Stratospheric ozone depletion, one of the nine planetary boundaries, is, fortunately, one boundary that we are still within a relatively safe zone “of linear behaviour for global ozone loss“.
In the late 1970s, scientists discovered a huge hole in the ozone layer over Antarctica. This hole – a potential earth-systems tipping point – was caused by human activities, slowly destroying the ozone layer that protects us from the sun’s harmful UV radiation. Over time, we have learned more about what causes ozone depletion, and we have taken action to reduce our emissions of ozone-depleting chemicals. Thanks to these efforts, the ozone hole’s size has gradually decreased.
What is ozone?
Before we dive into the hole, it’s important to understand what ozone (O3) is.
Simply put, it is a gas. Like CO2 and other GHG it can’t be seen with the naked eye – but has a familiar metallic odour. It’s very reactive, which means it acts on other materials easily. For example, when it comes into contact with rubber near the Earth’s surface, it causes the rubber to degrade and crack. Just imagine what it’s doing to our skin!
Just as ozone regulates temperature fluctuations in the Earth’s atmosphere, the depletion of this layer has a domino effect on our climate and the changes we have experienced in recent years.
Additionally, plant life is harmed by ozone and human lung tissues; however, this harm can be negated because ozone also has positive effects. Ozone, when collected in the ozone layer high above weather systems in our atmosphere, absorbs harmful components of sunlight known as UV-B radiation. The layer offers protection against UV-B for all living creatures below.
What is the ozone hole?
The ozone “hole” is not a hole but rather a large area of depleted ozone in the stratosphere over Antarctica. It’s been better described as a threadbare blanket.
Regardless of the descriptor that sparks our imagination into action, the “ozone hole” is caused by human activities, resulting in increased UV radiation reaching the Earth’s surface. This can have harmful effects on ecosystems, food production and human health, including cataracts, weakened immune systems, and skin cancer.
It forms every spring, and it typically reaches its maximum size in October. It’s worth noting that ozone holes have also formed in the Northern Hemisphere’s Arctic region in the past.
How did humanity cause the ozone hole?
Like today’s climate crisis, the ozone hole was caused by human activities, specifically by releasing ozone-depleting chemicals into the atmosphere. These chemicals were used in a variety of applications, including refrigeration, air conditioning, and aerosol propellants. Over time, the release of these chemicals has caused a large hole to form in the ozone layer over Antarctica. The size of the hole varies from year to year, but it typically reaches its maximum size in October.
Other toxic and hazardous chemicals such as chlorofluorocarbons, chloroform, and other bromine-containing emissions continue to destroy ozone molecules in the stratosphere. The greenhouse gases we produce have a large effect on the harm to the ozone layer.
These chemicals increase in the atmosphere because we allow them to; through our reliance on fossil fuels, we could see the conversation about the ozone hole returning to the zeitgeist.
Henri Rousseau’s The Dream (1910) famous painting. Original from Wikimedia Commons. Digitally enhanced by rawpixel.When decisive action has a real impact
In 1987, nations around the world came together and signed the Montreal Protocol, which banned the production and use of ozone-depleting chemicals. As a result, the size of the ozone hole has gradually decreased. The Montreal Protocol, the UN says, is “the only UN agreement ever” to be ratified by “every country on Earth – all 198 UN Member States.”
While we have made progress in reducing ozone-depleting emissions, we must continue our efforts if we want to fully repair the ozone hole. It will take many years for the ozone layer to recover, and we must continue to reduce our emissions of ozone-depleting chemicals if we want to protect ourselves and future generations from the harmful effects of UV radiation.
What can I do to help?
While the Montreal Protocol helped limit the production and use of ozone-depleting chemicals, it hasn’t stopped those chemicals from remaining in the atmosphere. Like all other tipping points, there are wider considerations at play.
By reducing our reliance on fossil fuels, which is contributing to global heating, we can continue to have a positive impact on all of Earth’s fragile systems.
We can also learn from the Montreal Protocol. It is only through collective action and will that we can successfully tackle the greatest threats to humanity.
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