Attorney General Bonta Opposes Trump Administration Interference on Climate Assessment, Supports Scientists

OAKLAND — California Attorney General Rob Bonta joined a multistate coalition of attorneys general in submitting a comment letter opposing the U.S. Global Change Research Program’s (USGCRP) proposal to amend the Fifth National Climate Assessment (NCA5). The NCA is a scientific document that provides an overview of the most current climate science and explores adaptation and mitigation strategies across a wide range of topics. USGCRP's flawed proposal seeks to retroactively modify the 2023 NCA5 to limit the interpretation and use by federal agencies of findings in the NCA5 that are based on certain worst-case, high emissions scenarios. If implemented, this proposal would put politics over peer-reviewed scientific findings to further the Trump Administration’s abandonment of the fight to protect the American public from the worst climate impacts. The comment letter explains that these changes are arbitrary and capricious and are therefore unlawful if ultimately adopted and relied on by federal agencies.

“The science doesn’t lie. Climate change is harming public health and causing devastating and ever-worsening disasters,” said Attorney General Bonta. “To restrict federal agencies from acknowledging or planning for these impacts is playing politics with people’s lives, and that’s exactly what President Trump is doing. This proposal will restrict federal agencies from relying on the NCA5’s worst-case projections, while at the same time the Trump Administration is doing everything it can to make those projections a reality. I will continue to support rigorous scientific findings backed by a peer review process, not wishful thinking or outright denialism, and I encourage the USGCRP to do the same by rescinding their proposal.” 

Federal law requires the USGCRP to prepare a National Climate Assessment (NCA) every four years. The most recent NCA, NCA5, was released in November 2023, under the Biden Administration. The Trump Administration has previously taken various steps to undermine NCA5, including canceling key contracts, dismissing scientists, gutting the USGCRP, and removing the NCAs from federal websites. This latest proposal continues to undermine NCA5 by attempting to downplay the gravity of climate change. 

On August 25, 2026, the USGCRP published a notice of its proposal to amend the NCA5 to limit federal agencies’ ability to utilize certain NCA5 results that depend on scenarios that outline a future where annual greenhouse gas emissions continue to rise and a transition to renewables and other climate-mitigating policies does not occur. Along with representing a politically motivated attack on climate science, the proposed amendment also fails basic federal information quality requirements that apply NCAs. It fails to identify who prepared and reviewed it and has characteristics of a document developed using artificial intelligence, raising serious concerns about its reliability. It does not appear to have undergone peer review or to have been prepared with the involvement of the National Academies of Science. Engineering, and Medicine. The proposed amendment also improperly constrains public review and input, imposes a word limit on comments, provides a mere 15-day comment period on amendments to the 2,000 page NCA5, and asserts that comments will not receive a response. In sum, this proposed amendment is not a serious attempt to reflect changes in scientific understanding, but rather a rushed and politically motivated attempt to downplay the threat represented by climate change and hinder federal planning to address it.