Of course the people behind the CFC ban are patting themselves on the back, but the role of other variables in the atmosphere may have been ignored or overlooked. Extracts from a BBC News report follow.
Researchers say they have found the first clear evidence that the thinning in the ozone layer above Antarctica is starting to heal.
The scientists said that in September 2015 the hole was around 4 million sq km smaller than it was in the year 2000 – an area roughly the size of India.
The gains have been credited to the long term phasing out of ozone-destroying chemicals. The study also sheds new light on the role of volcanoes in making the problem worse.
One finding that puzzled researchers was the October 2015 reading that showed the biggest ozone hole on record over Antarctica. The scientists believe that a key contributor to the record hole was volcanic activity.
“After an eruption, volcanic sulphur forms tiny particles and those are the seeds for Polar Stratospheric Clouds,” [US researcher] Prof Susan Solomon told Science in Action.
“You get even more of these clouds when you have a recent major volcanic eruption and that leads to additional ozone loss…Until we did our recent work no-one realised that the Calbuco eruption in Chile, actually had significantly affected the ozone loss in October of last year.”
The study has been hailed as “historically significant” by some other researchers in the field.
“This is the first convincing evidence that the healing of the Antarctic ozone hole has now started,” said Dr Markus Rex from the Alfred Wegener Institute for Polar and Marine Research in Germany.
“Right now the state of the ozone layer is still really bad, but I find it very important that we know the Montreal Protocol is working and has an effect on the size of the hole and that is a big step forward.”