In 2023, the Winooski River in Vermont overflowed and reached the Green Truss Bridge that crosses it. The river water even seeped into the marble floor of the state house due to 9 inches of rain falling within 48 hours, causing hundreds of millions of dollars in damage.

A year later, Vermont enacted the Climate Change Superfund Act, holding an oil and gas company financially responsible for the state’s climate damages. A similar law was passed in New York in 2024 and is pending in California, Maryland, and Massachusetts.

Understanding the law involves attribution science, a field that uses global temperature data to model numerous scenarios to determine if extreme weather events like floods and heatwaves are linked to emissions from burning oil, gas, and coal.

A new paper published in Nature Journal on Wednesday magnifies this work to connect emissions from specific entities to the economic impact of extreme events.

“The oil industry is astonished by the state’s climate superfund laws and their increasing popularity, as they are the first policies globally to hold a significant portion of the major losses responsible for the substantial damages incurred by their products.”

The response to the law was swift. In February, West Virginia and other Republican-led states sought to challenge New York’s laws, arguing that only the federal government has the authority to regulate emissions. President Trump signed an executive order this month criticizing the state law as a burden and ideological motivation, calling on Attorney General Pam Bondy to block enforcement.

Environmental attorneys have been exploring how harm can be attributed to greenhouse gas emissions for years, according to Martin Rockman, a climate law fellow at Columbia University’s Sabine Center.

“Attribution science is crucial because it establishes links between particular activities of businesses that profit from fossil fuels and specific harms to states and communities,” Rockman stated. “If you’re causing harm, you should be accountable for mitigating it, it’s that simple.”

The new study will enhance an approach known as “end-to-end” attribution, linking a specific emitter (e.g., a company) to a particular climate-related impact (e.g., extreme heat) and subsequent damage (impact on the global economy).

The study revealed that Chevron’s emissions caused heat-related losses totaling up to $3.6 trillion in the global economy. Christopher Callahan, a postdoctoral geoscientist at Stanford University and the study’s author, noted that such high costs still underestimate the global repercussions of fossil fuel combustion in less affluent tropical regions with minimal emissions responsibility.

“That astounding figure represents the detriment from just one of the climate impacts,” stated Delta Melner, associate director of the Science Hub for Climate Litigation at the Coalition of Concerned Scientists. “The overall harm caused by major emitters is undoubtedly much greater when considering the full range of climate risks.”

Theodore J. Bootras Jr., a Chevron Corporation lawyer, argued that the study “disregards the scientific impossibility of attributing a specific climate or weather phenomenon to a particular country, company, or energy consumer.” He labeled it as futile state litigation and a misleading advocacy campaign for energy penalties and regulations.

Overall, the paper estimated that the global economy would suffer $28 trillion in damages due to extreme heat caused by emissions from 111 major carbon producers between 1991 and 2020.

More than 100 climate-related lawsuits have been filed annually since 2017, as per a recent study. However, these cases scrutinize attribution studies that struggle to connect emissions to estimated economic losses.

This innovative framework can offer similar capabilities in other major damage and liability cases, analogous to those handled in tobacco-related lung cancer lawsuits and pharmaceutical claims for addiction.

Justin Mankin, a geography professor specializing in climate science at Dartmouth University and co-author of the Nature paper, remarked:

World Weather Attribution, a group based at Imperial College London, has regularly published attribution reports over the past decade.

“Unfortunately, we are still one of the few entities engaged in this work, and we are not an official institution. It’s essentially a project I undertake as a university professor in collaboration with a team of colleagues,” stated Friedrike Otto, a physicist aiding in attributing global weather.

Dr. Callahan and Dr. Mankin utilized open-source tools in their models, developing code and data resources they deployed to publish the global costs of climate change on their website.

“We advocate for transparent and open science, particularly since the research was funded by U.S. taxpayers,” Dr. Mankin emphasized, highlighting a significant portion of the research support originating from NOAA, the nation’s leading climate science agency facing funding cuts during the Trump administration.

Extreme weather events have disrupted communities and continue to exacerbate tensions. According to Vermont Senator Anne Watson, the 2023 flood cost Vermont hundreds of millions of dollars, prompting her to sponsor a bill quantifying state damages between 1995 and 2024.

Julie Moore, the secretary at the Vermont Natural Resources Agency, assisted states in organizing their inquiries for more information to better grasp the various approaches in attribution science and comprehend how to assign damages caused by greenhouse gas emissions.

“The charge against us is to establish guidelines on applying attribution science and ultimately send out a cost recovery notice,” Moore explained. According to state laws, oil and gas companies will receive this notice in early 2027.

“The expectation is that it will aid Vermont in securing a substantial amount to cover damages and adapt to a hotter, more humid climate resulting from carbon in the atmosphere,” Watson expressed. “We need a source to determine accountability for this.”