2.1. Climate and Health: From Broad to Targeted Research

Climate and health scholarship currently encompasses a broad range of stakeholders, such as researchers from climate science, public health, epidemiology, law, as well as international organizations and national institutions. Among international organizations, the Intergovernmental Panel on Climate Change (IPCC), the World Health Organization (WHO), and the Lancet Commission have become crucial sources of knowledge. When the first IPCC report was published in 1990, health issues were scarcely addressed.Footnote ²² However, reports have rapidly shifted their focus to heat-related mortality, infectious disease outbreaks, and displacement effects, and underlined that vulnerable groups (such as the elderly, people experiencing poverty, and those in disease-prone regions) were the most at risk from climate change.Footnote ²³ Confidence levels in these claims significantly increased,Footnote ²⁴ with more details on how specific groups face adverse health impacts through different pathways.Footnote ²⁵ On the health side, the WHO coordinates the collection and analysis of scientific data about climate and health, such as vulnerability and adaptation assessments, as well as developing research agendas for policymakers.Footnote ²⁶ For instance, the Research Agenda for Action on Climate and Health (REACH) initiative aims to support the translation of evidence into policy and practice.Footnote ²⁷ The Lancet also became an essential knowledge base when it established, in 2015, a Commission to assess the health impacts of climate change and develop policy guidelines. The Lancet Countdown on Health and Climate Change produces annual reports on the state of science on the interconnections between health and climate. Each yearly report dedicates a section to public and political engagement with health and climate change, showing that the number of scientific papers constitutes a growing body of literature.Footnote ²⁸ Epidemiologists have also contributed to the investigation of health and climate since the 1990s. The late epidemiologist Anthony McMichael, in particular, was a pioneer in exploring the relevance of epidemiological research in studying the health risks associated with climate change.Footnote ²⁹ He contributed to providing scientific evidence to strengthen the need for adaptive policies and participated in several IPCC reports.Footnote ³⁰

Regarding the unequal distribution of impacts among vulnerable populations, scientific research has underlined the importance of considering social determinants to understand the health impacts of climate change. According to the IPCC, ‘intersections of age, gender, socioeconomic class, ethnicity and race are recognized as important to the climate risks and differential impacts and losses experienced by vulnerable, marginal and poor in societies’.Footnote ³¹ It encourages considering social structures and power dynamics in the climate agenda.Footnote ³² Similarly, the WHO emphasized the unequal distribution of climate change impacts and their consequences on disparities between nations and populations.Footnote ³³ The WHO reports underline the importance of the social determinants of health to understand climate impacts and detail how gender, for example, influences climate adverse effects on the health of both women and men.Footnote ³⁴ Scientific scholarship has also engaged with such issues, as demonstrated by Li and co-authors’ scoping review of studies on social vulnerability, health and climate published between 2012 to 2022.Footnote ³⁵ The review, which includes 230 scientific papers, shows that some factors are more covered than others, despite the identification of 113 social vulnerability factors overall. Age, sex, education, economic status, poverty, ethnicity, and race are among the most widely studied factors globally.Footnote ³⁶ Aligning with the IPCC and WHO statements, Li and co-authors highlighted that the efforts to examine such issues resulted in a large body of literature able to ‘provide strong evidence for the role of social vulnerability and capacity in exacerbating or mitigating the negative impacts of climate change on a range of health outcomes – rendering some groups more susceptible to health-related harm than others’.Footnote ³⁷

2.2. Climate and Health: Science for the Courtroom

The link between climate change and health outcomes, particularly for vulnerable groups, goes beyond academic consensus. This has opened up new opportunities for using this evidence in legal contexts where establishing causation is crucial, such as in climate litigation. The sub-branch of climate science that assesses the extent to which greenhouse gas (GHG) emissions have caused specific types of climate-related harm, called attribution science,Footnote ³⁸ turned out to be essential for legal practice. The first attribution science study was conducted by climate scientists in 2004 to assess the extent to which human activities may have increased the risk of European heat waves in the summer of 2003.Footnote ³⁹ Since then, interdisciplinary work drawing on climate science, epidemiology, or economics has developed methodologies, particularly in the context of extreme event attribution, to determine how climate change affects the probability of specific extreme events.Footnote ⁴⁰

Since 2016, detection and attribution methods have been applied to health outcomes to detect changes in health over time and pinpoint which factors, including climate change, are responsible for the observed change.Footnote ⁴¹ Epidemiologists have conducted detection and attribution studies to determine whether climate change contributes to adverse health outcomes.Footnote ⁴² Through attribution methodologies, studies have revealed that deaths and illnesses can be attributed to climate change and that, based on these results, policymakers can make significant changes in health responses to climate change.Footnote ⁴³ Studies on health projections show a high level of agreement on the health risks associated with climate change; however, the diversity of methods used across these studies makes it challenging to combine their results quantitatively, and climate and health attribution research remains geographically limited.Footnote ⁴⁴

