Does the development of high-speed rail benefit carbon emissions reduction?

This study investigates, both theoretically and empirically, the causal impacts of the opening of high-speed rail (HSR) on total carbon emissions in China from 2002 to 2021. Exploiting a staggered Difference-in-Differences approach combined time and cross-city variations in the opening of HSR services, we find that, through traffic and economic re-equilibriums, the HSR contributes to the mitigation of climate change. The opening of HSR significantly reduces carbon emissions by at least 1.74 % on average but with noteworthy spatiotemporal heterogeneity. Consistent with the New Economic Geography, the Four-Vertical-and-Four-Horizontal HSR network demonstrates a prominent heterogeneous spatial distribution of impacts on emissions. We quantitatively reveal the HSR's contribution to climate change mitigation with a saved social carbon cost of no less than $30.97 billion. Given spillovers with heterogeneity, this study provides evidence for transportation planners with an emphasis on tailored line planning for regional balance.