After the flood: Brazil’s case against Shell opens up a new route for polluter-pays litigation
As Brazil’s federal prosecutors and a non-governmental organisation bring civil action against Shell Brasil for its alleged role in the climate change that contributed to devastating floods in southern Brazil in 2024, Juliana de Augustinis, Joana Setzer, Noah Walker-Crawford, Jameela Joy Reyes outline the complaint’s legal and evidentiary approach and the wider questions it raises for polluter-pays climate litigation.
In April and May 2024, persistent heavy rain fell across Rio Grande do Sul, Brazil’s southernmost state. The floods affected 478 of its 497 municipalities and around 2.4 million people, killing 183. The World Meteorological Organization classified the floods as the worst climate-related disaster ever recorded in Brazil, and the federal government allocated 111.6 billion Brazilian reais (BRL), equivalent to over 20 billion US dollars, to the state for relief and reconstruction.
On 9 October 2026, Brazil’s Federal Public Prosecutor’s Office (MPF) and the non-governmental organisation Instituto Preservar filed a public civil action before the federal court in Porto Alegre against Shell Brasil Petróleo Ltda, the Shell group’s Brazilian subsidiary. They are asking the court to hold Shell Brasil liable for the Shell group’s share of the damage resulting from climate change, which, they argue, made the rainfall more likely and more intense. It is the first case before Brazilian courts to rely on attribution science to claim climate-related damages.
Extreme rainfall has become a recurring feature in Rio Grande do Sul. In 2025 and 2026, repeated episodes have affected hundreds of municipalities, displacing thousands of people and causing further deaths. By September 2026, municipalities in the region had obtained 295 declarations of emergency or calamity from the federal government for this year alone. Could the courts make major emitters share the cost of disasters like these?
The legal framework
The complaint is grounded in Brazilian environmental civil liability, which treats climate-related damage as a form of diffuse environmental damage: harm to the ecologically balanced environment as a collective interest, rather than to identified individuals or groups.
Three features of that regime are central to the claim.
First, liability is strict. Under the ‘integral risk’ theory applied by Brazilian courts, claimants must establish damage and causation, but not fault. Traditional grounds for excluding liability (e.g. force majeure or third-party acts) are not accepted, and the lawfulness of an activity does not in itself exclude liability. How this regime applies to globally dispersed greenhouse gas emissions is one of the main questions the case will test.
Second, the concept of polluter extends to indirect polluters. The complaint characterises Shell Brasil as an integrated part of the Shell group, operating under the group’s business principles and brand, sharing in the economic benefits of a model built on producing and selling fossil fuels, and holding a significant position in the Brazilian fuels market.
Third, liability is joint and several. Where several polluters contribute to indivisible damage, each can be held liable for all of it, and the claimant may choose which polluter to sue. On this basis the Shell group’s share of historical emissions, as calculated by the Carbon Majors database, is attributed to the Brazilian subsidiary.
The complaint also invokes the precautionary principle to request a reversal of the burden of proof, so that Shell Brasil would have to show its activities did not contribute to the damage rather than the claimants having to prove they did. It draws on the advisory opinions of the Inter-American Court of Human Rights and the International Court of Justice.
The evidence: constructing the ‘causal chain’
The complaint constructs causation as a chain of three links, each resting on published science that predates this particular litigation. The first link draws on the Sixth Assessment Report (AR6) of the Intergovernmental Panel on Climate Change (IPCC): human emissions have unequivocally caused global warming and are likely the main driver of the observed increase in heavy precipitation. The second link, source attribution, uses the Carbon Majors database. That database attributes 2.02% of global fossil fuel and cement CO₂ emissions between 1854 and 2024 to the Shell group. The third link, event attribution, relies on a peer-reviewed study by Clarke et al., which built on a World Weather Attribution rapid analysis and found that with 1.2°C of global warming, rainfall of this kind had become about twice as likely and around 12% more intense.
