The right to a healthy environment is at the heart of the landmark Advisory Opinion 32/25 (AO-32/25) on the climate emergency from the Inter-American Court of Human Rights (IACtHR). After a detailed description of scientific evidence about the devastating impacts of the climate crisis, the IACtHR devoted more than thirty pages of its 234-page opinion to describing the content of the right to a healthy environment and the associated obligations of States. The IACtHR described the ongoing climate emergency as an existential threat to the future of humankind (paras. 289, 302), and identifies the right to a healthy environment “as the principal right affected by climate change” (para. 268). This blog post addresses three points related to the articulation of rights in the advisory opinion, namely the right to a healthy climate, the rights of Nature, and the recognition of a new jus cogens norm prohibiting massive and irreversible damage to the climate and the environment.
The IACtHR’s earlier jurisprudence on the right to a healthy environment
In AO-32/25, the IACtHR began its analysis of the right to a healthy environment, a right recognized in Article 11(1) of the San Salvador Protocol to the American Convention on Human Rights, by reiterating highlights of its earlier jurisprudence. Echoing its widely cited Advisory Opinion 23/17 (AO-23/17) on human rights and the environment, the IACtHR again described the right to a healthy environment as “fundamental to the existence of humanity” (para. 272).
The IACtHR also drew upon three of its earlier rulings in contentious cases involving the right to a healthy environment, all issued in 2024. In Pueblos Rama Y Kriol, Comunidad Negra Creole Indígena De Bluefields Y Otros Vs. Nicaragua, the IACtHR described the right to a healthy environment as comprised of a set of procedural and substantive elements. The procedural elements include access to information, public participation in environmental decision-making and access to justice with effective remedies. The substantive elements mentioned by the IACtHR include air, water, food, ecosystems and the climate, among others, as articulated by the UN Special Rapporteur on human rights and the environment.
In Inhabitants of La Oroya v. Peru, the IACtHR confirmed that clean air and clean water are substantive elements of the right to a healthy environment, effectively meaning that people have the right to breathe clean air and access safe and sufficient water. In U’wa Indigenous People and its members v. Colombia, the IACtHR highlighted that States must address the triple planetary crisis of the climate emergency, biodiversity loss and pervasive toxic pollution in an integrated, rights-based manner in order to fulfill their obligations under the right to a healthy environment.
The right to a healthy environment is consistently described by the IACtHR as an autonomous right, with individual and collective dimensions. At the individual level, environmental damage can have direct and indirect impacts on health, livelihoods, access to water, cultural practices, and more. At the collective level, the right belongs to present and future generations, both of whom require a healthy environment in order to survive, develop and flourish. Because of the wide-ranging impacts of environmental damage, the IACtHR reasoned, protection of the right to a healthy environment is a prerequisite for the enjoyment of all human rights. As the Supreme Court of Brazil (Supremo Tribunal Federal) warned in 2022 (see here), “there are no human rights on a dead or sick planet.”
The right to a healthy climate and associated State obligations
In AO-32/25, the IACtHR clarified that the right to a healthy climate is a substantive element of the right to a healthy environment. The IACtHR defines this right as requiring “a climate system free from anthropogenic interference that is dangerous to humans and to Nature as a whole” (para 300). Because the right to a healthy environment belongs to both present and future generations, States must avoid placing disproportionate burdens on either, by taking climate action (e.g. transitioning from fossil fuels to renewables) too slowly or too quickly.
The IACtHR explained that the right to a healthy environment and the right to a healthy climate require States to establish, implement and enforce a wide-ranging suite of measures to address the climate emergency (paras. 266 ff). These include mitigating and adapting to climate change, protecting Nature, and making progressive strides towards sustainable development. States are obligated to use the best available science and technology, complemented by traditional, local and Indigenous knowledge to address climate change.
For mitigation, States must: regulate, monitor and control, and require and approve environmental impact studies. Regulation includes defining a mitigation target, developing and implementing a rights-based mitigation strategy, and regulating the behavior of businesses. Regarding the appropriate target, the IACtHR highlighted the international consensus in the Paris Agreement on a temperature increase of no more than 1.5 °C above pre-industrial levels as valuable, but warned that even this seemingly ambitious goal does not eliminate the risk to millions of people in the region. Mitigation targets are to be as ambitious as possible, informed by a nation’s current and cumulative historical greenhouse gas (GHG) emissions, its capacity to contribute to mitigation measures, and other national circumstances (e.g. debt, poverty, inequality), with the long-term goal of being carbon neutral. States must adopt “binding measures” to achieve the mitigation target, apply the maximum available resources, avoid reliance on unproven technologies, and target the main sources of emissions (fossil fuels, agriculture and deforestation).