Current scientific knowledge on health and climate is nevertheless advanced enough to inform public policies or climate litigation.Footnote ⁴⁵ The stream bridging scientific climate knowledge and legal practice emerged to better integrate scientific evidence into legal claims and is now well established. Attribution studies can now link a weather event and its damage to GHG emitters, and the findings can be used to challenge their responsibilities.Footnote ⁴⁶ They are therefore particularly relevant for climate litigation, as they provide specific causal evidence.Footnote ⁴⁷ Scientists have worked to advance attribution science to help in overcoming the challenges of causation tests, the toughest in climate litigation.Footnote ⁴⁸ They have helped to link scientific evidence and standing, showing explicitly how attribution science helps to prove the alleged harm and, therefore, how climate change consequences are causing a concrete and particularized injury.Footnote ⁴⁹ Lawyers, in turn, have translated the methodology, framing, and results of climate studies into legal jargon to help the legal community to better understand them.Footnote ⁵⁰ The initiatives are numerous, whether to advise scientists on legal needs, educate judges on climate science, or conduct interdisciplinary litigation-focused research.Footnote ⁵¹ Rather than erasing disciplinary boundaries, this evolution reflects a growing collaboration between climate science, health sciences, and law. As a result, the study of scientific evidence related to health cannot be confined to a narrow disciplinary typology; it must instead consider a broad spectrum of evidence on health impacts.

3.1. The Rise of Intersectional Health Claims in Climate Litigation

The concept of ‘intersectionality’ has been used increasingly in the climate literature to help in understanding the causes and consequences of the climate crisis,Footnote ⁵² to the point that it has been described as a lens for examining the social determinants of health.Footnote ⁵³ Intersectionality is often attributed to Kimberlé Crenshaw’s work, but its origins are rooted in Critical Race Theory, the Black feminist movement, and the work of many authors, including Angela Davis, Patricia Hill Collins, and Bell Hooks.Footnote ⁵⁴ Intersectionality highlights how various forms of social identity – such as race, gender, class, and ability – interact to shape individual experiences of privilege and oppression.Footnote ⁵⁵ Crenshaw’s famous essays, ‘Demarginalizing the Intersection of Race and Gender’ and ‘Mapping the Margins’, revealed the limitations of discrimination law in understanding the intersection of factors contributing to oppression.Footnote ⁵⁶

In health-related climate litigation, an intersectional approach appears to be valuable, as some authors have already argued, for both its procedural and substantive promises.Footnote ⁵⁷ On the procedural side, admissibility criteria require that concrete and severe harm be demonstrated to grant standing. Although these requirements may vary from jurisdiction to jurisdiction, explaining how climate change disproportionately affects some individuals is often necessary to establish victim status. As intersectionality highlights the structural vulnerability of certain groups to climate change compared with the rest of the population, it should contribute to satisfying standing requirements.Footnote ⁵⁸ On the substantive side, intersectionality underlines that identities are not fixed categories that can be analyzed in a linear way and that some experiences can be understood only when integrating the intersection of factors such as race, gender, class, and age.Footnote ⁵⁹ For instance, an intersectional approach to the right to health in climate litigation helps to recognize overlapping inequalities that uniquely heighten the vulnerability of certain groups to climate change impacts.Footnote ⁶⁰ This would be valuable especially for the assessment of standing and the imminence of harm,Footnote ⁶¹ hence contributing to demonstrate a particularized health-related harm caused by climate change in the causal chain.

Despite the benefits of the intersectional approach for health-related climate litigation, several precautions relating to intersectionality should be considered. Firstly, there is a risk of essentializing plaintiffs and reducing their condition to an inherent vulnerability tied to their identity without highlighting the systemic and external aspects of these intersecting vulnerabilities.Footnote ⁶² As Hefti explains, the terms ‘victims’ and ‘vulnerable’ must be understood in their legal and procedural senses, not in the essentialist character they might imply.Footnote ⁶³ This is particularly relevant for health-related harm, where the claim should also be framed around the systemic aspects of the government’s failure to protect, rather than on the plaintiff’s vulnerability as an unchangeable parameter. Another potential risk related to essentialism revolves around the capitalization of plaintiffs’ lived experiences in climate litigation and the imposition of a burden to litigate. The intersectional approach for health claims is not merely used to leverage plaintiffs’ lived experience, but also to bring an intrinsic critical approach to the analysis of the legal reasoning. Here, it is worth recalling Crenshaw’s original aim in formulating intersectionality, which was to provide a critical tool for legal reasoning.Footnote ⁶⁴

With these precautions in mind, it is also important to clarify how intersectionality functions as an analytical lens in the present study. As demonstrated below, the legal claims filed in ‘unequal health impacts cases’ rarely, if ever, mention the term ‘intersectionality’. However, they often concern intersecting vulnerabilities, which, under current legal frameworks, are only partially recognized or codified. Given this gap between adverse effects and legal recognition, it is precisely in this context that intersectionality, as a tool for legal analysis, becomes crucial. It clarifies how various discrimination-related factors overlap to create specific types of harm and make this overlapping intelligible in a legal context. Indeed, the intersectional lens reveals the structurally produced, multilayered vulnerabilities, making them justiciable and therefore assessable through legal standards such as equality, non-discrimination, or the positive obligations of the state. This statement constitutes a foundational premise: intersectional analysis, as a critical interpretive framework for the study, serves as both an analytical tool and a normative bridge, without assuming that courts currently have the institutional capacity to recognize these intersecting vulnerabilities as justiciable. In this respect, the article refers to ‘intersectional health claims’ as a doctrinal interpretation of the claims, rather than their original formulation.

