By Asmaa Khadim, Guest Researcher, Leiden University, and Principal Consultant, Natura Legal and Policy Consulting

In a decision that could reshape the future of climate litigation, the International Court of Justice (ICJ) has made something unmistakably clear: climate change isn’t just about melting ice caps or rising seas – it’s also a human rights issue, with wide-ranging implications for how States are expected to protect their populations.

The ICJ advisory opinion, released in July 2025, articulated the legal duties of States in the face of global warming. For the first time, the ICJ connected the dots between environmental degradation and a wide spectrum of human rights – with health as an important consideration. The message is simple but powerful. Governments that fail to act on climate are not just neglecting the planet. They may also be violating the rights of their own people. The case has profound implications for health-based litigation moving forward.

The opinion was based on submissions from over 90 countries and organizations, many of which outlined serious public health threats already unfolding around the globe. These submissions, along with the Court’s opinion, build a compelling case for the centrality of health in climate governance, and offer a roadmap for litigants seeking accountability through the courts. The legal and moral takeaway? Protecting the climate is now squarely within the realm of protecting human lives.

ICJ’s recognition of climate connections to health

The ICJ addressed States’ obligations under international law in the face of worsening climate impacts. One significant outcome was the Court’s recognition that environmental harm, driven by inadequate climate action, directly impairs the right to health. The ICJ made four key findings that will likely influence everything from climate negotiations to lawsuits in domestic and international courts.

1. A healthy environment is integral to other human rights. In other words, the right to a healthy environment is not merely aspirational. It underpins the enjoyment of other rights, especially the rights to life and health. This reflects a growing global consensus that environmental integrity is inseparable from human well-being.

2. States have positive legal obligations. Governments must take concrete steps to protect human health from climate-related threats, like heatwaves, pollution, and the spread of disease. Choosing inaction is not neutral; it could constitute a breach of international law.

3. Vulnerability matters. The ICJ emphasized that the climate crisis hits some harder than others – particularly children, Indigenous communities, the elderly, and the poor. These disproportionate impacts are not just tragic; they’re legally relevant.

4. Health harms can lead to accountability. Perhaps most consequentially, the Court affirmed that when foreseeable climate harm leads to preventable health impacts, States may face legal responsibility, including obligations to repair the damage done.

These conclusions are not merely symbolic. They provide legal ammunition for courts, communities, and campaigners demanding serious action and accountability.

Health risks in a warming world

Analysis of the submissions to the ICJ reveals just how dire and diverse the health impacts of climate change really are. Nearly 80% of submissions explicitly raised health concerns. Among the most pressing were:

• Extreme heat is deadly. Countries from Africa to the South Pacific noted increased heat-related illness (e.g. heat exhaustion, heat stroke, and cardiovascular complications) and mortality from heatwaves, with children, the elderly, and outdoor laborers most affected.
• Infectious diseases are on the move. Many States flagged the expansion of vector-borne diseases such as dengue, malaria, chikungunya, Zika, tick-borne illnesses, and Schistosoma mansoni, driven by changing precipitation and temperature patterns.
• Water and food security are eroding. Droughts, salinization, crop failures, and ocean warming and acidification are jeopardizing access to clean water and stable food sources – fundamentals of public health, especially for the world’s poorest.
• Disasters aren’t just bad weather, they’re public health emergencies. Unpredictable rainfall patterns and extreme changes in precipitation resulting from climate change cause dangerous natural disasters, such as storms, floods, landslides, and droughts, contributing to significant and catastrophic injury and loss of life and damaging healthcare infrastructure.
• Pollution is intensifying. From toxic algal blooms to air pollution made worse by heat and wildfires, climate-driven pollution is directly linked to respiratory and gastrointestinal diseases.
• Mental and spiritual wellbeing is fraying. Psychological stress associated with the loss of homes, livelihoods, cultural heritage, and ecosystems can lead to mental health disorders. For many Indigenous communities, climate change also threatens not just physical safety but cultural identity, heritage, and psychological stability – particularly where sacred lands are at risk.

The ICJ took note. In elevating these harms to the level of legal obligations, the Court acknowledged that health impacts are not just unfortunate side effects; they’re central evidence of rights violations. Thus, health harms are not peripheral to climate law.

Health-based climate litigation: Promising avenues

So where do we go from here? The ICJ’s opinion doesn’t just set out principles – it points toward concrete legal strategies. The ICJ’s recognition of the right to health in the climate context opens new legal pathways and empowers affected communities to demand remedies through both domestic and international forums. Future climate cases may focus on four promising fronts:

• Air quality and fossil fuel pollution: Legal challenges can target governments for failing to enforce air quality laws or approving polluting infrastructure, especially in areas with rising respiratory illness.
• Heat wave preparedness and urban adaptation: Lawsuits demanding urban adaptation like heat action plans, public cooling centers, or green infrastructure, are gaining traction. Cities with documented mortality from past heatwaves that ignore the health consequences of rising heat may be exposing themselves to legal risk, particularly where vulnerable populations are concerned.
• Infrastructure and health system resilience: Climate-exacerbated disasters often disable hospitals and clinics. Future litigation could focus on States’ failures to climate-proof essential health infrastructure, or to conduct health impact assessments (HIAs) for large-scale projects in vulnerable regions.
• Environmental justice and vulnerable populations: Legal strategies may center on disproportionality. Courts have been more willing to act when evidence shows that vulnerable groups bear a greater share of health burdens. Litigation may allege violations of the rights to equality, life, and health under constitutional or international law.

On the international stage, litigants can also explore:

• Human rights complaintsbefore regional bodies (e.g. the Inter-American Court of Human Rights (IACHR) or the European Court of Human Rights (ECHR)), linking climate inaction to specific health harms;
• Cross-border claims when pollution or disease crosses national boundaries; and
• Climate finance lawsuits, where misallocation or neglect of adaptation funding undermines health resilience in developing countries.

Climate litigation is no longer just about carbon – it’s about care, prevention, and justice for the human body and mind.

A legal shift with life-saving potential

Health is no longer just a co-benefit of climate action; it is a core legal concern. The ICJ has validated what science and lived experience have long shown, that failing to address climate change is not only a breach of environmental stewardship, but it is also a failure to uphold the most basic rights of human beings.

Future climate litigation must continue to push courts to internalize this truth. By placing health at the center of legal arguments, advocates can appeal to both juridical logic and moral urgency, building a narrative that resonates with judges, policymakers, and the public alike. In doing so, they will not only shape the future of climate law – they will affirm that safeguarding human health is a legal imperative, and not a policy afterthought.

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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.