The Ecocide Tribunal

1. Introduction

1.1 Climate change is driven by human activities, principally through the emission of greenhouse gases (‘GHG’), and is taking an increasingly devastating toll on lives and health across the globe as well as causing irreversible harm to ecosystems and biodiversity. The science is clear: immediate and impactful measures are needed to safeguard human populations from the unavoidable impacts of climate change, while also protecting ecosystems and biodiversity from irreversible damage. To avoid pushing the climate system beyond the tipping point of adaptability, nations and corporations with the highest emissions must urgently reduce their GHG emissions. Only then can the health of vulnerable human communities and the biodiversity that underpins the stability of our planet be preserved.

1.2 Against this background of human-induced climate change, the People (the ‘Applicants’) submit this Complaint to the Court of the Citizens of the World (the ‘CCW’ or the ‘Court’) against five States, namely the United States of America, the Russian Federation, the Argentine Republic, the Kingdom of Saudi Arabia, and the People’s Republic of China (the ‘Respondents’).

1.3 The People’s Complaint is founded upon the advisory opinion (‘AO’) of the International Court of Justice (‘ICJ’) issued on 23 July 2025 (see section 3 below), which clarified the scope and nature of States’ obligations under international law to prevent and mitigate climate change. The ICJ’s AO affirmed that States are bound by customary international law, human rights treaties, and environmental conventions to take ambitious, science-based action to address climate change and protect vulnerable populations.

1.4 The People allege that each of the Respondent States have breached their international legal obligations to prevent and mitigate catastrophic climate change, thereby exposing their populations, the global community, future generations and the Earth’s ecosystems to foreseeable and preventable harm.

1.5 More particularly, the People allege that through acts and omissions, the Respondent States have:

• failed to adopt appropriate, substantial, rapid and sustained measures to mitigate GHG emissions;

• failed to regulate the emission of GHG by both private and public actors within their jurisdiction; and

• failed to provide adequate international cooperation and/or climate finance to assist vulnerable States and communities to mitigate and/or adapt to climate change.

2. Jurisdiction and Competence

2.1 The Court has jurisdiction to adjudicate the People’s Complaint and possesses the competence to do so in accordance with Rules 18 and 19 of its Statute.

2.2 The People have complied with the notification requirements set forth in Rule 39 of the CCW’s Statute and respectfully request that the Court proceed with the determination of the Complaint in accordance with its jurisdiction as outlined in the Statute.

2.3 As the ICJ clarified in its AO, States’ international legal obligations to address climate change are erga omnes partes obligations (paras 439-443), meaning these obligations are owed to all of humanity, including future generations.

2.4 The People’s Complaint asserts that each of the five Respondent States has violated their climate change obligations. The Court has the competence to determine whether these States have committed breaches of public international law, specifically in relation to their duties to combat climate change and protect human rights and the environment from the catastrophic effects of global warming.

3. Relevant legal framework

3.1 On 29 March 2023, the UN General Assembly (‘UNGA’) adopted Resolution 77/276 - which recognised that climate change is an ‘an unprecedented challenge of civilizational proportions and that the well-being of present and future generations of humankind depends on our immediate and urgent response to it’ - and formally requested that the ICJ provide an advisory opinion to answer the following questions:

• What are the obligations of States under international law to protect the climate system (and other parts of the environment) from anthropogenic GHG emissions, for present and future generations?

• What are the legal consequences under those obligations when a State, by their acts or omissions, causes significant harm to the climate system or environment, especially where harm is caused to particularly vulnerable States (such as small island developing States) and peoples and individuals of the present and future generations? 

3.2. On 23 July 2025, the ICJ delivered its AO, which was endorsed by all members of the Court. It provides authoritative clarification of the international legal responsibilities of States, specifically addressing their obligations to: 

• reduce GHG emissions; 

• implement adaptation measures to safeguard individuals from climate-related impacts; and 

• provide reparations for damage caused by climate change. 

