Study on the Spatial-Temporal Evolution and Influencing Factors of the Synergistic Efficiency of Reducing Pollution and Carbon in Beijing-Tianjin-Hebei and Surrounding Areas

Under the background of "double carbon '', it is of great practical significance to study the spa-tial-temporal evolution of the synergistic effect of reducing pollution and carbon in Bei-jing-Tianjin-Hebei and surrounding areas and its influencing factors, to promote the green transi-tion and realize the overall goal of the coordinated development of pollution reduction and carbon reduction. Based on"2 + 36" urban panel data from 2007–2022, the entropy weight method and cou-pling coordination model were used to evaluate the synergistic effects of pollution reduction and carbon reduction, and spatial autocorrelation analysis and kernel density method were applied to analyze the spatio-temporal evolution characteristics and coupling coordination of carbon and pollutant emissions, respectively. Using the spatial Dubin model, the factors affecting urban pollu-tion and carbon reduction, and the level of spatial spillover are discussed. The results show that (1) the "2 + 36" cities' pollutant emissions increase continuously, while carbon emissions rise slowly and then rapidly fall respectively. The synergistic effects of pollution and carbon reduction show a trend of continuous decline. (2) The degree of synergy "2 + 36" shows a trend of continuous decline, and since 2012, it has shown a “general decline and local rise", with significant spatial heterogeneity. (3) From 2007 to 2022, industrial structure, the input of science and technology, and the level of con-sumption of residents were the key factors in promoting the coordinated development of local pollution reduction and carbon reduction, and the spatial spillover effect was even more noticeable. The negative impacts of productivity level, green technologies, economic size, and urbanization rate on regional synergies in pollution reduction and carbon reduction are gradually strengthening. In the context of economic transformation, urbanization, and consumption polarization, it was nec-essary to optimize exchanges and cooperation, refine policy initiatives, and work together to im-prove environmental governance.