1,1,1,2,3,5,7,8,2,9,1- 1Institute for Atmospheric and Climate Science, Department of Environmental Systems Science, ETH Zurich, Zurich, Switzerland (yann.quilcaille@env.ethz.ch)
- 2International Institute for Applied Systems Analysis (IIASA), Laxenburg, Austria
- 3Climate Accountability Institute, Snowmass, Colorado, USA
- 4Department of Public Law and Governance, Tilburg University, Tilburg, Netherlands
- 5Climate Analytics, Berlin, Germany
- 6Atmospheric, Oceanic and Planetary Physics, Department of Physics, University of Oxford, Oxford, United Kingdom
- 7Laboratoire des Sciences du Climat et de l’Environnement, ESTIMR, CNRS-CEA-UVSQ, Gif-sur-Yvette, France
- 8Vrije Universiteit Brussel, Department of Water and Climate, Brussels, Belgium
- 9Integrative Research Institute on Transformations of Human-Environment Systems (IRI THESys) and the Geography Department, Humboldt-Universität zu Berlin, Berlin, Germany
Attribution research increasingly aims to quantify the full causal chain, from emissions to changes in climate extremes and their societal impacts. Furthermore, most extreme event attribution (EEA) studies remain focused on single events, and few assessments quantify contributions from specific emitting actors. Here we present a systematic framework that links historical greenhouse gas emissions to the changing likelihood and intensity of impactful heatwaves [1].
For all heatwaves reported in EM-DAT during 2000-2023, we apply an adaptation of the event attribution protocol by the World Weather Attribution using ERA5, BEST and CMIP6 data. After validation using goodness-of-fit and Granger causality, 213 heatwaves out of 226 are kept for analysis. Across events, we estimate how much anthropogenic warming since 1850-1900 altered the probability of occurrence and the intensity of these heatwaves. We then extend the attribution upstream to quantify the contribution of 180 carbon majors (fossil fuel and cement producers) to these changes, using company-level CO2 and CH4 emissions and reduced-complexity Earth system modelling (OSCAR) to derive counterfactual temperature trajectories and event-level heatwave metrics.
Results show that climate change made all 213 heatwaves more likely and more intense, with strong temporal escalation: the median heatwave in 2000-2009 became about 20 times more likely due to warming since 1850-1900, increasing to about 200 times in 2010-2019. About one-quarter of events were assessed as virtually impossible without climate change. Emissions from carbon majors account for roughly half of the increase in heatwave intensity since 1850-1900, and individual carbon majors’ contributions are sufficient to render 16 to 53 heatwaves virtually impossible in a pre-industrial climate into feasible events, depending on the actor.
By systematising EEA across many events, this work expands the scope of attribution for a more comprehensive perspective on heatwaves and enabling assessments across time and regions. Yet, we highlight limitations in the reporting of events, calling for more exhaustive datasets of events. By explicitly attributing portions of risk and intensity to major emitting entities, this analysis significantly contributes to the rapidly maturing field of source attribution, thus helping close an evidentiary gap between physical climate attribution and accountability-relevant quantification.
[1] Quilcaille, Y., Gudmundsson, L., Schumacher, D. L., Gasser, T., Heede, R., Heri, C., Lejeune, Q., Nath, S., Naveau, P., Thiery, W., Schleussner, C.-F., and Seneviratne, S. I.: Systematic attribution of heatwaves to the emissions of carbon majors, Nature, 645, 392-398, 10.1038/s41586-025-09450-9, 2025.
How to cite: Quilcaille, Y., Gudmundsson, L., Schumacher, D. L., Gasser, T., Heede, R., Heri, C., Lejeune, Q., Nath, S., Naveau, P., Thiery, W., Schleussner, C.-F., and Seneviratne, S. I.: Systematic Attribution of Heatwaves to the Emissions of Carbon Majors, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13939, https://doi.org/10.5194/egusphere-egu26-13939, 2026.
