Anthropogenic climate change is altering the landscapes of populations worldwide. In the Rocky Mountains, elevated temperatures are causing decreased snowpack and greater drought stress. Additionally, rising atmospheric CO2 concentrations ([CO2]) are affecting plant populations by increasing photosynthetic rates and enhancing plant growth. The negative effects of increased aridity may be offset by the fitness gains of elevated [CO2]. However, the interactive effects of [CO2] and temperature are rarely studied together. Here, we present the results of a multifactorial growth chamber experiment on Boechera stricta (Brassicaceae), a perennial forb native to the Rocky Mountains. We see increased photosynthesis in future [CO2] conditions but a decline in stress responses. Additionally, genotypes from lower elevations show elevated fitness and fecundity. These results are not evident under single factor manipulations and highlight the importance of examining climate change factors in multifactorial experiments.