Recovery of the Ozone Layer: an example in tackling Climate Change

How global cooperation saved the ozone layer and inspires the fight against climate change

Sunlight is indispensable for the development of plants and animals, but in excess, it ceases to be beneficial and becomes harmful. This is where the importance of the ozone layer comes in, a layer of gases, invisible and fragile, but essential for human life on earth.

To spread awareness on the subject, the United Nations General Assembly determined, in 1994, the International Day for the Preservation of the Ozone Layer. The date was chosen in celebration of the signing of the Montreal Protocol, established on September 16, 1987.

This gaseous layer is composed of oxygen atoms. However, unlike oxygen (O2), which we always hear about, ozone is a molecule that contains three oxygen atoms (O3). This modification in the structure makes the performance of the two molecules different.

While oxygen gas is used for respiration, combustion and oxidation, ozone forms a shield against ultraviolet (UV) radiation. And this is what makes it so important for controlling the greenhouse effect.

Want to know more about this subject? Read on to better understand how the ozone layer plays a role in maintaining life on Earth.

 

The Earth’s layers and ozone concentration

The Earth’s atmosphere is composed of several layers, among them, the closest to us are the troposphere and the stratosphere. The troposphere is approximately 9km high, it is where all human activity takes place. The stratosphere, which is between 10 and 51km high, is where ozone accumulates.

The amount of ozone in the air is measured in Dobson Unit (UD), – the number of molecules needed to create a layer 0.01 mm thick at 0°C and 1 atm. The average global concentration of this gas is around 300 UD. However, this amount varies, depending on the location.

In the Antarctic region, for example, the concentration is 220 UD, or less, after all, it is the location of the so-called ‘hole’ in the ozone layer. In reality, a hole is not formed per se, but the layer in this area has become thinner with the degradation of ozone molecules.

The degradation of ozone molecules happens through the so-called ozone-depleting substances (“ODS”). One of these substances is the well-known CFC (chlorofluorocarbon), widely used in the past in refrigeration and aerosols.

SDOs are substances that release chlorine and bromine when they come into contact with UV radiation. And chlorine and bromine, when in contact with the ozone molecule, destroy it. One chlorine atom can destroy more than 100,000 ozone molecules.

In other words, the reduction in the width of the ozone layer occurs much faster than its formation. Mainly because the accumulation of ozone occurs naturally, and the emission of SDOs occurs due to anthropogenic interference.

The risks of ozone depletion

The depletion of the ozone layer directly affects human life. Therefore, the use of this gas in the atmosphere is essential to prevent ultraviolet rays from reaching us, especially UVB-type rays.

But what is the difference between them? Ultraviolet A, or UVA, has a longer wavelength, and is associated with tanning and light burns. UVB, on the other hand, is capable of causing intense burns and, consequently, skin cancer.

In other words, in relation to human health, the ozone layer acts mainly to reduce the risk of skin cancer and the development of cataracts. 

But its degradation has an effect on everything.

Food security, for example, would be affected. With greater UVB irradiation, the cycle of plants is affected, which can reduce development and productivity. The change in water temperature interferes with marine life and biogeochemical cycles.

The entry of greater radiation modifies the performance of fauna and flora in the provision of their ecosystem services. In addition, it alters decomposition rates; photosynthesis; nutrient cycling and much more, ecologically affecting all spheres.

 

Policies for the Preservation of the Ozone Layer

With everything we have discussed above, we realize the importance of creating protocols and measures that encourage the protection of the ozone layer.

In the 1970s, scientists realized the urgency of the matter when they observed that the layer was being threatened and there was a risk of a hole forming. And in 1985, the answer they were looking for came with the Vienna Convention for the Protection of the Ozone Layer.

The Convention sought to develop mechanisms of action to protect the ozone layer. It was signed by 28 countries and led to the drafting of the Montreal Protocol on September 16, 1987.

The Montreal Protocol seeks to control the production and use of SDOs, with the ultimate goal of completely extinguishing their use. Currently, Brazil and all 196 countries and territories recognized by the United Nations are part of this commitment.

In the first ‘WMO Ozone and UV Bulletin’, the World Meteorological Organization showed that the production and consumption of SDOs reduced by 99%. This achievement is due to the development of the Montreal Protocol and the accession of countries.

For this reason, it is important to celebrate the protection and preservation of the ozone layer and other natural resources. With the joint action of the public and private sectors in climate change mitigation actions, we can work for a better future.

References

Geneva Environment Network. (2024). International Day for the Preservation of the Ozone Layer.  https://www.genevaenvironmentnetwork.org/resources/updates/international-day-for-the-preservation-of-the-ozone-layer/

NASA Ozone Watch. (2024). What is a Dobson Unit? Recuperado de https://ozonewatch.gsfc.nasa.gov/facts/dobson_SH.html

UCAR Center for Science Education. Ozone. https://scied.ucar.edu/learning-zone/air-quality/ozone

United Nations Environment Programme (UNEP). Ozone Day: Ozone & life — 35 years of ozone-layer protection. https://ozone.unep.org/ozone-day/ozone-life-35-years-ozone-layer-protection

United Nations. International Day for the Preservation of the Ozone Layer. https://www.un.org/en/observances/ozone-day

United States Environmental Protection Agency (EPA). (2025). Basic Ozone Layer Science. https://www.epa.gov/ozone-layer-protection/basic-ozone-layer-science United States Environmental Protection Agency (EPA). (2025). Health and Environmental Effects of Ozone Layer Depletion. https://www.epa.gov/ozone-layer-protection/health-and-environmental-effects-ozone-layer-depletion