For the first time, more than 130 states have agreed to collectively seek the opinion of the International Court of Justice (ICJ) regarding the survival of mankind.
Led by Vanuatu and a core group of countries, in April 2023 they agreed to consult the ICJ on the obligations of states to protect the climate system. The court, based in The Hague in the Netherlands, is the principal judicial organ of the UN.
The ICJ is now set to deliver an opinion on this matter, and on the legal consequences under international law of causing significant harm to the climate system. This includes issues related to the prevention of significant harm to the environment, and the protection and preservation of the marine environment, among others.
The Commission of Small Island States on Climate Change and International Law (Cosis), which requested the first climate-related advisory opinion from the International Tribunal for the Law of the Sea (Itlos), participated in the ICJ proceedings. Cosis presented the small islands’ perspective, and has drawn on the conclusions of the Itlos advisory opinion.
The written phase of the ICJ proceedings concluded in 2024, followed by two weeks of hearings involving 107 states and international organisations, which ended on 13 December. Vanuatu’s special envoy for climate, Ralph Regenvanu, captured the significance of the case at the opening of the hearings: “This may well be the most consequential case in the history of humanity.” The court’s opinion is expected for 2025. It will mark the first time a climate case has been brought before the ICJ since governments acquired, over half a century ago, scientific proof that burning fossil fuel increases atmospheric CO2 concentration and temperatures, which will ultimately jeopardise the ability to sustain human life on the planet.
Small island developing states (Sids) are both victims of climate change and moral leaders in the fight for environmental justice. They offer the Global North valuable lessons through their ancestral and intimate knowledge of the ocean and natural world, showcasing ways to live in harmony with nature, particularly the ocean. Despite their minimal historical contribution to greenhouse gas emissions, Sids have taken on moral leadership by bringing the ICJ into the effort to safeguard humanity. Vanuatu, supported by the Sids, achieved a tremendous feat by building consensus among more than 130 states to secure the UN General Assembly’s request to refer these questions to the ICJ.
International courts, rooted in Western justice systems, differ significantly from Indigenous systems of justice. Yet, we have witnessed lawyers from island nations – representing formerly colonised states – donning wigs to argue their case before the ICJ judges.
Sids propose a collective approach to the inaction of major polluters. They recall natural law and appeal to the shared sense of responsibility and wisdom of the international community, urging states to emerge from lethargy and assume their responsibilities as required by law, or else perish.
A global emergency, an exceptional legal action
As climate impacts multiply and intensify, this ICJ procedure bears witness to the international community’s overall perception of urgency. It reflects a growing awareness that our collective survival depends on decisive action by states.
The consensus reached by UN member states to request the ICJ’s advisory opinion is a testament to the widespread support for finding legal answers to questions that are crucial to humanity’s survival. It also demonstrates that the judiciary is recognised as being able to provide answers to the crisis.
This action not only brings the climate issue before the court but also signals a call for progressive interpretation of international law. A majority of states have shown that they interpret international law as mandating more action to reduce emissions and providing for accountability in the event of violations. In a context where political and economic solutions have failed to provide fully satisfactory responses to the environmental emergency, this procedure marks a significant milestone in efforts to provide a legal one.
The ICJ case comes at a time when the courts are increasingly being turned to as a tool to respond to the climate crisis. The 2023 Global Climate Litigation Report found a sharp rise in climate-related cases, with filings worldwide growing from 884 in 2017 to 2,180 in 2022, across 65 jurisdictions. These cases are mostly brought against governments or companies by NGOs, citizens, foreign investors or subnational governments. They might increase further given the damage caused by increasingly frequent extreme weather events, the loss of territory linked to climate change and the resulting migration of populations.
Three cases with a shared goal
Three advisory cases before regional and international courts and tribunals exemplify the international dimension of climate litigation, including the current ICJ case. Conducted over the past two years, these cases aim to harmonise international law and clarify states’ responsibilities in addressing the global climate emergency.
