Scaling climate adaptation planning: impacts and limitations of California’s Senate Bill 379 for local planning

This study examines the impact of the first state-level climate change adaptation planning mandate in the United States, California’s Senate Bill 379 (SB379). We analyze the content of local plans before and after the mandate and compare the quality of the mandated plans with a sample of voluntary climate change adaptation plans developed by local governments across the U.S. The research finds that plans developed after the mandate incorporated more climate adaptation strategies, a greater variety of strategy types, and addressed a wider range of climate hazards. The mandate is associated with increased “mainstreaming” of climate adaptation, primarily through add-on and programmatic strategies. SB379-mandated plans scored higher overall compared to voluntary climate plans from other states but lower on addressing uncertainty. The findings indicate that state mandates like SB379 can effectively catalyze local climate adaptation planning, but challenges remain in achieving high-quality, actionable plans across diverse communities.