Category: Blog

By Esther Gabriel, Juris Doctor, Harvard Law School, Visiting Scholar at the CRRP

Pabai v. Commonwealth of Australia sits as a defining national case within the broader Torres Strait Islander litigation context. It follows two successful judgements. First, Daniel Billy and others v. Australia (Torres Strait Islanders Petition), decided by United Nations Human Rights Committee, established that the Australian government’s climate change inaction was violative of its human rights obligations to the Torres Strait Islanders. In particular, and relevant here, the Committee found that Australia had violated the Torres Strait Islanders’ right to enjoy their unique culture, the Ailan Kastom, under Article 27. Declaring that, “in the case of indigenous peoples, the enjoyment of culture may relate to a way of life which is closely associated with territory and the use of its resources…[t]hus, the protection of this right is directed towards ensuring the survival and continued development  of cultural identity,” the Committee required Australia to make full reparations including providing adequate compensation to the authors for harms suffered (paras. 8.13, 11). A novel decision in furtherance of justice.

Next, a decision by the Australian Land Court in Waratah Coal Pty Ltd v. Youth Verdict Ltd et al. (No 6), made tangible the force of the Torres Strait Islanders’ cultural rights. In denying its recommendation for the issuance of a coal mining lease, the administrative court found, among others, that the evidence showed climate change impacts would have a profound impact on the cultural rights of the Torres Strait Islanders, risking the survival of their culture. This finding was largely driven by the direct application of the Human Rights Act 2019. The court accepted the causal relationship between the mining of coal and the harm to the cultural rights of First Nations peoples. Powerfully, the coal mine project was stopped.   

Drawing on this momentum and going a step further to secure enforceable remedies, Pabai v. Commonwealth of Australia, asked the Australian national court to operationalize its discretion to reach a similar judgement in tort law. However, the court declined to do so. In their primary case, claimants alleged that the Commonwealth owed a duty of care to all Torres Strait Islanders to take reasonable steps to protect them, their traditional way of life, and the Torres Strait and its marine environment, from the current and projected impacts of climate change on the Torres Strait Islands (Judgment Summary). They alleged that the Commonwealth breached this duty when setting disingenuous greenhouse gas emissions reduction targets in 2015, 2020, 2021 and 2022. As a result of the breach, they claimed that the Torres Strait Islanders suffered harms, primarily cultural losses. Their alternative case similarly alleged that the Commonwealth owed a duty to Torres Strait Islanders to take reasonable care to avoid causing property damage, loss of fulfilment of Ailan Kastom and injury arising from a failure to adequately implement adaptation measures to prevent or minimize the current and projected impacts of climate change in the Torres Strait Islands. This claim centered on a failed Seawalls Project. The court ultimately hung its hat, for both the primary and secondary case, on a political question, reasoning that government decisions and policies are not properly or appropriately made the subject of common law duties of care. The Commonwealth owes no such duty to Torres Strait Islanders.

Traditionally, a finding of no duty exhausts the inquiry. Here however, in its rigorous analysis of all elements including duty, breach, causation, and damages, the court marks critical signposts. So, towards achieving comprehensive justice—respect and remedy—Pabai teaches three fundamental lessons: (1) the need to communicate with specificity, resisting abstractness in litigation; (2) the need to adopt a fiduciary standard when executing remedies; (3) and the urgent need to diversify approaches to relief, minimizing risks flowing from failed climate litigation. An Indigenous child of Pasifika, I too, learn.

1. Claims must be concrete, and harms redressable.

The court rejects Pabai’s sweeping abstractions, occupying the claim from pleading to prayer for relief. Claimants’ application focuses heavily on laying the foundation for climate change and its broader implications such as sea-level rise. While important, it fails to also adequately make a case for specific individual harms, as is necessary for the tort of negligence. The court notes, “the applicant’s primary case was, it would be fair to say, pleaded in somewhat broad, elaborate and, at times, convoluted terms” (para. 32). Because climate change invokes unique spatial and temporal elements, it is tempting to stay in abstract ambiguity. While this litigation style worked previously in international and administrative fora, it does not pass muster in tort law at the national level. Claimants failed to sufficiently equip the court with the precise tools to translate tangible and intangible experiences into injuries-in-fact. The court summarizes that the loss of fulfilment of Ailan Kastom is not a recognized compensable “species of harm” (Judgment Summary). In its closing argument, the Commonwealth exclaims, there is no evidence to establish damage to property, or personal injury, disease or death, and claimants have not sought to quantify their losses (para. 11). Quantification is the language of tort law which seeks to remedy concrete harms. Thus, to succeed, legal arguments, harms, and remedies cannot be too attenuated or remote.

