By Mohammadhossein Latifian
According to the Office of the United Nations High Commissioner for Human Rights (OHCHR), climate change poses an existential threat to the effective enjoyment of a wide range of human rights, including those to life, water, food and sanitation, health, housing, self-determination, culture and development. Yet, the adverse impacts of climate change are not limited to those rights but extend to ocean acidification, ocean warming, biodiversity loss, floods, droughts, state extinction, water pollution, hurricanes, and storms, among others.
On 12 April 2023, the UN General Assembly requested the ICJ to clarify the obligations of States regarding the protection of the climate system. This request also asked the Court to determine the legal consequences resulting from the breach of states’ obligations regarding climate change. In response to this question, the ICJ examined various aspects of the pressing issues of climate change, including the impacts of the anthropogenic greenhouse gas emissions on the oceans and the enjoyment of human rights.
On 23 July 2025, the International Court of Justice (ICJ) delivered its highly anticipated advisory opinion on climate change. The Court unanimously held that states have human rights obligations in respect of the adverse impacts of climate change. Failure to comply these obligations, the ICJ held, can engage State responsibility.
The UN Secretary-General António Guterres described the ICJ’s decision as a ‘victory for our planet’, which paves the way for further climate action. What follows examines the most significant contributions of the World Court to addressing the pressing issue of climate change.
Is Climate Science Admissible as Evidence Before the World Court? The ICJ’s Findings on the Scientific Aspects of Climate Law
The ICJ recognized the scientific evidence of the adverse impacts of climate change on the enjoyment of human rights and the oceans. Relying on the reports of the International Panel on Climate Change (IPCC), the Court recognized that ‘…the consequences of climate change are severe and far-reaching; they affect both natural ecosystems and human populations.…’. These consequences, According to the Court : “…underscore the urgent and existential threat posed by climate change”. Based on the reports of the IPCC, the ICJ found that limiting warming to 1.5 degrees above the pre-industrial level has become the scientifically based consensus target under the Paris Agreement.
Mitigation and Adaptation Obligation
Are Nationally Determined Contributions (NDCs) voluntary and discretionary?
In its advisory opinion, the ICJ interpreted the mitigation and adaptation obligations of State parties to the UNFCCC and the Paris Agreement in light of the customary obligation to prevent harm to the environment.
During the ICJ written proceedings, some high-emitting states, such as the United States, requested that the Court limit its Opinion to climate treaties, arguing that treaties like the UNFCCC and the Paris Agreement constitute the sole basis for states’ obligations regarding the climate system. In their view, mitigation obligations should not be interpreted beyond the climate treaty obligations. However, the ICJ rejected their view and found that climate treaties must be interpreted in light of the customary obligations of States, namely the duty to prevent significant harm to the climate system. The Court observed that the determination of the ‘significant harm to the climate system’ must be assessed based on the best available science.
One of the contributions of the ICJ advisory opinion is its interpretation of the Nationally Determined Contributions (NDCs). Nationally Determined Contributions (NDCs) are climate action plans that each country creates under the Paris Agreement. They show how the country will reduce its GHG emissions. Each country decides its own goals based on what it can do, and updates the plan every five years to make it stronger.
To understand the Court’s contribution, it is noteworthy that some participants, such as the US, requested the ICJ to identify the NDCs as voluntary and discretionary commitments. However, the Court rejected this view and held that the NDCs must not be interpreted as entirely ‘discretionary’ and that States have a due diligence obligation to do their utmost and realize the objectives of the Paris Agreement , including the goal of a 1.5 °C temperature rise by implementing their NDCs. In this regard, the Court observed that the standard of due diligence to be applied in preparing the NDCs is stringent, because the threat posed by climate change is serious and irreversible.
Regulating the Conduct of Private Actors and Corporations Responsible for GHG Emissions
GHG emissions can result from the activities of corporations, such as oil and gas companies. Therefore, it is necessary to regulate corporations’ conduct that produces GHG emissions. In its advisory opinion, the World Court emphasized the due diligence character of the mitigation obligations. The Court observed that states have an obligation to regulate the activities of private actors as a matter of due diligence.
