经济集聚对碳排放强度的影响及传导机制

中国城市群的兴起催生经济集聚,化石能源消耗增多引发碳排放形势愈加严峻,探索经济集聚对碳排放强度的影响及传导机制至关重要。本文以2004-2016年京津冀、长江三角洲、粤港澳大湾区、成渝城市群的61个城市面板数据为研究样本,探索经济集聚与碳排放强度的关系及影响机制,创新性地使用抗日战争时期各城市是否有铁路通过、2003年各城市是否有机场、各城市历年的国家级经济技术开发区数量作为工具变量解决内生性问题,构建中介效应模型分别检验环境规制和城镇化水平对经济集聚影响碳排放强度的传导机制,并分析经济密度异质性下经济集聚对碳排放强度的不同作用路径。结果表明:①经济集聚与碳排放强度之间呈显著的负向关系,现阶段城市经济集聚水平的提高有利于降低碳排放强度;②相对于低经济密度城市,高经济密度城市经济集聚的降碳效果更为明显;③经济集聚不仅直接对碳排放强度产生影响,还通过环境规制与城镇化水平两条路径间接对碳排放强度产生作用,中介效应显著;④低经济密度城市经济集聚对碳排放强度的间接影响主要是通过城镇化水平来传导,而高经济密度城市经济集聚对碳排放强度的间接影响可以靠环境规制和城镇化水平两条路径来实现。据此本文认为,政府应推动城市群经济以促进区域融合发展,实现企业联动合作以提高经济集聚水平。针对经济密度不同的城市治理手段应有所侧重,高经济密度城市应以增强环境规制力度为主要碳减排手段,而低经济密度城市则应通过提高经济集聚水平,改善城市建设水平并最终达到碳减排的目标。

The impact and transmission mechanism of economic agglomeration on carbon intensity

Urban agglomerations in China have led to agglomeration economies.This is accompanied by the rapid growth of carbon emission as a result of the increasing consumption of fossil energy.This paper considers that it is crucial to explore the influence of agglomeration economies on carbon intensity and the transmission mechanism.Based on the panel data of 61 cities from the BeijingTianjinHebei area,the Yangtze River Delta,the GuangdongHong KongMacao Greater Bay Area and the ChengduChongqing urban agglomerations over 2004 to 2016,this paper analyzed the relationship and impact mechanism between agglomeration economies and carbon intensity.To solve the endogeneity problem,this paper innovatively selected the availability of railways during the AntiJapanese War period,the availability of airports in 2003,and the number of national economic and technological development zones in cities as instrumental variables.Moreover,a mediation effect model was constructed to examine the impact of environmental regulation and urbanization level on the relationship between the agglomeration economies and carbon intensity.Then,this paper presented how agglomeration economies affected carbon intensity in different ways under varying economic density level.The results show that:①Therewas a significant negative relationship between agglomeration economies and carbon intensity.The improvement of agglomeration economies in cities was conducive to reducing carbon intensity at this stage;②Compared with low economic density cities,agglomeration economies in those with high economic density had a more significant carbon reduction effect;③Agglomeration economies not only had a direct impact on carbon intensity but also impacted carbon intensity indirectly through environmental regulation and urbanization level;④For cities with low economic density,the indirect impact of agglomeration economies on carbon emission intensity was mainly transmitted through urbanization level.While for cities with high economic density,the indirect impact of urban agglomeration economies on carbon emission intensity could be realized through both environmental regulation and urbanization level.The results above indicate that the government should promote urban agglomerations to facilitate regional integrated development and enterprise cooperation and to promote agglomeration economies.At the same time,urban governance should be adjusted for different economic densities.Cities with high economic densities should focus on enhancing environmental regulation,while cities with low economic densities should pay more attention to the improvement of urban construction levels by increasing the level of agglomeration economies to achieve carbon reduction.