This compels us to ask, must the court expand tort law to include cultural loss or can concrete losses relating to cultural practices be described in such a way as to “fit” into existing tort jurisprudence? The answer is more normative, but to communities facing imminent loss, the machine is likely less important than the output. The priority is always on the award of remedies, as a matter of justice. The court is free to decide how to get there. Here, however, Pabai spins the court around by forcing too many novel and abstract inferences:

• To establish causation, plaintiffs advanced a seven-point causal chain that ultimately reasoned that it “matters not that it may not be possible to measure or quantify the effect that the additional emissions may have had on global temperature increases, or the specific impact that the increase in global temperature referrable to the increased emissions may have had on climate change in the Torres Strait” (para. 43).
• “As for the loss and damage suffered by the applicants and other Torres Strait Islanders, the applicants’ case ultimately focused primarily on what was said to be the collective loss of fulfillment of Ailan Kastom suffered by all Torres Strait Islanders arising from the damage to or degradation of the land and marine environment of the Torres Strait Islands. There was very limited evidence in respect of damage to the applicants’ personal or real property” (para. 44).
• “The applicants’ alternative case in negligence against the Commonwealth was also initially expressed in very broad and general terms. … Ultimately, however, the applicants were effectively compelled to fall back on a far more limited case” (paras. 45, 46).

Pabai’s prayer for relief does not rescue. It’s broad-brushed and speculative nature sparks a redressability concern. Can the court deliver what the claimants seek? Here, injunctive relief would require the Commonwealth to “… implement such measures as are necessary to: protect the land and marine environment of the Torres Strait Islands and the cultural and customary rights of the Torres Strait Islanders, including Applicants and Group Members, from GHG [greenhouse gas] emissions into the Earth’s atmosphere; reduce Australia’s GHG emissions with the Best Available Science Target; and otherwise avoid injury and harm to Torres Strait Islanders, including the Applicants and the Group Members, from GHG emissions into the Earth’s atmosphere” (para. 52). Arguably necessary as a global and political matter, this grand remedyasks the court to grant relief that is likely inappropriate and impractical for it to redress. Thus, beyond the scope of negligence, too squishy, Pabai fails.

Inundating the court with abstract claims and novel legal arguments left little room in its torts imagination to consider harmful impacts to culture, well within its discretion (see Stolen Generations’ cases). Justice Wigney conceded, “[w]hile I have considerable sympathy for the applicants’ contention that Ailan Kastom should be recognized as capable of protection by law, I do not consider that it is open to me, sitting as a single judge of this Court, to recognize, for the first time, that participation in, or enjoyment or observance of, customs, traditions, observances and beliefs, can constitute or comprise rights or interests capable of protection by law.” (para. 1131). Setting precedent on this point should have been the most salient priority as it would have been of greatest benefit to the Torres Strait Islanders and the broader Indigenous community. For remedies, especially compensation, to realize, cultural loss would be best if recognized at the national level. Billy decided, at the international level, that the Australian government ought to pay compensation. However, within their sovereign authority, Australia determined otherwise. Instead, they offered consultation and programmatic funding as more appropriate relief. Hence, individual and communal harms are best redressed at the national level where judgments are binding on the state and relief is not optional or open to interpretation, and enforcement fleeting.

Legitimizing cultural loss across legal fora is a necessary first step in adjudicating with justice in climate change. For Indigenous peoples, tortious harms to our person and property implicate cultural loss. This is a mere translation gap, not a values divergence. Establishing cultural loss as a harm in tort law does not depart from traditional jurisprudence. Underlying tort law is culture, with common examples to include ideals of privacy, products, property, and person. For instance, the innkeepers’ rule which imposes a heighted duty of care to guests and their property and attaches liability for loss and damage, advances a cultural expectation of travelers on their hosts, binding hotels even in the present-day. So, as applied to Torres Strait Islanders, Indigenous cultural expectations need an expression, a language in the law. The term ‘cultural loss’ serves merely to articulate claims and be made whole, fitting squarely within the purpose and intention of tort law. Sadly, Pabai kicks this finding down the road.

2. Remedy implementations implicate fiduciary duties.

Pabai’s argument in the alternative reveals a misplaced fiduciary expectation. Relying on the Council of Australian Governments (COAG) Principles, which sketch management roles and responsibilities for climate-change risks between the Commonwealth, State and Territory, and local governments, Pabai asserts that the Commonwealth, in its leadership role, assumed responsibility for the funding and proper execution of the local Seawalls Project (see para. 1156). The court expressly disagrees, calling the assertion a “misreading or misconstruction” (para. 1156). COAG Principles require local governments to play a critical role “contribut[ing] appropriate resources to prepare, prevent, respond and recover from detrimental climate impacts” (para. 1158). Offloading responsibility frustrates the court. COAG principles are grounded in cooperative governance to benefit Australia as a whole. It is a sharing, not a shifting of burdens. So, backed into a corner, the court egregiously comments “[i]t is difficult to see that the funding of an infrastructure project like the Seawalls Project involves a matter that may affect national prosperity or security” (para. 1157). It does (Parliamentary Acts affirm). At its core and as a matter of principle, refusing to embrace a shared fiduciary duty hurt Pabai.

