The Climate Litigation Network supports national organisations that are taking litigation action against their governments in respect of the adequacy and implementation of national climate policies and targets. This presentation will provide an overview of the role in science in climate cases that challenge governments’ overall emissions reductions (“framework cases”) – of which there are more than 100 globally. Drawing from a litigator’s perspective, it will address common legal questions (i.e., harm, causation, foreseeability and remedies) that arise in such cases, and provide examples of how science has been used in case studies. 

Across framework cases, scientific evidence has been critical to success. For example, many cases, including those based on human rights or tort law, require claimants to show how they have been impacted or have suffered harm. In this regard, supporting studies range widely, depending on the facts of the case. These could include studies concerning extreme weather events, flooding, landslides, impacts on crop production and availability to water, and impacts on health or culture. To establish legal liability, claimants typically must show that the government’s actions can be causally linked to the harm, and that the harm was foreseeable. In this regard, attribution science and climate science generally can play a role in evidencing why government action (or lack of action) is contributing to climate change impacts. In terms of remedies, several cases have sought to push governments to adopt emissions reduction targets that reflect their “fair share” of the remaining global carbon budget. Numerous fair share methodologies have been developed by academics, many of which seek to reflect obligations and principles set out in the United Nations Framework Convention on Climate Change and international environmental law. In some cases, there may also be questions concerning loss and damage, which could require detailed analyses of how much damage has been incurred, or could be incurred in future, due to the impacts of climate change.

Drawing on case studies from specific cases, this presentation will highlight the current deployment of science in climate cases against governments and explore new frontiers.

How to cite: Williamson, A.: Challenging governments’ response to the climate crisis: the role of science in climate litigation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21949, https://doi.org/10.5194/egusphere-egu24-21949, 2024.

To bridge the knowledge gap between climate scenarios and law, this presentation is aimed to demonstrate currently demanded mutual contributions by legal professionals and integrated assessment modellers on 1) how legal knowledge can be integrated into climate scenarios and 2) how scientific evidence generated from climate scenarios can better guide climate litigation cases. We expect that this could support judges in making trade-offs in climate-related court cases and could contribute to the acceptance of decisions by judges in such cases. Given the emissions gap and the measures that must be taken to comply with the Paris Agreement, the latter is likely becoming more relevant.

Regarding the first part, the results are based on an empirical research project on Improving the Integration of Legal Knowledge and Scholars in Climate Scenario Assessments (https://www.uu.nl/en/research/sustainability/improving-the-integration-of-legal-knowledge-and-scholars-in-climate-scenario-assessments) and a workshop  (https://www.uu.nl/en/research/sustainability/workshop-report-promoting-the-mutual-understanding-between-legal-and-governance-scholars-and-climate) resulted from this project held in May 2023. Via interviews and focus-group discussions with 24 experts in climate modelling, climate law and politics, and ethics, our research highlights four legal aspects for integration, which are: 1) implementation end enforcement of climate targets, 2) key normative principles, 3) legal uncertainties, and 4) the applicability of scenarios in regional and local legal contexts. Considering the challenges of integration due to epistemic distinctions between disciplines, experts held different opinions on the feasibility of integrating those four aspects. Regarding actionable steps for the short term, revising narratives and a ‘legal reality check’ are the most agreed ones. The former refers to adding legal obligations that safeguard justice, fairness and fundamental human rights - traceable to various treaties - to narratives of the global futures. The latter refers to scrutinising the ‘shared feasibility space’ between law on the one hand and modelled scenarios and emission reduction pathways on the other: it can be the compatibility of legal principles with modelled scenarios based on different assessment criteria (e.g. fair share of burdens), or to compare scenarios with and without regulatory boundary conditions in a specific jurisdiction on a specific mitigation solution (e.g. BECCS scenarios).

Regarding the second part, the currently ongoing research focuses on the adoption of authoritative scientific evidence from climate scenarios - typically the projections referred to in the IPCC reports - in climate litigation cases. First, inspired by the Daubert Criteria, this research explores the possibility of developing guidelines for judges to deal with scientific uncertainties contained in multiple projected futures and determining admissibility of scientific evidence. Second, seeing the increasing reference to ‘open norms’ (e.g. due diligence, fair share) and fundamental human rights (to private life or a healthy environment) in court cases, modelled scenarios could provide information for guiding judges in their interpretation of key concepts such as carbon budgets, fair share, emission gap, appropriate emission reduction obligations, and climate-induced harm and loss and damage. We expect that this could be beneficial to the supportability of judges' decisions in climate cases.

