Reparation for Climate Change: The Successes and Limits of Litigation

3.The Way Forward — A Look at Brazil and the International Sphere

a.The Example of Brazil

i.Why Brazil?

On their own, courts may not be the saviors of the climate. But recent cases demonstrate that they play an important role in the overall societal process of tackling the climate crisis, both nationally and internationally. At the same time, courts can only assume this role if they are aware of their sensitive position within the legal order and are prepared to take a creative approach to the multidimensional issues raised by climate litigation. This means, resuming the discussion above, anticipating and facing challenges to their legitimacy.

Not every judicial system faces the same questions of legitimacy. An international court such as the ICJ or the Inter-American Court of Human Rights faces different legitimacy challenges than, for example, the German Federal Constitutional Court, which is deeply embedded in a domestic legal order. The applicable law and the powers of the respective institutions can also differ. Consideration of legitimacy issues must, in other words, be contextual. Still, some generalizations are possible. In this regard, we believe that it is worthwhile to take a look at recent developments in Brazil. Here, large parts of the Amazon — one of the world’s most important CO2 sinks — are being illegally deforested. In 2023, there was a dramatic reduction in deforestation rates, but fires continue to contribute to significant losses of natural vegetation.⁵³ The — S. 382 —story of deforestation of the Amazon since the turn of the century has been a complicated one, with rates peaking in the 1990s and early 2000s, then declining briefly before rising again in 2012 and onwards.⁵⁴ This, along with the weakening of environmental regulations by the Brazilian government,⁵⁵ has led to significant climate and environmental litigation,⁵⁶ including even a (now dormant) communication to the international Criminal Court (ICC) concerning the alleged crimes against humanity committed by then-President Jair Bolsonaro.⁵⁷ As a result of this body of litigation, a progressive body of environmental and climate case law has emerged in Brazil. The next section’s summary of this case law provides a source of inspiration for the next generations of climate litigation. ii. Foundations in Brazilian Law Brazil recognizes a human right to an ecologically balanced environment in Article 225 of its Constitution. The Federal Supreme Court has interpreted this provision to include a right to a balanced climate, which applies to both current and future generations.⁵⁸ Martins da Rosa refers to this scheme as an iteration of climate constitutionalism.⁵⁹ In this context, two landmark rulings by the Federal Supreme Court are particularly noteworthy: PSB et al v Brazil on the Climate Fund⁶⁰ and PSB et al v Brazil on the Amazon Fund.⁶¹

In these cases, the Brazilian Supreme Court was called upon to review the government’s failure (reluctance) to mobilize resources under the Climate Fund and acts of dismantling governance mechanisms for the operationalization of the Amazon Fund, respectively. Essentially, both cases were about the government’s conduct in paralyzing the operation of these funds. In both cases, the Supreme Court found this conduct to be in violation of Article 225 of the Constitution. In these rulings, the Federal Supreme Court recognized climate protection as an integral part of environmental protection, which it understands as a human rights entitlement. Based on the recognition that the protection of the climate system is included in the content of the fundamental right to a healthy environment, the climate system is subject to constitutional protection in Brazil. As a result, the Court described the Paris Agreement as a human rights treaty, which is a highly influential development given that — as Maria Antonia Tigre and Joana Setzer have noted — it sets the stage for invalidating Brazilian domestic legislation that contradicts the Paris Agreement.⁶² What is particularly interesting is that a violation or a threat thereof triggers civil liability, because the civil liability regime in matters of environmental damage in Brazil is constitutional in scope.⁶³ Article 225(3) of the Brazilian Constitution enshrines triple responsibility (civil, criminal and administrative) for all infractors whose conduct harms the environment.⁶⁴ The fact that the Brazilian Constitution serves as the basis for imposition of both civil and criminal liability is a distinctive aspect of the Brazilian legal system.⁶⁵