The Seawalls Project lies incomplete; the budget ran out. Because the project funding was secured through a competitive grants scheme whereby approval hinged on an “efficient, effective and ethical” proposal, the Torres Strait Council, the local governing body, cemented their fiduciary duty in their proposal (para. 1163). Not mere words, they were obligated to act in the best interests of the beneficiary, the Torres Strait Islands—the place and its people.

So, what went wrong? A wholly reliant posture sought to delegate a non-delegable duty. The duty to lead and ensure completion of this project rested squarely on the Torres Strait Islanders as peoples of that land, not the Commonwealth, as argued. Australia could assist, but never rightfully take over. The court suggests an underestimation of the overall extent and costs to be the cause of the incompleteness, not deficiencies by the Commonwealth. It reminds, “The [Torres Strait Island Regional Council] was responsible for the implementation of the Seawalls Project” (para. 780). The local government failed to embrace its own fiduciary role and responsibility regarding the Seawalls Project. Consequently, the court held that while the Commonwealth provided funding, a combined project total of 64 million dollars, far exceeding the initial 5-million-dollar grant, they did not inhere a duty to lead and coordinate the project (Judgment Summary). That responsibility rightfully rests at home; our duty to place, as Indigenous peoples, is non-delegable.

3. Litigation risks to relief must be diversified.  

The Torres Strait Islanders cannot be left to battle the most devastating impacts of climate change alone. Their harms compel help. Because remedies are critical, solutions and hope cannot be concentrated on litigation alone. Litigation is but one tool in a much larger toolkit and as evinced here, it can fail.

The most detrimental cost of unsuccessful litigation is time. As the impacts of climate change increase and become more frequent, delays compound harm. Frontline communities must adopt a multi-pronged strategy for survival. While litigation percolates, remedies can operationalize with the help of private and public partners. Diversification ensures a minimum threshold of safety. The health and safety of a peoples so vulnerable to mass climate devastation must never be a zero-sum game.

At times, bold litigation moves for the benefit of all push to the back the basic and immediate priorities of individual claimants. For a time, they are heralded as heroic champions challenging the protected status quo. But with a loss, they soon fade into the noise, still without help. The strategic choice of establishing a new category in tort, cultural loss, over particularizing harms to fit within the traditional torts framework, proved consequential for the Torres Strait Islanders.

Taking a step back to consider fairness, we might ask: must those facing imminent tortious harms also be the pacesetters for legal innovation, celebrating occasional wins, but mostly burdened by catastrophic losses? I would proffer that there exists a balanced approach that a min, secures reasonable remedies, and when available, reaches for world-benefitting precedent. This is my ambition for climate litigation involving, especially, frontline communities who cannot afford to lose. Until the law begins to trust that Indigenous communities do not bring absurd claims, we must communally problem-solve to truly hear and understand what Uncle Pabai truly means when he whispers, “all our land has now washed away” (Fred Pabai Sworn Affidavit).

Concluding, respect requires prudent action. This is within reach.   

Viktoriya Gurash, postdoctoral researcher at the University of Zurich

Introduction

In response to the International Court of Justice’s (ICJ) advisory opinion on the Obligations of States in Respect of Climate Change, the BBC summarized the opinion by stating that ‘a top UN court has cleared the way for countries to sue each other over climate change.’ Indeed, the opinion not only offers a comprehensive clarification of states’ substantive obligations regarding climate change but also engages with important aspects of State responsibility in view of the special features of climate change. The central challenge lies in the fact that numerous states both contribute to and suffer from climate change, albeit to varying degrees (see para. 421).

From the outset, the ICJ made it clear that its task was to identify, in general terms, the legal framework within which a State’s international responsibility may be invoked for an internationally wrongful act, as well as to outline the remedies available in the event of such a breach (see para. 406). Importantly, the opinion clarified that the well-established rules on State responsibility under customary international law – principally reflected in the International Law Commission’s Articles on State Responsibility (ARSIWA) – apply in the context of climate change (see para. 420). To this end the Court affirmed that mechanisms such as the Loss and Damage Fund and the non-compliance procedures established under climate treaties do not constitute a lex specialis to these rules (see paras. 413-419). In its examination of the law on State responsibility, the advisory opinion specifically engaged with the issues of attribution and causation. This blogpost analyses the ICJ’s interpretation of these key elements, which underpin the conditions for compensation of climate-related harm.

Attribution of International Responsibility

The ICJ emphasised that the internationally wrongful act is not the emission of greenhouse gases (GHGs) per se, but the breach of an international obligation (see para. 427). Since these obligations are characterized as obligations of conduct, a breach may be attributed to states that have not exercised due diligence in taking appropriate measures to protect the climate system from GHG emissions. Accordingly, establishing international responsibility requires the existence of an internationally wrongful act and its attribution to a state, regardless of whether the act results in actual harm (see para. 433). Therefore, according to the ICJ, the issue of causation is not essential for establishing a breach of an international climate obligation.

