Study Links Dozens of Severe Heat Waves to Emissions from Major Fossil Fuel Producers

A study published Wednesday in the journal Nature found that emissions from 180 major cement, oil and gas producers significantly contributed to a set of 213 heat waves between 2000 and 2023, and that 55 of those heat waves would have been virtually impossible without human-caused climate change.

Researchers drew on the EM-DAT International Disaster Database, identifying 213 heat waves from 2000 through 2023 and applying climate attribution methods to assess how much warmer and more likely each event became because of planet-warming emissions. The study concluded global warming made all 213 heat waves more likely, and that 55 events were at least 10,000 times more likely than they would have been in a preindustrial climate.

The companies and state producers examined include publicly traded firms, state-owned enterprises and several national-level producers where production data were available. Collectively, those producers are responsible for about 57% of all carbon dioxide emissions from 1850 to 2023, the study found.

"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 singled out the 2022 string of heat waves in Europe, which has been linked to tens of thousands of deaths, as an example of the events with particularly grave consequences.

Climate scientists use complex computer models and historical weather records to perform event attribution, a 20-year-old field that estimates how human-driven climate change altered the likelihood or intensity of particular extreme-weather events. The Nature study differs from many attribution analyses by focusing on the share of influence coming from specific fossil fuel and cement producers rather than on single events alone.

"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 who was not involved in the study. Callahan said the study's methods are appropriate and of high quality, and noted that the results counter an argument sometimes made in legal and policy debates that any single contributor to climate change is too small to be linked to particular impacts.

The study's authors and outside experts said the findings could inform legal actions and policy decisions. Dozens of lawsuits have been filed globally against fossil fuel companies by activists, state governments and others seeking to hold producers accountable for damages tied to climate change. In the United States, Vermont and New York have enacted laws aimed at enabling accountability for damages attributed to fossil fuel companies' emissions.

"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. And this emerging science, both this paper and others, is showing that that’s not true," Callahan said.

Justin Mankin, a climate scientist at Dartmouth College who was not involved in the research, said the study clarifies the origins of heat-wave risk and could help guide decisions about who bears responsibility for losses and how to reduce future hazards.

"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 Nature paper used the widely referenced EM-DAT database to select events; the authors excluded only a small number of heat waves in the repository that were unsuitable for their analysis. The research adds to a growing body of attribution literature that quantifies the human influence on extreme heat and other climate-related hazards, providing data that scientists, policymakers and litigants can use to assess both risk and responsibility.

The study does not attribute legal liability, which remains a matter for courts and lawmakers, but it provides a scientific basis for linking a subset of extreme heat disasters to emissions produced by a relatively small group of industrial actors. As attribution methods continue to develop, researchers say such analyses can help inform adaptation, compensation and mitigation strategies.

The findings underscore the increasing role of human-driven emissions in shaping extreme-heat frequency and severity worldwide, and they highlight how a concentrated portion of historical emissions is associated with events that have caused significant human and economic harm.