3.3 The ICJ recognised the existential threat posed by climate change to both nature and humanity and the urgency of addressing the adverse effects of global warming:

‘The consequences of climate change are severe and far-reaching; they affect both natural ecosystems and human populations. Rising temperatures are causing the melting of ice sheets and glaciers, leading to sea level rise and threatening coastal communities with unprecedented flooding. Extreme weather events, such as hurricanes, droughts and heatwaves, are becoming more frequent and intense, devastating agriculture, displacing populations and exacerbating water shortages. Furthermore, the disruption of natural habitats is pushing certain species toward extinction and leading to irreversible loss of biodiversity. Human life and health are also at risk, with an increased incidence of heat-related illnesses and the spread of climate-related diseases. These consequences underscore the urgent and existential threat posed by climate change’ (para 73).

3.4 The ICJ noted that the 6th Assessment Report Summary for Policymakers (2023) issued by the Intergovernmental Panel on Climate Change (‘IPCC’) represents the best available scientific evidence and noted that:

‘75. The IPCC defines the climate system as “[t]he global system consisting of five major components: the atmosphere, the hydrosphere, the cryosphere, the lithosphere and the biosphere and the interactions between them” ….

76. According to the IPCC, climate change refers to “[a] change in the state of the climate that . . . may be due to natural internal processes or external forcings such as modulations of the solar cycles, volcanic eruptions and persistent anthropogenic changes in the composition of the atmosphere or in land use” …

77. The IPCC’s most recent reports were produced during the sixth assessment cycle, which was completed in March 2023 with the publication of Climate Change 2023: Synthesis Report. The Court observes that, in those reports, the IPCC found that widespread and rapid changes have occurred in the atmosphere, ocean, cryosphere and biosphere, and that “[h]uman-caused climate change is already affecting many weather and climate extremes in every region across the globe”. The IPCC stated that this has led to “widespread adverse impacts and related losses and damages to nature and people”, with vulnerable communities which have historically contributed the least to climate change being “disproportionately affected” …. In particular, the IPCC concluded that “[h]uman influence [is] very likely the main driver” of sea level rise since 1971 and has likely increased the chance of extreme events such as “heatwaves, heavy precipitation, droughts, and tropical cyclones” …. The IPCC also concluded with high confidence that climate change has caused substantial damage and increasingly irreversible losses in ecosystems, including the loss of species and biodiversity.

78. The IPCC has determined that approximately 3.3 to 3.6 billion people are highly vulnerable to climate change. It has concluded with high to very high confidence that, in all regions, increases in extreme heat events have resulted in human mortality and morbidity, and that there is an increased incidence of climate-related diseases. Moreover, increasing weather and climate extreme events have exposed millions of people to acute food insecurity and reduced water security. Individuals’ livelihoods have been affected through the destruction of homes and infrastructure, and the loss of property, income and human health.

79. The Court further notes that, according to the IPCC, “[h]uman activities, principally through emissions of greenhouse gases, have unequivocally caused global warming, with global surface temperature reaching 1.1°C above 1850-1900 in 2011-2020. Global greenhouse gas emissions have continued to increase, with unequal historical and ongoing contributions arising from unsustainable energy use, land use and land-use change, lifestyles and patterns of consumption and production across regions, between and within countries, and among individuals” …

80. More specifically, the IPCC has emphasized that the global surface temperature has increased faster since 1970 than in any other 50-year period over at least the last 2,000 years, that the increases in GHG concentrations in the atmosphere since around 1750 are unequivocally caused by GHG emissions from human activities (stating with high confidence that about 42 per cent of these cumulative emissions have occurred between 1990 and 2019), and that the concentrations of the three main GHGs (carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O)) are now higher than at any time in at least 800,000 years (very high confidence). It has noted that the average annual GHG emissions during 2010-2019 were higher than in any previous decade on record, and that emission reductions have been less than emission increases from rising global activity levels. The IPCC also underlined that historical contributions of GHG emissions vary substantially across regions, and that differences remain today, with the least developed countries and small island developing States having much lower per capita emissions of GHGs than the global average …

…

82. Furthermore, according to the IPCC, “[c]ontinued greenhouse gas emissions will lead to increasing global warming, with the best estimate of reaching 1.5°C in the near term [i.e. 2021-2040] in considered scenarios and modelled pathways. Every increment of global warming will intensify multiple and concurrent hazards . . . Deep, rapid, and sustained reductions in greenhouse gas emissions would lead to a discernible slowdown in global warming within around two decades, and also to discernible changes in atmospheric composition within a few years” …

83. The IPCC has also concluded with “very high confidence” that risks and projected adverse impacts and related loss and damage from climate change will escalate with every increment of global warming. It added that these risks, projected adverse impacts and related loss and damage are “higher for global warming of 1.5°C than at present, and even higher at 2°C” … Indeed, in 2018, the IPCC concluded with high confidence that “[w]arming of 1.5°C is not considered ‘safe’ for most nations, communities, ecosystems and sectors and poses significant risks to natural and human systems”.’

