eli5, how did the ozone layer patch itself?


eli5, how did the ozone layer patch itself?

In: 75

Ozone is naturally produced by things like lightning. By not actively destroying it, it was able to regenerate.

Ozone is generated in the upper atmosphere through the interaction of cosmic radiation with oxygen. So as soon as we stopped releasing CFC and other ozone destroying gasses the remaining gas was used up through chemical reactions and the ozone regenerated.

The upper atmosphere is getting hit with a lot of high energy rays from the Sun. These rays hit O2 molecules and O3 molecules, ripping them apart and combining them together again. This is how the ozone layer protects the surface from those rays.

But it also has some equilibrium ratio of ozone:oxygen. So even if it somehow gets disrupted by human activity, then as long as we stop that activity, it will slowly go back to that equilibrium. And because all modern life evolved to live within that equilibrium, that is good.

There are natural processes constantly creating ozone, and there are natural processes that destroy ozone. The two rates balance each other out and result in a very important “layer” of ozone in the atmosphere.

When the hole happened, it was because humans were releasing chemicals that also destroyed ozone, so now it was being destroyed faster than it was being produced, leading to depletion of ozone in the air and “holes” in the protective layer.

Then, humans noticed the holes, figured out they were being caused by human activity, and collectively agreed to laws and regulations such as [The Montreal Protocol](https://en.wikipedia.org/wiki/Montreal_Protocol) to limit the ozone-destroying chemicals we had been using.

This is a great example of how humans CAN in fact co-operate at a global scale and change enough to alter whether we are destroying or mending world-atmosphere sized issues. Ironically, “the ozone hole was supposedly bad too but now it’s a non issue” is used by climate-change deniers who don’t realize that the ozone hole *WAS a big deal until we actively fixed it* by passing a bunch of regulations and stopped emitting the chemicals that were causing the problem.

Ozone is a naturally occurring compound and is in a cycle with oxygen called the ozone-oxygen cycle. This cycle is drive by the sun which turns oxygen into ozone and vice versa. Currently it’s not in equilibrium meaning there is more oxygen being turned into ozone than ozone turning into oxygen.
The entire reason the ozone was depleting was due to CFCs which REGULATIONS by governments eliminated. No more CFC meant the ozone could start rebuilding.