The ICJ’s interpretation of the attribution of internationally wrongful acts is closely tied to the nature of the underlying substantive climate obligations. The distinction between obligations of conduct and those of result is crucial to understanding the role of the causation in establishing international responsibility. In a case involving obligation of conduct, the question is not the extent of harm caused by the state, but rather whether the state has taken appropriate measure to prevent such a harm (see Nollkaemper, p. 38). Although obligations of conduct do not require examination that a specific event or harm materialized, the element of causation nevertheless retains its relevance. An assessment of due diligence depends on consideration of the nature of the risk and the state’s capacity to mitigate it. For example, the European Court of Human Rights (ECtHR) in the KlimaSeniorinnen case noted that ‘what is important, and sufficient to engage the responsibility of the State, is that reasonable measures which the domestic authorities failed to take could have had a real prospect of altering the outcome or mitigating the harm’ (see para. 444). With an obligation of conduct, the causal nexus between the foreseeable negative effects of climate change (general causation, see Nollkaemper, p. 40) and the State’s capacity to act should be analysed. In matters of general causation, the potential effects of climate change may be reliably established on the basis of IPCC reports and therefore do not present a significant evidentiary challenge.

Causation of Climate Harm

Causation plays a critical role in the assessment of reparation, especially with respect to claims for compensation arising from climate-related harm. The ICJ acknowledged that the existing legal standard for establishing causation, as developed in its own jurisprudence, is capable of being applied in the context of climate change (para. 436). The advisory opinion emphasized that causation requires establishing a causal link between the resulting climate-related harm and the conduct of a specific State or group of States. The ICJ observed that while the causal link may be ‘more tenuous than in the case of local sources of pollution’, its identification is not impossible and ‘must be established in each case through an in concreto assessment’ (see paras. 437-438).

The Court’s pronouncement offers limited guidance on resolving the issue of the allocation of compensation for climate-related harm between states (see Reetz, Paddeu and Jackson). Moreover, Judge Nolte elaborates on the challenges for contentious proceedings that were not addressed in the advisory opinion, in particular with respect to claims for climate damages. In his view, the Court should have highlighted those difficulties more openly, in order to avoid creating false hope that climate litigation could serve as a substitute for existing mechanisms of financial transfers and remedies addressing climate-related harm (see Declaration of Judge Nolte). The main difficulty, as emphasized by Judge Nolte, lies in determining a combination of wrongful acts sufficient to have caused harm to the climate system, along with the need for a normative assessment of whether a specific level of GHG emissions constitutes a breach of the obligation to exercise best efforts (Nolte, paras. 19-30).

The climate science (see the IPCC’s Sixth Assessment Report) is clear that not all climate-related harm can be prevented through mitigation measures alone. Arguably, an important frontier of climate justice is to provide redress when harm occurs (see Rocha, Tigre and Cohen). To date, no international court has definitively addressed the standard of causation required to determine compensation for climate-related harm. The International Tribunal for the Law of the Sea in its advisory opinion on Climate Change and International Law acknowledged that ‘given the diffused and cumulative causes and global effects of climate change, it would be difficult to specify how anthropogenic GHG emissions from activities under the jurisdiction or control of one State cause damage to other States’ (para. 252). Despite the Inter-American Court of Human Rights having recognised the need for ‘compensation measures based on appropriate methodologies to assess the losses suffered’ in its advisory opinion regarding the Climate Emergency and Human Rights (AO-32/35) (para. 558), it did not engage with the complexity of cumulative causation. Furthermore, since the ECtHR in the KlimaSeniorinnen case rejected victim status for individuals (paras. 527-535), and the applicant association (para. 647) did not submit a claim for damages, it remains unclear how the ECtHR will determine causation for the compensation purposes.

Inquiries into how the problem of cumulative causation should be addressed in the context of compensation for climate harm can be found in the literature. For example, Nollkaemper offers concrete proposals, presenting two main alternatives: first, an obligation to provide full reparation to individual states; and second, an apportionment of compensation based on each actor’s relative share of contribution (for more details see Nollkaemper, pp. 51-54). Overall, the author supports an approach that prioritizes fairness and climate justice over strict mathematical causation (p. 54). While the ICJ could have shed more light on resolving the complexities of cumulative causation, it nevertheless affirmed the role of litigation in compensation of climate damages (para. 438).

Conclusion

It is doubtful whether the Court’s role in issuing this advisory opinion should be understood as either encouraging or discouraging climate litigation. If litigation is expected to deliver global justice by allocation of responsibility to compensate for climate harm among all the states, it is doubtful that any court alone could fulfil such a task. Rather, the significance of the ICJ’s pronouncement lies in affirming that international climate litigation between states remains a potential avenue for seeking compensation for climate-related harm within the broader framework of international legal instruments.

