Groundbreaking research published in Nature by ETH Zurich’s Department of Environmental Systems Science has drawn a direct line between the world’s largest carbon emitters and the rising severity and frequency of heatwaves. The study provides the strongest evidence to date that fossil fuel use in cement and other heavy industries is a key driver of extreme climate events, with implications that could accelerate plant closures and spark new waves of litigation.
Using Extreme Event Attribution (EAA), the research team systematically analysed 213 waves between 2000 and 2023, concluding that climate change made them vastly more likely and more intense. The emissions of 180 identified “carbon majors” – companies and state-owned entities with the largest historical carbon footprints – were each found to have contributed directly. Collectively, these majors are responsible for 60 per cent of all CO2 emitted since 1850, with land use changes accounting for the remainder.
Notably, the top 14 emitters – including the former Soviet Union, China (cement and coal), ExxonMobil, BP, Saudi Aramco and Shell – contributed as much as the other 166 combined. Their output intensified heatwaves by up to 2°C and made them hundreds of times more likely than in pre-industrial times. According to ETH Zurich researcher Yann Quilcaille, even the smallest major, Russian coal producer Elgaugol, was linked to 16 separate heatwaves.
A cement industry test case
The findings could bolster legal action. The new research strengthens climate litigation already underway, such as a lawsuit filed by four residents of Indonesia’s Pari Island against Holcim. The plaintiffs argue that rising seas, which have already submerged 11 per cent of their island, are tied to Holcim’s emissions. They are seeking compensation, along with funding for protective measures like mangrove planting and breakwater barriers. It is estimated the island could be completely underwater by 2050.
Holcim has pushed back, arguing that “the question of who is allowed to emit how much CO2” should be determined by legislators, not civil courts. Still, campaigners say the ETH Zurich study provides scientific backing for future legal challenges, especially against sectors such as cement where fossil fuel dependency remains high.
Broader research planned
“The ETH Zurich paper is hugely important in making connections between fossil fuel extraction, the responsibility companies have for their products and its significant influence on heatwaves around the world", said Andrew Gage, staff lawyer at West Coast Environmental Law in Canada. “This type of paper really makes it much more possible to sue for the harm from specific disasters and to point out that these companies were responsible to a large degree.”
The broader implication is clear: as attribution science advances, industries with high emissions face not only regulatory and financial pressure but also mounting legal accountability. At least 489,000 people died annually from heat between 2000-19, according to the World Health Organisation (WHO), many from climate-change fuelled heatwaves if this latest research is to be verified.
ETH Zurich’s researchers argue their work offers a “powerful evidentiary basis” for phasing out fossil fuels in cement and other carbon-intensive sectors to limit corporate-driven climate harms. The researchers behind this paper want to conduct similar studies on other extreme events, such as heavy rainfall, droughts or fires, and trace these events back to the contributions of individual actors and companies.
