On 23 July 2025, the International Court of Justice (the United Nations’ Organisation’s principal judicial body) delivered a landmark Advisory Opinion, affirming that states must protect the climate system from the catastrophic impacts of climate change, notably through instruments such as the Paris Agreement and its ambition to cap global warming at 1.5°C relative to preindustrial levels.
The court concludes in paragraph 457 (page 130) that “the climate change treaties set forth binding obligations for States parties to ensure the protection of the climate system and other parts of the environment from anthropogenic greenhouse gas emissions”.
These obligations, the court adds, emanate from several key instruments that states are party to, including among others: United Nations Charter; the Kyoto Protocol of 1997; the Conference of the Parties (COP) and its Paris Agreement of 2015; the UN Convention on the Law of the Sea; the Montreal Protocol; the Biodiversity Convention; the Convention on Desertification; the Customary International Convention; and international human rights law.
The work of the Intergovernmental Panel on Climate Change (IPCC) provided a lot of the scientific basis that the court used to determine the urgency of climate change.
Specifically, states’ responsibilities include: “mitigation of greenhouse gas emissions and adapting to climate change”; “limiting their greenhouse gas emissions and enhancing their greenhouse gas sinks and reservoirs”; co-operation “with each other in order to achieve the underlying objective of the Convention”; complying “with applicable provisions of the Protocol”; acting with due diligence in “making an adequate contribution to achieving the temperature goal set out in the Agreement” within the principle of common but differentiated responsibilities; “obligation to prepare, communicate and maintain successive and progressive nationally determined contributions”; and pursuing “measures which are capable of achieving the objectives set out in their successive nationally determined contributions”.
The court added that failure to protect the environment and limit climate change was an internationally wrongful act that exposed states to lawsuits or other formal processes for compensation, remediation or reparation.
Governments and activists around the world are hailing the ICJ decision as a game changer that can potentially turbocharge bolder and swifter climate action in light of increasingly severe extreme weather events. However, a lot of work still needs to be done for that dream to become a reality. Let us take a closer look.
Background
The idea to sue major polluting nations and corporations for their inaction as it pertains to moving faster to curb greenhouse gas (GHG) emissions was first initiated by students from the law faculty of the University of South Pacific. The government of Vanuatu backed the campaign and took it to the United Nations organisation (UN), which then referred it to the International Court of Justice (ICJ) on 12 April 2023. Vanuatu and parties wanted the court to answer the following two questions:
- What are the legal obligations of states to protect the climate, today and tomorrow?
- What are the consequences if they fail to do so, particularly concerning the most vulnerable countries?
The Southeast Asia, Asia Pacific regions, and even the Southwest Indian Ocean Islands have been watching nervously as sea levels rise. Vanuatu is among the Small Island Developing States that risk being wiped off the map due to rising sea levels caused by global warming, a fact highlighted by UN Secretary-General António Guterres in that famous Time Magazine cover.
Indonesia is moving its capital from Jakarta to Nusantara, and Fiji has witnessed very rapid sea rise in the last half-century. Closer to Africa, Mayotte witnessed its most devastating cyclone in 2024.
It is due to all these pressures that island nations are particularly active in international efforts to curb GHG emissions.
After the decision was lodged, at least 99 other countries and organisations joined Vanuatu to argue for greater enforcement of international climate treaties and justiciability.
Key paragraphs
The Advisory Opinion is a clear and concise document that brings together all international instruments as they relate to protecting the environment inside one document, giving governments, judges, negotiation processes, trade unions, and so on the clarity that they need and a clear roadmap to making decisions.
Where some have argued before that there is a void in terms of climate-change law, the court points out that there are more than enough legally binding instruments to draw from.
Although the entire document is packed full of important decisions, I want to highlight just a few:
Paragraph 249: “In light of the foregoing, the Court concludes that, rather than being entirely discretionary as some participants argued, NDCs must satisfy certain standards under the Paris Agreement. All NDCs prepared, communicated and maintained by parties under the Paris Agreement must, when taken together, be capable of realizing the objectives of the Agreement which are set out in Article 2.”
Paragraph 252: “Accordingly, since the domestic mitigation obligations under Article 4, paragraph 2, establish an obligation of conduct, parties are required to act with due diligence in taking necessary measures to achieve the objectives set out in their successive NDCs.”
Paragraph 256: “The Court finds that specific obligations pertaining to adaptation are contained in Article 7, paragraph 9, of the Paris Agreement, which provides that ‘[e]ach Party shall, as appropriate, engage in adaptation planning processes and the implementation of actions, including the development or enhancement of relevant plans, policies and/or contributions’. This provision, introduced with the terms ‘[e]ach Party shall’, imposes a legally binding obligation upon the parties to undertake adaptation planning actions.”
Paragraph 260: “The Court notes that the Paris Agreement establishes obligations of co-operation with respect to specific issue areas, such as adaptation, and loss and damage (Article 7, paragraphs 6 and 7; Article 8, paragraph 4).”