How to cite: Du, H., Brans, E., Scown, M., Chen, H.-H., Daioglou, V., Roelfsema, M., Triyanti, A., Hegger, D., Niamir, L., van Rijswick, M., Dai, L., Driessen, P., du Pont, Y., van Berkel, D., and van Vuuren, D.: Bridging the gap between climate scenarios and law - a roadmap for mutual contributions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3603, https://doi.org/10.5194/egusphere-egu24-3603, 2024.

Fossil fuel companies are no longer denying anthropogenic climate change in recent climate litigation but question the validity of climate science for establishing legal responsibility. Past research on social movement legal mobilization has primarily focused on plaintiffs’ perspectives, showing how they use the judicial process as a site of knowledge production. Drawing attention to the other side, I conduct an analysis of scientific disputes in major climate change lawsuits and develop a typology for studying defendants’ evidentiary arguments. Defendants build evidentiary counter-narratives, challenge the substantive quality of plaintiffs’ claims, and attack the scientific integrity of compromising evidence. Litigants’ legal narratives and factual claims are linked to broader normative concerns about how the underlying issues should be resolved. Fossil fuel companies’ legal arguments reflect broader strategies to evade responsibility for climate change.

How to cite: Walker-Crawford, N.: Save the Climate but Don’t Blame Us: Corporate Responses to Climate Litigation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8458, https://doi.org/10.5194/egusphere-egu24-8458, 2024.

In light of the global energy crisis and escalating climate change impacts, the liability of major fossil fuel companies is receiving heightened scrutiny, particularly in the context of climate litigation. This study initially establishes the feasibility of attributing climate damages to these companies. Utilizing the social cost of carbon methodology, we evaluate the damages inflicted by the top 25 oil and gas emitters from 1985 to 2018, comparing these to their financial profits. Our central estimate suggests partial damages of approximately 20 trillion USD, with the companies’ financial gains surpassing this by 50%, totaling around 30 trillion USD. This indicates the potential of carbon majors to cover their attributed damages while maintaining significant profits. In our analysis, we also explore how varying approaches to assigning responsibility and handling uncertainties in climate damages can markedly influence these findings. Additionally, we explore the role of sovereign wealth funds in perpetuating fossil-fuel derived wealth and the ensuing liability questions.

How to cite: Andrijevic, M., Schleussner, C.-F., Kikstra, J., Heede, R., Rogelj, J., Schmidt, S., and Simpkin, H.: Towards Evaluating the Financial Responsibility of Carbon Majors for Climate-Related Damages, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12601, https://doi.org/10.5194/egusphere-egu24-12601, 2024.

Numerous Extreme Event Attribution (EEA) studies have consistently shown that human-induced climate change has increased the likelihood of extreme heat events. The increasing relevance of these studies in the context of climate litigation underscores the demand for the quantification of climate change impacts. Heat, as the primary contributor to weather-related mortality on the European continent, has caused more than 61,000 heat-related deaths in Europe during the 2022 summer. We carry out this proof-of-concept study in which we apply Extreme Event Attribution methods combined with epidemiological models to quantify how anthropogenic warming has influenced extreme heat-related mortality events in Europe. In contrast to most health impact studies, we utilize open-access mortality data from Eurostat, which is available in near-real time.

Because of the complex, non-linear relationship between temperature and mortality, we conduct separate Extreme Event Attribution analyses for (i) temperature extremes and (ii) associated heat-related mortality events in 232 distinct administrative regions spanning over 35 European countries. Our findings reveal that the probability of the maximum weekly values observed in 2022 has increased 12-fold [95^th CI 3.51-147.15] for temperature and tripled [95^th CI 1.02-18.63] for mortality compared to the pre-industrial baseline. Notably, we identify significant geographical disparities, e.g. in Spain the mortality risk is even 30 times higher [95^th CI 3.33 – 1218.14] due to anthropogenic warming.

We find a statistically significant trend in 70% [90%] of the regions at the 0.95 [0.90] significance level, and across all age and sex groups, except for women aged 65 years or less, indicating that anthropogenic warming affects almost the entire European population.

This study establishes a foundation for subsequent analyses, not only for heat-related mortality events observed on different temporal and spatial scales but also for enabling an examination of other weather events and associated health impacts. By combining climate sciences and techniques with epidemiology and health data, it is possible to calculate the contribution of climate change to changes in health risks and mortality burdens by sociodemographic categories, such as sex, age, socioeconomic level, or comorbidities, especially in vulnerable groups. This transdisciplinary work has to potential to provide key information for climate-related health lawsuits and opens the door to inter- and transdisciplinary perspectives on how to integrate geoscience and epidemiology insights in litigation.

