Major fossil fuel and cement producers linked to 55 ‘virtually impossible’ heat waves, study finds

A study published Wednesday in the journal Nature concluded that 55 of 213 heat waves between 2000 and 2023 "would have been virtually impossible" without human-caused climate change, and that planet-warming emissions from 180 major cement, oil and gas producers contributed substantially to the events analyzed.

Researchers examined a set of 213 heat waves drawn from the EM-DAT International Disaster Database and found that global warming made all of those heat waves more likely. For 55 of the events, the scientists estimated the odds increased by a factor of at least 10,000 compared with pre-industrial climate conditions. The group of producers studied, which included publicly traded companies, state-owned firms and several countries where production data were available, were responsible for 57% of carbon dioxide emissions from 1850 through 2023, the paper reported.

The authors said their analysis combined established methods in climate-attribution science with historical weather records and computer modeling to estimate how much more likely individual heat waves became because of human emissions. The study differs from many attribution studies by explicitly linking extreme heat to emissions from a group of major fossil fuel and cement producers, rather than assessing the influence of greenhouse gases in the abstract.

"It just shows that it’s not that many actors … who are responsible for a very strong fraction of all emissions," said Sonia Seneviratne, a climate professor at ETH Zurich and a contributor to the study. She pointed to the 2022 series of heat waves in Europe, which has been linked to tens of thousands of deaths, as an example of an event with particularly grave consequences.

Climate scientists not involved in the research characterized the work as consistent with the growing body of attribution literature. "They are drawing on a pretty well-established field of attribution science now, which has existed for about 20 years," said Chris Callahan, a climate scientist at Indiana University. Callahan, who has used similar methodologies in his own research, called the new study appropriate and high-quality.

The study's authors used the EM-DAT database because it is the most widely used global disaster repository, though they excluded a small number of heat waves that were not suitable for the analytical approach. Their calculations produced two principal findings: that human-caused warming increased the likelihood of all 213 recorded heat waves in the sample, and that a subset of 55 events became overwhelmingly more probable because of emissions tied to the producers examined.

The research has policy and legal implications as governments, municipalities and activists increasingly seek accountability for climate-related damages. Dozens of lawsuits worldwide have targeted fossil fuel companies, and some U.S. states have enacted laws aimed at holding producers responsible for the costs of climate impacts. "For a while, it was argued that any individual contributor to climate change was making too small or too diffuse a contribution to ever be linked to any particular impact," said Callahan. "And this emerging science, both this paper and others, is showing that that’s not true."

Dartmouth College climate scientist Justin Mankin, who was not involved in the study, said the findings illuminate the origins of particular hazards and could inform discussions about responsibility and compensation. "As we contend with these losses, the assessment of who or what’s responsible is going to become really important," Mankin said. "I think there are some really appropriate questions, like who pays to recoup our losses, given that we’re all being damaged by it."

The study adds to a suite of research using climate models and historical data to quantify how much human-induced warming changes the frequency and intensity of extreme weather. Attribution science has matured over the past two decades, allowing researchers to make probabilistic statements about the influence of greenhouse gases on specific events. The Nature paper advances that work by attributing portions of those probabilities to emissions tied to identifiable producers.

The authors note that their analysis rests on available production and emissions records and on established modeling techniques; they caution that attribution involves probabilities rather than deterministic cause-and-effect for single events. Still, the findings underscore the concentrated role of a limited set of producers in historical emissions and the heightened risks that warming has introduced for extreme-heat events globally.

Policy makers and litigants may use the new evidence as they evaluate climate liability, adaptation funding and strategies to reduce future risks, but the study does not itself make legal or policy recommendations. It documents links between emissions from major producers and a subset of the most extreme heat waves recorded worldwide between 2000 and 2023, contributing data and analysis to ongoing scientific and public debates over accountability and the costs of a warming climate.