Paragraph 268: “… the Court considers that the climate change treaties establish stringent obligations upon States to ensure the protection of the climate system and other parts of the environment from anthropogenic GHG emissions”.
Paragraph 280: “The Court reaffirms that States must fulfil their duty to prevent significant harm to the environment by acting with due diligence.”
Paragraph 308: “Climate change is a common concern. Co-operation is not a matter of choice for States but a pressing need and a legal obligation.”
Paragraph 323: “States parties to the Montreal Protocol are under an obligation to phase out, according to a fixed schedule, the production and consumption of all the main ozone-depleting substances, including certain GHGs, through control measures.”
Paragraph 376: “The Court is thus of the view that the adverse effects of climate change, including, inter alia, the impact on the health and livelihoods of individuals through events such as sea level rise, drought, desertification and natural disasters, may significantly impair the enjoyment of certain human rights. The Court will consider some of these rights, without attempting to be exhaustive.”
Paragraph 393: “The Court thus concludes that, under international law, the human right to a clean, healthy and sustainable environment is essential for the enjoyment of other human rights.”
Paragraph 427: “Failure of a State to take appropriate action to protect the climate system from GHG emissions — including through fossil fuel production, fossil fuel consumption, the granting of fossil fuel exploration licences or the provision of fossil fuel subsidies — may constitute an internationally wrongful act which is attributable to that State.”
Paragraph 445: “As a general observation, the Court notes that breaches of States’ obligations under question (a) may give rise to the entire panoply of legal consequences provided for under the law of State responsibility.”
Paragraph 452. “In the event that restitution should prove to be materially impossible, responsible States have an obligation to compensate.”
Significance
In terms of the wider implications of the ICJ’s Advisory Opinion, this should change everything – in principle. That said, the opinion comes of course within a very difficult international context in which nihilism, political determinism and squabbles within and between the key political blocs make urgent climate action all but impossible.
The race for AI, and the continued deployment of massive energy-hungry data centres, is not helping either.
Let us recall that the UN Environment Programme’s Emissions Gap Report, published in October 2022, had already admitted that the international community was falling short of the Paris Agreement goals. The World Meteorological Organisation recently confirmed that 2024 was the warmest year on record.
In real terms, that translates to more intense heat waves, runaway fires, drought, deadly flash floods (in South Africa, Nigeria, Mali, the US), cyclones (Mayotte) and hurricanes (US). These events certainly used to occur before, but as we saw recently in the state of Texas in the US, they are developing faster and hitting communities with more ferocity.
That said, the biggest benefit of the document lies in the fact that it tells the international community that the panoply of treaties and conventions that most countries in the world have acceded to has legal effect. It clarifies justiciability.
Virtually every country on the planet is signatory to both the charter of the UN and the one setting up the United Nations’ Framework Convention on Climate Change, which oversees the Conference of the Parties (COP).
Legal jurisdictions can no longer wring their hands in anguish and complain that they do not have enough authority or precedence to rule on matters relating to climate change. Even the United States’ argument that international treaties constitute lex specialis and should therefore yield or be subordinate to more stringent national laws, was deemed erroneous.
Even countries that have not acceded to these instruments can also be held liable for their transgressions under customary international law.
Second, the Advisory Opinion specifically mentions fossil fuels (paragraph 427) as something that governments have a duty to bring under control.
I was in Nigeria the other day for a conference, and everybody was talking about Shell’s divestment efforts. Similar divestment efforts have been going on in South Africa. Shell is the first high-profile multinational to move so speedily in its divestment efforts, but the number of companies trying to evade responsibility for CO2 emissions will only grow, and so, civil society organisations must push their national governments to take swifter action to hold all polluters to account before they disappear.
The ICJ decision tells them how to prepare their arguments.
It also means that governments and civil society actors must forge closer ties with a variety of actors in the Global North to bring serial polluters to book.
Elsewhere, there has to be a realignment of the COP negotiation blocs. China caucuses with developing countries in the G77 plus China network at the Conference of the Parties, but during the proceedings, they argued that international climate agreements and conventions were only aspirational and should continue to be regarded as such.
In trying to protect its status as the factory of the world, China was effectively throwing under the bus countries like Vanuatu, Nigeria, Bangladesh and countless others that are already feeling the full impacts of climate change. Something has to give, although many of these countries hold a lot of Chinese debt.
Conclusion
The ICJ’s Advisory Opinion is going to be used in courts, boardrooms and government offices around the world for many years to come. However, the outcome in itself does not mean that governments will suddenly start respecting all their obligations.
In a highly corporatised context where most of the serial polluters are based in powerful Global North countries that fund both the UN and the ICJ, we are not about to witness a sea change in behaviour.
But there is more ammunition, no doubt about it. What we need to do more of is ramp up global North-South collaboration within a new internationalism that aggressively goes after major polluters.
The big win will come eventually. DM