3.2. A Case Review of the ‘Unequal Health Impacts Cases’

This subsection provides the methodological rationale for the case selection. The sample aims to gather cases that, even if not explicitly mentioning ‘intersectionality’, raise issues of intersecting health vulnerabilities to climate change. Case selection was made through four steps, which can be summarized as follows: (i) searching all health-related cases, (ii) refining the sample based on vulnerability factors, (iii) including only cases against governments, and (iv) selecting cases that have at least a complaint and a decision.

With regard to the first stage of the methodology, a sample of ‘health-related cases’ was created, followed by a selection of cases based on discrimination factors. Cases were filtered with different word searches. The first search was made in the Sabin Center database with the words ‘health’, ‘illness’, ‘sickness’, and ‘disease’ to select cases where health arguments were explicitly used in the lawsuit. Across both the United States (US) and non-US litigation filed from 1994 to 2024, 235 health-related cases were found – 129 in the US and 106 in other jurisdictions worldwide.

Cases were also chosen based on their consideration of factors such as race, gender, status, or age, thereby highlighting questions of intersectionality. Gender,Footnote ⁶⁵ race,Footnote ⁶⁶ Indigenous status,Footnote ⁶⁷ and ageFootnote ⁶⁸ are recognized as factors that exacerbate vulnerability to climate change. Different categories of plaintiffs bring health issues before the courts, mainly young people, women, and Indigenous groups. Therefore, ‘women’, ‘gender’, ‘race’, ‘ethnicity’, ‘Indigenous’, and ‘age’ were systematically searched in the entire database. Knowing that young people often bring issues of age before climate courts and that legal translation of their interest lies in the intergenerational equity principle,Footnote ⁶⁹ ‘future generations’ and ‘youth’ were also looked up to cover all cases that discuss age as a discrimination factor but would mention it differently.

In this second stage of the methodology, each category was placed in a table with six columns: cases involving health issues, cases related to gender, race/ethnicity, cases initiated by Indigenous peoples, cases about age and future generations, and cases based on the right to a healthy environment. Duplicates were extracted to include cases with health arguments and at least one other discrimination factor. After finding duplicates, these were put in another table: the ‘unequal health impacts climate litigation’ sample.

On a global scale, out of 106 health-related cases, 64 present other discrimination factors and bring intersecting health vulnerability issues. Regarding US litigation, only 5 cases bring out different discrimination factors out of 129. In this context, US cases are considered outliers based on the preference for global data to avoid US-centric results. Giving priority to global data serves a more comprehensive and inclusive understanding of legal patterns, transcending specific jurisdictional nuances. The case study includes the 5 relevant US cases; however, the US context is not used to conclude global phenomena in climate litigation. The aim is to ensure the broader applicability and relevance of findings, accounting for diverse legal frameworks beyond the specificities of the US.

Within this cross-jurisdictional analysis, a third specification on the methodology is that the study focuses on cases against governments, because these are considered to have a more significant duty to protect public health than private entities, bringing the total number of cases to 59. Finally, the fourth specification is that a case was considered adequate for the study when there was at least one complaint and a decision available to analyze how claimants frame their complaints and the judges’ reception of them.

This first step in the research brings one empirical finding and one substantive conclusion:

1. (1) In health-related climate litigation, 60% of claims focus on how health impacts are unequally distributed and present an intersectional dimension. Not only do plaintiffs argue that their health is at greater risk than the rest of the population, but they do so based mainly on intersecting factors.

2. (2) This ‘unequal health impacts climate litigation’ sample is meant to examine how legal systems address or fail to address the health needs of marginalized or disadvantaged groups, particularly in the context of broader social determinants of health. It can be defined as a collection of legal cases selected because they involve situations where health inequities arise from factors such as race, ethnicity, gender, or age. The unequal health impacts of climate change, as well as the intersectional lens, are reflected in climate litigation, as is now evidenced by empirical data.

4.1. Tracing Scientific Evidence in Six Cases

The systematic case selection is based on criteria that address the research question’s ambitions (1). A coding scheme or an analysis protocol is then defined to ensure the best objectivity and reproducibility of the study (2). Finally, a qualitative analysis is produced from the collected empirical data (3).Footnote ⁷⁰ Firstly, the criteria for selecting the cases have been outlined in Section 3.2. Then, the coding scheme or analysis protocol is created on the research questions mentioned in the introduction and health arguments are systematically examined to answer whether they are legal, scientific, or factual. The study analyses, firstly, how health arguments and their legal and scientific bases are formulated in complaints; secondly, how judges receive these arguments in their decisions and the judicial reasoning mechanisms that they employ.