States must ensure that both domestic and international policies are consistent with climate mitigation objectives, a requirement which would seem to bring into question current policies ranging from fossil fuel subsidies to investor-State dispute settlement provisions in international trade and investment agreements that impede climate action (paras. 344, 351). The IACtHR repeatedly emphasized the importance of applying the polluter pays principle (e.g. paras. 216, 287, 350), and urged States to eliminate emissions of short-lived climate pollutants, such as methane, as quickly as possible (because this category of GHGs exacerbates the climate crisis in the short-term, para. 50).
With respect to fulfilling the rights to a healthy climate and environment through protecting Nature and increasing ecosystem resilience, mitigation strategies also must include “measures aimed at protecting biodiversity and ecosystems, particularly those that play a key role in the regulation of the climate system and the planet’s natural cycles, including the oceans and the marine and coastal environment, soils, forests and mangroves” (para. 339). According to the IACtHR, States must expand terrestrial and marine protected areas with a focus on ecosystems particularly vulnerable to climate change impacts (para. 366). In Latin America and the Caribbean, the IACtHR highlighted the Amazon, wetlands, coral reefs, mangroves, the Andean Altiplano and its tropical glaciers, the Mesoamerican Barrier Reef System, the La Plata Basin and the Chocó Region (Tumbes-Chocó- Magdalena) as ecosystems particularly susceptible to climate change (para. 366).
The IACtHR also called for the development of regional platforms for sharing climate information; assessing impacts and risks and planning appropriate adaptation measures based on science and traditional, local and Indigenous knowledge; and establishing and implementing effective mechanisms to monitor and evaluate the strategies and policies developed.
Of paramount importance to address climate change is the obligation of prevention, which requires States to regulate, supervise and oversee the activities of State-owned and private businesses that create risks to human rights. States themselves must act with enhanced due diligence because of the extremely serious impacts of the climate emergency and the urgency of effective measures to avoid irreparable impacts on people. To address emissions from businesses, States must “enact legislation obliging companies to conduct human rights and climate change due diligence along the entire value chain” (para 347). While such legislation exists in Europe, it is unprecedented in the Americas and the Caribbean. States must also require businesses to disclose and reduce their emissions, avoid greenwashing, avoid undue influence on climate policy, and support human rights defenders (para. 347).
Nature as a subject of rights
In AO-32/25, the IACtHR reiterated its statement from AO-23/17 that the right to a healthy environment “protects the components of the environment, such as forests, rivers, seas and others, as legal interests in themselves, even in the absence of certainty or evidence of risk to individual persons” (para. 273). However, the IACtHR went further in AO-32/25, pushing the boundaries of international human rights law by articulating an expansive conception of the rights of Nature as implicit in, or linked to, the right to a healthy environment because of the vital importance of healthy ecosystems and biodiversity that “make life on the planet possible” (para. 273). Nature, according to the IACtHR, has the “right to maintain its essential ecological processes” (para. 279). As a result, States “have a positive obligation to adopt measures to ensure the protection, restoration and regeneration of ecosystems” (para. 283).
The IACtHR further emphasized the importance of integrating rights-based climate action and rights-based protection of Nature: “The protection of the global climate system requires safeguarding the integrity of ecosystems and the living and non-living components that make up and sustain them. In turn, the preservation of climatic conditions compatible with life is essential to maintain the balance and functionality of these ecosystems” (para. 315). In all policies and actions to protect and restore Nature, States are obligated to respect the rights of Indigenous and tribal peoples, as well as other communities that have a close relationship with local ecosystems.
The rights of Nature are increasingly incorporated in legal systems in Latin America through constitutions (e.g. Ecuador, several Mexican states), legislation (e.g. Bolivia, Panama), and court decisions (e.g. Colombia, Peru). However, this concept is still at a nascent stage in the legal systems of the Caribbean, Canada, the United States and many other regions of the world. While the discussion of rights of nature in AO-32/25 is a potentially significant development, it must be noted that three judges dissented from the majority’s ruling regarding the recognition of Nature as a subject of rights.