3.5 The ICJ then considered the first question it had been asked by the UNGA. It concluded that the international climate change treaties (including the United Nations Framework Convention on Climate Change (‘UNFCCC’) and the Paris Agreement) formed part of the directly relevant applicable law (para 121).

3.6 In addition, the ICJ concluded that: all States (including those that are not signatories to specific climate-related treaties (para 315)) have an obligation under customary international law to act with due diligence to prevent significant environmental harm (the ‘no-harm principle’) (paras 132-139); and that ‘the standard of due diligence for preventing significant harm to the climate system is stringent’ (para 138).

3.7 The ICJ also concluded that all States have a duty under customary international law to cooperate in good faith with other States to combat climate change (para 142 and para 457). 

3.8 Turning to human rights, the ICJ noted a number of decisions of regional human rights courts and UN treaty bodies where the interrelationship between human rights obligations and rules concerning the protection of the natural environment had been recognised, including the decision of the European Court of Human Rights in Verein KlimaSeniorinnen Schweiz v Switzerland (Grand Chamber, 9 April 2024, Application No. 53600/20); and the Advisory Opinion of the Inter-American Court of Human Rights on Climate Change. Having done so, the ICJ stated that both core human rights treaties and human rights recognised under customary international law form part of the most directly relevant applicable law (para 145 and para 457).

3.9 Consequently, the ICJ rejected the argument advanced by a number of States that their climate change obligations were limited to those laid down in international climate treaties, such as the UN Framework Convention on Climate Change and the Paris Agreement (paras 162–171). 

3.10 Instead, the ICJ expressly stated that the most directly relevant applicable law included not only those climate change treaties but also: 

‘… the customary duty to prevent significant harm to the environment and the duty to co-operate for the protection of the environment, and international human rights law, as well as certain guiding principles for the interpretation of various applicable rules and principles (sustainable development, common but differentiated responsibilities and respective capabilities, equity, intergenerational equity, and the precautionary approach or principle)’ (para 172).

3.11 On further analysis of the Paris Agreement, the ICJ noted that it had provided for limiting ‘global average temperature to well below 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5°C above pre-industrial levels’ (Paris Agreement article 2(1)(a)), but that States had subsequently agreed in the light of the latest scientific evidence to limit the global average temperature increase to 1.5°C above pre-industrial levels (para 224).

3.12 The ICJ also drew attention to the fact that the Paris Agreement imposed a duty on each State party to prepare and communicate nationally determined contributions (‘NDC’) that must set out the State’s efforts to reduce national emissions and adapt to the impacts of climate change (article 4(2)) and reflect ‘its highest possible ambition’ (article 4(3)). Having done so, the ICJ concluded that: 

‘… rather than being entirely discretionary as some participants argued, NDCs must satisfy certain standards under the Paris Agreement. All NDCs prepared, communicated and maintained by parties under the Paris Agreement must, when taken together, be capable of realizing the objectives of the Agreement which are set out in article 2’ (para 249).

3.13 Notably the ICJ also stated that:

• ‘[T]he climate change treaties [including the UNFCCC and the Paris Agreement] establish stringent obligations upon States to ensure the protection of the climate system and other parts of the environment from anthropogenic GHG emissions’ (para 268); and

• ‘While the scope and content of measures contained in the NDCs may vary in accordance with the means available to parties and their capabilities, parties do not enjoy unfettered discretion in the preparation of their NDCs. Each party has a due diligence obligation to do its utmost to ensure that the NDCs it puts forward represent its highest possible ambition in order to realize the objectives of the Agreement (Article 4, paragraph 2). Consequently, parties have an obligation to undertake best efforts to achieve the content of their NDCs’ (in para 270).  

