US science report says climate event attribution has improved

A new report from the United States' top science advisory body says scientists can now link some specific extreme weather events to human-caused climate change with greater confidence, a finding that could affect lawsuits seeking damages from fossil fuel companies.

The 254-page report, titled "Attribution of Extreme Weather and Climate Events and their Impacts," was published by the National Academies of Sciences, Engineering, and Medicine. It updates a 2016 assessment by the same institutions.

The report says attribution science is strongest for some kinds of events, including heat waves and heavy rainfall. James Hurrell, a Colorado State University atmospheric science professor who chaired the committee behind the report, said the models used for these studies have been shown to be suitable for those event types.

Confidence is much lower for local-scale events such as thunderstorms and tornadoes, Hurrell said, because climate models still have difficulty simulating events at that level of detail. The report also says attribution estimates are weaker in less developed parts of the world, where long-term and consistent weather records are more limited.

Extreme event attribution compares an event's probability or intensity in the current climate with a hypothetical world without human-caused emissions. The report says the field has improved over the past decade because of better understanding of physical drivers, more satellite and radar observations, new statistical methods and improved models.

The authors called for a common framework for attribution studies, saying different results from studies of the same event can confuse the public and other stakeholders.

The findings come as climate damages lawsuits move through US courts. Multnomah County in Oregon is suing fossil fuel companies for more than $51 billion over pollution it says helped fuel a deadly 2021 heat dome in the Pacific Northwest, during which hundreds of people died.

The report has also been politically contested. Republican lawmakers sent an April letter to the president of the academies alleging bias and asking for details about the authors' professional ties. Energy In Depth, an oil industry blog, criticized Delta Merner, a scientist with the Union of Concerned Scientists, in a January 2, 2025 post; she left the panel the same day. Hurrell said outside criticism did not affect his work as chair or the final report.

At the federal level, the Trump administration has sued Democratic-led states seeking climate damages from oil and gas companies and has sought to strike down state "Climate Superfund" laws requiring polluters to pay for climate-related consequences. Republicans in Congress have also introduced the "Stop Climate Shakedowns Act," which would block climate damage lawsuits from moving forward in court. Critics say the bill would effectively shield fossil fuel companies from such claims.