Are fossil fuel companies directly responsible for the climate change caused by burning their products – and if so, can they be sued for damages? Yes, say researchers who have developed a new method for tying greenhouse gas emissions from individual firms to specific climate-related economic harm.
“I think the answer is unequivocally, yes,” says at Dartmouth College in New Hampshire. His technique, developed with his colleague at Stanford University in California, links each of the world’s five largest fossil fuel companies to a loss in global income of more than $1 trillion over a three-decade period. The pair say it could be a potential boost to lawsuits aiming to hold emitters liable for damage caused by climate change. However, legal and political questions remain about who exactly should be held responsible for the effects of burning fossil fuels.
Hundreds of lawsuits around the world have been filed seeking to sue fossil fuel companies and other major emitters for climate-related damages, whether from extreme heatwaves, wildfires or floods. There is no doubt that emissions generated by producing and burning fossil fuels have played a central role in driving climate change in general. It is also well established that many extreme events have been exacerbated by climate change.
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However, legal standards may require narrower evidence for cause and effect: is it possible to link emissions from a particular fossil fuel firm to a specific damage, such as deaths during a heatwave in India? Without that full causal chain, “there’s always been this veil of plausible deniability that major emitters had”, says Mankin.
The pair have built on several recent advances made in this field of attribution science. First, the researchers simulated global average temperatures between 1991 and 2020, both with and without the emissions generated by extracting and burning the fuels produced by a particular large fossil fuel company. In their analysis, they considered emissions from extracting fuels, as well as the much larger volume of emissions created by end customers burning the fuels.
Because different parts of the planet warm at different rates, they then used records of spatial patterns of warming to translate the change in global average temperatures to changes at a local scale. They focused on changes in temperature on the five hottest days of the year in each location, which they found in previous is directly linked to declines in economic growth, for instance by increasing mortality, damaging crop yields and reducing labour productivity. They repeated this analysis for more than one hundred of the largest fossil fuel companies, known as “carbon majors”.
Comparing the results with and without a particular company’s emissions enabled them to quantify some of the economic harm resulting from that company’s emissions.
Considering all the companies together, they found the increase in extreme temperatures caused by these emissions during the three-decade period led to a decline in global GDP of somewhere between $12 trillion and $49 trillion. The top five largest emitters – Saudi Aramco, Gazprom, Chevron, ExxonMobil and BP – were each linked to more than $1 trillion in losses during that period. None of these firms responded to żěè¶ĚĘÓƵ’s requests for comment before publication.
The pair’s approach also enabled them to look at individual companies’ role in exacerbating specific heatwaves. For instance, they find raised temperatures due to Chevron’s global emissions shrank GDP in the continental US by between $4 billion and $61 billion during a 2012 heatwave.
“This is a significant advance in the field,” says at Stony Brook University in New York, adding that it is the first published example he knows of showing end-to-end attribution. In addition to potentially serving as evidence in climate litigation, he says making the link between specific emitters and damages could inform international debates about who should pay.
“I think this is going to be the future of climate litigation,” says at Climate Analytics, a think tank headquartered in Germany. While this study looked only at declines in GDP due to extreme heat, he says a similar approach could work for other types of climate-related damages, such as heat-related deaths or flooding from sea level rise.
Indeed, the findings have already played a role in shaping climate law: an early draft of the study was submitted to Vermont before the state passed a first-of-its-kind law fining fossil fuel companies based on their emissions; New York soon followed with a law of its own. Both laws are now being challenged in court by the fossil fuel industry.
The findings could also be relevant to other precedent-setting suits like that of the for climate damages, says at Columbia Law School in New York. “If the case is dismissed for failure to establish causation, this type of study could lead to new lawsuits,” she says.
But even the study’s authors point out that attribution research won’t win lawsuits on its own. “Many of the barriers to these cases are not scientific but political or legal,” says Callahan. For instance, courts could decide climate liability is a question for legislatures to decide, rather than a jury or a judge. Another question is who should be held accountable for the emissions from burning fossil fuels: the companies that produce them or the people that use them?
“This is not really a question that science can answer,” says Callahan. “Where you locate responsibility is a legal and social and political question.”
There is no guarantee a court would accept the details of this methodology either, says at the University of Oxford, who that climate science may eventually make it possible to sue emitters for damages. “Will the courts accept evidence of a statistical link between annual mean temperature and the impacts of extreme heat, as presented in this study, when it comes to attributing causes of the harm done by a specific heatwave? Some may.”
Nature
Article amended on 25 April 2025
We clarified the losses linked to the top five largest emitters