The six cases studied are the following: Demanda Generaciones Futuras v. Minambiente (Colombia); Dini Ze’ Lho’Imggin et al. v. Her Majesty the Queen (Canada); Juliana v. United-States; Verein KlimaSeniorinnen Schweiz and Others v. Switzerland; Sacchi and Others v. Argentina and Others; and Women from Huasco and Others v. Government of Chile, Ministry of Energy, Environment and Health. The cases were selected because they best represent the various jurisdictions, plaintiffs, and legal systems of the larger sample. They reflect the diversity of the larger sample in terms of jurisdiction (both domestic and international), legal system (civil and common law), and procedural status (pending and decided). Care was taken to ensure a geographically balanced selection that includes cases from the global north and global south, rather than focusing solely on one region. These cases also involve a diverse range of plaintiffs, including elderly women, young people, and Indigenous groups, encompassing a broad spectrum of identities across age, gender, and ethnicity (Table 1).

Table 1.

Introduction of the Six Cases and the Intersectional Lens

Table 1 Long description

A table comparing six legal cases involving climate change and health issues. The table has six rows and four columns. The columns are labeled Social factors increasing vulnerability, Health issues, and Intersectional health claims. Each row corresponds to a different case: Demanda Generaciones Futuras v. Minambiente (Colombia), LhoImggin v. Her Majesty the Queen (Canada), Juliana v. United States (US), Verein KlimaSeniorinnen Schweiz and Others v. Switzerland (Switzerland; ECTHR), Sacchi and Others v. Argentina and Others (UN CRC), and Women from Huasco and Others v. Government of Chile (Chile). Row 1: Demanda Generaciones Futuras v. Minambiente (Colombia). Social factors increasing vulnerability: Age (young people), Indigenous status (some). Health issues: Vector-borne diseases, cardiovascular diseases, access to water, climate anxiety. Intersectional health claims: Yes, highlights how children, particularly from Indigenous communities, are unequally affected. Row 2: LhoImggin v. Her Majesty the Queen (Canada). Social factors increasing vulnerability: Indigenous status, age (young, some). Health issues: Disease, premature death, psychological and social trauma as a result of political and historical background. Intersectional health claims: Yes, emphasizes how historical and political context (Indian Act, residential schools, racial discrimination) exacerbates climate vulnerability for Indigenous groups. Row 3: Juliana v. United States (US). Social factors increasing vulnerability: Age (young plaintiffs), Indigenous status (some). Health issues: Respiratory diseases, heat-related illnesses, mental health issues, asthma, pollen allergies. Intersectional health claims: Yes, argues that age and Indigenous status increase vulnerability to climate change impacts. Row 4: Verein KlimaSeniorinnen Schweiz and Others v. Switzerland (Switzerland; ECTHR). Social factors increasing vulnerability: Age, gender (elderly women). Health issues: Heat-related illnesses and mortality. Intersectional health claims: Yes, focuses on how older women are disproportionately affected by heatwaves. Row 5: Sacchi and Others v. Argentina and Others (UN CRC). Social factors increasing vulnerability: Age (children), Indigenous status (some). Health issues: Malnutrition, waterborne diseases, respiratory problems, weakness, dizziness, emesis. Intersectional health claims: Yes, highlights how children, particularly from Indigenous communities, are unequally affected. Row 6: Women from Huasco and Others v. Government of Chile (Chile). Social factors increasing vulnerability: Gender (women), age (children, older adults), socio-economic status (poverty). Health issues: Health risks from pollution and GHG emissions, respiratory diseases. Intersectional health claims: Yes, emphasizes how women and children bear a disproportionate burden of health issues, compounded by poverty.

4.2. Complaints: Plaintiffs’ Scientific Claims

In Dini Ze’ Lho’Imggin et al. v. Her Majesty the Queen (Lho’Imggin),Footnote ⁷¹ two Indigenous groups filed a complaint in 2020, claiming that Canada’s climate policy objectives were insufficient and violated principles of public trust, equitable waste, and intergenerational equity. The plaintiffs argued that their right to life was infringed by an increased risk of premature death caused by climate change. They further contended that their health was at heightened risk, exacerbated by systemic discrimination based on their Indigenous status, which compounded their vulnerability to climate-related impacts. In 2021, the Federal Court of Canada dismissed the case on grounds of competency.Footnote ⁷² On 26 September 2025, the Federal Court struck down the plaintiffs’ further amended claim but granted them leave to amend once again, allowing them to pursue a novel common law tort claim based on alleged breaches of customary international law.Footnote ⁷³

The legal basis of the complaint is rooted in health- and equality-related rights enshrined in the Canadian Charter of Rights and Freedoms.Footnote ⁷⁴ Specifically, it drew on Section 7, which protects every individual’s right to life, liberty, and security of the person, and Section 15(1), which guarantees equality before and under the law, equal protection, and the benefit of the law without discrimination.Footnote ⁷⁵ The plaintiffs invoked the risk of disease, premature death, and decreased food security.Footnote ⁷⁶ They explained how:

This claim highlights the intersectional approach to health impacts from climate change and emphasizes that historical and political contexts are crucial in understanding climate vulnerability. The plaintiffs also underlined the vital role of their lands, as well as their connection to fisheries and aquatic ecosystems, to explain that damage to their natural habitat has a direct impact on their health and well-being.Footnote ⁷⁸ Finally, with regard to scientific evidence, the Lho’Imggin complaint did not contain any citations or references to scientific studies. The health-related arguments, therefore, were only of a factual and legal nature, and relied primarily on descriptive narratives of climate impacts.Footnote ⁷⁹