Should claims for climate harm compensation come before international courts, causation will be a key issue. The way courts resolve it will significantly influence the effectiveness of litigation as a tool for providing redress. The ICJ has deferred this analysis to a future occasion, when it is presented with a concrete case featuring a claim for compensation and a claimant’s specific arguments concerning, for example, the role of historical emissions in determining causation. If a state brings a claim seeking redress for climate damages before the ICJ, provided the Court has jurisdiction and the claim is deemed admissible, it would be compelled to confront the causation puzzle. In this sense, the situation reflects the German saying, ‘was auf den Tisch kommt, wird gegessen’ – or, in other words, what is brought to the table must be dealt with.

By Ayyoub (Hazhar) Jamali, postdoctoral researcher at the University of Zurich 

1. What the Court Said

In its Advisory Opinion of 23 July 2025, the International Court of Justice (ICJ) addressed, among other matters, the scope of States’ obligations under international human rights law in relation to climate change. A central, though implicitly framed, issue was whether States bear extraterritorial human rights obligations for climate-related harms affecting individuals beyond their borders.

In the section titled “Territorial scope of human rights treaties” (paras. 394–402), the Court recalled its previous jurisprudence recognizing that human rights treaties may apply extraterritorially when a State exercises jurisdiction outside its own territory. The ICJ reaffirmed that this interpretation applies in the context of the ICCPR, referencing its 2004 Wall Advisory Opinion and its 2005 Judgment in Armed Activities on the Territory of the Congo, as well as its 2024 Advisory Opinion on the Occupied Palestinian Territory.

Quoting the Wall Opinion, the Court confirmed that Article 2(1) of the ICCPR may cover individuals outside a State’s territory but subject to its jurisdiction, based on the object and purpose of the Covenant and the drafters’ intention (travaux préparatoires) not to allow States to escape responsibility when exercising jurisdiction abroad.

The Court also reiterated prior interpretations of other treaties:

1. The ICESCR, while lacking an express territorial clause, may apply both to sovereign territory and to territory under the State’s jurisdiction (para. 400).
2. The Convention on the Rights of the Child applies to “each child within their jurisdiction”, and was held applicable in the “Occupied Palestinian Territory” (para. 401).

Despite this, the Court stopped short of determining under what conditions a State exercises jurisdiction extraterritorially, stating that such analysis must be treaty-specific. Importantly, it distinguished between treaty law and customary international law (para. 402), signaling that the two frameworks may diverge in how they address jurisdiction and obligations.

2. Gaps and Unresolved Questions

The Court’s treatment of whether, and under what conditions, States have extraterritorial human rights obligations for climate-related harm reveals several significant analytical and normative gaps.

First, while the Court engaged with the treaty body jurisprudence, it refrained from offering judicial analysis or placing those views within a broader doctrinal framework. The ICJ’s passive approach left open the question of whether States accept these extraterritorial interpretations or whether they are mere soft law positions. In this context, it should be noted that the ICJ’s advisory function is not limited to summarizing existing legal positions; it carries a responsibility to offer authoritative guidance on unresolved or contested points of international law. In this case, where significant interpretive uncertainty surrounds the extraterritorial application of human rights obligations in the climate context, the Court had a rare opportunity to provide clarity. Instead, it recited existing jurisprudence without taking a clear position, leaving core questions — such as the legal status of treaty body interpretations or the threshold for extraterritorial jurisdiction — largely unaddressed.

Second, the Court made no attempt to tailor its discussion to the particularities of climate change, despite its inherently transboundary nature. It did not engage with concrete examples where extraterritorial obligations might arise. For instance, consider a scenario where State A, a major emitter of greenhouse gases, fails to regulate its fossil fuel industry. As a result, rising sea levels and intensified storms displace communities in State B, a low-lying island nation. Does State A have extraterritorial human rights obligations toward individuals in State B, given the foreseeable and science-based nature of the harm? This is precisely the kind of factual matrix where environmental law principles (such as the no-harm rule) might intersect with human rights obligations. Yet, the Court did not explore whether such functional or effects-based jurisdiction could be justified in the climate context.

Third, a notable omission in the ICJ’s Opinion is its failure to engage with relevant jurisprudence from regional human rights courts. Most significantly, the Court made no reference to the ECtHR’s 2024 Duarte Agostinho judgment, which directly addressed the question of extraterritorial human rights obligations in the context of climate change. In that case, the Strasbourg Court rejected an expansive reading of jurisdiction that would cover transboundary climate impacts. The ECtHR adhered to the traditional “control over the victim” model, expressing concern that adopting a “control over the source” approach would effectively turn the ECHR into a global climate change treaty.

In contrast, the ICJ remained silent. Given its universal mandate and its stated role in clarifying international law, even a brief engagement with Duarte Agostinho would have enriched the Opinion’s doctrinal relevance and provided a valuable comparative perspective. The omission may reflect institutional restraint: acknowledging a controversial regional judgment could be seen as implicitly endorsing—or rejecting—a contested interpretive move.

