Synergistic reduction of air pollutants and carbon emissions in Chengdu-Chongqing urban agglomeration, China: Spatial-temporal characteristics, regional differences, and dynamic evolution

Abstract

Promoting the development of synergistic reduction of air pollutants and carbon emissions (SRAPCE) is crucial to respond to environmental protection and climate change. However, there is still a lack of comprehensive analysis of SRAPCE at the county scale based on an exploratory spatial-temporal data analysis (ESTDA) framework. Besides, there are few studies on urban agglomerations in western China. To fill the research gap, this study selected Chengdu-Chongqing Urban Agglomeration (CCUA) as an example, and measured SRAPCE level in 156 counties of CCUA and explored spatial-temporal characteristics, regional differences, and dynamic evolution of SRAPCE in CCUA at the county scale by ESTDA framework. The study showed that: (1) SRAPCE level in counties of CCUA is mainly in moderate imbalance, accounting for 61.54%–73.72%, and shows the obvious spatial heterogeneity, with a pattern of “high in the middle and low at the edge”. (2) The average overall Gini coefficient of SRAPCE is 0.19, elucidating a level of spatial imbalance, and its largest contribution degree is intra-regional differences. (3) Global Moran's I of SRAPCE ranges from 0.299 to 0.387, exhibiting a positive spatial correlation. There is a significant spatial agglomeration phenomenon, mainly dominated by HH and LL. (4) There are 98 counties with low relative length and medium relative length, which accounts for 62.82%, suggesting local spatial structure of SRAPCE is fairly steady. There are 136 counties with low tortuosity and medium tortuosity, which account for 87.18% of the total, suggesting the volatility of SRAPCE is fairly steady in the direction of local spatial dependence. There are 104 counties with collaboration growth type, which accounts for 66.67%, suggesting the pattern changes of SRAPCE exhibit a high level of spatial integration. The spatial-temporal cohesion index is 93.85%, and the spatial-temporal flux index is 6.15%, suggesting that local spatial correlation pattern of SRAPCE exhibits path dependences and space-locking characteristics to some extent. The research findings could provide scientific support for CCUA to achieve sustainable development and formulate environmental management policies, and inspirations for other urban agglomerations.