Climate geoengineering has been proposed as a possible means of mitigating anthropogenic warming. While analyses illustrating the impacts of stratospheric aerosol geoengineering on climate change under various projected emissions scenarios are comprehensively discussed, only a few studies have considered the terrestrial biogeochemical feedbacks to a geoengineered climate. These feedbacks could modify the atmospheric carbon dioxide trajectory by storing or releasing additional carbon in terrestrial and marine ecosystems and thus change the climate trajectory, requiring a modified aerosol injection strategy. In this study, we analyzed model output from the Stratospheric Aerosol Geoengineering Large Ensemble project to evaluate the terrestrial biogeochemical feedbacks to climate. Our results showed that terrestrial ecosystems stored an additional 79 Pg C (or 37 ppm CO₂-equivalent) from the atmosphere in a geoengineered climate compared to the climate without geoengineering, which could yield as much as a 7% reduction in atmospheric CO₂ by the end of the 21^th century under the RCP8.5 emission trajectory. Hypotheses regarding the causes of the different regional responses will be presented.