The impact of population factors and low-carbon innovation on carbon dioxide emissions: a Chinese city perspective

Spatial-temporal characteristics and influencing factors of carbon emission in Chengdu-Chongqing area: an urban transportation perspective

The Chengdu-Chongqing twin-city economic circle is a vital growth pole and a new power source for Chinese high-quality development. Studying the spatial-temporal characteristics of carbon emissions and the role of factors affecting them under the transportation perspective is of great significance for this region to realize the carbon peak and carbon neutrality and to formulate carbon emission reduction policies. We use the exploring spatial data analysis (ESDA) and spatial regression model combined with the STIRPAT model, and research finding: (1) The total carbon emissions in the research area gradually increased from 2014 to 2020, but the growth rate showed a significant decline in 2019. (2) There is significant spatial heterogeneity of carbon emissions in the study area; the hotspot areas of total carbon emissions are in Chongqing and Chengdu, forming a high-low aggregation of carbon emissions. Per capita carbon emissions show a high trend in the southwest and a low in the northeast. (3) From the factors of transportation perspective, highway density and private vehicles have a positive impact on carbon emissions, and urban road areas and public transportation have a very significant inhibition of carbon emissions and a spatial spillover effect. (4) Other factors, such as population size, national economic development, urbanization level, and industrial structure, all have a positive effect on carbon emissions, and disposable income has a negative effect on carbon emissions.

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.

Spatial-temporal evolution of carbon emissions and spatial-temporal heterogeneity of influencing factors in the Bohai Rim Region, China

The total change in carbon emissions in the Bohai Rim Region (BRR) plays a guiding role in the policy formulation of carbon emission reduction in northern China. Taking the 43 cities in the BRR as an example, the spatial-temporal evolution of carbon emissions in the BRR was analyzed using kernel density estimation (KDE), map visualization, and standard deviation ellipses, and the spatial autocorrelation model was used to explore the spatial clustering of carbon emissions. On this basis, the spatial-temporal heterogeneity of the factors influencing carbon emissions is explained using a Geodetector. The results are as follows: (i) During the study period, the carbon emissions in the BRR were on the rise, the share of carbon emissions in the Beijing-Tianjin-Hebei region (BTHR) and Liaoning Province was decreasing, and the contribution of Shandong Province was gradually enhanced. The spatial distribution of carbon emissions shows a geographical pattern of "middle-high and low-outside." (ii) Carbon emissions from different regions show the characteristics of BTHR > Shandong Province > Liaoning Province. The high-value carbon emission area continues to move from the northwest of Beijing-Tianjin-Hebei to the southeast. (iii) Municipal carbon emissions showed a significant positive spatial correlation in the later part of the study. The high-high aggregation area is in Tianjin, and the low-low aggregation area is in Liaoning Province. (iv) The level of transport development contributes to carbon emissions with the highest growth rate, followed by industrial structure. There are also regional differences in the dominant influences on municipal carbon emission differences. Population size, urbanization, and economic development level are the core influencing factors of carbon emissions in the BTHR, Shandong Province, and Liaoning Province, respectively. In addition, the explanatory power of the interaction between the level of economic development and other factors on carbon emissions is at a high level.

Have regional coordinated development policies promoted urban carbon emission efficiency?-the evidence from the urban agglomerations in the middle reaches of the Yangtze River

Improving carbon emission efficiency is the most direct and effective way to reduce pollution. Leading the construction of a resource-saving and environment-friendly society is an important goal of the coordinated development of urban agglomerations in the middle reaches of the Yangtze River. However, there is no systematic evidence to prove whether this policy can improve carbon emission efficiency. Taking 31 cities in the urban agglomeration in the middle reaches of the Yangtze River as the research area, we aimed to use the index decomposition method, the super-efficiency slack-based model, and the difference-in-difference model to examine the effect of policies on improving carbon efficiency. The results show that (1) regional coordinated development policies have a significant effect on improving the carbon emission efficiency of urban agglomerations, and there is an obvious imbalance in carbon emission efficiency among cities. (2) The impact of regional coordinated development policies on urban carbon emission efficiency is heterogeneous. We have grouped 31 cities according to their centrality, industrial transfer characteristics, and urban cluster characteristics. Policies have heterogeneous effects on cities with different functions and positioning. (3) Policy effects have opposite effects on urban carbon emission efficiency through urbanization rate and population density, while the effect of urban greening rate is not significant. The research results can provide a reference for China's urban agglomeration to achieve sustainable development and promote the construction of low-carbon cities.