This study quantifies the radiative forcing (RF) of future ozone changes. Under climate change, even the sign of the ozone RF can change depending on the greenhouse gas emissions scenario followed. Stratosphere–troposphere exchange plays an important role in driving ozone RF due to reductions in ozone-depleting substances (ODSs) and increases in methane abundance. These could negate the ozone-derived climate benefits of air-quality controls on non-methane ozone precursor emissions.