Ozone layer

Hi everyone,

What even is ozone? And the ozone layer? Where does the hole in the ozone layer come from and what does it mean? Is it dangerous? What can be done?

Often the ozone-talk can be complicated and confusing, keeping an overview is hard and understanding all the problems always difficult. Let us break it down a bit for you:

What is the ozone layer?

We'll start with the basics: The ozone layer is part of the stratosphere, which is the second layer of the Earth's atmosphere, between 10 and 50 km above the Earth's surface and made up of protective gases. One of these protective gases is ozone. There is not much ozone in the atmosphere, only 0.3 molecule of ozone per 1 million molecules of air. This is because ozone is chemically unstable and only forms when ultra violet radiation (UV light) hits oxygen and breaks the bonds between the atoms. It fact it is so unstable that even when it has formed, it breaks down again relatively quickly. This leads to ozone turning back into "normal" oxygen (two oxygen atoms, O2) and then reforming back into ozone (three oxygen atoms O3) in a continuous cycle. The reason why ozone doesn't naturally form closer to the Earth's surface is that there isn't enough UV light here to break the very stabile bond between within normal oxygen molecules. Because of this even in the ozone layer, ozone is still quite rare compared to other gases: only around 10 ozone molecules per million.

What does it do?

Despite ozone being so rare, it is indispensable. This is because the ozone layer acts a bit like a shield from the sun's UV radiation. This radiation causes sunburns and skin irritation, but also cancers and premature aging. But remember how ozone needs the UV radiation in order to form? It actually absorbs the UV radiation in the process of forming new chemical bonds. And because the ozone is constantly reforming this happens continuously, allowing the ozone layer to absorb up to 99% of the UV radiation from the sun. This allows for life to thrive on the Earth's surface, although don't forget to use sunscreen, because the ozone layer doesn't stop all of the UV radiation.

Is it in danger?

We've all heard of ozone holes before. But what does that actually mean? From the 1970s onwards, scientists have been worried about the human effects on the ozone layer, especially considering how important it is. More specifically, they are worried about chlorofluorocarbons (CFCs) which are chemicals found in many plastic products. For a while, they seemed like a miracle material as they are cheap to produce and are neither poisonous nor flammable. However it was soon discovered that they damage the ozone layer if they're emitted into the atmosphere. They mess up the cycle of ozone breaking down and reforming. More specifically: when the ozone breaks down, it becomes oxygen (O2) and the CFCs then form chemical bonds with the oxygen, preventing it from reforming back into ozone (O3). Over time, this means that less and less ozone is able to form. Luckily, since the 1970s many CFCs have been banned around the world because of this. In fact, the ozone layer is the only aspect on the planetary boundary model that we have made positive progress on.

However this doesn't mean that everything's completely fine. There is currently a huge ozone hole over Antarctica, which is twice the size of mainland Antarctica! Now an ozone hole isn't an actual hole in the ozone layer, it's just means that the ozone layer is a lot thinner in that area. But it is still quite dangerous, especially in concerns of sunburns and skin cancers. The 1987 Montreal Protocol on Substances that Deplete the Ozone Layer has improved the condition of the ozone layer a lot, but the problem is not entirely solved. Some natural disasters are capable of changing the ozone layer as well. For example, the Hunga Tonga-Hunga Ha'apai volcano eruption in 2022 reduced the ozone layer by up to 7% in some areas of the Southern Hemisphere, because it released 35 million tons of water vapour into the atmosphere, which then reacted with the ozone.

We hope you found this post about the ozone layer interesting, and will be back with a new post next Saturday.

Your Green World Blog Team💚

Sources:

https://www.sciencedaily.com/releases/2023/11/231121175239.htm

https://www.sciencedaily.com/releases/2023/11/231120170922.htm

https://education.nationalgeographic.org/resource/ozone-layer/

Image:

“Snapshot of the Antarctic Ozone Hole 2010”, owned by NASA Goddard Space Flight Center (on flickr.com), is licensed under CC BY 2.0.

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