3.14 Returning to the subject of customary international law obligations, the ICJ identified the following elements as being of particular relevance to the question whether a State has acted with ‘due diligence’ (para 280): 

• whether a State has put in place appropriate rules and measures to achieve the deep, rapid and sustained reductions of GHG emissions that are necessary for the prevention of significant harm to the climate system; 

• the availability of and the need to acquire and analyse scientific and technological information; 

• consideration of current standards; 

• given the obligation of a State ‘to use all the means at its disposal’ (see para 290), the respective capabilities of a State; 

• the precautionary principle; 

• a requirement that a State comply with procedural steps such as risk assessments and environmental impact assessments; and 

• a requirement that a State notifies and consults in good faith with other States on risks arising from its conduct. 

3.15 The ICJ then revisited the subject of human rights and expressed the view that:

‘… a clean, healthy and sustainable environment is a precondition for the enjoyment of many human rights, such as the right to life, the right to health and the right to an adequate standard of living, including access to water, food and housing’ (para 393).

3.16 Having done so, the ICJ reached the following conclusions:

‘403. Taking into account the adverse effects of climate change on the enjoyment of human rights, the court considers that the full enjoyment of human rights cannot be ensured without the protection of the climate system and other parts of the environment. In order to guarantee the effective enjoyment of human rights, states must take measures to protect the climate system and other parts of the environment. These measures may include, inter alia, taking mitigation and adaptation measures, with due account given to the protection of human rights, the adoption of standards and legislation, and the regulation of the activities of private actors. Under international human rights law, States are required to take necessary measures in this regard.

404. The court is of the view that international human rights law, the climate change treaties and other relevant environmental treaties, as well as the relevant obligations under customary international law, inform each other … States must therefore take their obligations under international human rights law into account when implementing their obligations under the climate change treaties and other relevant environmental treaties and under customary international law, just as they must take their obligations under the climate change treaties and other relevant environmental treaties and under customary international law into account when implementing their human rights obligations’.

3.17 The ICJ then turned to consider the second question posed by the UNGA and the legal consequences arising from a State’s acts and omissions that cause significant harm to the climate system. It began by observing that the responsibility for breaches of obligations under the climate change treaties, and in relation to the loss and damage associated with the adverse effects of climate change, is to be determined by applying the well-established rules on State responsibility under customary international law (para 420).

3.18 The ICJ next considered the issue of attribution. When doing so, it noted that some States had argued that:

‘… the application of the rules on state responsibility is difficult in the context of climate change, since the emission of GHGs as such is not an internationally wrongful act and difficulties arise for its attribution. They also asserted that the plurality of responsible and injured states makes attribution difficult, if not impossible’ (para 426).

3.19 The ICJ dismissed those alleged difficulties in attributing actions or omissions to a State, emphasising that attribution will be based on the ‘well established rule of international law’ that ‘the conduct of any organ of a state must be regarded as an act of that state’ (para 427). By way of example, the Court noted: 

‘Failure of a state to take appropriate action to protect the climate system from GHG emissions – including through fossil fuel production, fossil fuel consumption, the granting of fossil fuel exploration licences or the provision of fossil fuel subsidies – may constitute an internationally wrongful act which is attributable to that state. The court also emphasizes that the internationally wrongful act in question is not the emission of GHGs per se, but the breach of conventional and customary obligations identified under question (a) pertaining to the protection of the climate system from significant harm resulting from anthropogenic emissions of such gases’ (para 427).

3.20 Likewise, with regard to the conduct of private actors resulting in emissions of GHGs, the ICJ observed that:

‘… the obligations it has identified under question (a) include the obligation of States to regulate the activities of private actors as a matter of due diligence. Therefore, attribution in this context involves attaching to a state its own actions or omissions that constitute a failure to exercise regulatory due diligence. In such circumstances, the question of attributing the conduct of private actors to a state does not arise. The legal standard to assess compliance with the obligation to regulate, as well as the nature of the actions or omissions that lead to attribution, has been set out by the Court in several cases … Thus, a state may be responsible where, for example, it has failed to exercise due diligence by not taking the necessary regulatory and legislative measures to limit the quantity of emissions caused by private actors under its jurisdiction’ (para 428).

3.21 The ICJ also rejected the argument that holding States responsible for climate change is problematic due to the cumulative nature of the harm, which arises from the actions and omissions of multiple States over an extended period.

