In a study published in Nature, SPARCCLE researchers find that greenhouse gas emissions from just 180 fossil fuel and cement producers have significantly intensified global heatwaves. The emissions from these “carbon majors” account for approximately 60 percent of humanity’s total cumulative CO2 emissions from 1850 to 2023.

The researchers looked at 213 heatwaves that occurred on all seven of Earth’s continents between 2000 and 2023. The study included all heatwaves that were reported by authorities or the media due to significant casualties, economic losses, or calls for international assistance. Africa and South America were significantly underrepresented in the study, however, due to underreporting and lack of usable data from these regions. Nevertheless, the trend is clear: Climate change makes heatwaves more likely and increasingly severe.

In terms of figures, this means that global warming made heatwaves 20 times more likely between 2000 and 2009, and as much as 200 times more likely between 2010 and 2019, compared with the period between 1850 and 1900.

Another aspect of the study considers who contributes to this trend. Researchers analysed the emissions that were facilitated by the 180 largest producers of fossil fuels and cement – referred to in the study as “carbon majors”. The emissions from these carbon majors account for 60% of humanity’s total cumulative CO₂ emissions from 1850 to 2023, with the rest of the CO₂ emissions largely attributable to land use activities. The researchers then calculated the contribution of each carbon major to the change in global average temperature.

“Past studies have mostly looked at emissions from people and countries. This time, we’re focusing on the big carbon emitters,” explains SPARCCLE researcher Yann Quilcaille.

According to the authors, these entities have protected and continued their business activities through strategic disinformation and intense lobbying. With this study, the research team aimed to fill a gap in scientific knowledge by using attribution studies to cover a wider range of extreme events and connect them to specific actors. However, their findings could also serve as a basis for establishing responsibility for increasingly frequent heatwaves and making the necessary adjustments to case law. The damage caused by heatwaves could also be assessed more strictly according to the “polluter pays” principle.

According to Nature, nearly 1,000 news stories have been published to date, reflecting global media attention, including coverage by CNN, The Guardian, and beyond.

Adapted from a press release by ETH Zurich. Read the original article here.

For more information:

Quilcaille, Y., Gudmundsson, L., Schumacher, D.L., Gasser, T., Heede, R., Heri, C., Lejeune, Q., Nath, S., Naveau, P., Thiery, W., Schleussner, C-F., & Seneviratne, S.I. (2025). Systematic attribution of heatwaves to the emissions of carbon majors. Nature, 645, 392-398. https://doi.org/10.1038/s41586-025-09450-9