The International Court of Justice (ICJ) stated on Wednesday, July 23, 2025, that climate inaction on the part of national governments may violate their legal obligations to current and future generations under international law. It has also stated that those already impacted have legal routes to demand loss and damage funding.
The opinion was published upon a request from the UN General Assembly, led by Vanuatu and other small island states. They asked the court to clarify what responsibilities governments have to address climate change and what legal consequences they can face if they flout these responsibilities.
Driven by a demand from Pacific youth and island nations supported by a coalition of civil society, Indigenous Peoples and States, the World’s Court has taken action to put high emitters on notice. This advisory opinion will shape international norms and now exists as a tool that leaders can use to negotiate stronger climate policy in a struggling multilateral system.
This landmark opinion is said to be yet another example of the world’s most impacted nations, like Vanuatu, continuing to lead the charge on climate action.
In its advisory opinion, the court stated that climate change is an “urgent and existential threat” and that greenhouse gas (GHG) emissions are “unequivocally caused by human activities.”
Judges stated that states have a duty to act on the latest climate science, in line with the international goal to limit warming to 1.5C, as set out in the 2015 Paris Agreement.
The court described the climate system as a vital part of the environment that must be protected for present and future generations. Though the opinion is non-binding, it carries significant legal and political weight and may shape future climate litigation and treaty negotiations.
It comes amid increasing efforts to hold governments accountable for climate change through legal avenues. In a separate landmark ruling last year, the European Court of Human Rights (ECHR) ruled in favour of a group of older Swiss women who argued their government’s insufficient action on climate change exposed them to deadly heatwaves.
The Strasbourg court found that inadequate climate policy can amount to a violation of human rights, setting a precedent for similar cases across Europe.
Criminalising ecocide
At the international level, discussions are underway to make large-scale environmental destruction a crime.
Last year, the International Criminal Court (ICC) began formal discussions on recognising ecocide as a new crime under the Rome Statute.
The proposed definition of ecocide covers acts committed with knowledge that they are likely to cause severe and widespread or long-term damage to the environment.
If adopted, this would allow the court to prosecute individuals, including corporate executives and government leaders, for environmental destruction such as large-scale oil spills or deforestation.
The mortality cost of carbon
The ecocide proposal, backed by several Pacific Island nations, faces legal hurdles as ecocide is not yet part of customary international law or recognised as a core international crime.
Nevertheless, climate litigation is gaining momentum, driven in part by advances in climate attribution science, which now makes it possible to connect specific weather events and deaths to human-driven climate change.
Researchers recently estimated that the heatwave in southern England in June this year caused 263 deaths in London, 171 of which were attributed to the increased temperatures linked to climate change.
Legal challenges are increasingly drawing on this science. Friends of the Earth recently announced it will take its case against the UK Government’s climate adaptation plan to the ECHR.
The group argues that the Government’s failure to prepare adequately for climate impacts breaches the rights of people in the UK, especially those most vulnerable to heat and flooding. The UK High Court previously ruled the Government’s adaptation plan lawful.
The ICJ’s opinion adds a new layer of legal clarity on what governments are required to do to prevent climate harm. While the court cannot enforce its ruling, it reinforces the growing view that states may be held accountable for climate inaction under international law.
ICJ reaction: ‘A rocket boost for climate justice’
Reacting to the ICJ’s opinion decision, the Grantham Research Institute on Climate Change and the Environment’s Noah Walker-Crawford said: “The ICJ’s advisory opinion brings the weight of international law behind what climate science has shown for decades. By grounding states’ obligations in scientific consensus and human rights law, the Court affirms that governments must not only reduce their own emissions but also regulate companies to do the same.
“This creates a powerful foundation for future claims to hold both states and major emitters accountable.”
Power Shift Africa’s director, Mohamed Adow, said: “This ruling is a rocket boost for climate justice. The ICJ has confirmed what Africa has long demanded: that rich nations must be held accountable for the damage their emissions have caused.
“For a continent like Africa – least responsible but most affected – this decision is a lifeline. It strengthens our call for reparations, debt relief, and real climate finance – not loans that deepen poverty… the law now backs our moral case.”
“The era of polluters hiding behind vague promises is over.”
Greenpeace International’s legal counsel, Danilo Garrido, said: “This is the start of a new era of climate accountability at a global level. The ICJ advisory opinion marks a turning point for climate justice, as it has clarified, once and for all, the international climate obligations of states, and most importantly, the consequences for breaches of these obligations.
“This will open the door for new cases, and hopefully bring justice to those who, despite having contributed the least to climate change, are already suffering its most severe consequences.
“The message of the Court is clear: the production, consumption and granting of licenses and subsidies for fossil fuels could be breaches of International Law. Polluters must stop emitting and must pay for the harms they have caused.”
The Climate Group’s executive director of government and policy, Champa Patel, said:”This is an historic affirmation that states have legal obligations to act decisively on climate change. This strengthens the mandate for national governments to accelerate their climate action in line with international law. Legal certainty can not only strengthen domestic policy, but it can also unlock global cooperation.
“National governments are not alone in this endeavour. To achieve high ambition and accelerate the transition, governments should work with businesses, cities, states and regions. Their leadership and collaboration can help translate legal obligations into real-world impact, supporting national governments to meet their responsibilities and protect the rights of current and future generations.”
Fenton Lutunatabua, Deputy Head of Regions at 350.org, says: “The oceans are rising, but so are we. Once again, young Pacific Islanders have stepped up with courage and made sure that our reality, as a community on the frontlines of the climate crisis, is witnessed by the world’s highest court. Today’s outcome adds strength to our fight for our future, placing our basic human rights at the heart of states’ climate obligations, and setting a new legal and moral benchmark for climate action. The ICJ has upheld the call for greater accountability, at this crucial time for our survival. A line has been drawn, and high-emitting states now have the obligation to address their climate responsibilities head on.”
Anne Jellema, Chief Executive at 350.org, says: “This landmark outcome came about because Pacific youth chose to fight rather than drown, and it gives hope to everyone out there protecting their communities from being engulfed by climate chaos. Years of shameful delays and diversions by world leaders have pushed humanity to a precipice, but today, the ICJ has made it clear that our governments are obliged under law to act, and act now. That starts with agreeing on a concrete timeline at COP30 to draw the line against the fossil fuels overheating the planet.”
Dr Grethel Aguilar, IUCN Director General, said: “IUCN welcomes this important advisory opinion, which strengthens the global legal framework and reinforces the urgent imperative to limit warming to 1.5 °C. IUCN has been actively engaged at every stage of these historical proceedings and congratulates the ICJ on this key decision that will shape the future of our planet.
“Climate change is not only a crisis of rising temperatures; it is a crisis for both humanity and nature with profound implications for human rights. By undermining ecosystems, climate change weakens the life-support systems upon which people’s rights to life, health, food, water, and culture depend. As the global authority on the state of nature, IUCN urges all States to strengthen their commitments – recognising that protecting nature is not just part of the solution, it is essential to delivering climate justice and safeguarding our collective future.”
According to observers, the announcement comes at a time of unprecedented climate upheaval, marked by extreme weather events and record-breaking heating. These impacts, they stated, underscore the urgent need for decisive action and reinforce the importance of holding major polluters accountable for their contributions to this intersectional crisis. The advisory opinion must compel rapid fossil fuel phase outs and the necessity for climate finance, including reparations for loss and damage.
Across the globe, diverse movements are uniting in the face of intersecting crises. As climate change intensifies alongside rising living costs and ongoing conflicts worldwide, communities are coming together to demand systemic change and a just future for all.