iii.Solutions for Notorious Litigation Hurdles

The Brazilian case law has set important precedents that, some have argued, can support litigation seeking to advance climate justice.⁶⁶ Aside from cases where the litigant enforces the constitutional right to an ecologically balanced environment in its individual or collective dimension, Martins da Rosa theorizes that there is potential for climate litigation which seeks to hold “polluters” of the climate system, ie emitters of large quantities of GHGs,⁶⁷ liable for damages. Environmental case law in Brazil evinces that courts are attentive to the complexity of defining environmental damage. Such damage — S. 384 —is understood as multi-dimensional, encompassing both damage to the environment in itself (under an autonomous liability regime) and damage that derives from harmful effects on the environment that impact other protected assets (such as life, health, well-being, and material and intangible heritage).⁶⁸ Martins da Rosa argues that climate-related damage is merely a type of environmental damage that occurs on a planetary scale.⁶⁹

As regards the causal link between GHG emissions and the afore-described environmental damage, liability can arise if it can be proven that the polluter’s conduct contributed to the risk of such damage.⁷⁰ Concerning the capacity to sue and to be sued, Brazilian law envisages public or collective civil action for environmental damage and a broad notion of polluters, encompassing both direct and indirect contributors to pollution.⁷¹ In environmental cases, public or collective civil action for environmental damage can be filed against a “polluter,” a natural or legal person responsible for an activity that causes environmental degradation.

As Martins da Rosa explains, it remains to be seen whether Brazilian courts will accept claims against GHG-emitting agents as direct polluters and for example banks and financing agents as indirect polluters, in light of the principle that liability is not based on fault.⁷² However, developments in litigation concerning deforestation in the Amazon region show that Brazilian courts have made some progress in their engagement with the concept of climaterelated damage. While these cases are certainly reminiscent of classic (environmental) cases revolving around a destructive conduct, where the central question at the end is how much the polluter must pay, they have gained significance in today’s context. The question they raise is how, if at all, courts should distinguish between environmental damage and climate-related environmental damage.⁷³ In this regard, approaches amongst different courts are not yet uniform. One approach that has emerged is that of ordering damages for the lost benefits of carbon storage and sequestration. Indeed, other than GHG emissions from fossil fuel combustion, deforestation and agriculture are the “main human causes of climate change.”⁷⁴ Here, the damages would — S. 385 —include the value (in monetary terms) of emissions which would have otherwise been removed from the atmosphere if not for the deforestation in question. While there are divergent judicial pronouncements on this point,⁷⁵ in some cases, the order for damages to be paid by the defendants accounted for climate damage estimated based on the “social cost of carbon” (as understood in studies by the Economic Commission for Latin America and the Caribbean that have been relied on by the Brazilian courts).⁷⁶

In October 2021, the National Council of Justice (CNJ), an administrative organ of the judiciary in Brazil that has constitutional status,⁷⁷ issued Resolution No 433 establishing the National Policy of the Judiciary for the Environment. Article 14 of this resolution states that when quantifying environmental damage, courts must consider the impacts of the damage on global climate change, diffuse losses suffered by affected peoples and communities and provide the deterrents required to internalize externalities.⁷⁸ The quantification of dano clim á tico or climate damage is a highly technical exercise, and the lack of consensus and legally approved methodology might dissuade courts from ordering damages under this heading. Thus, to assist courts in applying Article 14 of its resolution, in 2024 the CNJ adopted a Protocol for Judging Environmental Lawsuits containing a detailed guide for judges to quantify climate damage in pursuance of Article 14.⁷⁹ To summarize, the protocol prescribes that climate damage must be quantified in six steps, viz (1) identifying the extent of the deforested or burnt area, in hectares (using satellite images); (2) estimating the average carbon stock in that area or biome, per hectare; (3) multiplying (1) and (2) to find the carbon stock lost due to the conduct; (4) converting this carbon stock into tons of carbon dioxide equivalent (CO2e); (5) taking the — S. 386 —prevailing price of each ton of CO2e, which the Protocol leaves to be determined by regulations in Brazil, but for the time being ought to be no less than the price determined by the Amazon Fund (which it admits constitutes a negotiated figure); and finally (6) multiplying (4) and (5) to arrive at a final value. Admittedly, according to the wording of Article 14 of Resolution No 433 and the content of the 2024 Protocol,⁸⁰ this methodology applies to cases involving degradation of the local environment through deforestation and fires, rather than GHG emissions from the combustion of fossil fuels. Liability for excessive GHG emissions remains a frontier that Brazilian courts are yet to cross. Nevertheless, developments regarding quantification of (globally diffuse) climate-related damage in deforestation cases should be of importance to observers of climate litigation across the globe.

