Models predict that CO2 doubling in the atmosphere cools the stratosphere by as much as 10 ¿C. We argue that this effect alone, through the temperature dependence of the ozone spectrum, can result in an increase of a few percent in UV-B (280--320 nm) penetration at the Earth's surface. The increase in Erythema-weighted UV radiation is about 1%. Future spectral observations of UV at the surface could distinguish this effect from any result of changes in ozone abundance. ¿ 1997 American Geophysical Union