Non-Federal Climate Leadership Can Sustain U.S. Emissions Reductions Under Federal Policy Uncertainty

Alicia Zhao, Kiara Ordonez Olazabal, Claire V. Squire, Kowan T.V. O'Keefe, Matthew Binsted, Adriana Bryant, Stephanie Vo, Dhruv Modi, Steven J. Smith, Ryna C, Nate Hultman

Recent federal climate policy rollbacks in the United States have slowed progress toward high-ambition climate targets under the Paris Agreement. In the absence of federal climate leadership, there is a growing need to better understand the potential impacts of non-federal climate action. We assess the impacts of recent changes in federal policy, non-federal climate leadership, and potential federal re-engagement on U.S. greenhouse gas (GHG) emissions through 2035 using an integrated assessment model with state-level detail. We find that if all states adopt high-ambition policies and the next federal government re-orients on climate policy, a 56% reduction in GHG emissions can be delivered by 2035, relative to 2005 levels. A 45% reduction can be achieved with high-ambition actions from climate-leading states only, under existing federal policies. This compares to a 35% reduction under existing federal and subnational policies. Total electricity demand could increase by 24% to 34% from 2021 levels due to electrification policies and data center growth, with more than 90% of new capacity additions coming from renewables across scenarios. These findings highlight the potential impacts of non-federal leadership on near-term targets, and offer specific policy actions that can support electricity demand growth and domestic climate action.