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Fossil fuel giants linked to deadly heatwaves, landmark study finds
International study shows direct link between emissions from the world’s largest fossil fuel and cement producers and the increasing frequency and intensity of extreme heatwaves.
A landmark study published in Nature has directly connected the emissions of the world’s largest fossil fuel and cement producers to the rising frequency and intensity of extreme heatwaves. Led by ETH Zurich, the research is the first to systematically trace more than 200 heatwaves worldwide between 2000 and 2023 back to specific corporate emitters – the so-called “carbon majors.”
The findings are stark: climate change made heatwaves 20 times more likely in the early 2000s, and up to 200 times more likely between 2010 and 2019 compared with pre-industrial levels. The emissions of just 180 companies account for around 60% of all cumulative CO₂ since 1850. The top 14 – including Saudi Aramco, Gazprom, and ExxonMobil – are each linked to over 50 heatwaves that would have been almost impossible without human-induced warming.
“Climate change has made each of these heatwaves more likely and more intense, and the situation has worsened over time,” said Yann Quilcaille, lead author of the study and postdoctoral researcher at ETH Zurich.
“These results underline that extreme heatwaves are not abstract, ‘natural’ disasters – they are being fuelled directly by the emissions of a relatively small number of powerful actors,” Dr. Quilcaille added.
Professor Wim Thiery, climate scientist at VUB and co-author of the study, stressed the human dimension: “This supports our recent study where we showed that under current levels of warming, half of the children born in 2020 will live through unprecedented heatwaves, compared to only one sixth of those born in 1980.”
Beyond the science, the findings have important implications for accountability. “Attribution studies are extremely important for the work of climate litigators across the world who can use these results in climate cases,” said Prof. Thiery. “This new and direct scientific evidence of the responsibility of individual companies was a key but missing item until now.”
By filling this gap, the ETH Zurich team hopes their work will help establish responsibility for increasingly frequent heatwaves and strengthen the application of the “polluter pays” principle in policy and law. They now plan to extend attribution studies to other extreme events such as floods, droughts, and wildfires.
Research
The study was conducted by researchers from ETH Zurich, IIASA, the Climate Accountability Institute, the University of Zurich, Climate Analytics, the University of Oxford, Vrije Universiteit Brussel (VUB), the Integrative Research Institute on Transformations of Human-Environment Systems (IRI THESys), and Humboldt University of Berlin.
Quilcaille Y, et al. Systematic attribution of heatwaves to the emissions of carbon majors, Nature (2025). doi:10.1038/s41586-025-09450-9
Contact ETH Zurich
· Dr. Yann Quilcaille, postdoc terrestrial climate dynamics at ETH Zürich, yann.quilcaille@env.ethz.ch
· Prof. Dr. Sonia Seneviratne, senior professor terrestrial climate dynamics at ETH Zürich and vice president of the working group I of the IPCC – Intergovernmental Panel on Climate Change, sonia.seneviratne@ethz.ch
Contact VUB
· Prof. Dr. Wim Thiery, professor, research group bclimate, wim.thiery@vub.be, https://bsky.app/profile/wimthiery.bsky.social, +32 2 629 30 29
· Dr. Marie Cavitte, valorisation officer, marie.cavitte@vub.be, +32 470 19 24 15
Koen Stein