The second case, initiated by Cosis, was brought before Itlos and marked the first request for a climate-related advisory opinion from an international tribunal. In May 2024, Itlos issued a resounding advisory opinion, concluding that greenhouse gas emissions are pollution of the marine environment under the UN Convention on the Law of the Sea. It therefore sets out the obligations of states to preserve and protect the marine environment, and to prevent, reduce and control its pollution.
The third case, brought by Chile and Colombia, is before the Inter-American Court of Human Rights. It concerns the obligation of states to respond to the climate emergency from the perspective of international human rights law. The opinion is expected in 2025.
Some cases in international law, like the case before the ICJ, are known as “advisory proceedings”, because they are not contentious. They seek a court’s guidance on a set of legal questions.
Advisory opinions do not function to settle cases, but to express a particular court’s interpretation of existing law. It is a non-binding opinion that is designed to advise and guide the parties, and constitutes an important legal precedent.
The three advisory proceedings have been running in parallel and feeding into and reinforcing each other. One way a case can influence another is when judges look to the reasoning of other courts when constructing their reasoning in a case. In the ICJ case, states referred extensively to the Itlos advisory opinion in their oral statements and written comments. It is therefore hoped by many pushing for stronger action against climate change that the ICJ will give deference to Itlos jurisprudence, particularly for questions relating to the law of the sea.
Itlos and the ICJ advisory opinion
The Itlos opinion is particularly relevant to the ICJ case on several substantive points of law. Firstly, Itlos made it clear that greenhouse gas emissions constitute pollution of the marine environment under the UN Convention on the Law of the Sea.
Another key finding of considerable importance to the ICJ proceedings and any subsequent climate cases was that the science is irrefutable. Itlos considered it an objective factor that must guide courts and tribunals in determining the risk of harm caused by greenhouse gas emissions. Science must therefore help determine the degree of due diligence necessary for states to meet their climate obligations. The tribunal concluded the Intergovernmental Panel on Climate Change reports to be the source of the best available science.
The tribunal also made clear that the minimum threshold of emission-mitigation measures necessary under the UN Convention on the Law of the Sea must be determined objectively using the best available science, precaution in the absence of scientific certainty, and climate-related treaties and instruments. Thus, state measures must evolve to comply with existing obligations under international law, becoming more ambitious over time as the climate changes and scientific knowledge advances.
Another central question in the ICJ advisory opinion request is determining which instruments apply to inform states’ obligations in relation to climate change. Most participants in the ICJ case used the tribunal’s conclusion that the Paris Agreement does not limit, modify or take precedence over all previous international law instruments regulating marine pollution from anthropogenic emissions. Thus, these participants took the view that the Paris Agreement is not the only text informing states of their obligations to take all necessary measures to prevent, reduce and control such pollution.
The Itlos conclusion also fed into arguments by Cosis to harmonise a contemporary regime – still being formed – that can achieve the goals of the Paris Agreement to keep global temperatures to 1.5C above pre-industrial levels. A harmonious interpretation of states’ obligations means considering the UN Convention on the Law of the Sea in conjunction with other specific obligations of states under the “international climate regime”, not in isolation. Interpreting and applying available legal instruments in a vacuum would contribute to the fragmentation of the regime, which is what historical polluters have attempted to do in their pleadings.
Hope for the ocean, the environment and the future
Cosis and island states are not asking for the moon. They want the existing rules of international law to be understood, applied and respected.
The ICJ opinion could clarify existing rules, enabling all states to read them in the same way and apply them consistently. A clear legal precedent, with a certain level of particularity, would enable island states to determine with certainty which state measures are appropriate, and which are in breach of international law. An opinion on the climate issue that does not shy away from the realities we face, would help guide the relevant legal and political bodies in negotiations, public policies, and subsequent court decisions, ensuring that states’ actions comply with international law.
In the long term, we hope to see a change in the behaviour of states – particularly the biggest polluters – toward greater ambition in meeting scientifically established emissions reduction targets. The goal is to ensure liveable conditions for present and future generations, and prevent further cataclysms. At stake is the survival not just of island and coastal populations but of humanity as a whole.
