Heterogeneity in carbon footprint trends and trade-induced emissions in China’s urban agglomerations

Mitigation at the city level is vital for climate goals, yet most strategies overlook intercity interactions. This study examines carbon footprint changes in 16 Chinese urban agglomerations from 2012 to 2017 using city-level input-output models. Five agglomerations reduced emissions, six increased, and five plateaued. Drivers of reductions include consumption decline (Harbin-Changchun, 97.7%), low-carbon consumption (Beijing-Tianjin-Hebei, 701.4%), and technological advancement (Shandong Peninsula, 124.3%). Increases stem from rising per capita consumption, while plateaus reflect a balance of production and consumption factors. Although local emissions fell by 351.9 Mt, intercity trade raised external emissions by 801.7 Mt. A no-trade scenario shows trade-induced reductions declined from 1562.7 Mt in 2012 to 1374.5 Mt in 2017, indicating weakening trade mitigation. By 2017, 11 agglomerations still achieved net trade reductions, while others saw increases, underscoring regional heterogeneity. The findings stress the need for region-specific strategies integrating production, consumption, and trade to reduce urban carbon footprints effectively.