Transportation development paths in 30 provinces of China in the context of carbon quota allocation

Establishing a scientific mechanism for allocating carbon allowances in the transportation sector is vital for achieving net-zero emissions targets, especially considering China's significant regional disparities. Nonetheless, the current methods are inadequate. By exploring the causal mechanism of transportation CO2 emissions (TCE), this study addresses the aforementioned gap by developing a carbon allowance allocation method utilizing innovative econometric tools. The method calculates the cost of carbon emission reductions in each province using the non-radial directional distance function (NDDF). We constructed a three-dimensional spatial (SEE) transportation carbon quota allocation model grounded in Stability, Equity, and Efficiency, aimed at facilitating scenario analysis up to 2030. Results highlighted: (1) There is a positive correlation between transportation carbon quotas and the economic scale of each province, with Guangdong Province reaching the highest at about 76 million tons (low-carbon scenarios), further demonstrating that China's transportation carbon emissions have not yet decoupled from economic growth; (2) the marginal carbon abatement costs across provinces vary significantly, exhibiting a pattern of higher costs in the west and lower in the east, with a price range of RMB 40–690 per ton; (3) provinces focused on green transportation, such as Beijing, and those driven by economic driven, like Hebei, can achieve Pareto improvement and balance economic development with carbon emission reductions through reasonable trading. The study provides a methodological basis for China's transportation carbon quota allocation system and offers guidance on selecting development models for different regions.