How to cite: Beck, T. M., Gudmundsson, L., Schumacher, D. L., Seneviratne, S. I., Achebak, H., and Ballester, J.: Quantifying the human-induced climate change impact on heat-related mortality events in Europe with Extreme Event Attribution Methods , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15814, https://doi.org/10.5194/egusphere-egu24-15814, 2024.

Climate change is already increasing the frequency, intensity and duration of many extreme weather events around the world, as well as driving impacts on communities through slow-onset changes, and will continue to do so with each additional degree of warming. Young and future generations will face an ever-greater number of such events during their lifetimes, raising concerns regarding the intergenerational inequity inherent in climate change. In response to these concerns, child and youth-led climate litigation is emerging as an avenue to push for more ambitious climate policies at national and regional scales, by applying legal duties and obligations in a forward-looking way and presenting courts with  scientific evidence of observed and projected climate risks and impacts. Recent complaints led by young people, including, for example, Sacchi et al. v. Argentina et al., lodged in 2019 with the United Nations Committee on the Rights of the Child and Duarte Agostinho et al. v. Portugal et al., which was heard in 2023 by the European Court of Human Rights, have broken new ground by bringing the rights of children and future generations to the fore. Based on a review of recent and ongoing cases, we will investigate (i) what harms are claimed by youth plaintiffs, and (ii) whether, how and to what extent scientific evidence is used to support their claims. By comparing the cases in relation to their claims, jurisdictional frameworks, reference to human and/or children’s rights, and status, we will shed light on how youth applicants have addressed the main challenges of this specific category of climate litigation, including meeting the victimhood requirement, and what role evidence from the geosciences and other scientific fields has played.

How to cite: Pietroiusti, R., Adelman, S., Savaresi, A., and Thiery, W.: Does climate change violate children’s rights? Investigating the use of scientific evidence in child and youth-led climate litigation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16721, https://doi.org/10.5194/egusphere-egu24-16721, 2024.

The integration of natural science concepts into climate change litigation, particularly in cases related to glacier lake outburst floods (GLOFs) in mountainous regions like the Andes, faces significant challenges due to the differing nature of scientific and legal frameworks.

Scientific understanding of climate change impacts on phenomena such as GLOFs relies heavily on scenarios, modeling, and projections that evolve over time with advancements in technology and knowledge. These models need to be comprehensive, and consider an array of factors including glacier retreat, temperature changes and various risk factors. However, legal standards often require definitive proof of causation. There may arise a discrepancy creating  a gap in case of prevailing uncertainties inherent to high-mountain processes which may not always meet the exacting evidentiary requirements of litigation.

An illustrative example of this challenge is the case of a citizen in Huaraz, in the Andes of Peru, using a major German energy producer over the risks of a catastrophic flood from a GLOF at Lake Palcacocha. The German court’s decision to admit this case is groundbreaking in climate litigation. It implies a recognition of legal responsibilities of large emitters for potential losses and damages caused by anthropogenic climate change globally, provided a causal relation between emissions and risk can be established. This case exemplifies the challenge in linking complex scientific causation with legal accountability.

In the Palcacocha case, the German court defined to distinguish between i) the hazard and risk posed to the plaintiff in Huaraz, and ii) the attribution to anthropogenic climate change and the emissions produced by the defendant. Here we report on the geoscientific studies undertaken to analyze the hazard situation posed by potential rock and ice avalanches, impacting the glacial lake and producing potentially devastating floods in the city of Huaraz. Critical among other are concepts and methods to quantify probability of occurrence of an event, and the effect of cascading slope and mass flow processes.

In conclusion, the challenges in adapting natural science concepts for climate change litigation, particularly regarding GLOFs, stem from different concepts, standards of proof, and conceptual understandings in science and law. Bridging this gap is essential for effective climate litigation and requires innovative interdisciplinary approaches that facilitate the translation of scientific findings into legally cogent arguments. The framework, methods and standards we applied in the case of Palcacocha could serve for other litigation cases in similar environments, highly impacted and vulnerable to anthropogenic climate change. 

How to cite: Muñoz, R., Huggel, C., Haeberli, W., Mergili, M., Emmer, A., Arenson, L., and Sturzenegger, M.: From Glaciers to Courtrooms: Translating Natural Science Concepts into Legal Frameworks for Climate Litigation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17250, https://doi.org/10.5194/egusphere-egu24-17250, 2024.

