science corner edition 3

the ozone layer and global warming

sunset with clouds wallpaper landscape

Is the ozone layer related to global warming?

When I’m teaching primary schoolers about fossil fuels, I often ask “Do you know what problem all this extra CO2 causes?” and almost every time, a kid will put up their hand and say “It damages the ozone layer?” Now, I can’t blame anyone for getting mixed up with their atmospheric layers, but the ozone layer is not actually something most of us need to be concerned about anymore.

The ozone layer was a huge environmental issue. Emphasis on was. The Montreal Protocol (which committed countries to phasing out ozone-depleting substances) was passed in 1987, several months before I was even born. It was incredibly successful at stopping the use of these chemicals, and the hole in the ozone layer has been slowly repairing itself ever since. Other than slip-slop-slapping, you just don’t need to think about the ozone layer anymore. It’s now just another bit of earth trivia, like the aurora borealis, or oxbow lakes.

It’s a rare and happy thing in this day and age, to be able to put an environmental issue in your mental “don’t worry about it” basket, but you can do that with the ozone layer. (Unless you’re an atmospheric scientist, in which case, keep an eye on it please, and let us know if we should start worrying again, cheers thanks bye).

Now for those of you who are over 30, and are still a little confused about how the new atmospheric apocalypse connects to the old atmospheric apocalypse, short answer: it doesn’t.

Long answer: it doesn’t much.

The ozone layer is the part of the atmosphere with a lot of ozone in it (ozone is just 3 oxygens: O3). This stuff is so good at blocking UV radiation that the UV-B level on Earth is 350 million times lower than in space. Which is good. Certain chemicals such as CFCs (which was commonly used in cooling systems and aerosols) destroy ozone. Which is bad. Ozone mostly doesn’t affect global warming.

Greenhouse gases are things like water vapour, carbon dioxide, methane, and friends, that absorb heat before it can escape back into space. They mostly don’t interact with ozone or UV.

There are only a few small links between ozone and greenhouse. A lot of the CFCs that destroy ozone are also potent greenhouse gases. Like, thousands and thousands of times more powerful than CO2. But their replacements, the more ozone-friendly HFCs are just as bad.

Ozone is a natural greenhouse gas, so the hole in the ozone layer actually cools the earth slightly. But not enough to make a real difference. Getting rid of all the world’s ozone would only counteract about 25% CO2’s warming effect (and kill all life on the planet, so a bit of a pyrrhic victory).

And finally, greenhouse gases actually cool the stratosphere (because of the heat being trapped lower down) which accelerates the ozone depleting-effects of remnant CFCs just a little.

But really, these are very small effects. By and large, the ozone layer is a problem we just don’t need to actively worry about, while global warming is one which we need to very actively worry about.

And if there’s anything we need to learn from the ozone layer, it’s that even these stratospherically large problems can be solved, as long as we move fast enough, big enough, and firmly enough. And hopefully one day, this problem will be in the past as well.

By Tom Lang

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