iv.Still Challenging: Monetarization of Climate Damage

Climate litigation in Brazil shows promise in several areas owing to the absence of procedural hurdles that typically hinder such cases in other jurisdictions, as well as the robust environmental law framework such litigation occurs under. However, the country still lacks a ruling by the Federal Supreme Court on the question of liability for climate-related damage and its quantification.

De Andrade Moreira summarizes the developments in this regard as follows:

[S]o far, the few decisions that address this issue are first-instance judgments, remaining subject to further appeals, and diverge on whether distinct climatedamage awards are appropriate. In each, the evidentiary record proves pivotal in confirming the scale of injury and the proportionality of any monetary remedy. Some judgments (in 14 cases) have recognised the existence of climate damage (direct climate damage) and awarded compensation in line with the valuation methodology put forward in each case. In others (3 cases), however, the courts have held that the quantification of climate damage lacks consensus and objective benchmarks, since scientific uncertainties, the absence of case law, statutory or doctrinal guidance, and the dearth of technical studies preclude the setting of a definitive monetary figure.⁸¹

Like any comparative legal exercise, findings made by the Brazilian courts cannot be directly transferred to other countries. However, a look at this caselaw makes it clear that certain concepts should be examined in greater depth in the specific context of climate litigation. This applies to jurisdiction, the — S. 387 —legitimacy of asserting and defending claims, the causal link and, finally, the definition and assessment of damages. In all these respects, the Brazilian case law is innovative and forward-looking. And, with great relevance for present purposes, the cases have impressively demonstrated that barriers to climate litigation can be overcome, and that such cases can lead to successes for the interests of litigants.

b.At the International Level

Between early 2024, when we were planning the conference that served as the impetus for this book project, and the summer of 2025, when we put the finishing touches on this book, three important climate rulings from international courts had been issued: one from the ECtHR,⁸² one from the ITLOS,⁸³ and one from the Inter-American Court of Human Rights (IACtHR).⁸⁴ These three rulings made one thing clear: climate change has irrevocably reached the attention of the international courts and tribunals. Each of these courts recognized the existential threat posed by climate change, and interpreted legal instruments which do not squarely address climate change as containing binding obligations concerning its mitigation — including customary obligations, environmental and human rights treaties. While it is now clear that climate change has entered the international docket, it is equally apparent that the matter of assessing and calculating damage is not yet being accorded high priority in these contexts. For the ECtHR, this may be due to the fact that the Court was not asked, in its initial climate cases, to grant compensation for material damage and — even if it had been asked to do so — it rarely awards high damages, particularly in environmental cases.⁸⁵ For the other courts in question, the lack of concrete damage assessments is due to the fact that they issued advisory opinions, which did not require them to pronounce findings assessing and calculating damage in detail.