While human-induced climate change shows no sign of slowing down, calls to steer to a more sustainable path grow louder. Countries are sued for their lack of ambitious climate action, and high-emitting companies for their responsibilities. However, climate litigation is often impeded by the lack of scientific evidence directly relevant to the legal cases. Available attribution research can provide support for claims, but some key elements are still missing. First, event attribution studies are limited to a few selected events, depending on available researchers’ time and interests. Second, the contributions of high-emitting companies to recent extreme events has not yet been quantified. Here, we fill in both of these gaps. We present the first collective attribution of 149 historical heatwaves reported over the 2000-2021 period. We apply a well-established extreme weather attribution (Philip et al., 2020) to heatwaves reported in the EM-DAT database (EM-DAT, 2023). For each listed heatwave, we identify the event in observational data (ERA5, BEST) and CMIP6 data, then we estimate its occurrence probabilities for present and pre-industrial climate conditions. Subsequently, we calculate the contributions in global mean surface temperature of 110 fossil fuels and cement companies using their CO₂ and CH₄ emissions (Heede, 2014) and the reduced-complexity Earth system model OSCAR (Gasser et al., 2017). These contributions combined to the collective attribution allow for the calculation of the contributions of these carbon majors to all of the analyzed historical heatwaves. These carbon majors represent 76% of the CO₂ emissions over 1850-2021, and half of this 76% is due to only six actors (nation-state of China for coal & cement; nation-state of the Former Soviet Union for coal, oil and gas; Saudi Aramco; Chevron; ExxonMobil; Gazprom). In terms of global mean surface temperature, these six majors contribute to 0.30°C, while the others contribute to an additional 0.34°C. The majority of heatwaves are made substantially more probable and intense due to these six carbon majors. Though, other carbon majors cannot be neglected, as their sole contribution may be enough to make some heatwaves possible. This attribution of a large number of heatwaves and the link to the contributions of the carbon majors will provide useful resources for climate litigation, paving the way towards their legal responsibility.

EM-DAT, CRED / UCLouvain: www.emdat.be, last access: 09.01.2024.

Gasser, T., Ciais, P., Boucher, O., Quilcaille, Y., Tortora, M., Bopp, L., and Hauglustaine, D.: The compact Earth system model OSCAR v2.2: Description and first results, Geoscientific Model Development, 10, 271-319, 10.5194/gmd-10-271-2017, 2017.

Heede, R.: Tracing anthropogenic carbon dioxide and methane emissions to fossil fuel and cement producers, 1854–2010, Climatic Change, 122, 229-241, 10.1007/s10584-013-0986-y, 2014.

Philip, S., Kew, S., van Oldenborgh, G. J., Otto, F., Vautard, R., van der Wiel, K., King, A., Lott, F., Arrighi, J., Singh, R., and van Aalst, M.: A protocol for probabilistic extreme event attribution analyses, Adv. Stat. Clim. Meteorol. Oceanogr., 6, 177-203, 10.5194/ascmo-6-177-2020, 2020.

How to cite: Quilcaille, Y., Gudmundsson, L., Gasser, T., and Seneviratne, S. I.: Contributions of carbon majors to historical heatwaves, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18367, https://doi.org/10.5194/egusphere-egu24-18367, 2024.

The number of climate change lawsuits is exploding,  and so is the need for scientific evidence on climate change in courtrooms. Here we identify four roles that climate researchers can take up in light of these recent developments: expert witness, party support, amicus curiae, and litigation-relevant research. For each role, we highlight recent examples and best practices, as well as pitfalls and their overcoming. These examples overall highlight the urgent need for interdisciplinary research between climate science and legal scholars to bring both research communities closer together. In addition, and in activities where exchange with litigators takes place, it is critical that ingestion of scientific information occurs right from the start of the litigation process.

How to cite: Thiery, W., Pietroiusti, R., Savaresi, A., and Smis, S.: Four roles for geoscientists in climate litigation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19683, https://doi.org/10.5194/egusphere-egu24-19683, 2024.

This study investigates the impact of Conference of the Parties (COP) meetings on the stock prices of oil companies and the broader implications for renewable energy sectors to examine the relationship between international climate negotiations and market responses in the energy sector. The analysis focuses on stock price movements and volatility within the oil and renewable energy industries. We look at the data of the 10 largest stocks in each category and investigate their behaviour during COP. The findings indicate that, with the exception of notable negative stock price movements during COPs 20 and 21 (before and during the signing of the Paris Agreement), COP meetings generally do not significantly influence the value of oil companies. There is also no impact on oil prices during COP itself, though some sign of disturbance in the period immediately afterwards. The study also addresses the renewable energy sector, finding no strong effects from most COP meetings but a notable decrease in stocks during COP6's failure. We conclude that the majority of COPs have not produced market signals indicating a green transition, although these signals are potentially detectable.

How to cite: Lamboll, R. and Al Khourdajie, A.: How stocks judge COPs: market impacts of climate conferences, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20599, https://doi.org/10.5194/egusphere-egu24-20599, 2024.