The impact of population characteristics on transportation CO₂ emissions-does population aging important?

Reducing transportation CO₂ emissions and addressing population characteristic changes are two major challenges facing China, involving various requirements for sustainable economic development. Due to the interdependence of population characteristics and transportation, human activities have become a significant cause of the increase in greenhouse gas levels. Previous studies mainly focused on evaluating the relationship between one-dimensional or multi-dimensional demographic factors and CO₂ emissions, while few studies have reported on the effect of multi-dimensional demographic factors on CO₂ emissions in transportation. Analyzing the relationship between transportation CO₂ emissions is the foundation and key to understanding and reducing overall CO₂ emissions. Therefore, this paper used the STIRPAT model and panel data from 2000 to 2019 to investigate the effect of population characteristics on CO₂ emissions of China's transportation sector, and further analyzed the effect mechanism and emission effect of population aging on transportation CO₂ emissions. The results show that (1) population aging and population quality restrained CO₂ emissions from transportation, but the negative effects of population aging were indirectly caused by economic growth and transportation demand. And with the aggravation of population aging, the influence on transport CO₂ emissions changed and presented a U-shape. (2) Population living standard on transportation CO₂ emissions exhibited an urban-rural difference, and urban living standard was predominant in transportation CO₂ emissions. Additionally, population growth is under a weakly positive effect on transportation CO₂ emissions. (3) At the regional level, the effect of population aging on transportation CO₂ emissions showed regional differences. In the eastern region, the CO₂ emission coefficient of transportation was 0.0378, but not significant. In central and western regions, the influence coefficient of transportation was 0.6539 and 0.2760, respectively. These findings indicated that policy makers should make relevant recommendations from the perspective of coordinating population policy and energy conservation and emission reduction policy in transportation.