Urban Forest Development and Extreme Heat Mitigation: The Climate Adaptation Effects of China’s National Forest City Policy

Against the backdrop of global warming, extreme heat events have become increasingly frequent and persistent across Chinese cities, posing severe threats to public health, industrial safety, and urban operations. Enhancing urban climate adaptation through the development of green infrastructure has therefore emerged as a critical governance priority. As a major national initiative promoting urban forest development and ecological civilization, the National Forest City Policy offers a potentially important pathway for mitigating extreme heat, yet its climate adaptation effects remain insufficiently examined through rigorous empirical evidence. This study takes the implementation of the National Forest City Policy as an exogenous policy shock to urban greening and employs panel data from Chinese 243 prefecture-level cities from 2000 to 2023 to conduct a difference-in-differences model, supplemented by an event-study approach, to identify the policy’s impact on annual extreme heat days. The empirical findings indicate that, after controlling for a series of socioeconomic characteristics, the National Forest City Policy significantly reduces the number of extreme heat days experienced by cities each year. Further mechanism analysis reveals that the National Forest City Policy’s mitigation effect is more pronounced in cities with higher Green Coverage Rate, Urban Climate Conditions, and Urban Green Space Quality. By evaluating the environmental impacts of the National Forest City Policy from a climate adaptation perspective, this study enriches the literature on urban forest development and extreme climate events, and provides empirical evidence and policy insights for enhancing urban climate resilience and optimizing greening strategies under China’s “dual-carbon” goals and a warming climate.