The story so far: In a landmark announcement, the International Court of Justice (ICJ) on Wednesday (July 23, 2025) said countries and territories are obligated to combat climate change through efforts to the best of their capabilities. In a unanimous advisory opinion, the ICJ said rising temperatures and extreme weather events, caused because of human-induced climate change, lead to biodiversity loss and while risking human life and health.
According to the ICJ, it is the responsibility of the states to protect the earth’s climate systems and environment from anthropogenic greenhouse gas (GHG) emissions, and limit global warming.
What is an advisory opinion?
An advisory opinion of the ICJ is non-binding legal advice delivered by the international court, requested by the United Nations or its specialised agencies on specific matters.
The ICJ advisory opinion is usually a reflection of what is required to be done under international law.
Despite being non-binding, these opinions carry “legal weight and moral authority”, according to the UN.
What are the particulars of the opinion?
The ICJ opined that it is the duty of states to prevent environmental harm under customary international law and that states must reduce GHG emissions and protect the rights of present and future generations.
Climate change poses an “urgent and existential threat,” the court said. Its opinion relies heavily on observations of the Intergovernmental Panel on Climate Change (IPCC), an international scientific body under the UN that collects and organises evidence of climate change.
The Court emphasised that based on due diligence, countries are required to reduce their GHG emissions and support vulnerable nations. The due diligence does not end at adoption of measures but also includes “a certain level of vigilance in their enforcement and the exercise of administrative control”.
It also noted that the Nationally Determined Contributions, which are country-level en route to attaining net-zero emissions, fall under the principle of due diligence and that member states should ensure these goals represent their “highest possible ambition”.
The parties also have an obligation to do their best to achieve these targets.
According to the ICJ, climate action is not based on any one law but is rather a mix of international law provisions like the UN charter, and international treaties like the Kyoto Protocol, the UN Framework Convention on Climate Change (UNFCCC), and the Paris Agreement, among others, and that they should influence the actions that member states take to protect the environment.
These three international agreements are legally binding.
Although the opinion noted that it’s not the court’s responsibility to establish individual responsibility for damage to climate systems, it added the legal consequences arising from a breach of international agreements can lead to assurances and guarantees that such acts will be stopped and not repeated, as well as full reparations to affected states.
Countries and territories are also obligated, under international human rights law, to protect climate systems and other parts of the environment, the court said.
The ICJ also recognised the human right to a clean, healthy and sustainable environment in its opinion.
“UN climate negotiations have struggled over the last three decades to decisively address climate change, but the ICJ’s opinion will empower courts to hold states accountable for weak climate action, and support vulnerable countries in pushing for climate justice through lawsuits and negotiations,” Lavanya Rajamani, professor of environmental law at the University of Oxford, said.
How did the ICJ deliver this opinion?
The UN General Assembly formally requested the ICJ’s opinion on March 29, 2023, including on the obligations of states under international law to protect the environment mainly from GHG emissions, and the legal consequences of failing to do so.
The seeds of this discussion were however sown years ago, when a group of law students from the University of the South Pacific launched a campaign in 2019 for climate justice advisory opinion from the ICJ.
This led to the formation of Pacific Island Students Fighting Climate Change, a grassroots youth movement. The World’s Youth for Climate Justice joined forces with the movement in 2020.
In 2021, Vanuatu – a small island developing state in the South Pacific Ocean – said it would lead a diplomatic process to build support among nations for a UNGA resolution seeking an ICJ climate justice advisory opinion.
Vanuatu has been disproportionately threatened by climate change and has led multiple global efforts to address the effects.
In 2022, more than 1,500 civil society organisations joined Vanuatu’s diplomacy efforts for an ICJ advisory opinion.
What’s the opinion’s legality?
While an advisory opinion is legally non-binding, it can still influence judicial decisions and executive action.
“The advisory opinion can help in the development of international environmental law, especially when it comes to obligations of states and consequences of breach of law,” environmental lawyer Ritwick Dutta said.
“At present, international environmental conventions are weak on legal consequences of harm and violation. Further, the advisory opinion, by highlighting the interconnection between climate change treaties and other environmental convention such as Convention on Biological Diversity and UN Convention on Law of the Sea, might force the U.S. to finally ratify these treaties which they have evaded for years.”
What does the opinion mean for India?
The opinion talks extensively about protecting climate systems rather than only focusing on carbon emissions.
“This move beyond ‘carbon obsession’ would mean that measures to deal with climate change must be in consonance with protection of climate systems – river, grasslands, forest, oceans well as rights of both human and nature,” Mr. Dutta said.
“The narrow focus on climate led to judicial decisions in India such as the one on the great Indian bustard, where the Supreme Court highlighted the need to promote renewable energy to meet climate goals but undermined biodiversity conservation.
“As I see it, the fight against climate change will be now on holding the state and private entities liable for breach of its obligation to prevent harm to humans as well as the environment in totality.”
Although historically India hasn’t contributed significantly to GHG emissions, it is currently the third-largest emitter of greenhouse gases. It also continues to use coal as its primary source of energy but has ambitious plans to transition away. India is committed to reaching net-zero emissions by 2070.
“India’s official position is that it will move away from coal to cleaner modes of generating electricity. Therefore, the ICJ’s opinion is not contrary to the stand of India in coal,” according to Mr. Dutta.
“In an affidavit filed before the Supreme Court in M.K. Ranjitsinh v. Union of India, the Ministries of Power, Environment, and New and Renewable Energy had categorically taken the stand the dependence of coal is against both the economic interest of the nation as well has adverse impact on health of the citizens.”
The opinion doesn’t imply that the use of fossil fuels should stop but that its use should be rationalised by focusing on energy efficiency and by cutting subsidies, “especially when it comes to those who are not poor,” Mr. Dutta added.
“Despite its low per capita emissions and substantial energy access challenges, as a major carbon emitter with growing energy demands, India will undoubtedly face intensified pressure to ramp up its ambition and accelerate its transition away from fossil fuels towards renewable energy,” Harjeet Singh, a climate activist and founding director of the Satat Sampada Climate Foundation, said.
“The ICJ’s nuanced approach to differentiated responsibilities, which may question the static nature of ‘developed’ or ‘developing’ status based on current circumstances, directly challenges India’s traditional standpoint of limiting its climate responsibilities based solely on historical classifications.”
“This demands a careful recalibration of India’s global climate diplomacy. However, it is crucial to remember that the primary and overriding responsibility for the climate crisis, including the obligation for significant emission reductions and financial support, unequivocally remains with developed nations due to their disproportionate historical emissions and greater capabilities,” Mr. Singh added.
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