The ozone layer acts as a protective barrier between ultraviolet rays emitted by the Sun and the Earth. This is an essential element for the proper functioning of the planet's various ecosystems. However, it has been damaged by human actions over the decades, causing it to become depleted until a hole forms which becomes problematic!

Ozon layer

Also known as the “ozonosphere,” it protects the people and ecosystems of planet Earth. an important role in protecting has . It got this name because it is characterized by a much higher concentration of this gas compared to other parts of the atmosphere. It is one of the four layers that make up our atmosphere: troposphere (10 km), ozonosphere or stratosphere (20 to 50 km), mesosphere (100 km), thermosphere (600 km altitude) and exosphere.

It is an indispensable element for the proper structure of the Earth's atmosphere and for life on Earth. In fact, it is emitted by the Sun that can cause damage. absorbs most ultraviolet rays (UV-B) thing . These harmful rays can be extremely harmful on a biological level and are considered highly mutagenic (altering the DNA of plants, animals and insects).

In the atmosphere and stratosphere ozone concentration variability protects . Many factors such as temperature, geographical area or atmospheric and meteorological conditions must be taken into account. Some substances found in the emissions of volcanic gases and ashes are also ozone It may be responsible for certain changes in the concentration of .

These different natural factors not only cause changes in the amount of gas in the atmosphere, but also the observed level of degradation and in the protective barrier It should be noted that it is not responsible for the formation of holes.

Hole in the ozone layer

In fact, it is not natural events as mentioned before that cause a hole in the ozone layer.
In 1974, Mario Molina and Frank Sherwood Rowland, two American scientists and chemists, raised the possibility that the ozone layer might be in the process of depletion. This will turn into a hole over the years of thinning They quickly identified the source. The reason is more CFC It was identified as ChloroFluoroCarbons, known as ChloroFluoroCarbons.

CFCs were introduced in 1938 and popularized in the 1970s by a variety of equipment such as refrigerators, aerosols, air conditioners, and fire extinguishers. are artificial chemicals . These were mainly aimed at industry and consumers.

These substances are why the ozone layer has been closely monitored since the early 1980s. Their use not only caused minor damage to it, but also caused a huge hole to form on Antarctica. This hole is located at the South Pole and when discovered by scientists it was almost as large as North America (about 25 million km2).
Its size can be calculated through satellites equipped with special cameras that can detect ultraviolet light and therefore ultraviolet rays. These satellites were therefore able to determine its location and thus evaluate fluctuations and evolutions (positive or negative). For example, thanks to this technology, it was possible to determine that the phenomenon of ozone layer degradation increases, especially in the period from August to November.

The hole in the ozone layer is caused by man-made and today greenhouse gases (carbon dioxide) It is the second largest negative impact of humans on the environment and climate, after the increase of ) .

Consequences for humans and biodiversity

People who are inevitably exposed to excessive UV rays that are not filtered by the ozone layer face new risks. Among the direct and most serious consequences, different skin cancer
There is a risk of developing types of . External mucous membranes may also be damaged, for example the eyes may be affected and risks of cataracts emerge It may come out. The immune system is also strained and tends to weaken due to exposure to UV radiation. These different health risks for humans are also the same for animals exposed to UV-B for long periods of time.

This hole is also a concern for the well-being of the environment and our planet, as our entire ecosystem can suffer from exposure to UV rays for too long and at too high a rate.
Firstly, the growth of all organisms is affected because plants no longer respond normally and have to adapt to a new environment leads to a decrease in agricultural productivity. Also, if the hole in the ozone layer is not rapidly reabsorbed the extinction of certain plant species
We must also take into account that it may lead to Moreover, plants and ecosystems are intrinsically linked, the extinction of certain species due to UV-B radiation can create a butterfly effect and lead to the extinction of other species.

plants oxygen Let's not forget that it is an important source of production, so if many plant species disappear, this will lead to a great risk for humanity and the environment. The aquatic ecosystem is also affected.
Finally, one of the main and inevitable ecological consequences in such conditions is is global warming .

Montreal Protocol

The Montreal Protocol is an international agreement signed and entered into force on 16 September 1987. When signed, 24 countries and the European Economic Community agreed on what the hole in the ozone layer represents. They agreed on some measures to combat the climate emergency.

The first and fundamental decision adopted by this protocol is CFCs (chlorofluorocarbons), HCFCs (hydrochlorofluorocarbons), methyl bromide and is a very strict restriction on other halons. Indeed, member states of the Montreal Protocol must comply with certain basic rules of this agreement to limit the use of these unregulated products. To achieve this, member countries of these substances or prohibit all use, manufacture, import or export of products that use them as an ingredient. Imports and exports from or to non-member states of the protocol are also prohibited.
Only basic uses of these products may be permitted.
The ban on these products has been gradually completed, starting from the most developed countries. Chlorofluorocarbons (CFCs) were officially banned worldwide in 2010, and checks are carried out annually through reports provided to the Protocol Secretariat to verify imports, exports and consumption by each member country. This protocol has had a global impact and is the first international environmental protocol established. in 2009” universal approval
It was the first treaty to reach ”. The number of countries committed to taking action to repair the ozone layer is now 197.

To monitor the presence of these substances fixed or portable freon detectors There are tools such as .

Repairing the hole in the ozone layer

Repairing this hole is not a quick and easy task. It will take many years, even decades, to reach a full conclusion.
Of course, thanks to the Montreal Protocol and recent environmental awareness, repairing the hole in the ozone layer is on the right track, but we must continue to redouble our efforts to achieve a rapid result.
According to many studies, the situation should return to normal in the northern hemisphere by 2030, in the southern hemisphere by about 2050, and in the polar regions by 2060. To do this, it is of course necessary to sustain efforts and continue to take adequate measures.

If it takes this long for the tide to change, it is because the vast majority of substances produced by human activities (CFCs, HCFCs, methyl bromide, etc.) remain in the stratosphere for many years.

The UN said in a statement that "the ozone layer in some parts of the stratosphere has improved by 1 to 3 percent per decade since 2020." When the hole was discovered in the 1970s, 10 percent of its surface had already disappeared.

A fragile stability

Ozone hole restoration, even if on track, still fluctuates and may stagnate or even decline .
In 2022, scientists report that the hole in the stratosphere is the largest observed since 2015 and has continued to increase over the last 3 years. Recent surveys measured 26.4 million square kilometers.
Therefore, this depletion continues to be monitored very closely, even though scientists believe it should not be considered alarming at this time.