Fourth, in paragraph 402, the Court underscored a doctrinal distinction between treaty law and customary international law, stating that they must be analyzed separately. While the Court did not elaborate, this statement is more than a procedural clarification — it has important implications for the future development of extraterritorial obligations in the climate context.

Unlike treaties, which are based on explicit consent and often contain jurisdictional clauses (such as Article 2(1) of the ICCPR), customary international law is grounded in general practice accepted as law (opinio juris) and may evolve independently of treaty frameworks. By distinguishing the two, the Court subtly acknowledged that even if human rights treaties do not currently impose extraterritorial obligations in climate cases, customary law might still do so in the future — especially where transboundary harm is foreseeable and scientifically attributable (see para. 429).

This distinction could justify a different interpretive posture: the Court may be unwilling to extend extraterritoriality under treaty law due to concerns about textual fidelity and state consent, but customary law offers more normative flexibility. This is particularly relevant in the context of climate change, where global harm arises from cumulative emissions, not isolated acts, and where rigid territorial frameworks struggle to reflect real-world causal chains.

Moreover, the ICJ’s separation of treaty and customary law might also reflect institutional caution. Endorsing a customary rule allowing for extraterritorial environmental responsibility (without explicit treaty basis) could be seen as less politically provocative than redefining treaty obligations. Thus, the Court may be laying groundwork for future claims based on customary principles like the no-harm rule, the duty to cooperate, or emerging norms linking environmental harm to the enjoyment of human rights.

3. Conclusion

The ICJ’s restrained approach to extraterritoriality in the climate context is both telling and incomplete. Its silence reflects a delicate balancing act. While the Court reaffirmed universal obligations under customary international law (e.g., the duty to cooperate, the duty to prevent significant transboundary harm, and the erga omnes nature of climate obligations) it stopped short of clarifying whether these obligations entail extraterritorial jurisdiction in specific cases. In doing so, the Opinion preserves an appearance of judicial deference while simultaneously inviting further litigation and interpretation by regional courts and treaty bodies.

Nevertheless, the Opinion leaves room for legal development—whether through future litigation, the evolution of treaties, or the formation of customary law. The challenge now facing courts, States, and advocates is to ensure that this legal space does not remain undefined for too long.

By Ayyoub (Hazhar) Jamali, postdoctoral researcher at the University of Zurich

In recent months, two international courts have recognised climate change-related obligations under two different legal regimes. In the case of Verein KlimaSeniorinnen Schweiz and Others v Switzerland, the European Court of Human Rights (ECtHR) has found that the right to life and the right to private and family life impose positive obligations on States to implement measures and regulations necessary to address climate change, insofar as it poses a risk to these rights. Similarly, the International Tribunal for the Law of the Sea (ITLOS) highlighted in its advisory opinion that States have a duty to take all necessary measures to prevent, reduce, and control anthropogenic greenhouse gas (GHG) emissions, guided by the best available science and international standards. In both cases, the reports by the Intergovernmental Panel on Climate Change (IPCC) played a significant role in shaping the courts’ decisions and findings. This underscores the critical influence of scientific research in guiding legal interpretations and reinforcing the necessity for international cooperation in combating climate change. The analysis below provides a short summary of the growing value of the IPCC reports and their application by the ECtHR and ITLOS in their recent findings and pronouncements.

The Value of IPCC Reports

The IPCC is a unique collaboration involving thousands of scientific experts from around the world, bringing together the most comprehensive and up-to-date understanding of climate science. This collaborative effort is unprecedented in the history of science, not only for its scale but also for the acceptance and reliance it has garnered from governments globally.

In fact, the IPCC’s research and updates of the state of knowledge on information relevant for the understanding of the risk of climate change have been crucial for the development of international climate law (Ghaleigh 2016). Beyond its role in shaping the collective response to climate change, the IPCC’s findings have also played a crucial role in the adjudication of climate litigation by courts. The IPCC has been described as the ‘world’s most authoritative assessment body on the science of climate change’ (Gloucester Resources Limited v Minister for Planning [2019] NSWLEC 7, paras. 431-435) and its reports have been crucial in both constructing the factual background of the case and underpinning the necessity of urgent and stringent climate mitigation policy (Urgenda Foundation v The State of the Netherlands, Supreme Court of the Netherlands, 2019; Commune de Grande-Synthe v France, Conseil d’État, 2021; Neubauer et al. v Germany, German Federal Constitutional Court, 2022).

Both the ECtHR and ITLOS, have extensively referenced various IPCC reports in support of their recent findings regarding the impacts of climate change on human rights and the marine environment respectively, as well as their reasoning underlying their conclusions. The IPCC reports indicated that increasing temperatures and heatwaves, exacerbated by climate change, lead to significant health risks and increased mortality. The ECtHR cited the IPCC’s conclusion that climate change results in more frequent and intense heatwaves, which disproportionately affect older adults, women, and those with chronic diseases (paras. 510, 511, 530). This evidence supported the applicants’ claims that the Swiss authorities’ failure to mitigate climate change posed a direct threat to their health and well-being, thus engaging positive obligations under Articles 2 and 8 of the European Convention on Human Rights.

