This year, the ozone hole over Antarctica reminds us of what could have been.
In 1987, the world’s nations agreed to the Montreal Protocol, banning the use of chemicals that destroy ozone.
The ozone layer began to recover.
The ozone hole reaches an annual maximum size at the end of each southern winter.
In recent years, these maximums have been getting slightly smaller.
The ozone hole fluctuates with temperature – chemical destruction of ozone is enhanced when it’s colder.
This year, the South Pole region was relatively cold, so the hole grew larger than in the previous two years.
Scientists were able to compare this year’s ozone layer to models of what the ozone layer might have looked like without the Montreal Protocol.
In spite of the colder temperatures, the ozone hole was still much smaller
than it would have been, evidence of ongoing scientific success.