Unpacking the Implications of the International Court of Justice Advisory Opinion on Climate Change
The International Court of Justice (ICJ) made history with its long-awaited opinion on climate change in 2025. We’re laying out what states need to know about their legal obligations.
In July 2025, the ICJ delivered its landmark Advisory Opinion on the Obligations of States in Respect of Climate Change. The opinion provides authoritative legal guidance on states’ obligations to address climate change and prevent significant harm to vulnerable countries and communities. While the opinion is non-binding, it makes clear that failure to act can trigger legal consequences—applying the pressure urgently needed to accelerate ambitious climate action at international, regional, and national levels.
States require timely and accessible analysis to understand their legal obligations and the consequences of breaching them. This project aims to unpack the implications of the opinion and suggest clear actions governments can take to ensure compliance across five critical areas: climate adaptation, environmental impact assessments, environmentally harmful subsidies, international investment law, and multilateral environmental agreements.
Photo: Frank van Beek
What the ICJ Advisory Opinion Means For…
Climate Change Adaptation
States cannot continue to view climate change adaptation as voluntary. How can they demonstrate they are doing their best to meet international obligations?
Environmental Impact Assessments
End-use emissions from burning fossil fuels must now be factored into environmental impact assessments. What do states need to clarify when changing the rules?
Environmentally Harmful Subsidies
States now have a legal obligation to phase out subsidies that harm the environment. What steps can they take to reduce their legal risk?
International Investment Law
Investment protection cannot override states' climate obligations. How can states leverage this opportunity to align investment governance with climate action?
Multilateral Environmental Agreements
Multilateral environmental agreements can no longer operate in legal silos. How can states interpret and implement them in an integrated, coherent way?
Latest
You might also be interested in
IISD Next: Campus Workshop Series on Sustainability
A free workshop series on sustainability to educate and empower youth worldwide with tools on policy, sustainable development goals, and more.
Public Financial Support for Energy
Public financial flows influence the global energy landscape, shaping investment decisions by producers and consumer choices. In this project, IISD analyzes public financial support for both fossil fuels and clean energy as well as their socio-economic and climate effects.
Advancing the Transition Away from Fossil Fuels
IISD research supports the development of credible roadmaps to transition away from fossil fuels, providing practical guidance for policy-makers and practitioners.
Rethinking International Investment Governance
IISD’s long-running research project, Rethinking International Investment Governance, positions IISD at the forefront of global efforts to reimagine the outdated international investment regime and tailor it to the challenges facing decision-makers today. The project provides original research and new ideas across the main investment instruments: treaties, national laws, and investor-state contracts.