In its AO, the Tribunal highlighted the IPCC’s findings on the necessity of limiting global warming to 1.5°C to mitigate severe impacts on marine ecosystems and human communities. It also underscored the need for rapid and substantial reductions in greenhouse gas emissions, as outlined in the IPCC reports, to meet international climate goals​​. In fact, the Tribunal’s reliance on authoritative scientific evidence provided by the IPCC underscores the importance of integrating robust climate science into legal deliberations. By utilising IPCC definitions and confidence levels in assessing climate change impacts, ITLOS was able to clarify key concepts (e.g., climate change, GHG emission, ocean acidification), prioritize issues, and reinforce its stance on the urgent need for States to address marine pollution and protect the marine environment (paras. 57-66, 157, 209-210, 241, 398).

Notably, the validity of the IPCC reports was not questioned by most participants in the AO proceeding or the Swiss government in the KlimaSeniorinenn case. The Swiss government even argued that its national emissions reduction targets relied on the IPCC’s assessment report (para 91). This broad acceptance of the IPCC’s findings highlights their critical role in shaping international climate-related legal obligations and policies.

Conclusion

The ECtHR and the ITLOS have both recognized climate change-related obligations under different legal regimes, emphasizing states’ responsibilities to mitigate climate risks. The ECtHR affirmed that climate change poses a direct threat to human rights, necessitating positive state actions, while ITLOS highlighted obligations to protect the marine environment from GHG emissions. The IPCC reports have played an important role in these judicial decisions and opinions, providing authoritative scientific evidence that underpins the necessity for urgent climate action. The recognition and reliance on IPCC reports by these courts reflect their authoritative status in climate science and their significant influence on international climate law and litigation.

By Pranav Ganesan, PhD candidate at the University of Zurich

Two international courts have now recognized the existence of climate change-related obligations under two different legal regimes. The European Court of Human Rights (‘ECtHR’), in the case of Verein KlimaSeniorinenn Schweiz and others v Switzerland (‘KS’) has found that the right to life and right to private and family life under the European Convention of Human Rights (‘ECHR’) encompass positive obligations on states to take measures and regulations necessary to address climate change to the extent that it poses a risk of harm to those rights. The International Tribunal on the Law of the Sea (‘ITLOS’) concluded in its advisory opinion (‘AO’), that states parties to the 1982 UN Convention on the Law of the Sea (‘UNCLOS’) have specific obligations to protect the marine environment and prevent transboundary harm to other states through prevention and control of pollution from greenhouse gas (‘GHG’) emissions, and international cooperation. The AO was issued upon the request of the Commission on Small Island States (‘COSIS’), an international organization which was constituted as a vehicle for global cooperation in contributing towards definition, implementation and progressive development of rules and principles of international law concerning climate change (Article 1(3), COSIS Agreement). Article 2(3) of its constative treaty explicitly authorizes it to request an advisory opinion from the ITLOS on any legal question within the scope of UNCLOS). The creation of COSIS was presumably inspired by the conclusion by the ITLOS in the SFRC Advisory Opinion, that it can exercise advisory jurisdiction over a legal question if an international agreement related to the purposes of the UNCLOS specifically provides for such a request (para 219).

This blogpost will highlight the ECtHR and ITLOS’ engagement with the UNFCCC and Paris Agreement, and specifically Article 2.1(a) of the Paris Agreement which expresses an international commitment to pursue efforts to keep the global average temperature from increasing beyond 1.5°C, and well below 2°C (‘Paris temperature targets’). While there are commonalities between how the two courts clarified the relationship between their constitutive treaties the UNFCCC and Paris Agreement, there seems to be a difference between what they held in regard to the Paris temperature targets.

Interaction between climate treaties and the ECHR/UNCLOS

Both the ECtHR and the ITLOS found that the UNFCCC and Paris Agreement are relevant for the purposes of determining the content of due diligence obligations to reduce GHG emissions, under the ECHR and UNCLOS, respectively (KS, paras. 455-456; AO, para. 222). The climate treaties do not supplant climate-related obligations arising out of the ECHR and UNCLOS, and a states’ compliance with the provisions of the former does not equate to compliance with the latter (KS, para. 547, AO, para. 223).

Both the ECtHR and the ITLOS specifically pointed out that the Paris temperature targets contained are salient for interpretation purposes. In the context of climate related positive obligations under the ECHR, the ECtHR noted that ‘the global aims as to the need to limit the rise in global temperature, as set out in the Paris Agreement, must inform the formulation of domestic policies’ (para. 547). The ITLOS similarly noted that “[i]n particular, the temperature goal and the timeline for emission pathways set out in the Paris Agreement inform the content of necessary measures to be taken under article 194, paragraph 1, of the [UNCLOS]” (para. 222). The Tribunal has been criticised for stopping short in its consideration of the provisions of the Paris Agreement, since beyond the temperature thresholds and the timeline for the collective achievement of net-zero, which are found in Articles 2.1 and Article 4.1 respectively, there are other obligations and legal principles in the Paris Agreement which may be regarded as relevant for interpretation purposes (Voigt).

