This study focuses on 55 shrinking cities selected by the urban shrinkage index using data about the urban population of 250 prefecture-level Chinese cities from 2012 to 2017. It analyzes the theoretical impacts of urban shrinkage on haze pollution and the spatial distribution and autocorrelation of urban shrinkage. The spatial error model (SEM) and the fully modified least squares (FMOLSs) regression are used to empirically examine the impacts of urban shrinkage on haze pollution at national and regional levels. The results indicate that shrinking cities showed spatial agglomeration and that northeast China had the largest number of shrinking cities. Nationwide, urban shrinkage reduced haze pollution. An increase in the proportion of secondary industries, economic development, and built-up areas intensified haze pollution, while an increase in the green area in parks alleviated such pollution. Regionally, except for west China, the impacts of urban shrinkage on haze pollution were significantly negative. Urban shrinkage in central China had the greatest impacts on haze, followed by northeast China and east China. Haze pollution was intensified by the increase in the proportion of secondary industries in east, central and west China, alleviated by economic development in east and west China, slowed down by the increase in green area in parks in northeast, east and west China, and aggravated by the rise in built-up areas in northeast, central, and west China. Targeted suggestions are proposed herein to reduce haze pollution, adapt to urban shrinkage and build quality small cities based on local conditions.
China is vigorously building a unified domestic market, with priority given to regional market integration while maintaining a national unified market. Limited research has been conducted on whether market integration affects renewable energy technology innovation (RETI). This paper empirically studies this topic based on panel data of 30 Chinese provinces from 2004 to 2020 using FMOLS (Fully Modified Ordinary Least Squares), DOLS (Dynamic Least Squares method), and FGLS (Feasible Generalized Least Squares). Research results have been verified by robustness tests. The main conclusions are as follows: (1) Market integration has an important positive impact on RETI, namely, boosting it. This conclusion remains robust when different indicators of innovation and market segmentation are included. (2) The regional impacts of market integration on RETI are heterogeneous, being the greatest in east China, followed by west China and central China. (3) Market integration affects RETI through energy structure and technological innovation. It can optimize energy structure, improve technological innovation, and thus enhance RETI. Based on the above conclusions, in order to improve RETI in China and expand its contribution to carbon neutrality and carbon peaking, China needs to strengthen the construction of a national unified market and implement differentiated market integration policies in east, central, and west China. Furthermore, it is necessary to give full play to the role of energy structure and technological innovation in market integration by optimizing energy structure and improving technological innovation.
Panel data of 234 cities in China from 2011 to 2018 is used to measure the urban shrinkage index. PM2.5 is used as an indicator of haze pollution, and labour supply is the mediator. On this basis, the influence mechanism of haze pollution on urban shrinkage is analysed theoretically. Next, using the dynamic panel model and the mediating effect model, we empirically examine the impact of urban shrinkage on haze pollution and the mediating effect of labour supply. The main findings are as follows: haze pollution increases the degree of urban shrinkage, and labour supply plays a regulatory role in the process of haze pollution affecting urban shrinkage. According to our research, pertinent policies and suggestions are proposed to reduce both urban shrinkage and haze pollution.
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