ENVIRONMENT The ozone hole is at its smallest size since 1988, thanks to hot air and a massive international effort

One of the layers of atmosphere that protects all life on our planet is the width of two pennies, and hangs out six to ten miles above the Earth’s in an environment that human activity made extremely hostile. Every year when winter ends and warmer weather returns to Antarctica, chemicals that we put into the air rip a hole in the layer. But this year, that hole is smaller than usual.

This week, NASA and NOAA announced that 2017’s ozone hole, at 7.6 million square miles, was the smallest since 1988.

Ozone is a molecule made of three oxygen atoms bonded together. On the ground, it can form harmful smog. But above the Earth, it acts like sunscreen, protecting life from harmful solar radiation. When elements like chlorine and bromine undergo a particular chemical reaction in clouds, ozone takes a beating.

This year it was warmer than usual in Antarctica’s lower stratosphere, with temperatures the likes of which you'd normally see over the Arctic. The odd weather pattern was not conducive to the formation of ozone-killing clouds, giving that precious layer of the atmosphere a break.

The ozone hole was first discovered in Antarctica in 1985, and quickly linked to the increased use of ozone-depleting chemicals like chlorofluorocarbons (CFC’s). CFC's were everywhere at the time, and were seen as a better replacement for earlier industrial chemicals. They were non-toxic to humans, non-flammable, and used in refrigeration, air conditioning, and aerosols.

Alarmed by the effect that human actions were having on the planet, nations around the world signed the Montreal Protocol just a few years later, agreeing to ban CFC’s and other ozone-depleting chemicals. The agreement went into effect in 1989; but with CFC’s long lifetime, it wasn’t until very recently that researchers—who were constantly monitoring the health of the ozone layer—were able to truly notice signs of healing.

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