Summary/Abstract
This expert report was written by Steven W. Running, Ph.D. & Cathy Whitlock, Ph.D., and filed by plaintiffs in the case Held v. State of Montana.
In this report, the authors provide a broad overview of the linkages between anthropogenic emissions of carbon dioxide and other greenhouse gases and climate change, and connect global climate change to specific impacts in Montana. The authors assess changes in average temperature, declines in Montana’s snowpack and changes in seasonal runoff, exacerbation of Montana’s multi-year and decadal droughts, among other climate change impacts.
In a subsequent rebuttal expert report, filed by plaintiffs on November 30, 2022, the authors respond to the expert reports of Dr. Terry Anderson and Dr. Judith Curry, filed on behalf of the State of Montana, and reiterate the conclusion of their September 30, 2022 expert report.
The underlying case, Held v. State of Montana, arose when, on March 13, 2020, sixteen young people filed a lawsuit in a state court in Montana, United States, asserting climate change-based claims under the Montana constitution against the State of Montana, its governor, and state agencies. In particular, the case challenged the constitutionality of Montana’s fossil fuel-based State Energy Policy and the “Climate Change Exception” in the Montana Environmental Policy Act. For more information about this case, visit the Sabin Center’s Climate Litigation Database.
Note: This climate attribution research was presented in the context of a contested legal proceeding. Different countries, courts, and legal forums may have different standards for expert testimony, and may conduct fact-finding based on legal standards of proof that differ from those applied in academic publishing. Readers should independently investigate and understand the bases for the assertions made in this document before applying this research in other contexts.