ICJ Climate Case: States Are Legally Obliged To Combat Climate Change, Says IUCN
The International Union for Conservation of Nature (IUCN) has asserted that States have binding legal obligations under international law to combat climate change and protect the global climate system. Legal experts from the IUCN presented these arguments during the International Court of Justice (ICJ) climate hearings, marking a significant moment in international climate law.
These obligations, the IUCN argued, derive not only from global climate treaties such as the Paris Agreement but also from human rights treaties, biodiversity conventions, the Law of the Sea, and customary international law. Failure to meet these obligations should result in accountability, the experts said.
“Every State has the obligation under international law to do its utmost to reduce greenhouse gas emissions in line with holding global warming to 1.5 degrees, limiting any overshoot, and reversing it,” stated Professor Christina Voigt, Chair of the IUCN World Commission on Environmental Law.
The IUCN presented its case on December 13, 2024, during the final day of oral hearings at The Hague. This landmark proceeding is the first time the ICJ, also known as the World Court, has addressed States’ obligations to mitigate climate change and the consequences of significant harm caused to the environment.
The case was initiated following a 2023 request by the United Nations General Assembly for an Advisory Opinion on States’ legal responsibilities regarding climate action. Nearly 100 States and 12 international organizations have participated in the historic hearings, submitting written briefs and oral arguments over several months.
The IUCN, which represents both State and non-State members, brought a distinctive perspective to the proceedings, drawing on the expertise of its 17,000 legal and scientific experts in 170 countries. Its delegation included Director General Dr. Grethel Aguilar Rojas, Prof. Christina Voigt, and Prof. Francesco Sindico, Co-chair of the Climate Change Law Specialist Group.
“This Advisory Opinion is pivotal in clarifying international law, shaping future climate action, and addressing the global climate crisis in an equitable and enforceable manner,” said Dr. Aguilar during the proceedings. She emphasized the opinion’s importance for vulnerable communities, indigenous peoples, migrants, women, children, and the natural world.
According to the IUCN, States are obligated under multiple legal frameworks, including the Paris Agreement, the UN Convention on the Law of the Sea, and international human rights treaties. Obligations include setting and adhering to nationally determined contributions (NDCs) and ensuring that actions within their jurisdiction do not harm other States’ environments.
Prof. Sindico stressed that States breaching these obligations should face legal consequences, including measures to fulfill their duties, prevent further breaches, and make reparations in the form of restitution, compensation, or guarantees against recurrence.
The ICJ is expected to deliver its Advisory Opinion in 2025. While the opinion will not be legally binding, it is anticipated to hold considerable influence, reinforcing the need for stronger accountability, international cooperation, and urgent action to limit global warming to 1.5 degrees Celsius.
This historic case underscores the growing intersection of international law and climate action, setting a critical precedent for global efforts to address the climate crisis.