However, international courts could soon be called upon to answer questions concerning the liability of responsible states for climate-related damage. In contentious proceedings, provided that they have jurisdiction, the conditions for admissibility are met, and a breach of obligations is found, courts will also have to rule on the question of legal remedies for addressing climate-related damage. What paths could be taken in the future to raise the issue of climate damage? Building on the findings made by the contributors to this volume, the following considers possible legal bases in international law. We acknowledge that our comments are currently speculative and will remain so until a final contentious ruling on damages has been handed down by an international court or tribunal. Assuming that it is a matter of time before such a ruling is made, we aim to outline both the potential of relevant claims and the difficulties of making them.

i.Legal Bases of Reparations Claims

Unlike certain national legal systems,⁸⁶ international law does not recognize any customary rule of strict liability for lawful acts, even if they are extremely dangerous. The “polluter pays” principle, which is sometimes extensively developed in national law (eg, for financing waste disposal or contaminated site remediation), is not established in international law to the extent that it could form the basis for liability between states.⁸⁷ However, there are prospects for the emergence of a primary legal norm prescribing strict liability for damage resulting from a state’s hazardous activities. This inevitably recalls the work of the International Law Commission (ILC) in this area.⁸⁸ However, it should be noted that the ILC’s work on the draft articles in this area does not necessarily reflect customary international law.⁸⁹ Furthermore, the application of the draft articles in climate cases would hinge on whether the emission of CO2 and other GHGs per se constitutes a hazardous activity. We do not believe this qualification is always justified, nor is it applicable at every point in time.

Aside from the issue of strict liability, one of the key questions that the ICJ must answer in its advisory opinion on climate change is whether the customary duty not to cause significant harm to the environment also applies

to the climate sphere.⁹⁰ If so, this customary rule would provide an important basis for claims for damages. We recognize significant potential here, given that the international climate regime (the UNFCCC and the Paris Agreement) are essentially silent on state responsibility.⁹¹ Therefore, we assume that the norms of state responsibility as they exist in general international law are applicable to breaches of climate-related international obligations. However, this does not mean that the climate regime will be completely irrelevant in liability or compensation cases. In cases involving state parties to the climate treaties, an international court will deal with the question of reparations in case the respondent has breached obligations under international law, including — for a court of general jurisdiction like the ICJ — the climate treaties. Turning back to the customary no harm rule, the ICJ has emphasized that the duty not to cause significant harm to the environment of other states, which is in turn, “based on the principle of prevention,” has “its origin in the due diligence that is required of a State in its territory.”⁹² Due diligence is a standard of conduct that is determined by various factors, including the circumstances of the relevant state, and that can change over time.⁹³ In our view, the same should apply to the prevention of transboundary harm caused by global warming.⁹⁴ Furthermore, in an environmental context, due diligence requires a state to “use all the means at its disposal to avoid activities in its territory or under its jurisdiction causing significant environmental damage to another state.”⁹⁵ This argument was recently reiterated by the ITLOS, which stated that a State must “put in place a national system, including legislation, administrative procedures and an enforcement mechanism necessary to regulate the activities in question, and [...] exercise adequate vigilance to — S. 390 —make such a system function efficiently, with a view to achieving the intended objective.”⁹⁶

In specific cases, due diligence is determined by applying standards from written and unwritten international law.⁹⁷ At this stage, an international court could refer to the specific state’s obligations under the climate regime in case it is a party to the relevant treaties. A key factor here is Article 4 of the Paris Agreement, which enshrines an obligation to pursue domestic measures with the aim of achieving the objectives of a State’s nationally determined contribution (NDC) — which gives rise to one of the most pressing questions pending before the ICJ, on which the opinions of states are divided.⁹⁸ Insofar as NDCs are not simply at the discretion of the states, and are instead legally binding, they might be taken as an indication of whether a state has fulfilled its due diligence obligation. However, a given State’s NDC may also be out of line with the overall temperature limits enshrined in the Paris Agreement, meaning that it is insufficiently ambitious to avoid warming beyond 1.5 or 2°C (Article 2(1)(a) of the Paris Agreement). In this regard, it could be argued that it is not the content of the NDC itself, but rather the principles enshrined in the climate treaties which should inform the requisite standard of diligence — including for example the Paris Agreement’s principles of highest possible ambition, progression and common but differentiated responsibilities and respective capabilities, in the light of different national circumstances (Articles 2(2), 3, and 4(3) of the Paris Agreement). If a State determines an NDC in contravention of these principles, its fulfillment of that same NDC would not necessarily mean that it had complied with its international obligations, including those under customary law or human rights law. Any other conclusion would render the climate targets, and the ideas of cooperation and collective effort that inform the Paris Agreement, moot.

