Image Source: IUCN

Legal experts from the International Union for Conservation of Nature (IUCN) presented compelling arguments before the International Court of Justice (ICJ) on Thursday, asserting that states worldwide have binding legal obligations to protect the global climate system. The case, which marks a historic moment in international climate law, aims to clarify the responsibilities of states under existing global treaties, including those related to climate change, human rights, and biodiversity. It could also establish significant legal consequences for nations that fail to meet these obligations.

IUCN’s arguments were presented during the final day of oral hearings for the ICJ’s Advisory Opinion on the legal duties of states in combating climate change. The proceedings, which began in December 2024, have drawn participation from almost 100 countries and 12 international organizations, marking a pivotal moment in the fight for global climate justice. The Advisory Opinion, expected in 2025, will not be legally binding but is anticipated to carry substantial weight in shaping international climate policy.

Binding Climate Obligations Under International Law

During her intervention, Prof. Christina Voigt, Chair of the IUCN World Commission on Environmental Law, underscored that states must take urgent action to limit global warming to 1.5°C above pre-industrial levels, as agreed under the Paris Agreement. She emphasized that this responsibility stems from a combination of legal sources, including climate treaties, international human rights agreements, and customary international law. Voigt argued that every state has an obligation to reduce greenhouse gas emissions, prevent climate harm, and take effective action toward mitigating the climate crisis.

"Every state has the obligation under international law to do its utmost to reduce greenhouse gas emissions aligned with holding warming to 1.5 degrees," said Voigt, addressing the Court. "This includes not only reducing emissions but also reversing any overshoot in global temperature increases."

IUCN's involvement in the case is especially significant, as it represents a coalition of state and non-state actors, including more than 17,000 experts across 170 countries. This gives the organization a unique perspective as a bridge between governments, civil society, and the scientific community, ensuring that legal arguments are rooted in both legal precedents and cutting-edge climate science.

Image Source: IUCN

Legal Consequences for States Failing to Protect the Climate

The hearing also focused on the legal consequences that states could face for failing to uphold their climate obligations. Prof. Francesco Sindico, Co-chair of IUCN’s Climate Change Law Specialist Group, argued that states should be held accountable for breaching both treaty-based and customary international law obligations. He explained that failure to meet climate targets would not only require states to take corrective measures but also obligate them to provide reparations for the damage caused, including restitution, compensation, and guarantees against future violations.

"States would need to implement and effectively enforce measures to fulfill their climate obligations," Sindico told the Court. "They must also provide assurances that they will not breach their obligations again and make full reparations for the harm caused by their inaction."

IUCN’s Director General, Dr. Grethel Aguilar Rojas, highlighted the broader implications of the case for vulnerable populations, such as indigenous communities, women, children, and those living in regions most affected by climate impacts. She called on the Court to send a clear message to states and corporate actors responsible for emissions, urging swift, deep, and sustained reductions in greenhouse gases.

"This Advisory Opinion is crucial for shaping a more equitable and enforceable climate response," Aguilar said. "It will have a profound impact on the most vulnerable communities, who are already experiencing the devastating effects of climate change."

As the world continues to grapple with the escalating climate crisis, the ICJ’s upcoming Advisory Opinion will play a critical role in defining the legal parameters of state responsibility for climate protection, offering hope for a more accountable and collaborative global response to the climate emergency.