A new study has found that 55 of the heat waves recorded over the past 25 years would have been virtually impossible without human-caused climate change, highlighting the role of major fossil fuel and cement producers in driving extreme heat events.

Published Wednesday in the journal Nature, the study examined 213 heat waves worldwide from 2000 to 2023 using data from the EM-DAT International Disaster Database. It found that planet-warming emissions from 180 major companies — including publicly traded and state-owned oil, gas, and cement producers — significantly contributed to all the heat waves analyzed. Collectively, these producers are responsible for 57% of carbon dioxide emissions since 1850.

“Just a small number of actors are responsible for a large fraction of all emissions,” said Sonia Seneviratne, a climate professor at ETH Zurich and a study contributor. Some heat waves, including Europe’s deadly 2022 events, resulted in tens of thousands of deaths, underscoring their severe consequences.

The study used climate attribution methods to link emissions from fossil fuel producers to extreme heat events, an approach that could influence ongoing lawsuits against polluters. Experts say the findings highlight not only the sources of climate-driven disasters but also the importance of accountability for future losses.

“As we deal with the impacts, assessing responsibility is crucial,” said Justin Mankin, a Dartmouth climate scientist. “It raises important questions about who should bear the costs of these damages.”