If an international court were to conclude that the customary international law obligation to prevent significant transboundary harm to the environment is applicable in the context of climate change, and that there has — S. 391 —been (and continues to be) a breach of this obligation due to conduct falling short of the relevant standard of diligence, that state is responsible for the consequences of its breach. The responsible state would then suffer the consequences as under Part Two, Chapter I of the Articles on the Responsibility of States for Internationally Wrongful Acts (ARSIWA). Wrongful acts give rise to an obligation on the respondent state to compensate the injured state for the harm caused by such acts (Article 36(2) ARSIWA).

This gives us a potential legal basis on which to build a possible climate compensation case. However, it also brings us to the major hurdles facing such a claim.

ii.Potential and Hurdles

Climate damage is usually caused by a combination of factors, rather than by a single factor for which a particular country is responsible. The extent of the damage caused by global warming is characterized by its transnational nature. This means that CO2 emitted somewhere can have a devastating impact anywhere on the planet. The context of the emitting activity does not necessarily have to be transboundary; its effects are planetary in nature. In many cases, the damage is not caused by a single event, but by the gradual accumulation of greenhouse gases over time, the sources of which can change. While industrialized countries in the Global North were mainly responsible for CO2 emissions in the 19th century, emerging economies are increasingly responsible for a large proportion of CO2 emissions in the 21st century. These cumulative emissions interact with other vulnerabilities, eg historical, political, cultural, geographical and infrastructural ones.⁹⁹ This complexity in scientific terms raises difficult questions of causality and attribution in legal terms. At this juncture, it is also obvious that the courts’ handling of scientific findings and data will have a decisive impact on liability cases.¹⁰⁰

The ARSIWA regime certainly offers a way to answer questions of temporality and multifactoriality. Article 14(2) ARSIWA provides that “[t]he breach of an international obligation by an act of a State having a continuing character extends over the entire period during which the act continues and remains not in conformity with the international obligation.” Article 47(1) ARSIWA also appears to be relevant in this context. It states that “[w]here several States are responsible for the same internationally wrongful act, the responsibility of — S. 392 —each State may be invoked in relation to that act.” At first glance, these are two principles that could guide the courts in climate liability cases. However, applying them in concreto is likely to be more difficult.

Various scientific disciplines are developing approaches that could help the courts answer these challenging questions. One such approach is to determine a reference point from which it can reasonably be assumed that CO2 emissions are harmful to the climate.¹⁰¹ Another is the field of attribution science,¹⁰² which seeks to link specific emissions to specific impacts, and finally, the definition of a national carbon budget.¹⁰³ However, translating these scientific findings into the language of legal responsibility is no easy task for litigators and judges.¹⁰⁴

While there is accordingly potential for future climate damage claims under the ARSIWA regime, the hurdles are high, and many complex questions will only be clarified through future case law. Given the short and urgent timeframe available for tackling the climate crisis, this is only partially encouraging. In a few years, we may conclude that the ARISWA framework is insufficient for successfully pursuing climate damage compensation claims for three main reasons: firstly, because the legal hurdles are too high. Secondly, because the ARSIWA responsibility regime is too lenient, as many CO2-emitting actions are excluded from the outset because they cannot be classified as wrongful acts. This means that damage resulting from CO2 emissions that are permissible is excluded from the liability regime in ARSIWA. Thirdly, these damage proceedings may prove too slow to deliver timely relief, giving rise to frustrations as climate-related impacts intensify and tipping points are crossed.¹⁰⁵