Not sure we need an ozone thread, but...

My two cents:

1) If bromine had been cheaper than chlorine, we'd have been in some very deep trouble. Since there is no necessary connection between economics and chemistry, I'd say that's just plain dumb luck.
Our Lucky Ozone Escape | Mother Jones

2) C02 increase cools the stratosphere (though exactly why it cools the stratosphere is surprisingly hard to describe). So to some degree this parallels other phenomena in global warming -- when you add in a steady trend to natural variation, you get higher highs or lower lows. (For example, that is how the Texas state climatologist characterized the current drought.) The arctic ozone has been thinning for a couple of decades. And now we hit a new low within the instrumental record. What would have been within the range of normal variation becomes a new record.

3) A while back, I mapped patterns of skin cancer prevalence in Medicare, by state, adjusting for racial mix (Caucasians have about 4x the incidence of skin cancer as others.) My clients thought I had made a mistake. They expected the highest rates in the South (and Hawaii). Not so. Rates are highest in the Rocky Mountain states. For delivering UV to the skin, thin air trumps semi-tropical location. Apparently, we here in the US mid-latitudes get a pretty good extra dose of UV as the ozone hole breaks up at the end of winter. And have been for some years.

4) Your point about not being able to stuff the genie back into the bottle is well taken. For CFCs, literally -- anybody else here old enough to remember CFC-driven aerosol cans for everyday household products? That's one where, with 20-20 hindsight, you just have to say, what were they thinking? Between leaded gas and CFCs, at least the government has gotten the notion that dispersing exotic materials across the landscape on an industrial scale has some risks. I guess MTBE is another story along the same lines -- replaced lead, and now is replaced by ethanol, though more through threat of lawsuit than anything else. And the arsenic in old-style pressure-treated wood, now replaced by formulations that exclude the arsenic. Again, a voluntary private action, but ... with a lot of pressure behind it. You just have to wonder how many more are out there that haven't been found yet. And for all of those, you could get the job done because there was some alternative plug-and-play formulation that would work. For C02, we're not there yet.

 

Arctic Ozone Loss In 2011 Unprecedented - Science News

According to this, the Arctic hole wasn't driven by CFC's. It was driven by sunlight, a stable wind vortex, prolonged cold (which is related to the stable wind vortex), and special chlorine-altering clouds.

 

Duplicate post

 

I thought the primary source of chlorine radicals in the stratosphere was the ultraviolet-induced breakup of CFCs. It's just that the other conditions make that more effective for destroying ozone.

Yeah, here, unknown source, but matches what I thought I'd see:

 

It is not as if this was not predicted -
I'll put in my favorite source for pop science, feel free if you disagree or prefer something more authoritative

Arctic Ozone Hole Enlarged by Severe Cold Spell | Wired Science | Wired.com

not colder, but cold longer.

Problem identified and solved, but full solution will take decades longer.

 

There is a parallel to CO2, in that humans are putting contaminants in the atmosphere. However, the ozone hole caused by ChloroFluoroCarbons refrigerants (eg; freon) was different in that - following a few years of bickering - the entire world agreed that the CFC's were seriously endangering life on earth, so CFC's (eg; freon) were fairly promptly banned. Unfort it will still take several hundred years for the atmosphere to recover.

In contrast for +CO2, it is less clear if life on earth is threatened. So there is less concensus on the need to ban fossil fuels.