How to reduce urban agglomeration carbon emissions through transportation management? A case study of the Yangtze River Delta in China.

Rapid urbanization has led to massive carbon dioxide emissions, which exacerbates global climate change, and further causes systemic issues such as ecological degradation, public health risks and socio-economic instability. Transportation is a major source of urban carbon emissions, and its dynamic emission characteristic poses a challenge for carbon mitigation. Most transportation carbon reduction strategies treat the cities within urban agglomeration equally or focus on specific influencing factor. There is still a lack of quantitative evidence on coordinated transportation management strategies for diverse cities in urban agglomeration and their complex impact mechanism on carbon reduction. This work aims to develop an extended stochastic impact by regression on population, affluence, and technology (STIRPAT) model, to analyze the impacts of transport intensity (passenger and freight volume), demand (bus and taxi ownership and bus passenger volume), and layout (commuting time, expressway mileage, and urban road area) on carbon reduction of the Yangtze River Delta (YRD) urban agglomeration. The maximum carbon emission reductions by optimizing transportation layout, intensity, and demand are 15 %, 7 %, and 5 %, respectively. By jointly reducing commuting time, highway mileage and road area, carbon emissions of core, transportation hubs, secondary and peripheral cities can be reduced by up to 10.04 %, 11.51 %, 13.45 % and 15.18 %, respectively. It suggests shifting from road to rail and waterway transport in YRD urban agglomerations, increasing the allocation of new energy vehicles, and optimizing traffic networks according to city characteristics. A management framework should be established through policy guidance, industrial collaboration, and public participation. The findings contribute to achieving the goals of carbon neutrality and peaking, further advancing urban environmental management and sustainable development strategies.