1.5°C Temperature target

Article 2.1 (a) of the Paris Agreement contains two negative temperature targets: 1.5°C and 2°C, with different language qualifying each of them. The provision a does not in itself create distinct individual or collective legal obligations for Parties, but are operationally relevant in the calibration of individual states parties’ own mitigation efforts under their NDCs (see Rajamani and Werksman). This leads to concerns about what it means for due diligence obligations to be interpreted on the basis of the Paris temperature targets. To illustrate this issue by way of a question: consider three scenarios where a state choses to determine its own mitigation efforts: (a) on the basis of the 2°C target without considering the 1.5°C target, (b) on the basis of a pathway with limited overshoot of 1.5°C but no exceedance beyond 2°C, and (c) on the basis of its own (different) assessment of what constitutes safe levels of atmospheric GHG concentrations. How do each of these three determinations affect the state’s compliance with due diligence obligations under Article 8 ECHR/ Article 194(1) UNCLOS?

The ECtHR did not specify if one out of the two temperature targets are relevant in defining states’ positive obligation to mitigate climate change under Article 8. It held that regulations and measures must be “aimed at preventing an increase in GHG concentrations in the Earth’s atmosphere and a rise in global average temperature beyond levels capable of producing serious and irreversible adverse effects on human rights, notably the right to private and family life and home under Article 8 of the Convention” (para. 546, emphasis added). As for the ITLOS, the advisory opinion neither dwells on the relationship between the two temperature targets, and how each of them have particular effects on the interpretation of the UNCLOS provisions containing due diligence obligations to protect the marine environment. It merely identifies the UNFCCC and the Paris Agreement as two some amongst the many reference points for assessing necessary measures (para. 214). However, it does speak to temperature thresholds in a different context: of IPCC’s findings. In its review of the best available science, which the Tribunal had earlier identified as playing a crucial role in the determination of states’ due diligence obligations (para. 212), it held that ‘there is also broad agreement within the scientific community that if global temperature increases exceed 1.5°C, severe consequences for the marine environment would ensue’ (para. 241). In its conclusion, the Tribunal held that ‘necessary measures to prevent, reduce and control marine pollution from anthropogenic GHG emissions’ under Article 194(1) UNCLOS:

‘should be determined objectively, taking into account, inter alia, the best available science  and relevant international rules and standards contained in climate change treaties such as the UNFCCC and the Paris Agreement, in particular the global temperature goal of limiting the temperature increase to 1.5°C above pre-industrial levels and the timeline for emission pathways to achieve that goal’ (para. 243)

The two courts’ pronouncements still leave the question of how exactly the Paris temperature targets ought to inform states’ due diligence obligations open. It is likely that they will be called upon to provide clarity on this aspect in the future.

Conclusion

In responding to the questions that was posed before the two courts, they seem to have wielded the tool of systemic integration. The two pronouncements reflect a common understanding: that broad legal obligations such as the duty to protect individuals’ right to life and prevent unjustifiable interferences with their right to private and family life, and the duty to protect the marine environment, albeit arising out of treaty provisions which were not drafted with climate change in mind, require individual mitigation measures against anthropogenic climate change. This action needs be informed by the provisions of the Paris Agreement as opposed to, whereas states’ compliance with the latter would not suffice in ensuring legal compliance with what other legal regimes require in regard to climate change. However, this does not mean that the ECtHR and the ITLOS spoke with one voice in regard to all issues. In particular, their engagement with the Paris temperature targets, insofar as interpretation of due diligence obligations arising from the relevant treaties is concerned seemed different. While the ITLOS specifically interpreted Article 194(1) as implying a duty to take measures that take into account the 1.5°C temperature target under the Paris Agreement specifically, the ECtHR’s interpretation was that ECHR parties’ measures be informed by both temperature targets. It remains to be seen whether in future cases, courts will be able to nuance the practical difference between a duty to take into account the lower 1.5°C temperature target, and a duty take into account both targets in the determination of mitigation measures.

P.S. In engaging in discourse on the temperature targets, it is important to keep in mind that there is nothing magical about the 1.5°C and 2°C numbers. These are temperature targets which have been noted in the Paris Agreement as a result of a political compromise, and based on predictions about the consequences of breaching these thresholds. States’ (differentiated) responsibility for breaching obligations associated with the prevention of the devastating impacts of climate change on populations and ecosystems do not begin only after the 1.5°C threshold is breached. It would be unreasonable to argue that international human rights law and the law of the sea are apathetic to the human suffering and the devastating impacts for the marine environment in a warming world that is yet to cross the 1.5°C threshold.