Demanda Generaciones Futuras v. Minambiente (Colombia)Footnote ⁸⁰ was filed by 25 young plaintiffs challenging Colombia’s climate policies, particularly regarding the deforestation of the Amazon. The plaintiffs argued that climate change, exacerbated by inadequate governmental efforts to curb deforestation, violated their rights to a healthy environment, life, health, food, and water.Footnote ⁸¹ Using a tutela action (a constitutional mechanism in Colombia designed to protect fundamental rightsFootnote ⁸² ), they claimed that the deterioration of the Amazon ecosystem jeopardized their health and livelihoods.Footnote ⁸³ In 2018, the Supreme Court of Colombia overturned an initial dismissal and recognized the fundamental links between health, life, minimum subsistence, freedom, human dignity, and the environment.Footnote ⁸⁴ Notably, the Court declared the Amazon Forest to be a subject of rights, emphasizing the direct impact of climate change on the plaintiffs’ health and well-being.Footnote ⁸⁵

In the complaint, the plaintiffs challenged the state’s inaction to stop deforestation in the Colombian Amazon as a threat to their fundamental right to life with dignity, to water, to health, and to food.Footnote ⁸⁶ They used the Colombian Constitution, which protects the right to health and its correlative obligation for the state to organize, direct, regulate, and guarantee its provision.Footnote ⁸⁷ The complaint offered a very detailed record of the way in which the plaintiffs’ lives and health are affected by climate change.Footnote ⁸⁸ Whether it is the threat of contracting vector-borne or cardiovascular diseases, access to water, or climate anxiety, the plaintiffs explained how these risks affected their right to health. They successfully explained how the temperature increase had an impact on their daily lives, outdoor activities, social relationships, and professional projects. Most of the claims were substantiated by references to scientific studies. For example, they referred to many reports from the WHO about heatwaves, waterborne diseases, and environmental health. They also based their claims on studies by the Institute for Hydrology, Meteorology, and Environmental Studies (IDEAM)Footnote ⁸⁹ about rainfalls, risks, and vulnerability.Footnote ⁹⁰ There was a strong mobilization of health-related climate science showing the impacts of the climate crisis on specific health outcomes, such as outbreaks of illness.

Women from Huasco and Others v. Government of Chile, Ministry of Energy, Environment and Health was a constitutional action filed on 25 November 2021 by a group of women against the Chilean government’s decision to shut down two units of a thermoelectric power plant.Footnote ⁹¹ Despite Chile’s commitment to the Paris Agreement and its decarbonization agenda, the government scheduled the plant’s closure for 2040, against which the plaintiffs argued. The Court of Appeals of Copiapo considered the petition a disagreement with the state’s decarbonization policy rather than a legal omission warranting constitutional review. It dismissed the case, arguing that the issue was not a judicial matter but rather a question that fell within the scope of political decision-making.Footnote ⁹²

The complaint highlighted the health risks posed by prolonged exposure to pollution and GHG emissions, with particular emphasis on the health of women and children, who bear a disproportionate burden of climate-related health issues. The claimants invoked the constitutional right to life and the physical and mental integrity of the person,Footnote ⁹³ the right to equality before the law,Footnote ⁹⁴ and the right to health, which is protected under constitutional law regulating the exercise of the constitutional right to health protection.Footnote ⁹⁵ In this case, factual and scientific grounds were intertwined as well. The plaintiffs explained:

The climate-related science in this complaint was framed primarily around decarbonization policies and the impact of fossil fuel combustion on GHG emissions. With regard to health-related science, the complaint mobilized numerous studies, from international organizations such as the WHO, and from local institutions such as the Municipality of Huasco and the Regional Ministerial Secretariat of Health of the Atacama Region, both of which recognize the health impacts of pollution.Footnote ⁹⁷ The plaintiffs explicitly cited epidemiological and medical studies on changes in pulmonary function and respiratory symptoms, and referred to studies on lung function in children, as well as those on increased mortality and respiratory consultations.Footnote ⁹⁸ They also integrated local evidence with disease statistics compiled by the Municipality of Huasco and a 2021 study by the School of Public Health of the Pontificia Universidad Católica de Chile, which showed higher morbidity rates in Huasco and records of hospital discharges being higher as a result of respiratory diseases.Footnote ⁹⁹ The complaint combined environmental studies, epidemiological evidence, and institutional reports, highlighting the health impacts of climate change.

