The chemical reactions responsible for stratospheric ozone depletion a
re extremely sensitive to temperature(1). Greenhouse gases warm the Ea
rth's surface but cool the stratosphere radiatively(2-5) and therefore
affect ozone depletion. Here we investigate the interplay between pro
jected future emissions of greenhouse gases and levels of ozone-deplet
ing halogen species using a global climate model that incorporates sim
plified ozone-depletion chemistry. Temperature and wind changes induce
d by the increasing greenhouse-gas concentrations alter planetary-wave
propagation in our model, reducing the frequency of sudden stratosphe
ric warmings in the Northern Hemisphere(4). This results in a more sta
ble Arctic polar vortex, with significantly colder temperatures in the
lower stratosphere and concomitantly increased ozone depletion. Incre
ased concentrations of greenhouse gases might therefore be at least pa
rtly responsible for the very large Arctic ozone losses observed in re
cent winters(6-9). Arctic losses reach a maximum in the decade 2010 to
2019 in our model, roughly a decade after the maximum in stratospheri
c chlorine abundance. The mean losses are about the same as those over
the Antarctic during the early 1990s, with geographically localized l
osses of up to two-thirds of the Arctic ozone column in the worst year
s. The severity and the duration of the Antarctic ozone hole are also
predicted to increase because of greenhouse-gas-induced stratospheric
cooling over the coming decades.