International Court says that States are obliged to reduce carbon emissions
Historic decision acknowledges that the climate crisis jeopardizes human rights and imposes legal obligations to countries
O presidente da CIJ, Yuji Iwasawa, anuncia parecer sobre deveres legais dos Estados frente à crise climática, em Haia, 23/07/2025. (Foto: John Thys/AFP)
In a novel opinion, the International Court of Justice (ICJ), connected to the United Nations, declared that States are legally obliged to protect the global climate system from greenhouse gas emissions caused by human action. The decision, announced last Wednesday (23) in The Hague, is considered a high watermark in international law and reinforces the understanding that the climate crisis is an urgent and existential threat to human rights.
The consultive opinion was requested by the UN General Assembly in 2023, based on two main issues: the obligations of States, under international law, to protect the climate system; and the legal consequences for those who fail to observe these obligations. The document indicates that the omission or insufficient action of countries may constitute a violation of international law, subject to sanctions and accountability.
While reading the opinion aloud, judge Yuji Iwasawa highlighted that the impacts of climate change already severely affect ecosystems and populations worldwide. “Greenhouse gas emissions are unequivocally caused by human activity”, he stated. According to him, the right to a clean, healthy and sustainable environment is an essential condition for the exercise of other human rights.
Read more
The Court also gave legal weight to the Nationally Determined Contributions (NDCs) – climate commitments assumed by countries under the Paris Accords – and recognized the need for reparations in the face of environmental damages, particularly in cases that disproportionately affect insular and underdeveloped States and vulnerable peoples.
A victory for climate justice
In a press release, UN Secretary-General António Gutierres celebrated the decision: “This is a victory for the planet, for climate justice and for the power of youth in carrying out transformations”. To him, the opinion by the ICJ emboldens international accountability amidst a scenario of environmental emergency.
The opinion joins the ranks of the recent Advisory Opinion no. 32 of the Inter-American Court of Human Rights (I/A Court H.R.), published in early July, recognizing the direct responsibility of States in containing the climate crisis. The decision of the I/A Court H.R. establishes that the climate emergency structurally compromises human rights in the American continent and compels countries to act more diligently, based on the best science available and knowledge of local peoples.
The Inter-American Court also raised the obligation to prevent irreversible environmental damages to the category of peremptory norm (jus cogens). This level is seldom achieved in international legal decisions.
Both decisions indicate significant progress in the articulation between climate justice and international human rights protection. They also emphasize that the efforts to face the climate crisis require concrete commitments from governments and the engagement of all fields of knowledge, as the ICJ itself recognized.
“Though advisory in nature, the opinion of the ICJ is of legal and moral consequence when it states that a clean, healthy, and sustainable environment is a condition for the exercise of all human rights”, states Thales Machado, advisor at Conectas. “The decision strengthens the role of NDCs as an objective criterion when it comes to assessing State actions, expands possibilities of accountability for omissions and lends a voice to the Global South, which has historically been silenced”.
To Thales, by acknowledging the duty of States to control private entities under their jurisdiction, the opinion creates a path for comprehensive reparations for climate damage. “The emphasis on international cooperation and on loss and damage mechanisms also legitimizes the claims of developing countries”, he concludes.