Juliana v. United States Footnote ¹⁰⁰ was initiated in 2015 by 21 young plaintiffs, who challenged the US government for violating their constitutional rights by failing to address climate change adequately. The plaintiffs asserted that the government’s inaction endangers their rights to life, liberty, and property, and undermines their ability to live in a stable climate, in violation of the Fifth Amendment of the US Constitution.Footnote ¹⁰¹ They further argued that climate change has serious health implications, including increased risks of respiratory diseases, heat-related illnesses, and mental health challenges caused by environmental degradation. After years of procedural battles, Judge Aiken allowed an amended complaint to proceed to trial in 2018.Footnote ¹⁰² However, in May 2024, the Ninth Circuit dismissed the case for lack of standing, followed by a decision of the US Supreme Court in March 2025, denying the plaintiffs’ petition for a writ of certiorari.Footnote ¹⁰³

In the complaint, the plaintiffs described themselves as ‘an insular minority with no voting rights and little, if any, political power or influence’.Footnote ¹⁰⁴ Although age, Indigenous status, and health issues do not intersect for each plaintiff, they argued that the age and the Indigenous status of some of them were increasing risk factors for climate change.Footnote ¹⁰⁵ The complaint also provided a detailed record of the plaintiffs’ health impacts, ranging from psychological and emotional harm, health and bodily integrity, personal well-being, recreational interests, asthma, pollen allergies, to disruptions to cultural practices.Footnote ¹⁰⁶ The plaintiffs mentioned the fact that fossil fuel extraction and combustion are contributing to many different health impacts,Footnote ¹⁰⁷ that 8,000 Americans died from health-related illnesses, and pointed out the increase in Lyme disease and asthma over the last three decades.Footnote ¹⁰⁸ The plaintiffs cited the scientific consensus regarding climate change risks, the role of climate change in sea-level rise, and National Aeronautics and Space Administration (NASA) records of the hottest years.Footnote ¹⁰⁹ The complaint integrated various scientific evidence to substantiate health claims, combining personal experiences of harm, links between fossil fuel extraction and health impacts, and references to empirical evidence.Footnote ¹¹⁰

Verein KlimaSeniorinnen and Others v. Switzerland,Footnote ¹¹¹ challenging the Swiss government’s climate policies, was initiated in 2016 by a group of elderly women, asserting that these omissions breach the sustainability principle,Footnote ¹¹² the precautionary principle,Footnote ¹¹³ and their right to life.Footnote ¹¹⁴ The plaintiffs claimed that the government’s inaction violates their rights to life and health, emphasizing their heightened vulnerability to climate-related health impacts as a result of their age and gender. Specifically, they argued that rising temperatures disproportionately affect older women, leading to higher rates of heat-related illnesses and mortality. To substantiate their claims, they relied on IPCC reports, WHO reports on gender, health and climate, and reports of national institutions such as the Federal Office of Public Health, the Federal Office for Agriculture, and the Federal Office for the Environment.Footnote ¹¹⁵ They underlined the state’s obligation to protect them as the ‘most vulnerable group’.Footnote ¹¹⁶ The Swiss case was especially interesting for its combination of diverse scientific evidence (international reports, local studies, medical certificates), and its strategic focus on localized data specific to Switzerland.Footnote ¹¹⁷

After being dismissed by the Swiss Federal Tribunal, the plaintiffs brought the case before the European Court of Human Rights (ECtHR). In April 2024, the ECtHR issued its first ruling on climate change,Footnote ¹¹⁸ recognizing violations of Articles 6 and 8 of the European Convention on Human Rights (ECHR).Footnote ¹¹⁹ While beyond the scope of the study, the ECtHR decision is worth underlining as it set standards for victim status and underlined the need to consider ‘local conditions and individual specificities and vulnerabilities’.Footnote ¹²⁰ The Grand Chamber emphasized ‘a high intensity of exposure to the adverse effects of climate change’ requiring significant levels of harm or risk and demonstrating the ‘pressing need to ensure the applicant’s individual protection’.Footnote ¹²¹ While the Court described this threshold as ‘especially high’,Footnote ¹²² it also insisted on considering local conditions, individual specificities, and vulnerabilities. This decision suggests that intersectional health claims may be increasingly relevant in climate litigation, as they can help to narrow the specificity of vulnerability required to meet this high threshold. However, this is nuanced by the fact that the ECtHR rejected the individual claims because they did not prove sufficient vulnerability,Footnote ¹²³ which raises questions about the health-related evidence that would be needed to meet this ‘especially high’ threshold.

Sacchi et al. v. Argentina et al. Footnote ¹²⁴ is the first case to be heard before the United Nations (UN) Committee on the Rights of the Child (CRC). The petition was filed by 16 children against Argentina, Brazil, France, Germany, and Turkey. They argued that the countries’ failure to reduce GHG emissions violated their rights to life, health, and cultural practices, affecting particularly children from Indigenous communities.Footnote ¹²⁵ They highlighted the health risks of climate change, including malnutrition, waterborne diseases, and respiratory problems, which disproportionately affect children in vulnerable populations.Footnote ¹²⁶ The petition called for recognizing these violations and urged the CRC to recommend mitigation and adaptation measures to address climate-induced health disparities. It triggered Article 24 of the UN Convention on the Rights of the Child, which requires states to ‘pursue full implementation’ of the ‘right of the child to the enjoyment of the highest attainable standard of health’.Footnote ¹²⁷ The plaintiffs revealed numerous adverse consequences of climate change: sea-level rise is threatening Pacific islands, forcing people to leave their homes;Footnote ¹²⁸ storms and sea-level rise have caused flooding in Tunisia;Footnote ¹²⁹ and diseases such as malaria and dengue fever have increased significantly in the Marshall Islands.Footnote ¹³⁰ The narratives around health impacts were very detailed, including symptoms such as weakness, dizziness, and emesis.Footnote ¹³¹ Regarding the scientific evidence, the plaintiffs also used reports from the IPCC, the UN Environment Programme (UNEP), and Climate Analytics, to support their claims and show how climate change can cause various health impacts.Footnote ¹³²

