Regional Differences In The Impact Of Economic Openness On Carbon Efficiency

China’s rapid economic development through foreign openness has brought about enormous pressure on the environment.The continuous increase in carbon emissions has seriously affected China’s high-quality economic development.To achieve low-carbon development goals,China has proposed the concepts of "carbon peak" and "carbon neutrality." This article analyzes the relationship between economic openness and carbon efficiency at the theoretical level and its pathways.At the empirical level,this study considers economic and energy efficiency and uses the non-directed Super SBM method to measure carbon efficiency.The study then conducts a regression analysis of the relationship between FDI,foreign trade,and carbon efficiency.Based on the development stage of metropolitan areas,the study explores their heterogeneity and investigates the role of population distribution in this relationship.Finally,the study proposes corresponding policy recommendations,which are of great significance to the government’s coordination of carbon emissions and economic development.Research findings:(1)Carbon efficiency has improved in most regions in recent years,but there is still room for improvement.Urban clusters that are in the optimization and improvement phase have seen faster growth in carbon efficiency.(2)Overall,FDI has a positive effect on carbon efficiency due to its technological effect,and this effect weakens with the concentration of population distribution.Urban clusters with high levels of human capital are better able to absorb advanced technology from FDI and have a stronger promoting effect on carbon efficiency.The size and structural effects of FDI are stronger in urban clusters in the cultivation and development stage,which inhibits the improvement of carbon efficiency.The impact of FDI on carbon efficiency has a significant second-order threshold effect,which inhibits carbon efficiency at low levels of FDI.As FDI increases,its inhibitory effect on carbon efficiency weakens,and after crossing the second threshold value,FDI begins to promote the growth of carbon efficiency.(3)Overall,foreign trade only significantly promotes carbon efficiency in urban clusters in the cultivation and development stage.There is an "S"-shaped correlation between foreign trade and carbon efficiency.As foreign trade increases,its promoting effect on carbon efficiency first increases and then decreases.(4)Overall,the concentration of population distribution significantly inhibits the improvement of carbon efficiency,but in urban clusters in the cultivation and development stage,where the population is sparse,the concentration of population has the advantage of promoting carbon efficiency through scale effects.When the concentration of population distribution is different,FDI,foreign trade,and population distribution have different effects on carbon efficiency.The promoting effect of FDI on carbon efficiency increases continuously with the concentration of population.(4)Foreign trade significantly promotes carbon efficiency growth when the population distribution is relatively dispersed,and this promotion effect increases with population concentration,but when the concentration of population distribution is too high,foreign trade has a negative impact on carbon efficiency and is not significant.The population distribution index has a stable and negative correlation with carbon efficiency,and after crossing the threshold,the rate of carbon efficiency decreases faster with population concentration.