The Ozone Layer's Unwelcome Return?

Phil Berardelli in ScienceNOW Daily News:

Once greeted as good news, the recovery of the ozone layer is increasingly seen as a mixed blessing. In April, researchers found that a healing ozone hole could amplify global warming by trapping more heat in the atmosphere (ScienceNOW, 24 April). And in tomorrow's issue of Science, climatologists report that ozone recovery could disrupt wind patterns in the Southern Hemisphere, potentially leading to a warming of Antarctica. The findings suggest that actions taken by humans to protect the planet from the harmful effects of solar radiation could accelerate climate change on the frozen continent.

Ever since most nations signed the 1987 Montreal Protocol, which banned the manufacture of ozone-destroying chemicals called chlorofluorocarbons, the fragile ozone layer has been set on a slow path to recovery. The layer's return to health is estimated to take another 60 years. By then, the so-called ozone hole should no longer appear over Antarctica every polar spring and persist until autumn. And the cancer-causing ultraviolet (UV) rays that ozone filters out of sunlight will largely be blocked from hitting the surface.

But there's a catch. The appearance of the ozone hole actually created a unique wind pattern called the Southern Annular Mode (SAM), which prevents warmer air from reaching Antarctica.