Abstract. Increasing atmospheric carbon dioxide concentration [CO2] caused by anthropogenic activities has triggered a requirement to predict the future impact of [CO2] on forests. The Hindu Kush Himalayan (HKH) region comprises a vast territory including forests, grasslands, farmlands and wetland ecosystems. In this study, the impacts of climate change and land use change on forest carbon fluxes and vegetation productivity are assessed for HKH using the Lund-Potsdam-Jena General Ecosystem Simulator (LPJ-GUESS). LPJ-GUESS simulations were driven by an ensemble of three climate models participating in the CMIP5 (Coupled Model Intercomparison Project Phase 5) database. The modeled estimates of vegetation carbon (VegC) and terrestrial primary productivity were compared with observation-based estimates. Furthermore, we also explored the net biome productivity (NBP) and VegC over HKH for the period 1850–2100 under the future climate scenarios RCP2.6 and RCP8.5. A reduction is observed in modeled NBP and VegC from 1951–2005 primarily due to land use change. However, an increase in both NBP and VegC is predicted under RCP2.6 and RCP8.5. The findings of the study have important implications for management of the HKH region and inform strategic decision making, land use planning and clarify policy concerns.