The extent of ozone depletion for any given period depends on complex interaction between chemical and climatic factors such as temperature and wind. The unusually high levels of depletion in 1988, 1993 and 2002 were due to early warming of the polar stratosphere caused by air disturbances originating in mid-latitudes, rather than by major changes in the amount of reactive chlorine and bromine in the Antarctic stratosphere.

The Antarctic continent is circled by a strong wind in the stratosphere which flows around Antarctica and isolates air over Antarctica from air in the midlatitudes.