20 years ago, the environmentalists were running around telling us, “zomg like stop using CFC’s cuz they’re making a hole in the ozone layer. It’s gonna give you skin cancer!!111one!”
Nowadays, I don’t hear much about the ozone layer. Did we nip the problem in the bud? Is the hole gone now, or is it still there but getting smaller every year or at least not growing? Is the hole growing but it’s no longer considered a hot button issue because scientists think the additional cancer risk from the hole was grossly overestimated?
Wiki has a relatively good summary. NOAA has one that’s not quite as good.
Basically, the ozone layer is still depleting, but the rate of increase in depletion is slowing and expected to stop and reverse as an effect of policies banning CFCs. Estimates have ozone concentrations largely recovering late this century.
Note that there never was a permanent “hole” but large seasonal areas of very thin concentration, particularly over the Antarctic and occasionally the Arctic, and the holes got bigger and bigger each year (again, the increase in hole area is slowing).
If it’s out of the news cycle, it’s because it’s kind of boring to hear “Yup, it’s still getting worse in line with our predictions but getting better and still on track to eventually recover thanks to regulations restricting the use of some chemicals. Good thing we stopped using all those CFCs, eh?”.
Thanks for the reply to the OP <!bob. If you’re still reading, then I have some questions also…
(Of course they are for anyone, not just <!bob)
Two weird things I saw in that wiki article which may be of interest:
The nasa animation (of projections to 2040 if we hadn’t done anything) seemed to imply that the ozone is much thicker at the poles, and it’s just that they have been depleted far more. This is totally at odds with everything else in the article, so is the scale wrong or am I misunderstanding it?
I see that there are localised ozone holes. Do you know of any? Googling doesn’t seem to find any at first glance.
I’m not a atmospheric scientist, just interested since my primary school days, so I welcome any expert input here.
From what I remember, ozone formation is itself greatest near the equator and occurs in the summer (ozone formation depending on UV radiation). Wind circulation patterns concentrate ozone towards the poles and are seasonally related. Apparently, the same wind circulation concentrates CFCs towards the poles more and since they don’t break down for decades, the effect is most pronounced where they get concentrated.
Again, that’s my layman’s understanding, and I’d love more input from anybody who has a better understanding.
["]Wiki]([QUOTE=Simple Linctus;15825649) has at least one over Tibet in 2006.
Off the top of my head, I recall one somewhere over the Caribbean or many closer to South America some time in the 90s, but I can’t seem to find a reference right now. Might just be my imagination. Of course, as with the polar holes, it’s not really a hole so much as a massive seasonally related decrease in ozone concentration.
Also, the CFC’s aren’t immediately harmful to ozone, it’s the compounds they break down into that does the damage, and that breakdown only happens in the stratosphere. So you’re only going to see holes where the winds allow CFC’s to stay in an area long enough to decay, or where the winds tend to concentrate pollutants like that.
If you’re curious about CFC’s , there’s a great explanation at http://www.apis.ac.uk/overview/pollutants/overview_CFCs.htm that covers why they were so popular, and why they’re so damaging. It’s the same principle that makes carbon monoxide poisonous to humans while carbon DIoxide (with only one more oxygen atom than CO1) is just another product of respiration.