In its first-ever ruling on climate, the International Court of Justice (the “World Court”) makes it clear that States have an obligation to protect the environment from greenhouse gas emissions and act with due diligence and cooperation to fulfill this obligation.
It makes it clear that governments, and by extension companies, must halt climate pollution and compensate vulnerable nations and communities for the harm they have caused.
The International Court of Justice (ICJ) in The Hague, Netherlands, issued its advisory opinion on the obligations of States in respect of climate change, read out by the President of the Court, Judge Iwasawa Yuji, on Wednesday, 23 July.
The UN’s principal judicial body (ICJ) ruled that this includes the obligation under the Paris Agreement on climate change to limit global warming to 1.5°C above pre-industrial levels.
The Court further ruled that if States breach these obligations, they incur legal responsibility and may be required to cease the wrongful conduct, offer guarantees of non-repetition and make full reparation depending on the circumstances.
‘A victory for our planet’
UN Secretary-General António Guterres issued a video message welcoming the historic decision, which came a day after he delivered a special address to Member States on the unstoppable global shift to renewable energy.
"This is a victory for our planet, for climate justice and for the power of young people to make a difference," he said.
Reasoning of the Court
The Court used Member States’ commitments to both environmental and human rights treaties to justify this decision.
Firstly, Member States are parties to a variety of environmental treaties, including ozone layer treaties, the Biodiversity Convention, the Kyoto Protocol, the Paris Agreement and many more, which oblige them to protect the environment for people worldwide and in future generations.
But, also because “a clean, healthy and sustainable environment is a precondition for the enjoyment of many human rights,” since Member States are parties to numerous human rights treaties, including the Universal Declaration of Human Rights, they are required to guarantee the enjoyment of such rights by addressing climate change.
Pacific Islands
Yesterday’s landmark ICJ ruling and advisory opinion was welcomed by many in the Pacific.
In Fiji, the Director of the Pacific Islands Students Fighting Climate Change, Vishal Prasad noted, “Today the world’s smallest countries have made history. The ICJ’s decision brings us closer to a world where governments can no longer turn a blind eye to their legal responsibilities. It affirms a simple truth of climate justice: those who did the least to fuel this crisis deserve protection, reparations, and a future. This ruling is a lifeline for Pacific communities on the frontline.”
In Solomon Islands, the President of the Pacific Islands Students Fighting Climate Change, Cynthia Houniuhi, said, “The Pacific has shown what’s possible when governments lead with courage and unity to protect people and the planet. Now, the world’s highest court has confirmed what the youth and frontline communities have long demanded: bold climate action rooted in justice. The ICJ's ruling is a powerful signal that the law is on our side. It must now guide not only courtrooms, but climate negotiations and policy decisions worldwide. The ICJ’s opinion is more than a legal milestone—it’s a call to action, and we’re ready to keep building this momentum together.”
In Vanuatu, the Climate Change Adaptation, Environment and Disaster Management Minister, Ralph Regenvanu said the ICJ ruling marks an important milestone in the fight for climate justice. "We now have a common foundation based on the rule of law, releasing us from the limitations of individual nations' political interests that have dominated climate action. This moment will drive stronger action and accountability to protect our planet and peoples."
“We will now take the ICJ ruling back to the United Nations General Assembly and pursue a resolution that will support implementation of this decision.
“Even as fossil fuel expansion continues under the US’s influence, along with the loss of climate finance and technology transfer, and the lack of climate ambition following the US’s withdrawal from the Paris Agreement, major polluters—past and present—cannot continue to act with impunity and treat developing countries as sacrifice zones to further feed corporate greed."
From Palau, the Chair of the Alliance of Small Island States (AOSIS) and Permanent Representative of Palau to the United Nations, Ambassador Ilana Victorya Seid noted this opinion reflects the strength of collective advocacy.
"It is the result of sustained advocacy by Pacific youth, legal experts from vulnerable nations, and States that chose not to remain silent. The ICJ’s findings demonstrate that moral clarity and legal authority can reinforce one another. This ruling must serve as a foundation — not a conclusion. We now call on all States to act with renewed urgency and ambition, in accordance with their legal obligations and the demands of justice.”
Australia
In Australian, Executive director and founder of the Grata Fund, Isabelle Reinecke said, “This historic ruling by the world’s highest court officially marks the end of an era of states ducking and weaving legal responsibility for climate harm.
“The ruling seriously calls into question the legality of Australia’s current and past policy settings under international law, including its past and ongoing approval of fossil fuel projects and subsidisation of the activities of private actors which cause escalating greenhouse gas emissions and put the climate system and vulnerable communities at risk."
“Australia is the third largest exporter of fossil fuels globally after Russia and the United States. This month, the Federal Court found that Torres Strait people and culture are being “ravaged by human induced climate change”, and that the Australian Government “paid scant, if any, regard to the best available science” when setting its emissions targets.
“Communities in Australia and around the world are increasingly bringing climate cases to courts of all levels. The facts are already on their side, and now this landmark ruling provides even more legal scaffolding for judges to rule in their favour."
Senior specialist lawyer at Environmental Justice Australia, Retta Berryman, commented, “The Court’s opinion is advisory, but it is based on a far-reaching review of international laws that countries – including Australia – have committed to upholding.
“This opinion will be significant for measuring whether Australia’s upcoming revised climate plan is sufficiently ambitious. Key arguments routinely used by high-emitting countries like Australia to limit their climate responsibility have today been rejected by the ICJ."
She said Australian courts, industry and governments have long argued it’s not possible to attribute specific climate impacts to a particular emitter.
Professor of International Law at the Australian National University, Donald Rothwell believed the Court’s opinion will pave the way for political and diplomatic exchanges between climate change-impacted states and large polluting states over reparations.
The ICJ adopted this advisory opinion unanimously, only the fifth time in its nearly eighty-year history that it has done so.
The Court has held public hearings in these proceedings from in December 2024, during which 96 States and 11 international organizations presented oral statements. It was the highest level of participation in a proceeding in both the history of the Court and that of its predecessor, the Permanent Court of International Justice.
Case background
In September 2021, the Pacific Island State of Vanuatu announced that it would seek an advisory opinion from the Court on climate change. This initiative was inspired by the youth group Pacific Island Students Fighting Climate Change, which underscored the need to act to address climate change, particularly in small island States.
After the country lobbied other UN Member States to support this initiative in the General Assembly, on 29 March 2023, it adopted a resolution requesting an advisory opinion from the ICJ on two questions: (1) What are the obligations of States under international law to ensure the protection of the environment? and (2) What are the legal consequences for States under these obligations when they cause harm to the environment?
The UN Charter allows the General Assembly or the Security Council to request the ICJ to provide an advisory opinion. Even though advisory opinions are not binding, they carry significant legal and moral authority and help clarify and develop international law by defining States’ legal obligations.
This is the largest case ever seen by the ICJ, evident by the number of written statements (91) and States that participated in oral proceedings (97).
The ‘World Court’
The ICJ, informally known as the “World Court”, settles legal disputes between UN Member States and gives advisory opinions on legal questions that have been referred to it by UN organs and agencies.
It is one of the six main organs of the UN alongside the General Assembly, the Security Council, the Economic and Social Council (ECOSOC), the Trusteeship Council and the Secretariat and is the only one not based in New York.
