College of Economics and Management, Northwest A&F University, Yangling, Xianyang, 712100, China.
College of Finance, Tianjin University of Finance and Economics, Tianjin, 300222, China.
Environ Sci Pollut Res Int. 2023 Aug;30(36):86165-86177. doi: 10.1007/s11356-023-28564-z. Epub 2023 Jul 4.
As a gathering place for human production activities, cities are the main places where energy consumption and carbon dioxide emissions occur. How to accurately measure city size and test the impact mechanism of city size on carbon emissions of different city levels is still controversial. This study uses the global nighttime light data to identify urban bright areas and built-up areas, and accordingly constructs the city size index of 259 prefecture level cities in China from 2003 to 2019. It avoids the problem of only considering the single index of population size or space size, and makes the measurement of city size more reasonable. We use a dynamic panel model to study the impact of city size on urban carbon emissions per capita, and discuss the heterogeneity of various cities under different population levels and economic development levels. The empirical results indicate that in the scale of cities in China showed a fluctuating growth trend in recent years. The city size index of most cities is clustered at medium and high values. The city size index of cities with different economic development levels and different population-scale levels shows obvious gradient differences but maintains an upward trend. The expansion of supercities (with a population of more than 5 million) introduces a drastic increase in carbon emissions. The carbon emissions growth caused by the expansion of cities that are classified as third tier and below is the smallest, while that caused by the expansion of cities that are classified as first-tier is the largest. The findings suggest differentiated emissions reduction suggestions for cities with different sizes.
作为人类生产活动的聚集地，城市是能源消耗和二氧化碳排放的主要场所。如何准确衡量城市规模并检验城市规模对不同城市能级碳排放的影响机制，仍存在争议。本研究利用全球夜间灯光数据识别城市的亮灯区域和建成区，由此构建了 2003-2019 年中国 259 个地级市的城市规模指数，避免了仅考虑人口规模或空间规模单一指标的问题，使得城市规模的衡量更加合理。我们采用动态面板模型研究城市规模对城市人均碳排放的影响，并探讨了不同人口规模和经济发展水平下各类城市的异质性。实证结果表明，近年来中国城市规模呈波动增长趋势，大多数城市的城市规模指数集中在中高水平。不同经济发展水平和人口规模水平城市的城市规模指数表现出明显的梯度差异，但均呈上升趋势。超大城市（人口 500 万以上）的扩张带来了碳排放的急剧增加，三、四线城市扩张带来的碳排放增长最小，而一线城市扩张带来的碳排放增长最大。研究结果为不同规模城市提出了差异化的减排建议。