The jus cogens nature of the obligation not to cause irreversible damage to the climate and the environment
Another remarkable aspect of AO-32/25 is that for the first time, an international court directly confronts the existential threat posed by multiple, related planetary environmental crises. Drawing upon well-established scientific evidence, the IACtHRt identified a list of human activities that threaten the ecological conditions necessary for life on Earth by directly causing irreversible damage to ecosystems, including:
- large-scale and irreversible deforestation of primary forests crucial for biodiversity, climate regulation and hydrological cycles;
- extensive and lasting destruction or damage to biodiversity with massive and irreversible loss of species and degradation of critical habitats;
- persistent and large-scale pollution of vital resources, such as freshwater sources, the oceans or the atmosphere, with long-lasting and irreversible effects on the health of species and the viability of ecosystems;
- the release of persistent toxic substances, large-scale radioactive contamination or severe ocean acidification; and
- the irreversible alteration of natural biogeochemical cycles such as carbon, nitrogen or phosphorus, on which the life of species on the planet depends, such as that produced by anthropogenic climate change in its extreme manifestations.
The IACtHR emphasized that the “development of the normative tools necessary to make the survival of present and future generations on a habitable planet feasible constitutes a universal value that is the subject of growing concern, deliberation and action on the part of the international community” (para 287). This leads to the IACtHR’s conclusion that there is a jus cogens norm prohibiting human activities that have massive and irreversible impacts on the climate, the environment or the vital balance of the planetary ecosystem (see Markus Gehring’s contribution to this symposium on this point).
The IACtHR added: “It is evident that the preservation of the vital balance of the ecosystem that makes the life of species – including our own – possible on the planet, constitutes a sine qua non condition for the validity of all human rights recognized by international law, and immediately the rights to life, integrity, health and non-discrimination” (para. 293). This is likely to be one of the most contentious aspects of AO-32/25, as reflected in the fact that three judges dissented on this point.
Courts are understandably cautious in articulating jus cogens norms because there are no derogations permitted by these powerful norms–they are binding on all States. Yet in light of the profound threats to human and more-than-human life posed by the climate emergency, the IACtHR’s reasoning seems unassailable. Actions that jeopardize the future of life on Earth should be prohibited by law.
Conclusion
In the face of recent backtracking on climate commitments by governments (e.g. United States and Canada) and businesses (e.g. major financial institutions, oil and gas companies), AO-32/25 comes at a critical juncture in the efforts to stave off an existential threat to many people, species, communities, ecosystems and nations.
Three of the most striking aspects of the ruling are the articulation of a right to a healthy climate, the expansive description of the rights of Nature, and the recognition of a new jus cogens norm prohibiting massive and irreversible damage to the climate and the environment.
Finding that a right to a healthy climate is a substantive element of the right to a healthy environment builds on a strong foundation of existing jurisprudence and is unlikely to be contentious. The right to a healthy environment enjoys widespread recognition at the national level, as 165 UN member States (over 85 percent of States) recognize this right in law. AO-32/25 is the latest in a series of developments advancing the right to a healthy environment, sparked by landmark resolutions of the UN Human Rights Council in 2021 and the UN General Assembly in 2022, that include international declarations, constitutional amendments, ground-breaking legislation, and court decisions.
The bold developments related to Nature as a subject of rights and a new jus cogens norm prohibiting irreversible damage to the climate and the environment are more likely to be controversial. While the IACtHR’s reasoning is sound on both issues, those who support the incremental development of international law through State-led negotiations rather than judicial intervention are likely to be critical.
At the end of the day, AO-32/25 marks the clearest ruling to date from an international court on the urgency of transformative changes to address the existential threat of the planetary environmental emergency caused by human activities. According to the IACtHR, the effective defence of the right to a healthy climate requires “moving decisively towards a truly sustainable development model that harmonises human activity with the ecological limits of the planet” (para 316). The ruling sets a high bar for the forthcoming advisory opinion from the International Court of Justice, which is also expected to address the right to a healthy environment and its implications for State action to address the climate crisis in its forthcoming advisory opinion.
David R. Boyd
David R. Boyd is a Professor at the University of British Columbia and the former UN Special Rapporteur on the human right to a clean, healthy and sustainable environment
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