Using a general-circulation climate model to drive an energy-use model, we projected changes in USA energy-use and in corresponding fossil-fuel CO₂ emissions through year 2025 for a low (1.2°C) and a high (3.4°C) temperature response to CO₂ doubling. The low-ΔT scenario had a cumulative (2003–2025) energy increase of 1.09 quadrillion Btu (quads) for cooling/heating demand. Northeastern states had net energy reductions for cooling/heating over the entire period, but in most other regions energy increases for cooling outweighed energy decreases for heating. The high-ΔT scenario had significantly increased warming, especially in winter, so decreased heating needs led to a cumulative (2003–2025) heating/cooling energy decrease of 0.82 quads. In both scenarios, CO₂ emissions increases from electricity generation outweighed CO₂ emissions decreases from reduced heating needs. The results reveal the intricate energy-economy structure that must be considered in projecting consequences of climate warming for energy, economics, and fossil-fuel carbon emissions.