Are States that Are Not Parties to Climate Treaties Still Responsible for the Harm to the Environment?
According to the ICJ, the non-party states to climate treaties have still responsibility to protect the climate system, as they must prevent significant harm to the climate system according to principles of customary international law, namely the obligation to prevent significant harm to the environment. Accordingly, these states can be held accountable for environmental harm, even if specific treaty obligations do not bind them.
On 20 January 2025, the United States withdrew from the Paris Agreement. The Court’s decision means that the Paris Agreement quitters are not safe and can be held accountable for their inaction.
UNCLOS and Climate Change: Obligations of States to protect the Marine Environment from GHG emissions
In recognizing the adverse impacts of climate change on the oceans, the ICJ stated that GHG emissions constitute the pollution of the marine environment within the framework of the United Nations on the Law of the Sea (UNCLOS). To the view of the ICJ, states parties to the UNCLOS have an obligation under Article 194, paragraph 1, of UNCLOS to take all necessary measures to reduce and control pollution resulting from the GHG emissions.
In examining the obligations of states to protect the marine environment, the ICJ has also drawn upon the jurisprudence of other international courts and Tribunals, including the Advisory opinion of the International Tribunal for the Law of the Sea (ITLOS) on climate change.
The Adverse Impacts of Climate Change on the Enjoyment of Human Rights
Is Human Rights law Applicable to the Question of Climate Change?
During the ICJ proceedings on climate change, some States argued that human rights law does not apply to the question of anthropogenic climate change emissions, because human rights conventions do not specifically address the issue of climate change. For instance, Australia argued before the ICJ that human rights instruments are not directly applicable to climate change, because they do not contain any express obligations in this regard. But, the ICJ rejected their view and stated that “the core human rights treaties, including the International Covenant on Economic, Social and Cultural Rights and the International Covenant on Civil and Political Rights, adopted in 1966, and the human rights recognized under customary international law form part of the most directly relevant applicable law”.
Right to a Clean, Healthy and Sustainable Development
In recognizing the applicability of human rights law to the question of climate change, the Court observed that ‘a clean, healthy and sustainable environment is a precondition for the enjoyment of many human rights, such as the right to life, the right to health and the right to an adequate standard of living, including access to water, food and housing’.
Taking Climate Obligations Seriously: Erga omnes character of the human rights obligations in respect of Climate Change
According to the ICJ, human rights obligations in respect of climate change have an Erga omnes character, as they pertain to the common concerns of humankind. According to the Court, that all States have a common interest in the protection of global environmental commons such the atmosphere and the high seas.
Can Countries sue Each Other? The Legal Consequences Resulting from the Harm to the Climate System
The ICJ stated that a breach of mitigation or adaptation obligations may constitute an internationally wrongful act, giving rise to state responsibility. States that have violated their mitigation obligation have a responsibility to cease and to provide assurances of non-repetition. Notably, the World Court held that responsible states may be required to pay full reparation to injured States in the form of restitution, compensation and satisfaction, provided that a sufficiently direct and certain causal nexus can be established between the wrongful act and the injury.
Conclusion
The ICJ advisory opinion is regarded as an authoritative interpretation, clarifying the obligations of states in respect of climate system. This opinion is characterized as a significant decision that has brought clarity and predictability to the obligations of states in respect of climate system, which is essential for states and private actors transitioning toward carbon neutrality. Furthermore, the Court’s decision could assist national courts in interpreting domestic climate laws and constitutional principles.
Mohammadhossein Latifian is a PhD candidate at Monash Law School. His research, titled “How Interpretation Shapes International Climate Law: On Semantic Innovations in the Anthropocene“, examines the role of international climate litigation in shaping the evolution of climate law.
This post was originally published on Castan Centre for Human Rights Law .