Research on the impact of county urbanization in Jiangxi Province on carbon budget balance.

Investigating the effects of urbanization at the county level on the balance of the carbon budget is essential for progress toward achieving "dual carbon" objectives at the county scale. Based on land use and economic data, this study elucidates the spatiotemporal evolution of urbanization and carbon budget balance ratio in 84 counties in Jiangxi Province from 1980 to 2020. Optimal geographic detectors and geographically weighted random forests were used to explore the impact of urbanization on the carbon budget balance ratio. The results indicate that (1) after 2000, the net carbon emissions of Jiangxi Province increased rapidly from - 0.54 × 10 to 217.99 × 10 tonnes, with the overall carbon sink area transitioning into a carbon source area; (2) the average carbon budget balance ratio of the counties decreased from 5.45 in 1980 to 0.49 in 2020, and the number of regions with a moderate or higher carbon deficit increased from 8 to 59, primarily concentrated in the Poyang Lake urban agglomeration. Carbon surplus areas decreased from a majority of counties to only 10, now concentrated in less developed areas. (3) The 4 km grid is the optimal spatial scale, and the patch cohesion index, night light index, population density, and civilian vehicle ownership are the main factors affecting the carbon budget balance ratio across different dimensions of urbanization. (4) In terms of spatial relationships, influenced by different stages of urbanization and policy interventions, the nonlinear impact of key urbanization factors across various dimensions on the carbon budget balance ratio is significantly greater than that of the linear model. The effect of the same variable on the carbon budget balance ratio shows significant differences across counties. Therefore, it is essential to comprehensively consider the diverse impacts of urbanization on the carbon budget balance when formulating policies aimed at "carbon reduction and increase."