Spatiotemporal evolution of carbon budget and carbon compensation zoning of urban agglomerations in the Yellow River Basin.

As a crucial industrial, agricultural, and energy base in China, the urban agglomerations in the Yellow River Basin (YRB) have faced increasingly significant pressure for carbon emission reduction since the implementation of the "Dual Carbon" strategy. This study focuses on 615 counties within the major urban agglomerations in the YRB, analyzing the spatiotemporal evolution of carbon budget in land use from 2000 to 2020. Methods such as the normalized revealed comparative advantage (NRCA) index and SOM-K-means model are employed to explore the carbon compensation zoning of counties in the urban agglomerations in the YRB from the perspective of main functional zones. The results show that: (1) From 2000 to 2020, there was a significant and continuous widening gap between carbon emissions and carbon absorption in the study area. The total carbon emissions increased significantly from 3.64 × 10 to 13.56 × 10 t, showing a "north high, south low" spatial distribution pattern. Meanwhile, the carbon absorption remained stable at around 6.47 × 10 t, with a spatial distribution pattern roughly characterized by "higher in the west, lower in the east, and highest in the central part". The carbon budget of various types of functional zones generally aligns well with their strategic positioning. (2) There is a significant regional difference in net carbon emissions among urban agglomerations, with the greatest internal variation observed in the Guanzhong Plain Urban Agglomeration (Gw = 0.471) and the most notable differences between the Lanzhou-Xining Urban Agglomeration and others (Gb = 0.554). (3) The study area consists of 273 payment zones, 257 balanced zones, and 85 compensated zones. Combining with the reconstruction of main functional areas, seven types of carbon compensation zones are identified.