ASU Research E-Magazine: How the Ozone Got Its Holes

Antarctica’s cold temperatures make it the ideal place to get frostbitten—or sunburned.

While the polar continent may not benefit much from the sun’s heat, it does get an extra high dose of ultraviolet (UV) radiation. Specifically, Antarctica is exposed to high levels of UVB light, the kind that has been found to cause skin cancer in humans.

Normally, the ozone layer high up in the Earth’s atmosphere protects us from UVB rays. But over Antarctica, the ozone layer is deteriorating. Why is the ozone hole there?

Scientists have found that low temperatures promote chemical reactions that lead to ozone depletion. These reactions are caused by chlorofluorocarbons (CFCs) released into the atmosphere from sources like refrigerants and aerosol cans. The CFCs combine with ozone to form new molecules, reducing the amount of free ozone in the atmosphere.

Although global efforts to find alternatives to CFCs have been fairly successful, ASU scientist Tad Day says that existing CFCs in the atmosphere will be around for at least 50 to 100 more years.

The problems are not just in Antarctica. Day says that an ozone hole can drift.

“In recent years, the ozone hole has drifted over South America, where there are people and crops,” he explains. A second hole sometimes drifts down from the North Pole to Canada and over the United States.

“It’s not just an Antarctic problem or even a polar problem anymore.” —Diane Boudreau