Evidence from 2021–2024 shows that when the Biden administration took office, U.S. climate policy and climate‑related initiatives clearly regained and sustained strong momentum relative to the prior Trump era:

• On his first day in office (Jan. 20, 2021), President Biden signed an executive order to rejoin the Paris Climate Agreement and began reversing Trump‑era environmental rollbacks, which analysts described as a major policy shift on climate action. (cnbc.com)
• In April 2021, at the Leaders Summit on Climate, Biden announced a new U.S. target to cut greenhouse gas emissions 50–52% below 2005 levels by 2030, submitted a new Nationally Determined Contribution, and this was described by Climate Action Tracker as the biggest climate step by any U.S. government in history. (en.wikipedia.org)
• The Bipartisan Infrastructure Law (Infrastructure Investment and Jobs Act), signed in November 2021, made historic investments in clean energy transmission, grid modernization, public transit, EV buses, and climate resilience—described by the administration and DOE as a once‑in‑a‑generation, foundational clean‑energy and climate investment. (bidenwhitehouse.archives.gov)
• In August 2022, Biden signed the Inflation Reduction Act, widely characterized as the largest climate and clean‑energy investment in U.S. history, with hundreds of billions of dollars for renewables, EVs, efficiency, and industrial decarbonization, and projected to significantly cut U.S. emissions by 2030. (en.wikipedia.org)
• The White House climate task force summary reports that during Biden’s term the U.S. added over 100 GW of clean energy (more than half of all U.S. solar ever installed), EV sales quadrupled, and public EV charging more than doubled—indicators of strong practical momentum behind climate‑related initiatives. (bidenwhitehouse.archives.gov)

Later rollbacks under a subsequent Trump administration (e.g., renewed Paris withdrawal and efforts to dismantle IRA programs) show that momentum can be reversed politically, but they do not change the fact that with the Biden administration coming into office, U.S. climate policy and initiatives indeed regained substantial momentum, matching Friedberg’s prediction.