3.22 The ICJ accepted that there may be some difficulty in determining whether and to what extent an individual State’s breach of a climate obligation has caused significant harm to the climate system. However, it observed that ‘it is scientifically possible to determine each state’s total contribution to global emissions, taking into account both historical and current emissions’ (para 429), and that the rules on State responsibility under customary international law are capable of addressing a situation in which there exists a plurality of injured or responsible States (para 430).

3.23 The ICJ turned to consider the issue of causation. It noted that causation is a legal concept that plays a role in determining reparation and that it must be established between the wrongful act of a State (or group of States) and particular damages suffered by the injured State (or, in the case of a breach of obligations under international human rights law, by the injured individuals). It also concluded that to establish causation there must be ‘a sufficiently direct and certain causal nexus’ between the alleged wrongful act or omission and the harm claimed (para 436).

3.24 The ICJ then considered the nature of the obligations on States to protect the climate system, and it concluded that they are obligations erga omnes partes; that is, obligations owed to the international community as a whole (paras 439–443). As a consequence, the Court noted that, under the rules on State responsibility, ‘[a]ny state other than an injured state is entitled to invoke the responsibility of another state … if … the obligation breached is owed to the international community as a whole’ (para 442).

3.25 Finally, the ICJ addressed the legal consequences arising from international wrongful acts. It began by noting that a State’s failure to comply with its climate change obligations would constitute an ‘internationally wrongful act’ that would entail the international responsibility of the State (para 444). 

3.26 The ICJ then gave a non-exhaustive list of such international wrongful acts, stating that they:

‘… may range from breaches of treaty obligations, such as the procedural obligation of a state to prepare, communicate or implement NDCs under article 4 of the Paris Agreement, to breaches of obligations under customary international law, such as the failure of a state to regulate emissions of GHGs under its duty to exercise due diligence to prevent significant harm, or its failure to conduct [environmental impact assessments]’ (para 444). 

3.27 The ICJ also noted that the breach of a State’s climate obligations ‘may give rise to the entire panoply of legal consequences’ provided for under the law of State responsibility (para 445), including the requirement to: 

• cease the wrongful act or omission; 

• provide assurances or guarantees of non-repetition; and 

• provide full reparation to injured States in the form of restitution, compensation and satisfaction (paras 446-455).

3.28 In summary, the ICJ concluded that:

• States must prevent significant environmental harm, including transboundary climate impacts;

• Obligations arise under:

• Customary international law;

• Human rights law;

• Climate change treaties; and

• The principle of common but differentiated responsibilities and respective capabilities (‘CBDR-RC’), which requires States to act proportionally to their capabilities and historical emissions.

3.29 In order to comply with their climate change obligations States must:

• Adopt and implement comprehensive domestic measures to rapidly reduce GHG emissions in line with the 1.5°C limit;

• Regulate the GHG emissions of private and public entities within their jurisdiction;

• Cooperate internationally through finance, technology and capacity-building;

• Provide transparency and accountability consistent with the requirements in the Paris Agreement; and

• Prevent foreseeable transboundary and intergenerational harm.

3.30 If a State fails to comply with those requirements (despite having the capacity to do so) then it will be in breach of its international climate change obligations.

4. Evidence in support of the Complaint

4.1 The People will rely upon both expert and lay witness testimony and upon the following evidential material in support of their Complaint:

• The Intergovernmental Panel on Climate Change (‘IPCC’) 6th Assessment Report Summary for Policymakers (2023);

• The IPCC Special Report on the impacts of global warming of 1.5°C (2018);

• The 2025 Report of the Lancet Countdown on Health and Climate Change;

• The Emissions Gap Report 2025;

• The UNFCCC NDC Synthesis report published on 28 October 2025; and

• The analysis by the Climate Action Tracker of each Respondent’s efforts to tackle climate change. 

5. Alleged breach of international law

5.1 The People complain that each Respondent State has committed a wrongful international act, having failed to comply with its obligations under international law to prevent and mitigate climate change.

5.2 In support of its Complaint, the People rely upon the analysis of each Respondent State’s efforts to prevent and mitigate climate change by the Climate Action Tracker (‘CAT’).