In the 80s and 90s, a lot of effort was put into banning chlorofluorocarbons, or CFCs, a nasty little family of organic compounds that like to eat the ozone that's protecting us all from dying of sunburns. A couple decades later, we're just starting to see this proactive environmentalism begin to pay off.
CFCs are incredibly awesome and useful chemicals. They have low toxicity, low reactivity, low flammability, and they make great refrigerants. Problem is, when released into the air, they float up into the upper atmosphere where they can live for a hundred years, tearing ozone molecules apart. And ozone molecules are the things that absorb a bunch of the dangerous ultraviolet radiation that the sun is throwing at us.
In the interest of keeping the planet from turning into a burnt cinder, CFCs have been largely banned worldwide for the last 20 years. Despite this, we haven't really noticed much in the way of recovery of the worst areas, most notably around the giant ozone hole that CFCs create above Antarctica every spring.
Australian researchers have just recently been able to accurately model a bunch of the complicated seasonal weather patterns over the pole, and armed with this new information, for the first time they've been able to accurately estimate the systematic changes in ozone levels over the last few years. Happily, the data show that the ozone levels are rising, and have improved by 15% since they hit an all-time low in the late 1990s. This is good news, but it's a slow process, and it may take another fifty or sixty years or more for everything to get back to normal.
Funnily enough, since ozone absorbs heat, the ozone hole over Antarctica has actually been helping to forestall global warming down there, and there's a worry that when the hole eventually heals up, the whole place is going to just melt into a giant puddle. Well, okay, not really, but it is possible that things are going to heat up relatively quickly when the ozone levels return to normal. Man, we just can't win with this climate stuff, can we?