Inequality repercussions of roads on the coupling relationships between carbon supply and demand

Roads have a close connection to the carbon cycle of the ecosystem. Nevertheless, it is still unclear how roads affect the balance between carbon supply and demand and where these influences take place. Taking the Min Delta region of China as a case, we analyzed the spatial coupling relationship between carbon supply and demand from 2000 to 2020, and explored the inequality of the impacts of roads on it by using buffer analysis and the geographically weighted regression model. The results showed that: (1) Carbon supply is higher in the western inland and lower on the eastern coast, while carbon demand expands from the east to the west. (2) From 2000 to 2020, a noticeable spatial mismatch between carbon supply and demand. Areas with a carbon surplus reduced from 99.4% to 96.0%, whereas carbon-deficient areas increased from 0.6% to 4.0%. (3) There is a clear spatial negative correlation between carbon supply and demand (P＜0.01), with Moran's I of -0.272, -0.275, and -0.316 for 2000, 2010, and 2020, respectively. The spatial agglomeration patterns are characterized by high supply-low demand (H-L) in the west and low supply-high demand (L-H) in the east. (4) Carbon supply increases with the distance from roads, while carbon demand decreases with higher road grades. (5) The influence of road density on carbon dynamics differs significantly across space. There is a remarkable negative effect on carbon supply in the north and southwest of the study area. Meanwhile, the positive effects on carbon demand are more obvious in the north of the study area. The results offer scientific support and direction for creating energy-saving, emission-reducing, and green low-carbon transportation plans within the dual carbon goals context.