First framework tying emissions to specific climate harms

A new study published in the journal Nature sets out a scientific framework to trace specific climate damages back to emissions from individual fossil fuel companies. The team from Dartmouth University’s Climate Modeling & Impacts Group in the US said the framework provides a tool for potentially recouping the costs of extreme weather amplified by climate change.

The researchers noted that as a growing number of local and national governments struggle to recover from – and protect against – more frequent and destructive climate disasters, some have sought compensation directly from fossil fuel companies through civil cases and ‘polluters pay’ laws.

But they said many of these actions are being challenged or slowed in court, partly due to the difficulty in showing that specific climate impacts occurred because of any one company’s greenhouse gas emissions.

The framework combines climate modelling with publicly available emissions data to contrast the current climate and its impacts to what it would be like without the heat-trapping gases a company’s activities released into the atmosphere, the study says, adding that this causal link is known as a ‘but for’ standard – as in, a climate catastrophe likely would not have occurred but for an individual firm’s actions.

“We argue that the scientific case for climate liability is closed, even if the future of these cases remains an open question,” said Justin Mankin, the study’s senior author and an associate professor in the Department of Geography. The study, he said, answers a question first posed in 2003 of whether science could ever link an individual firm’s emissions to climate change.

“Just over 20 years later, we find the answer to be ‘yes,’” said Mankin, who directs the Climate Modeling and Impacts Group. “Our framework can provide robust emissions-based attributions of climate damages at the corporate scale. This should help courts better evaluate liability claims for the losses and disruptions resulting from human-caused climate change.”

Mankin and the study’s first author, Stanford postdoctoral scholar Christopher Callahan, deployed the framework to provide the first causal estimates of regional economic losses due to extreme heat resulting from the emissions of individual fossil fuel companies.

Extreme heat linked to carbon dioxide and methane from 111 companies cost the world economy $28trn from 1991 to 2020, with $9trn of those losses attributable to the five top-emitting firms, according to the study. The highest-emitting investor-owned firm the researchers examined may be responsible for $791bn to $3.6trn in heat-related losses over that period, says the study.

“Our findings demonstrate that it is in fact possible to compare the world as it is to a world absent individual emitters,” said Callahan. “The affluence of the Western economy has been based on fossil fuels but just as a pharmaceutical company would not be absolved from the negative effects of a drug by the benefits of that drug, fossil fuel companies should not be excused for the damage they’ve caused by the prosperity their products have generated.”

The researchers said the model goes a step further than existing research by removing total emissions – measured in billions of tons – from the equation to identify a company’s specific greenhouse gas footprint. Previous attribution models have hinged on concentrations of greenhouse gases in the atmosphere, which are measured in parts-per-million that are harder to attribute to specific sources.

“Our approach simulates emissions directly, allowing us to trace warming and its repercussions back to specific emitters,” Callahan said.

Mankin added: “Extreme heat is indelibly linked to climate change itself, and the losses from it have been an instigator for legal claims. So it’s an obvious place to illustrate the broad application of our approach. We also live in a world that has warmed considerably over the past 20 years. This analysis is not a predictive exercise where we ask what the future holds. Instead, it’s a documentary effort where we show what has already happened and provide the reason why.”