The complaint seeks to reinforce each link by measuring the evidence against the Inter-American Court of Human Rights’ criteria for ‘best available science’, and notes that Brazil’s National Water Agency and National Adaptation Strategy have themselves relied on the World Weather Attribution findings.
From hazard to damage
The complaint’s most distinctive element is how it connects the causal chain to the damage. Polluter-pays cases have generally had to show, through an impact assessment, how a climate-driven hazard translated into specific harm. This complaint takes a shorter route, treating the change in hazard intensity itself as the measure of attributable harm. Its formula for material damages multiplies the disaster’s public cost by 12% (the percentage attributed to climate change), then by 2.02%, an attribution factor of 0.24%. Applied to the BRL 111.6 billion federal allocation as a minimum base, this gives BRL 270,518,400. The claimants present this figure as an estimate, to be settled at the damages-assessment stage, but are asking the court to fix the calculation method when ruling on liability.
The complaint presents the 12% intensity figure as a legal criterion rather than a scientific finding. It acknowledges other contributing factors, including natural variability, El Niño, territorial vulnerability, shortcomings in urban planning and fragile infrastructure.
It describes the approach as conservative on two grounds. First, the claimants seek only a proportional share, although joint and several liability would in principle allow a claim for the full damage. Second, it uses the lower of the study’s two metrics: the finding that the rainfall became twice as likely would, as the complaint notes, imply an attributable fraction of risk of around 50%. The claimants also rely on case law of the Superior Court of Justice holding that, where many actors contribute to environmental harm and individual shares cannot be established with conventional certainty, a relevant contribution suffices. Whether a court will accept hazard intensity as a proxy for damage, without hydrological and impact modelling, is likely to be a central point of contention.
The complaint also seeks a separate, equal amount in collective moral damages, including a punitive component, bringing the total claimed to around BRL 541 million. The company’s conduct becomes relevant only at this point: the claimants argue that the Carbon Majors knew of the climate consequences of their activities from at least the 1960s. The complaint proposes that any award be paid into a dedicated fund under judicial oversight, with a spending plan prepared by an independent technical advisory body and developed with the participation of affected communities.
Aggregation shapes the scale of the claim. Because the Public Prosecutor’s Office is suing on behalf of the collective, the harm is pleaded at the state level, not as losses suffered by identified individuals. This avoids a hurdle facing individual claimants. In Lliuya v. RWE, Peruvian farmer Saul Luciano Lliuya had to show how climate change affected the risk to his home. It also explains the size of the claim against energy multinational RWE: Lliuya sought 0.47% of the cost of protective measures, around €17,000. The Hamm court accepted the claim in principle but dismissed it on the facts in 2025. By contrast, a 0.24% share of an aggregated public bill yields BRL 270 million.
Implications beyond Brazil
The case differs from earlier polluter-pays claims in targeting a major emitter’s national subsidiary in the jurisdiction where the damage occurred. Because Brazilian strict liability is joint and several and holds indirect polluters accountable like direct ones, the claimants can sue the local subsidiary for the group’s whole share in the courts where the damage occurred. By contrast, in Lliuya v. RWE and Asmania v. Holcim (a building materials company), claimants from Peru and Indonesia had to sue in the emitters’ home courts in Germany and Switzerland respectively, in proportion to each of the defendants’ shares. In Casquejo v. Shell, survivors of Typhoon Odette in the Philippines sued Shell plc in the English courts using Philippine substantive law. And Milieudefensie v. Shell targeted Shell’s parent company where it was registered (in the Netherlands, before its 2022 move to England and Wales).
The court will need to resolve several questions. Can a group’s global emissions be attributed to a local subsidiary? Is the intensity proxy an adequate basis for apportioning damage? Is public expenditure the right measure of harm? And how does a proportional claim sit within a regime of joint and several liability? The answers will indicate whether domestic environmental liability rules can provide a route around some of the jurisdictional and attribution barriers faced by transnational climate damages claims, and whether other jurisdictions with similar rules might follow.