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The ozone layer is an important part of the atmosphere. It is a protective shield of the gas ozone against the sun’s UV rays. The rays are otherwise harmful for life on Earth, such as humans, animals and plants. A thinning or hole in the ozone layer is therefore a health risk.

In the 1970s, the ozone layer began to thin as a result of human emissions. Fortunately, the thinning was reduced thanks to a successful global collaboration. Today, the current state of the layer suggests that it is in recovery. If it continues to recover, it could be fully restored in a few decades. However, this naturally depends on a continued and successful collaboration between all nations on Earth. In other words, if everyone follows the rules of no emissions that can harm the ozone layer.

What is the ozone layer?

The ozone layer is a protective layer of ozone that is part of the stratosphere – one of four layers of the atmosphere. The stratosphere is located about 10-15 km from the Earth’s surface. As mentioned, it protects all life on Earth from absorbing too much UV radiation. This is because ozone is a gas with the ability to absorb UV effectively. Furthermore, high levels of UV radiation pose a health risk that can result in various diseases.

The ozone layer can be weakened by other gases that break down the ozone. Particularly freon is highly damaging for the layer. Emissions of this gas used to be released frequently in the past.

Human impact on the ozon layer

In the 1980s, it was discovered that human emissions of mainly CFCs (chlorofluorocarbons) were thinning the ozone layer. Chemical compounds containing chlorine and fluorine are also known as freons. At the time, these substances were commonly used in refrigerators, freezers and as insulation materials. Freons were also used in foam plastic and spray cans. As a result of these emissions, the ozone layer had depleted around 3 % in the 1990s. This was a very serious consequence of human emissions.

Montreal Protocol

The discovery of the damaged ozone layer received a lot of media attention. It was followed by an international commitment to suspend and ban the use of substances that could damage it further. In the 1980s, in 1987 to be precise, this led to an international agreement known as the Montreal Protocol.

The agreement ensured to phase out the products that were damaging the ozone layer worldwide. In other words, it worked to reduce or completely end the use of ozone-depleting gases. As a result, freons were banned. Huge productions were then forced to change and use other substances instead.

Furthermore, scientists have stated that the Montreal Protocol was a success. If it weren’t for the protocol, the ozone layer over Europe, for example, would be half the size of today.

The atmosphere seen from space, including the ozone layer.

A successful collaboration

The protection of the ozone later is a positive example of a successful global cooperation for the environment. Possibly, thanks to the media attention that it recieved in the 1990s. It was considered a high-profile environmental threat, engaging scientists and the public. Kofi Annan, the former Secretary-General of the United Nations, was very content with the outcome. He even said that the cooperation was “perhaps the most successful international agreement to date…”.

Furthermore, the Swedish SMHI says that the ozone layer could be fully restored by 2060. In other words, the protective ozone layer could be at the same level as before industrialisation. As mentioned, this is dependent on countries following and respecting the Montreal Protocol.

Other harmful gases

Unfortunatly, there are more gases than freons that destroy the important layer. One of these gases is called nitrous oxide. Researchers from SLU state that the gas is “one of the worst enemies of the ozone layer”. In fact, it is believed that nitrous oxide could replace freons as the ozone-depleting substance of the century. The gas is released when using artificial fertilisers, amongst other things. As a matter of fact, over 60 % of emissions come from agriculture.

If one looks at Sweden as an example, the emissions of nitrous oxide have been phased down since the 1990s. However, they have increased by 30 % globally. The largest problem is that over half of the world’s population depends on food from crops produced with artifical fertiliser. More so, nitrous oxide has not been regulated by the Montreal Protocol. Making it legal to emit. Therefore, scientist warn the world that nitrous oxide could destroy the ozone layer, much like freons did in the 1980s.

A natural decrease

The thinning or change of the layer also happens naturally. For example, it is common that the ozone layer is thinner over Antarctica. More so, it is thinner in the spring. Which shows that the ozone layer changes with the changing seasons. Furthermore, the layer tends to be affected by both weather and climate.

An example of the above occured in 2020. Back then, there was a major thinning of the ozone later over the Arctic. This change followed a strong vortex, meaning it was caused by the weather. This affected nations in the north to the point that skiers were warned about the increased UV radiation.

Risks of the ozone layer

For humans, a thin ozone layer, or a hole in it, poses serious health risks. Such as skin cancer, damages on the eyes and/or the immune system. Other species on Earth face the same risks. Increased UV radiation can also have a negative impact on agriculture and disrupt importaecosystems both on land and at sea.

UV radiation

UV radiation stands for ultraviolet radiation and is harmful to life on Earth in a larger amount. As mentioned, the ozone layer filters out much of the harmful radiation. Water vapour, oxygen and carbon dioxide also absorb the radiation and thus protect the Earth’s surface.

Ultraviolet radiation is divided into three groups: UVA, UVB and UVC. UVA, for example, is what makes humans sunburnt in the summer. Too much UVA causes ageing of the skin and can lead to skin cancer. Furthermore, too much UVB causes sunburns. Like UVA, too much of this radiation can lead to skin cancer. Finally, UVC radiation does not reach the Earth’s surface as all UVC radiation is absorbed by the atmosphere.

Sources:  The Swedish Environmental Protection Agency, Uppsala UniversitySMHI


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