Changes in land use and land cover (LULC) are critical for the carbon balance and are closely linked to ecosystem carbon storage. This study focuses on Gansu Province in northwest China within the context of China's "dual carbon" strategy. The PLUS-InVEST-Geodetector framework is applied to assess carbon storage under different land-use scenarios. The impacts of land-use changes from 1980 to 2020 on carbon storage are analyzed. Ecosystem carbon storage for four 2030 development scenarios (ND, ED, EP, and CD) is also projected, and the main drivers of these changes are identified. The results show: (1) cropland and unused land declined, while built-up area expanded, and woodland, grassland, and water areas showed an overall increase. (2) During this period, Gansu Province's total carbon storage rose from 2686.17 & times; 10(6) Mg C to 2701.34 & times; 10(6) Mg C. Grasslands contributed the largest share. By 2030, carbon storage is projected to keep increasing under all four scenarios. The CD scenario will increase by 5.38 & times; 10(6) Mg C, achieving a balance between carbon sequestration potential and regional economic development. (3) The spatial pattern of carbon storage, from 1980 to 2020 and across the four 2030 scenarios, stays broadly consistent. Carbon storage is lower in the west and higher in the east. Precipitation, NDVI, human land use intensity, and population density mainly drive this spatial heterogeneity. Among natural factors, precipitation has the greatest impact (q = 0.795). Interactions between natural and human influences further enhance their effect on spatial variation in carbon storage.