Cultural, Economic, or Transport Link: Does Carbon Emissions Trading Promote "Good Neighbor" Carbon Emission Reduction?

Carbon emission reduction was a crucial objective for China's green transformation, yet establishing regional cooperation with neighboring areas posed a significant challenge in carbon governance. We investigated the spillover effects of carbon emissions trading (CET) on carbon emissions among Chinese cities, employing spatial difference-in-differences (DID), Callaway and Sant'Anna DID (CSDID), and other methodologies. Our paper integrated datasets on high-speed rails, dialects, and carbon emissions at the prefecture-level city scale. The findings revealed that (1) CET reduces emissions by 11.55% in pilot regions, although the impact of the second policy pilot was not significant. (2) In terms of spillover effects, CET increased emissions in neighboring cities with economic and geographic ties, creating a "beggar-thy-neighbor" reduction model. Conversely, it reduced emissions in cities with shared cultural ties, fostering a "good neighbor" reduction model. (3) The policy spillover effect exhibited an "inverted N" curve, first decreasing, then increasing, and finally decreasing as economic and geographic distance increased. (4) Technological advancement was identified as the primary mechanism driving the spillover effects of CET. To achieve the dual-carbon goal, avoiding harmful economic competition and promoting low-carbon cultural exchanges were essential.