The Montreal Protocol of 1987 placed strict controls on the release of ozone-depleting substances. A new study now shows what would have happened to the ozone layer in the absence of this critically important international treaty — and it wouldn’t have been pretty.
And it's not even technically an ad.
A hole in Earth's protective ozone layer above the Antarctic has become an annual event for the last 25 years, greatly increasing the South Pole's exposure to ultraviolet rays. Now, the same thing is happening above the Arctic Circle.