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

In the 1970s, the ozone layer began to get thinner due to human emissions. Fortunately, a successful global collaboration managed to reduce the thinning. Today, the layer is in recovery. It could be fully restored in a few decades if it continues to recover. However, this depends on a continued and successful collaboration between all nations on Earth. In other words, all countries must follow the restrictions on releasing harmful emissions.

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 about 10-15 km from the Earth’s surface. As mentioned, it protects all life on Earth from UV radiation since ozone can absorb UV effectively. Some gases, like freon, can damage the ozone layer. Emissions of this gas used to be released frequently in the past.

Human impact on the ozone layer

In the 1980s, scientists discovered that human emissions of mainly CFCs (chlorofluorocarbons) were thinning the layer. Chemical compounds with chlorine and fluorine are also known as freons. At the time, it was common to use the substances 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 by around 3 % in the 1990s.

Montreal Protocol

The discovery of the damaged ozone layer received a lot of media attention. Public awareness put pressure on politicians and eventually led to an international commitment that banned the use of ozone-damaging emissions. The agreement is called the Montreal Protocol.

The Montreal Protocol ensured that nations phased out the use of products that could damage the ozone layer. In other words, it worked to reduce or stop the use of ozone-depleting gases. As a result, freons got banned. Furthermore, scientists often highlight the Montreal Protocol as a global success. If it weren’t for the protocol, the ozone layer over Europe, for example, would be half the size of today.

A successful collaboration

Protecting the ozone layer is a positive example of successful global cooperation for the environment. Possibly, thanks to the media attention that it received in the 1990s. It got 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 said that the cooperation was “perhaps the most successful international agreement to date…”.

If the development continues, the layer has the potential of being restored by 2060. If so, it would look like it did before industrialization. As mentioned above, this possibility depends on countries following and respecting the Montreal Protocol.

Other harmful gases

Unfortunately, there are more gases than freons that destroy the 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”. They also say that nitrous oxide could replace freons as the ozone-depleting substance of the century. The gas gets released when using artificial fertilizers, amongst other things. Over 60 % of emissions come from agriculture.

If one looks at Sweden as an example, nitrous oxide emissions have been phased down since the 1990s. However, they have increased by 30 % globally. The most significant problem is that over half of the world’s population depends on food from crops produced with artificial fertilizer. More so, the Montreal Protocol does not include nitrous oxide. Hence, these emissions are still legal. Therefore, scientists warn the world that nitrous oxide could destroy the ozone layer, much as freons did in the 1980s.

A natural decrease

The thinning or change of the layer also happens naturally. For example, the ozone layer is thinner over areas like Antarctica. More so, it is thinner in the spring. The difference shows that the ozone layer changes with the seasons. Furthermore, it gets affected by both weather and climate.

An example of the above occurred in 2020 when the layer got thinner over the Arctic. The change was caused by a strong vortex, meaning the weather caused it. Nations in the north got warned about the situation, as there was an increase in UV radiation.

Risks of a thinner ozone layer

A thin ozone layer, or a hole in it, poses serious health risks for humans. Such as skin cancer and damage to the eyes and the immune system. Other species on Earth face the same risks. Increased UV radiation can also harm agriculture and disrupt important ecosystems on land and at sea.

UV radiation

UV radiation stands for ultraviolet radiation and is harmful to life on Earth. 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 gets divided into three groups: UVA, UVB and UVC. It is UVA and UVB that are dangerous to humans. These kinds cause sunburns and skin ageing. More so, too much radiation can lead to skin cancer. Finally, UVC radiation does not reach the Earth’s surface as all UVC radiation gets absorbed by the atmosphere.

Sources: The Swedish Environmental Protection Agency, Uppsala University, SMHI