In the mid-1980s British scientists at Halley Station in Antarctica noticed that their ozone-measuring instrument seemed to have gone wrong – ozone levels were vastly lower than had ever been recorded before. Unfortunately, it was not their instrument that had gone wrong, but the ozone itself – ozone levels over Antarctica in springtime were dropping to a fraction of the regular amount.
Soon after, they isolated the culprit: chlorofluorocarbons (CFCs), which are manmade gases used in aerosols, refrigeration, air-conditioning, industrial solvents, asthma inhalers and fire control. Most of the time CFCs are innocuous, but in the Antarctic springtime the combination of very cold temperatures and the return of sunshine to the polar region allow the CFCs to rapidly gobble up the stratospheric ozone, resulting in the famed ozone hole. As spring progresses, Antarctic temperatures start to warm, and the ozone begins to recover, only to be depleted again when the next spring arrives.
Ozone protects the Earth's surface from UV radiation, the stuff that causes sunburn and skin cancer, among other things. The ozone hole has impacted Southern Patagonia more than any other inhabited area on earth, particularly during spring when the ozone hole is at its worst. Visitors, especially children, should wear brimmed hats and sunglasses, and slather on the sunscreen.
The 1987 Montreal Protocol banned CFCs, and Antarctic ozone levels are finally beginning to recover, but it will take another couple of decades to get back to normal. Unfortunately, many of the gasses that are now used in place of CFCs are greenhouse gasses, adding to the warming of our planet.
Jocelyn Turnbull, atmospheric scientist