"Carbon emissions from oil giants directly linked to dozens of deadly heatwaves for first time", 10 September 2025
Carbon emissions from the world's biggest fossil fuel companies have been directly linked to dozens of deadly heatwaves for the first time, according to a new analysis. The research has been hailed as a "leap forward" in the legal battle to hold big oil accountable for the damages being caused by the climate crisis.
The research found that the emissions from any one of the 14 biggest companies were by themselves enough to cause more than 50 heatwaves that would otherwise have been virtually impossible. The study shows, in effect, that those emissions caused the heatwaves.
The carbon pollution from ExxonMobil's fossil fuels, for example, made 51 heatwaves at least 10,000 times more likely than in an unheated world, the researchers found, as did the emissions from Saudi Aramco.
Global heating is making heatwaves more frequent and more intense across the globe, contributing to at least 500,000 heat-related deaths a year...
The new research found that the total emissions from the 180 "carbon major" companies included in the analysis were responsible for about half the increase in intensity...
"Being able to trace back the contribution of these single [carbon major] emitters and quantify their contribution could be very useful for establishing potential liability," said Prof Sonia Seneviratne, at ETH Zurich university in Switzerland, a senior author of the report.
Dr Davide Faranda, a research director at the French National Centre for Scientific Research and not part of the study team, said: "This study adds a crucial new step: it connects the dots between specific climate disasters and the companies whose emissions made them possible. This bridge could become a cornerstone for legal and policy action to hold polluters accountable."
Cassidy DiPaola, a spokesperson for the Make Polluters Pay campaign, said: "We can now point to specific heatwaves and say, 'Saudi Aramco did this. ExxonMobil did this.' When their emissions alone are triggering heatwaves that wouldn't have happened otherwise, we're talking about real people who died, real crops that failed, and real communities that suffered, all because of decisions made in corporate boardrooms."
..."Here's the evidence the courts have been waiting for," said DiPaola. "The bill is coming due, and it's time these polluters pay for the damage they've done."
The research, published in the journal Nature, used a type of analysis called attribution. This compares the hotter world today with the world before mass burning of fossil fuels to assess how emissions have driven up temperatures, using weather data and computer models.
The scientists first worked out how much each carbon major's emissions had pushed up temperatures and then how much these higher temperatures increased the likelihood of heatwaves. Previous research has linked hundreds of individual events to global heating, but this study is the first to systematically analyse a series of events.
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Even the emissions from the fossil fuel companies at the bottom of the list of carbon majors had a significant impact on heatwaves. The carbon pollution from each of these caused 16 heatwaves to become at least 10,000 times more likely than before the climate crisis.
"This study is a leap forward that could be used to support future climate lawsuits," said Dr Karsten Haustein, at the University of Leipzig in Germany, and not part of the study team...
Carbon emissions are emitted when people use oil, gas or coal to heat their homes or power their transport, but [Dr Yann Quilcaille of ETH Zurich, the lead author of the study] said fossil fuel companies had a particular responsibility - they had pursued profit through disinformation and lobbying, despite having known since the 1980s that burning fossil fuels would lead to global heating.
However, no polluter had yet been held accountable in court and challenges remained, said Prof Michael Gerrard and Dr Jessica Wentz, of the Sabin Center for Climate Change Law at Columbia University.
"The problem is the various legal issues that must be resolved before scientists can take the witness stand," they said in a commentary in Nature. The issues included which courts should hear the cases, whether fossil-fuel producers should be liable for their customers' emissions, and if long campaigns of deception by some fossil fuel companies were relevant, Gerrard and Wentz said.
"The new study is one more building block, and a useful one, but the road to actual liability for the carbon majors is still littered with legal and evidentiary potholes," they said.
ExxonMobil and Saudi Aramco did not respond to requests for comment.