Since the 1980s, a hole in the ozone layer has loomed over Antarctica for three months of every year. During these months, the concentration of the ozone decreases, and harmful ultraviolet light, which causes sunburn and skin cancer, seeps through to the Earth's surface. Environmentalists have long looked to the ozone hole as evidence of man's negative impact on the atmosphere, but recent findings may ease their minds: Measurements indicate the hole in the ozone layer is the smallest it has been in 10 years, and could be completely gone within a few decades.

So why is it shrinking? The hole was originally said to be caused by human-made chlorofluorocarbons (CFCs), chemicals that, until they were banned in the 1980s, were commonly used in aerosols. By getting rid of CFCs, we've allowed the ozone layer to slowly repair itself, the European Space Agency reports.

Does this mean we can stop worrying about the ozone? Not quite. CFCs hang out in our atmosphere for a really long time, so their effects will continue to linger for years. And there's a new hole, this one above the Arctic Circle, which was spotted in 2011. If anything, Antarctica's shrinking ozone hole "goes to show that nations working together to address climate change can have a real and noticeable impact," says Adam Clark Estes at The Atlantic Wire.

The South Pole ozone, 1996-2012: Smaller ozone holes are evident during 2002 and 2012. (BIRA/IASB)