Land-use alterations exert a profound impact on carbon storage within terrestrial ecosystems. Exploring the spatiotemporal dynamics of regional land use and carbon storage is crucial for optimizing national spatial planning and fostering low-carbon development. For this study, we utilized land-use data spanning from 2000 to 2020 for the Tibetan Plateau and assessed the spatial and temporal variations in carbon storage using the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model. We adjusted the carbon density within the provinces in the study area as a prerequisite. Moreover, we integrated the Grey Multi-objective Decision-making (GMMOP) model with the Patch-generating Land-use Simulation (PLUS) model to forecast carbon storage alterations in 2030 across various scenarios. The findings indicated that between 2000 and 2020, the overall carbon storage witnessed a decrease of 18.94 × 108 t. Carbon storage in grassland decreased by 22.10 × 108 t, and carbon storage in unused land, forest land, cultivated land, construction land, and water increased by 1.56 × 108 t, 0.92 × 108 t, 0.66 × 108 t, 158.50 × 104 t and 26.74 × 104 t, respectively. The soil organic carbon pool exhibited the highest average carbon storage of 195.63 × 108 t, whereas the litterfall organic carbon pool contained the lowest average carbon stock of 15.07 × 108 t. In comparison with the levels observed in 2020, the total carbon storage experienced a reduction of 8.66 × 108 t and 5.29 × 108 t under the inherent progression and economic growth scenarios, respectively. Conversely, it rose by 11.87 × 108 t and 16.21 × 108 t under the environmental preservation and holistic progression scenarios, respectively. Under the holistic progression scenario, the belowground biomass organic carbon pool exhibited the highest carbon storage increase of 5.59%. These findings offer valuable insights for the management and enhancement of carbon sinks in the Qinghai-Tibet Plateau.