to Vanuatu, it could clarify the obligations of states under existing legal frameworks. Vanuatu’s Minister of Climate Change Ralph Regenvanu has also expressed this view. In a video statement, Regenvanu said that the “resulting Advisory Opinion will help States revise and enhance their Nationally Determined Contributions under the Paris Agreement, and strengthen domestic laws and policies.” The minister of climate change also stated that despite the “initial optimism” that accompanied the Paris Agreement, “little has changed,” leading states especially vulnerable to climate change  such as Vanuatu to feel it necessary to take this step.

Despite the support of a majority of U.N. member states, not all states support the initiative. The United States’s special presidential envoy for climate, John Kerry, recently described the effort as “Vanuatu sort of just jumping ahead and going to court.” As described by Secretary Kerry, the United States had committed to “resolve the issue of loss and damage” but had concerns about the way the question was framed in the resolution. However, the issue of loss and damage is distinct from forward-looking obligations to “ensure the protection of the climate system and other parts of the environment from anthropogenic emissions of greenhouse gases” (as phrased in the draft resolution), since loss and damage addresses only damage that has already occurred. While the first meeting of the Transitional Committee on the operationalization of the loss and damage fund is scheduled to take place later this month and there is hope for progress at the 2023 U.N. Climate Change Conference (COP28), there have been delays in appointing members of the Transitional Committee and the loss and damage fund has yet to be operationalized. Furthermore, countries have failed to fulfill their previous pledges to provide $100 billion per year toward climate change adaptation and financing for poor countries. 

There are also specific concerns with ITLOS exercising jurisdiction in the request from COSIS. ITLOS previously determined it has advisory jurisdiction pursuant to Article 288 of the convention, Article 21 of the statute of the tribunal, and Article 138 of its rules of procedure in the Request for an Advisory Opinion Submitted by the Sub-Regional Fisheries Commission (SRFC). Exercising advisory jurisdiction in that case was objected to by the United States and other state parties to UNCLOS and has also been described as an “expansion of its powers.” The request for an advisory opinion from COSIS may highlight concerns regarding the “dangers of abuse and manipulation” if a small number of states “seek to gain an advantage over third States” by concluding agreements for the purpose of conferring advisory jurisdiction on ITLOS. The COSIS agreement that conferred jurisdiction on ITLOS was initially executed by just two states: Antigua and Barbuda together with Tuvalu. Its membership has since expanded and currently includes Palau, Niue, Vanuatu, and Saint Lucia. These states represent just six of the 168 state parties to UNCLOS. Although the advisory opinion is only meant to concern the obligations of state parties to COSIS and is not binding, the framing of the question may implicate the obligations of other state parties to UNCLOS. At the same time, the agreement and the request demonstrate the ingenuity of states most vulnerable to the impacts of climate change in pursuing every available legal avenue to ensure their very survival. 

The Path Forward

Even if all three tribunals determine they have jurisdiction over the three respective requests, international tribunals have discretionary power to refuse to give an advisory opinion. Both the ICJ and ITLOS have interpreted this power to mean that they should not exercise their discretionary power to decline to issue an advisory opinion unless there are “compelling reasons” to do so, such as if the wording of the question is vague or if it would result in the judicial settlement of a dispute to which a state had not consented. Similarly, the IACtHR has determined it must have “compelling reasons based on the fact that the petition exceeds the limits of its competence in the sphere established in the Convention.” 

It seems unlikely that any of the three tribunals will use their discretionary power to decline to give an advisory opinion in any of the cases. The IACtHR request is in line with a prior advisory opinion on the environment and human rights. Additionally, the IACtHR has declined to respond to a request for an advisory opinion only five times, in comparison to the 30 advisory opinions that it has issued. The ICJ, in turn, has never exercised its discretion to decline to hear a request where it otherwise had jurisdiction and only once found that it did not have jurisdiction to hear a request for an advisory opinion, in the case of the Legality of the Use by a State of Nuclear Weapons in Armed Conflict. The court ultimately determined that the question fell outside the scope of the activities of the World Health Organization, the specialized agency requesting the opinion. The request to ITLOS is only the second request for an advisory opinion to be submitted to the full tribunal. As described above, it determined it had advisory jurisdiction in the SRFC case. However, given the potential reach of an advisory opinion on the obligations of states to protect and preserve the marine environment from the impacts of climate change, states may again argue that the full tribunal does not have advisory jurisdiction under UNCLOS and cannot be granted broader jurisdiction by the statute of the court or the rules of procedure

How the three advisory opinions may influence each other remains to be seen. The ICJ has rendered advisory opinions within a few months to a few years after receiving a request. In its most recent advisory opinion responding to a request from the General Assembly, concerning the Legal Consequences of the Separation of the Chagos Archipelago from Mauritius in 1965, the court held oral hearings a little over a year after the General Assembly resolution was adopted and issued an opinion less than six months later. Following that timeline, a decision in this case could be expected before the end of 2024, assuming the General Assembly resolution is adopted later this month. Written statements are expected to be submitted in the ITLOS case in June of this year, and an opinion could also be rendered at the end of 2024, based on the previous case timeline. A decision from the IACtHR may come soon after, in January 2025. 

While counsel to Vanuatu recently expressed optimism that the ITLOS opinion will likely be issued first and at a time in which the ICJ can build upon it, it is not at all clear that this will be the case. If opinions are issued simultaneously or in short succession, there is a risk that they will not clarify the obligations of states under international law but, rather, create additional confusion if the opinions are at odds with each other. In contrast, however, the dueling proceedings may create pressure on the tribunals to “outdo” each other in order to be “seen on the right side of history.”


All three advisory opinion requests come at a time of urgency to address the climate crisis. In its synthesis of its sixth assessment report released on March 20, the Intergovernmental Panel on Climate Change gave what has been characterized as a “final warning” that emissions must be cut in half by 2030 if we are to limit warming to 1.5 degrees Celsius, the threshold beyond which the climate system will be fundamentally altered and may exceed humanity’s ability to adapt. Meanwhile, emissions continue to rise. In its 2022 Emissions Gap Report, the U.N. Environment Program assessed that the world is currently on track for a 2.8 degrees Celsius increase in global temperatures by the end of the century. Even if countries implement policies to fulfill their existing pledges under the Paris Agreement, it will only reduce the projected warming to 2.6 degrees Celsius. As noted by U.N. Secretary General António Guterres in a recent Security Council debate, this level of warming would be a “death sentence for vulnerable countries.” 

There is a narrow window to avoid the most devastating impacts of climate change. That window is rapidly closing. Already, the world will experience impacts that are unavoidable and irreversible for thousands of years, including sea level rise. The adverse effects of climate change are not distributed equally and most often fall on the states least responsible for climate change. For those states that are facing the potential loss of their entire territory and the displacement of their population, no amount of financial redress could ever provide adequate compensation for that immeasurable loss. While there is the possibility that the advisory opinions could set the global community back in terms of its ability to address climate change, the potential for a positive outcome appears to be worth the risk for states faced with losing everything under the current status quo. Every fraction of a degree matters.

Melissa Stewart is a Research Fellow and Adjunct Professor of Law at Georgetown University Law Center, where she writes and teaches in the areas of international law and human rights. She is an Assistant Professor of Law Designate at the University of Hawai'i at Mānoa, William S. Richardson School of Law and will join the faculty in August 2023. Prior to academia, Stewart practiced in the area of public international law as an Associate in the International Litigation and Arbitration Department and United Nations Practice Group at Foley Hoag, LLP.

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