The cases discussed present some similarities worth outlining. With regard to the legal basis, the plaintiffs all refer to fundamental rights. Despite diverse legal traditions, there is a consistent use of national constitutions or charters. Reliance on fundamental rights in climate litigation has been observed for some time, and described as ‘the human rights turn in climate litigation’.Footnote ¹³³ Indeed, it is common for the legal protection of health to fall under the umbrella of fundamental rights, enshrined in approximately 67.5% of constitutions worldwide, as well as in international treaties and domestic statutes that establish the binding obligations of states to protect public health.Footnote ¹³⁴ Constitutional rights are recognized as a platform to address health inequalities and vulnerabilities, and to hold states accountable for their obligations in the judicial arena.Footnote ¹³⁵ It follows that cases from both common law and civil law countries ground claims in high-order legal norms, such as constitutional provisions, fundamental rights charters, or international human rights treaties.

The scientific evidence serves as a cornerstone in the building of complaints (Table 2). Lho’Imggin stands apart as the only complaint that did not rely explicitly on scientific evidence. In contrast, Generaciones Futuras, Women from Huasco, Juliana, KlimaSeniorinnen, and Sacchi all integrate diverse forms of climate and health-related scientific evidence. From epidemiological studies, public health data, and attribution science, the complaints mobilize international (WHO, IPCC, UNEP) and national (IDEAM, national health offices, universities) scientific bodies and reports to substantiate their arguments. Despite this real reliance on health-related scientific evidence, it appears that issues of intersecting vulnerabilities are not addressed through scientific evidence but mainly through plaintiffs’ narratives. Most cases effectively bridge global climate science with concrete, localized health impacts and personal narratives (for example, Women from Huasco, Generaciones Futuras, Juliana, KlimaSeniorinnen, and Sacchi). This is particularly visible in Generaciones Futuras, Juliana, and Sacchi, in which health narratives help to ground climate impacts into real lives and experiences, and exemplify the direct and concrete impacts on population and individual health. The plaintiffs highlight how climate affects their health and how their status (gender, age, race, ethnicity) is a vulnerability factor in climate adaptation. They seem to stand as context for judges, evidence for the plaintiffs’ standing and to function as climate impacts’ ‘mini laboratories’.Footnote ¹³⁶

Table 2.

Health-related Legal and Scientific Claims in the Six Complaints

Table 2 Long description

A table with six rows and five columns comparing health-related legal and scientific claims in six complaints. The columns are labeled Claim, Legal basis, Type of health-related scientific evidence used, and EDH. The rows are labeled with the names of the complaints: Demanda Generaciones Futuras v. Minambiente (Colombia), LhoImggin v. Her Majesty the Queen (Canada), Juliana v. United States (US), Verein KlimaSeniorinnen Schweiz and Others v. Switzerland (Switzerland; ECHR), Sacchi and Others v. Argentina and Others (UN CRC), and Women from Huasco and Others v. Government of Chile (Chile). Each row details the specific claims, legal basis, and types of scientific evidence used in each complaint. The table highlights the diverse forms of scientific evidence and legal arguments presented in each case.

4.3. Decisions: Judicial Engagement with Scientific Evidence

Among the six decisions, five dismissed the case for procedural reasons: lack of standing to sue/victim status, lack of competence, or failure to exhaust domestic remedies (Table 3).

Table 3.

First-related Decisions: Health Arguments and Scientific Evidence

Table 3 Long description

A table comparing health arguments and scientific evidence in legal cases across different countries. The table has six rows and four columns. Column headers are Health arguments mentioned, Scientific evidence used or mentioned, and Legal outcome. Row labels are Demanda Generaciones Futuras v. Minambiente (Colombia), Lho'Imgngin v. Her Majesty The Queen (Canada), Juliana v. United States (US), Verein KlimaSeniorinnen Schweiz and Others v. Switzerland (Switzerland; ECTHR), Sacchi and Others v. Argentina and Others (UN CRC), and Women from Huasco and Others v. Government of Chile (Chile). Each row provides details on health arguments mentioned, scientific evidence used or mentioned, and legal outcomes for each case.

In Lho’Imggin, the Federal Court studied the case and concluded that ‘while undoubtedly important, the issue of climate change is fundamentally political, not legal, and falls within the executive and legislative powers of government’Footnote ¹³⁷ and that the claims were doomed to fail.Footnote ¹³⁸ The judge emphasized that, although climate change impacts are real, there was no demonstrated direct causal link between GHG emissions and Canadian laws, and thus no connection with the alleged harm.Footnote ¹³⁹ As the plaintiffs did in the complaint, the Canadian Federal Court did not explicitly mention scientific evidence in the decision.

