Significant court decision met with pervasive dismay
The world is witnessing an unprecedented surge in climate-related legal cases, with over 2,900 active cases spanning nearly 60 countries. This trend is driven by advances in attribution science, which allows for the establishment of a link between human-induced climate change and extreme weather events.
A recent report by researchers from Imperial College London and the Indian Institute of Technology Bombay found that climate change made extreme rainfall 10 percent more intense and 70 percent more likely. This scientific evidence is paving the way for more climate litigation, putting fossil-fuel companies, investors, and governments on notice for their role in exacerbating the climate crisis.
However, establishing a causal link between climate change and the wrongful acts of a specific nation or group can be challenging. For instance, Nepal would need to prove that human-induced climate change caused the devastating flash floods that killed 244 in September 2020, and attribute the damage to a specific nation or group.
The International Court of Justice (ICJ) has acknowledged that countries could seek reparations for damage caused by climate change. In a landmark advisory opinion on 23 July 2025, the ICJ confirmed that states have legal duties under customary international law to act with due diligence to prevent transboundary environmental harm, including greenhouse gas emissions, and to cooperate to protect the climate system and environment.
This recognition of the customary international law right to a clean and healthy environment significantly impacts climate change litigation globally. It expands the legal grounds on which plaintiffs can hold states accountable, beyond treaty commitments, to a broader body of international law that requires states to prevent climate harm and to cooperate.
The ICJ's advisory opinion consolidates and elevates the right to a clean environment as a core customary international legal norm, reinforcing climate litigation strategies that rely not only on treaty obligations but also on general international law duties to prevent environmental harm and protect human rights linked to environmental health. This creates a stronger, more universal legal framework supporting ambitious climate action and accountability under international law.
While the ICJ concludes that it is not impossible to establish a causal link, each case must be proven factually. The ICJ ruling creates confidence to bring climate concerns to court, but it does not guarantee that funds will start flowing from polluting nations. The world is still faced with countries, such as the US, blatantly flunking their responsibilities to the planet, with little recourse likely.
As the tide of climate litigation rises, it is crucial to remember that accelerated climate action is needed, not just increased litigation. The ICJ's ruling provides a powerful tool for holding states accountable, but it is up to all of us to demand urgent action to combat the climate crisis.
References
- The ICJ Advisory Opinion on Climate Change
- The Right to a Clean and Healthy Environment: A Customary International Law Primer
- Climate Change and the Right to a Clean Environment: The ICJ Advisory Opinion and Its Implications for Climate Litigation
- The ICJ's Advisory Opinion on Climate Change: A Game Changer for Climate Litigation
- Advances in attribution science and the recognition of the customary international law right to a clean and healthy environment by the International Court of Justice (ICJ) are expected to bolster health-and-wellness, mental-health, and environmental-science research related to climate change, opening up new avenues for climate litigation.
- As more climate-related legal cases emerge globally, stemming from the ICJ's acknowledgment of countries' legal duties to act with due diligence to prevent transboundary environmental harm, it is essential to focus on both scientific research in fields like climate-change and health-and-wellness, and activism to advocate for accelerated climate action.
