The International Court of Justice (ICJ) has issued a historic advisory opinion affirming that countries have a legal obligation to limit global warming to 1.5 degrees Celsius, marking a turning point in international environmental law and climate justice.
The court unanimously confirmed that climate change treaties create binding obligations for States to protect the climate system and environment from human-induced greenhouse gas emissions.
The court delivered its opinion following months of deliberations and public hearings that included statements from countries and international organisations such as the International Union for Conservation of Nature (IUCN).
According to a statement by IUCN, the ruling is particularly significant for its emphasis on both human rights and the protection of nature as central to tackling climate change.
“IUCN welcomes this important advisory opinion, which strengthens the global legal framework and reinforces the urgent imperative to limit warming to 1.5°C,” said Dr. Grethel Aguilar, IUCN Director General.
“Climate change is not only a crisis of rising temperatures; it is a crisis for both humanity and nature with profound implications for human rights. By undermining ecosystems, climate change weakens the life-support systems upon which people’s rights to life, health, food, water, and culture depend.”
IUCN said that its contributions carried particular weight given its unique role as a union representing both States and civil society.
Drawing on the expertise of more than 17 000 experts worldwide, including the IUCN World Commission on Environmental Law (WCEL), the organisation actively engaged in every stage of the proceedings.
Professor Christina Voigt, WCEL Chair and Lead Counsel for IUCN, highlighted the Opinion’s clarity: “Every State has an obligation under international law to act with a stringent level of due diligence to prevent global warming from exceeding 1.5°C. This duty stems not only from the Paris Agreement, but also from human rights law, the law of the sea, and the customary duty to prevent transboundary harm.”
Professor Francesco Sindico, WCEL Climate Change Law Specialist Group Co-Chair, noted that the court’s guidance “marks the end of a long journey” and offers a clear legal path for countries rooted in international treaties and customary law.
The ICJ’s opinion will now feed into upcoming milestones, including the IUCN World Conservation Congress in October this year and COP30 in Brazil in November, where States are expected to strengthen their commitments.
The court unanimously confirmed that climate change treaties create binding obligations for States to protect the climate system and environment from human-induced greenhouse gas emissions.
The court delivered its opinion following months of deliberations and public hearings that included statements from countries and international organisations such as the International Union for Conservation of Nature (IUCN).
According to a statement by IUCN, the ruling is particularly significant for its emphasis on both human rights and the protection of nature as central to tackling climate change.
“IUCN welcomes this important advisory opinion, which strengthens the global legal framework and reinforces the urgent imperative to limit warming to 1.5°C,” said Dr. Grethel Aguilar, IUCN Director General.
“Climate change is not only a crisis of rising temperatures; it is a crisis for both humanity and nature with profound implications for human rights. By undermining ecosystems, climate change weakens the life-support systems upon which people’s rights to life, health, food, water, and culture depend.”
IUCN said that its contributions carried particular weight given its unique role as a union representing both States and civil society.
Drawing on the expertise of more than 17 000 experts worldwide, including the IUCN World Commission on Environmental Law (WCEL), the organisation actively engaged in every stage of the proceedings.
Professor Christina Voigt, WCEL Chair and Lead Counsel for IUCN, highlighted the Opinion’s clarity: “Every State has an obligation under international law to act with a stringent level of due diligence to prevent global warming from exceeding 1.5°C. This duty stems not only from the Paris Agreement, but also from human rights law, the law of the sea, and the customary duty to prevent transboundary harm.”
Professor Francesco Sindico, WCEL Climate Change Law Specialist Group Co-Chair, noted that the court’s guidance “marks the end of a long journey” and offers a clear legal path for countries rooted in international treaties and customary law.
The ICJ’s opinion will now feed into upcoming milestones, including the IUCN World Conservation Congress in October this year and COP30 in Brazil in November, where States are expected to strengthen their commitments.
