The ozone hole is finally closing up

Scientists have found evidence that the hole in the ozone layer over Antarctica is finally beginning to heal. If progress continues, it should be closed permanently by 2050.

The news comes almost 30 years since the world worked together to phase out ozone-depleting chemicals, so we're allowed to give ourselves a little pat on the back. "We can now be confident that the things we’ve done have put the planet on a path to heal," said lead researcher Susan Solomon from MIT.

In the '80s and '90s, the hole in the ozone layer was the environmental threat that everyone was worried about. After decades of pumpingchlorofluorocarbons (CFCs) into the atmosphere - through dry cleaning, aerosols, and old refrigerators - scientists found that the ozone over Antarctica had become seriously thin.

That's not great, seeing as the ozone layer is the shield that absorbs much of the Sun's harmful UV rays before they reach Earth.

To combat the problem, most countries on the planet signed the Montreal Protocol in 1987, which was a global treaty that governed the gradual phase-out of CFCs and other ozone-damaging chemicals.

And now researchers using new longitudinal measurements have shown that the hole is finally starting to heal, and has shrunk by 4 million square kilometres since its peak in 2000. That's roughly half the size of the mainland US.

It did expand to a record size in 2015 due to the eruption of the Chilean volcano, Calbuco, but if environmental progress continues, the hole should be fully closed by mid-century.

"Which is pretty good for us, isn’t it?" said Solomon. "Aren’t we amazing humans, that we did something that created a situation that we decided collectively, as a world, 'Let’s get rid of these molecules'? We got rid of them, and now we’re seeing the planet respond."