The Impact Of Urban Agglomeration Innovation Scale Distribution On Carbon Emissions

Urban agglomeration,as a large spatial unit containing multiple cities of different sizes and functions,is not only the main body of energy consumption,but also a highly concentrated area of carbon emissions.Due to the spatial correlation of carbon emission,it will transfer and leak with the economic activities between cities,resulting in the carbon emission problem of urban agglomeration is more complicated than that of single city.In the long run,low-carbon development needs to be driven by collaborative innovation.However,innovation has significant spatial heterogeneity.The spatial distribution and agglomeration of innovation factors reflect different distribution patterns of innovation scale,which may produce different environmental effects based on the logic of "structure-behavior-performance".Therefore,it is of great significance to explore a reasonable distribution pattern of innovation scale and promote collaborative innovation among cities in urban agglomeration for the realization of carbon emission reduction targets.This paper first uses primacy index method and city index method to calculate the single-center index and multi-center index which represent the distribution of urban agglomeration innovation scale.Furthermore,partial correlation analysis and Kernel density estimation were used to analyze the temporal evolution characteristics and distribution dynamics of innovation scale and carbon emissions in eleven major urban agglomerations in China from 2003 to 2017.Secondly,from the theoretical perspective,the theoretical framework of the impact of urban agglomeration innovation scale distribution on carbon emissions was constructed based on the regional spatial structure theory and spatial agglomeration theory,and the research hypothesis was proposed.Then,static panel model,moderating effect model and mediating effect model were constructed according to the research hypothesis to test the impact and transmission mechanism of urban agglomeration innovation scale distribution on carbon emissions.The results show that:（1）In the sample period,the multi-center pattern of innovation scale distribution was mainly distributed in Huhu,Baotou,Eryu,Yangtze River Delta,Beibu Gulf,middle Reaches of Yangtze River,Pearl River Delta,Chengdu-Chongqing,and Harbin-Changchun urban agglomeration.The single-center mode of innovation scale distribution is more prominent in Beijing-Tianjin-Hebei urban agglomeration,Guanzhong Plain urban agglomeration and Lanxi urban agglomeration.From the time series evolution characteristics of carbon emissions,the average annual carbon emissions of all urban agglomerations showed an upward trend in the sample period.In general,the single-center pattern of innovation scale distribution in urban agglomerations is positively correlated with carbon emissions,while the multi-center pattern is negatively correlated with carbon emissions.（2）The measurement results show that the single-center model and the multi-center model of urban agglomeration innovation scale distribution promote and restrain carbon emissions,respectively,and with more urban entities incorporated into the multi-center model framework,its inhibition effect on carbon emissions gradually increases.At the same time,innovation can not only restrain carbon emissions through structural effect,but also promote carbon emissions through scale effect.（3）In the process of agglomeration innovation scale distribution affecting carbon emissions,agglomeration size has a positive moderating effect.Specifically,under the single center mode of innovation scale distribution,urban agglomeration size will strengthen its promoting effect on carbon emissions;However,in the polycentric mode of innovation scale distribution,urban agglomeration size will strengthen its promoting effect on carbon emissions.In addition,functional division and regional economic integration of urban agglomerations are also effective ways for the distribution of innovation scale in urban agglomerations to affect carbon emissions.Based on this,this paper puts forward the following suggestions: optimize resource allocation,establish the energy conservation and emission reduction mechanism of urban agglomeration collaborative innovation;Strengthening the intensity of environmental regulation in non-central cities and strengthening the spillover effect;The transmission path of emission reduction of multi-center structure of Chang Tong innovation agglomeration,optimizing the functional division of urban agglomeration,and realizing dislocation development and differentiated competition;We will promote regional economic integration and avoid the risk of marginalization of non-central cities.