长江中游城市群碳效率时空演化特征——基于三阶段SBM-DEA模型

Spatio-temporal evolutionary characteristics of carbon efficiency in the middle reaches of the Yangtze River urban agglomeration based on a three-stage SBM-DEA model

长江中游城市群作为我国区域发展格局的中坚力量,其碳效率的提升对助力我国实现“双碳”目标意义重大。采用三阶段SBM-DEA模型测度2006—2019年长江中游城市群28市的碳效率并进行环境变量影响分析,以探究长江中游城市群碳效率的影响路径;进而运用核密度估计、中心-标准差椭圆等方法分析碳效率的时空演化特征,以探明各区域碳效率差异并给出相应提升策略。研究结果表明:(1)长江中游城市群整体碳效率水平不高,但呈现出逐年波动上升的趋势;(2)长江中游城市群碳效率呈现出“武汉城市圈>环长株潭城市群>环鄱阳湖城市群”的空间分异格局,效率中心整体向东北方向移动,标准差椭圆长轴标准差整体缩小,短轴标准差相对稳定;(3)长江中游城市群碳效率存在正向空间溢出效应,城镇化进程、产业结构和科技支撑强度是影响碳效率的重要因素。

As the backbone of China's regional development pattern,increasing carbon efficiency in the middle reaches of the Yangtze River urban agglomeration is of great significance to help China achieve the"double carbon"goal.In order to explore the carbon efficiency differences and influence paths of each region in the middle reaches of the Yangtze River urban agglomeration and propose corresponding improvement strategies,we applied a three-stage SBM-DEA model to measure the carbon efficiency of 28 cities in the middle reaches of the Yangtze River urban agglomeration from 2006 to 2019 and analyze the impact of environmental variables,which excluded the influence of external environment and random factors.Then,we also used kernel density estimation and center-standard deviation ellipses to analyze the spatial and temporal evolution of carbon efficiency,which aimed to find a site-specific approach to make targeted suggestions for carbon efficiency improvement.The results show that:①the overall carbon efficiency of the middle reaches of the Yangtze River urban agglomeration is not high but shows a trend of the fluctuating upward year by year.There is no GDP output redundancy among cities,and the main reasons affecting carbon efficiency in the middle reaches of the Yangtze River urban agglomeration are focused on capital,labor,energy inputs,and CO2 emissions.②The carbon efficiency of the middle reaches of the Yangtze River urban agglomeration shows a spatial divergence pattern of Wuhan city circle>Changzhutan urban agglomeration>Poyang Lake urban agglomeration,while the center of efficiency moves to the northeast.The standard deviation of the long axis of the standard deviation ellipse decreases as a whole,and the standard deviation of the short axis is relatively stable.The overall area of the standard deviation ellipse has decreased,which means that the difference in carbon efficiency between regions is reducing year by year.③There is a positive spatial spillover effect of carbon efficiency in the middle reaches of the Yangtze River urban agglomeration,and the urbanization process,industrial structure,and technology support intensity are crucial factors affecting carbon efficiency.Within the middle reaches of the Yangtze River urban agglomeration,Wuhan city circle,Changzhutan urban agglomeration,and Poyang Lake urban agglomeration have some competitive relationship in capital,labor,and energy input.Therefore,the better-developed areas siphon resources to the surrounding areas,which formed the negative spatial spillover effect within the middle reaches of the Yangtze River urban agglomeration.