In the Colombian case, Generaciones Futuras, judges cited scientific studies showing how climate change has led to increased morbidity, difficulties in accessing healthcare services, and food insecurity.Footnote ¹⁴⁰ Most references to the scientific evidence presented by the plaintiffs were made in the background section of the decision. With regard to climate-related scientific studies, the Court reiterated the IDEAM temperature projections and the study of economic impacts of climate change.Footnote ¹⁴¹ As for health-related science, the Court referred to scientific evidence about the risk of increase in vector-borne diseases, respiratory diseases, and the difficulty in accessing health services because of climate change.Footnote ¹⁴² It also noted that Julio Carrizosa, a renowned environmental researcher and former head of IDEAM, supported the appeal, as did the Legal Clinic of Environment and Public Health (MASP) attached to the Faculty of Law at the University of the Andes in Bogotá (Colombia).Footnote ¹⁴³ However, the Court denied relief and stated that a tutela action was not the appropriate legal mechanism for such issues.Footnote ¹⁴⁴

Comparably, in Women from Huasco, the Court dismissed the case on justiciability grounds, stating that the issue was beyond its competence and concerned the executive branch. The Court explained that such matters require expertise and consideration of social, cultural, economic, and environmental factors, which fall beyond judicial review.Footnote ¹⁴⁵ It dedicated a significant portion of its written decision to transcribing the plaintiffs’ arguments, including all the scientific and health-related evidence they brought through the complaint.Footnote ¹⁴⁶ This extensive review of the scientific evidence presented by the plaintiffs cannot be interpreted as a validation from the Court, because in a recurso de protección the court must demonstrate that it has thoroughly considered the different bases of the claims.Footnote ¹⁴⁷ Consequently, while the Court’s engagement with the record acknowledged the importance of the evidence, the dismissal on justiciability grounds precluded the case from reaching a substantive assessment of the merits.

In Juliana, Judge Aiken denied the motion to dismiss, allowing the case to go to trial. Given that the motion to dismiss stage does not analyze the merits of the case, scientific evidence is not subjected to the same review as it would be at trial. The Court stated explicitly that ‘at the motion to dismiss stage, a federal court is in no position to say it is impossible to introduce evidence to support a well-pleaded causal connection’.Footnote ¹⁴⁸ It does not undertake a definitive assessment of scientific evidence but a control to determine if the plaintiffs’ allegations, which incorporate scientific concepts, are sufficient to proceed. The cited scientific elements are embedded within judicial decisions; Washington Environmental Council v. Bellon Footnote ¹⁴⁹ was used as a reference about scientific knowledge, with the mention, for example, that the effect on climate change of emissions from the five oil refineries was ‘scientifically indiscernible’.Footnote ¹⁵⁰ The decision further cited the work of Engel and Overpeck,Footnote ¹⁵¹ as well as Dr Hansen’s expert testimony.Footnote ¹⁵² As for health-related science, there was no specific mention made by the judge; however, health impacts appeared within the detailed descriptions of the plaintiffs’ alleged injuries. The parties indeed had to prove the specific and personal injuries they have experienced caused by climate change.Footnote ¹⁵³ The judge used the plaintiffs’ narratives to counter the government’s argument that these injuries were not particular to the plaintiffs, as climate impacts are affecting everyone globally. She explained that the widespread nature of the damage does not automatically make it a general grievance. Among others, Judge Aiken quoted the narrative of a 13-year old plaintiff about the damage caused by a flood. The testimony reported that ‘floodwaters were pouring into our home through every possible opening. … Soon the sewage was everywhere. We had a stream of sewage and water running through our house’, and also that the family had to stay in the flooded house for weeks after the event.Footnote ¹⁵⁴ Based on these narratives, the judge claimed that the alleged damage had an impact on the personal, economic, and aesthetic interests of the plaintiffs, qualifying the injuries as concrete and particularized.Footnote ¹⁵⁵

In KlimaSeniorinnen, the first instance tribunal acknowledged the variations of adverse impacts among different population groups.Footnote ¹⁵⁶ It mentioned IPCC reports and the Federal Office of the Environment report, and relied on scientific studies of past summer heatwaves, which had confirmed the statistical finding that older women, in particular, were affected most by summer heatwaves in terms of mortality and adverse health effects.Footnote ¹⁵⁷ The Court also noted the general impacts of climate change on people, animals, and plants, with varying effects across population groups. It cited heatwaves as a particular health burden, as a result of the formation of heat islands and the vulnerability of children to dehydration.Footnote ¹⁵⁸ The judges rejected the case by finding that elderly women (over 75) in Switzerland are not uniquely affected by climate change compared to the general public.

The UN CRC, in Saachi, dismissed the petition on procedural grounds, as the parties had not exhausted available remedies. While there were no specific scientific references, the CRC acknowledged the consensus that states’ GHG emissions contribute to climate change and its impact on human rights.Footnote ¹⁵⁹ It also acknowledged that existing scientific evidence demonstrates the impact of cumulative GHG emissions on the enjoyment of human rights.Footnote ¹⁶⁰ The CRC appreciated the allegations made by the parties and believed that:

In this case, the role of scientific evidence was essential, and the CRC relied on the scientific consensus while also considering health narratives as crucial in demonstrating victim status.