Every year on 16 September, the world celebrates the International Day for the Preservation of the Ozone Layer – a day recognized by the United Nations. This day reminds us of the importance of the ozone layer and how we can protect it.

However, we may ask: what does the ozone layer have to do with trees?

The answer is simple: the ozone layer helps protect all life on Mother Earth, including trees and forests. At the same time, another type of ozone, found closer to the ground, can harm trees.

Illustration of Ozones

Ozone is a gas made from three oxygen atoms. Most of the Earth’s ozone is found high in the atmosphere, in a region called the stratosphere. This is the ozone layer.

The ozone layer acts like a natural shield around our planet. It absorbs much of the Sun’s harmful ultraviolet (UV-B) radiation before it reaches the Earth’s surface.

As we already know, plants need sunlight to grow, but too much UV-B radiation can damage plants and affect their growth and development. Therefore, a healthy ozone layer helps create the conditions that trees, plants, animals, and we as human beings need to live.

Now, let’s consider how we as humans have damaged the ozone layer.

During the 20th century, humans developed and widely used chemicals called chlorofluorocarbons (CFCs) that were useful in products such as refrigerators, air conditioners, aerosol sprays, and fire-extinguishing systems. Other ozone-damaging substances included halons, methyl bromide, carbon tetrachloride and methyl chloroform.

These chemicals could travel slowly into the upper atmosphere. There, sunlight could break them apart and release chlorine or bromine. These elements then destroy ozone molecules. In fact, one chlorine atom can destroy more than 100,000 ozone molecules!

Even today, old equipment can contain ozone-depleting substances. If these chemicals are released when equipment is repaired or thrown away, they can still harm the ozone layer. Proper recovery and disposal are therefore important.

Ozone and trees: a second connection

There is another important part of the story.

Ozone can also exist near the ground, where it becomes an air pollutant. This is called “ground-level ozone”, and it is not the same as the protective ozone layer high above us.

Ground-level ozone can form when pollution from vehicles, factories, and other sources reacts in sunlight.

This ozone can enter the leaves of trees and other plants. High levels can reduce photosynthesis, the process plants use to turn sunlight into energy, and it can slow plant growth and make some trees more vulnerable to insects, disease, and other environmental stresses.

This means that ozone can affect trees in two different ways: the ozone layer protects them from excessive UV radiation, while ground-level ozone pollution can damage them directly.

Considering all of this, what can we do to preserve the “good” ozone, and how can we prevent creating a “bad” ozone?

Well, there is good news! The world has already shown that environmental problems can be addressed when we work together.

In 1987, countries agreed to the Montreal Protocol, an international agreement to reduce and eventually eliminate many ozone-depleting substances. Since then, levels of most of these substances in the atmosphere have fallen significantly, and the ozone layer is on a path towards recovery. 

We can support this progress by using energy responsibly, reducing pollution, maintaining cooling equipment properly, and making sure old refrigerators and air conditioners are disposed of correctly.

And of course, we can also protect and plant more trees! As we explored many times in the past, healthy forests support biodiversity, improve local environments, store carbon, and provide food and shelter for countless species.

This reminds us of the interconnectedness between people, trees, the atmosphere, and the wider natural world, which we cannot even see with our eyes! Let’s take some time to consider how our actions have impacts far beyond what we can imagine. Knowing this, we can start to act with a sense of universal responsibility.

When we protect the ozone layer, we help protect life on Earth. When we reduce pollution and protect trees, we help save our planet for future generations.

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References:

Images:
Title image of clouds: https://www.pexels.com/photo/clouds-in-a-blue-sky-17807335/
Image of ozone layer: https://www.nesdis.noaa.gov/news/unlocking-the-secrets-of-the-stratosphere-the-jpss-ozone-mapping-and-profiler-suite-omps
Ozone-damaging material: https://i.ytimg.com/vi/gE506hhowJI/maxresdefault.jpg

Sources of information:
https://www.un.org/en/observances/ozone-day
https://ozone.unep.org/treaties/montreal-protocol
https://ozone.unep.org/facts-and-figures-ozone-protection
https://www.epa.gov/ground-level-ozone-pollution/ecosystem-effects-ozone-pollution
https://www.epa.gov/ozone-layer-protection/frequently-asked-questions-about-ozone-layer