Ozone hole

Also: Hole in the ozone layer

Each year during the Antarctic spring, the concentration of ozone in the stratosphere decreases in a region around Antarctica. This is called the ozone hole, and it occasionally appears in the arctic too.

The ozone hole has only a minor connection to global warming. The hole is caused by CFCs and HCFCs that humans have released into the atmosphere; CFCs/HCFCs also have a large global warming potential. Since the ozone hole lets more UVB radiation reach the surface, CFCs have a very small additional warming effect on top of their greenhouse effect.

CFCs and HCFCs have been phased out under the Montreal Protocol, but still linger in the atmosphere. They have been replaced by HFCs, which do not deplete the ozone layer but still contribute to global warming.