We investigate how rising CO₂ changes the migrating diurnal tide driven by solar heating and latent heat. Using a state-of-the-art model under the most extreme scenario in the Intergovernmental Panel on Climate Change report, we find that the tide strengthens between 20–70 km but weakens between 90–110 km. The increase likely reflects lower density and stronger tropical convection, whereas the decrease is consistent with enhanced diffusion.