By Romina Picolotti and Sebastian Luengo, Institute for Governance & Sustainable Development (IGSD)

As climate change increasingly impacts our lives, international and regional judicial advisory opinions are reshaping our approach to the climate emergency from an international law perspective. We are at an historic juncture, with three major international courts issuing advisory opinions on States’ obligations to address the climate emergency. These opinions could become crucial tools in advancing human rights protection and science-based climate governance. They may prompt concrete, timely climate actions and policies, transitioning from discretionary to mandatory measures and potentially igniting a new wave of climate litigation.

Courts worldwide recognize that the climate emergency is a human rights emergency. Recent decisions include that of the European Court of Human Rights (ECtHR) in the case of Verein KlimaSeniorinnen Schweiz and Others v. Switzerland and the advisory opinion of the International Tribunal for the Law of the Sea (ITLOS). Furthermore, the UN Human Rights Committee and the Inter-American Commission on Human Rights (IACHR) have acknowledged that human rights law plays a crucial role in clarifying, shaping, and strengthening States’ obligations to address the climate crisis.

Two additional advisory opinions are expected in the coming months. First, the Inter-American Court of Human Rights (IACtHR), which held hearings on its pending advisory opinion in Barbados and Brazil earlier this year, is expected to issue an advisory opinion on the climate emergency and human rights in early 2025. Second, the International Court of Justice (ICJ), which is expected to deliver its advisory opinion on the obligations of States in respect of climate change in 2025, oral proceedings starting in December 2024.

As the climate crisis intensifies, advisory opinions from international courts can offer deeper insights into how international and regional legal frameworks can tackle this existential threat. Given the doctrine of conventionality control developed by the IACtHR, its advisory opinions have strong legal effects and apply to all three branches of state government. Conventionality control is the judicial mechanism exercised to verify that the laws, regulations, or actions of state authorities comply with the norms, principles, and obligations of the American Convention on Human Rights and other international treaties. An advisory opinion is the highest interpretation of the Convention.

From a human rights perspective, and considering the extraordinary harm posed by climate change, ensuring that the global temperature rise remains below 1.5°C above pre-industrial levels (or that any exceedance is limited) requires our courts and legal systems to reassess critical factors to protect citizens.

From discretionary to mandatory actions

Addressing the climate emergency is fundamentally about ensuring human rights protection. The IACtHR has acknowledged that severe, widespread, and irreversible environmental damage caused by climate change threatens human survival. The UN Secretary-General has concluded that this climate crisis is an existential threat. The ECtHR has also recognized that environmental degradation has serious and potentially irreversible adverse effects on the enjoyment of human rights. Similarly, the ITLOS has acknowledged that climate change represents an existential threat and raises human rights concerns.

Human rights law has historically played a pivotal role in limiting the discretion of States. Courts now have an extraordinary opportunity to ensure that States’ commitments to tackle the climate emergency are mandatory, by providing clarity on the legal obligations of States. Indeed, the discretion of States to act or not to act has placed humankind at great risk.

One of the most successful environmental treaties is the Montreal Protocol on Substances that Deplete the Ozone Layer. Its success lies in its mandatory obligations, which are time-bound and measurable, differentiated for developed and developing countries, and flexible enough to evolve over time to reflect new scientific, technical, and economic developments. The Protocol also established the Multilateral Fund, funded by developed countries, which provides financial and technical support to help developing countries phase out ozone-depleting substances (ODS). Additionally, it includes trade measures, such as prohibiting trade in ODS and products containing them between parties and non-parties and requiring licensing systems for ODS imports and exports. This combination of enforceable commitments, adaptability, and international collaboration has made the Montreal Protocol a model for effective environmental governance. It demonstrates that well-developed mandatory measures can deliver results at the scale and speed humanity needs. By interpreting the climate emergency through a human rights lens, courts can help States move from discretionary commitments to mandatory obligations.

The scope of the obligations

The IACtHR has a clear mandate from the advisory opinion request to clarify the scope of State obligations in their individual and collective dimensions to respond to the climate emergency within the framework of international human rights law.

The requirement for States to act upon the “best available science” is a cornerstone of international environmental law. For instance, the Paris Agreement on climate change requires parties to undertake rapid emission reductions “in accordance with the best available science” (Art. 4(1)) and to undertake a global stocktake of the implementation of the Agreement “in light of the best available science” (Art. 14(1)). Thus,climate science can meaningfully support the Court’s deliberations on the scope of human rights obligations – not only because it helps inform the content of the obligations but also because it offers clear guidance to States on how to address the climate crisis from a public policy and regulatory perspective.

Domestic courts have interpreted “best available science” to consist of the latest research and observations from organizations such as the Intergovernmental Panel on Climate Change (IPCC), the World Meteorological Organization (WMO), and the UN Environment Programme (UNEP), as well as independent research institutes, peer-reviewed academic research, and evidence from national scientific or specialist bodies. Therefore, science, not politics, can provide a solid basis for the Court’s interpretation of human rights conventions to establish specific obligations that match the scale and uniqueness of the climate crisis.

Science tells us that the climate emergency is a challenge of temperature, tipping points, and time. The Earth is already too hot at today’s 1.2°C of warming above pre-industrial levels. Tipping points are just ahead and will cause irreversible and catastrophic impacts. Without fast action to slow warming, we are likely to exceed the 1.5°C threshold by the end of the decade. The urgency of the climate crisis is evident in today’s impacts, and the window of opportunity to prevent massive, abrupt, and irreversible violations of the human rights to life, to health, to a healthy environment, and to food, among many other human rights, is shrinking. The ICJ and the IACtHR can help guide States to prevent such harm.

To address the climate emergency, we must slow the rate of warming as quickly as possible. A dual strategy to reduce both short-lived climate pollutants (SLCPs)and carbon dioxide (CO2) emissions is essential for keeping global temperatures within reasonably safe limits and protect human rights for present and future generations, although not necessarily sufficient. Failure to take effective measures or implement adequate measures to address the climate emergency could constitute a breach of international human rights law.

Courts can guide States in adopting science-based actions by mandating timely and effective mitigation, adaptation, and restoration measures before reaching irreversible climate tipping points, using the best available science, as the Institute for Governance & Sustainable Development (IGSD) proposed to the IACtHR and the ICJ in its amicus curiae briefs.

The human right to resilience

In response to escalating climate threats, recognizing the human right to resilience emerges as a critical imperative. Pope Francis, through his Planetary Call to Action for Climate Change Resilience, underscores this necessity.

The familiar climate conditions that have nurtured human civilization are rapidly changing. The evolving interpretation of human rights treaties must now encompass the existential threat posed by the climate emergency, recognizing the human right to resilience as a derivative of the right to life.

The human right to resilience refers to the right of every individual and group to access, develop, and maintain the capacity to withstand, adapt to, and recover from the adverse impacts of climate change. This right ensures that both present and future generations can sustain their essential functions, identities, and structure in the face of climate-related stresses and shocks. It requires that policies, investments, and actions by States, international institutions, and private entities prioritize climate change adaptation, mitigation, and restoration efforts that bolster the resilience of individuals and communities against the escalating threats of climate change.

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This Guest Article is part of a project that seeks to raise awareness and build momentum and knowledge around the ICJ advisory opinion on obligations of States in respect of climate change and to promote a better understanding of the implications of the advisory opinion among sustainable development decision makers.