Upper Ozone Depletion Declining

Silas writes "This SF Chronicle article (and many others) reports that destruction of the upper part of Earth's ozone layer has slowed because of the international effort more than a decade ago to ban ozone-damaging aerosols. More about the study and techniques used is here. We're still a long way away from recovery, but it's a nice example of humans taking an active role in reversing some of the damage we've done."

Comments

Re:Misunderstanding

[TripleA]

Exactly, the ozone layer is still getting thinner.

Re:OR....

[KnightNavro]

You can break out the "no proof" card for global warming, but ozone depletion is pretty well proven. The chemical mechanism is well documented and demonstrated.

Re:Chemistry Question

[Guy Harris]

How does a chlorofluorocarbon molecule, which is heavier than air, affect the Earth's upper atmosphere at the poles? Responses with detailed analyses are appreciated. Please limit your responses to 500 words.

OK, how about one URL (to a page whose word count I'm not going to bother computing) for a page entitled How Can Chlorofluorocarbons (CFCs) Get to the Stratosphere If They're Heavier than Air?.

Different ozone

[hcetSJ]

Ozone created from lightning is different from the ozone in the ozone layer. How? Well, it's not in the ozone layer (nor would it really make its way there). Having ozone at ground level is a problem--particularly for asthma sufferers and the like--so ozone from lightning (or arc welding, for that matter) isn't going to help.

Of course, if one were to arc weld while riding an SR-71...

Re:OR....

[ndinsil]

So how can we prove that it was the meager efforts of us humans that made the change, and not just a natural cycle?

The same way we can prove the "meager" efforts of humans started the problem in the first place. See, for example, this FAQ that lays out the argument. In addition, you should probably have continued your quote of that article, where it says "Sunspot variations only account for 2 to 4 % of the total variation in ozone concentrations."

Re:OR....

[Jazu]

Here's how this works.
Without chlorine:
1. UV ray hits O2. O2 -> O + O
2. 2O + 2O2 -> 2O3
3. 2 UV rays hit 2O3. 2O3 -> 3O2
Steps 1-3 repeat ad infinitum, 3 UV rays are absorbed in each cycle.

With chlorine:
1. 2 UV rays hit 2 CFCs. CFCs lose 2Cl, rest of CFC molecules are inert.
2. UV ray hits O2. O2 -> O + O
3. 2O + 2O2 -> 2O3
4. 2Cl + 2O3 -> 2ClO + 2O
5. 2ClO + 2O -> Cl + O2

Repeat steps 2-5 ad infinitum. 2 extra rays are absorbed in the beginning, but in the repeating reaction, 1/3 fewer UV rays are absorbed if chlorine interferes. Sorry, I don't see the nonsense.