Population urbanization, trade openness and carbon emissions: an empirical analysis based on China

The key to control carbon emissions is to clarify the cause of carbon emissions and their transfer process. This paper focuses on the relationship and its internal mechanism of population urbanization, trade openness and carbon emissions using the threshold model and the moderated mediating model, which is based on the panel data of China during 2003-2016. The results show that the higher the level of population urbanization is; the more carbon emissions are. There is a significant threshold effect on trade openness. That is, when the threshold value of urban population density is 24,211 people per square kilometer, the relationship between trade openness and carbon emissions is inverted U. The population urbanization can also affect carbon emissions through trade openness indirectly, and its moderated mediating effect is significant. The moderated variables can be divided into four categories: scale effect, structure effect, technological progress effect, and social effect. Different moderated variables have different effects on carbon emission path, but they show an effective tendency of controlling emissions on the whole. By quantifying the conditional indirect effect, this paper analyzes the internal channel of population urbanization, trade openness, and carbon emissions. Then, according to the characteristics of different moderated effects, the effective emission control policy in China will be formulated in the future.