World Ozone Day: A look at the ozone layer’s road to recovery

Team Udayavani, Sep 16, 2023, 10:51 AM IST

The ozone layer that was once under threat has been mending itself ever since the chemicals causing its destruction were phased out. This natural barrier, situated 15 to 30 kilometers above the Earth, shields us from harmful ultraviolet radiation from the sun and has almost recovered after efforts spanning close to 40 years.

Environmentalists have been concerned about the formation of the Ozone hole over the Earth’s poles. Ozone-depleting substances (ODS) — chemicals like chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) — were identified as the chief culprits behind the phenomena. These chemicals were widely used in many areas – cooling, electronics, firefighting, aerosols, medicine, and as fumigants in agriculture.

Normally, the creation of Ozone and its destruction in the ozone layer is a cyclic process. The ozone breaks down while blocking the harmful UV radiation and recombines. This perennial process breaks down, when ODS released into the atmosphere reaches the ozone layer. ODS  interact with the ozone, permanently breaking down ozone molecules and causing the layer to thin out. The consequences are severe.

The ozone hole leads to an increase in harmful ultraviolet (UV) radiation reaching the Earth’s surface. This heightened UV exposure poses significant health risks, including higher rates of skin cancer, cataracts, and weakened immune systems. Furthermore, it can have detrimental effects on ecosystems, damaging crops, plants, and marine life. This environmental imbalance underscores the critical need to phase out ODS and protect the delicate ozone layer.

Why is the Southern Hemisphere More Affected?

The Southern Hemisphere, particularly Antarctica, bears the brunt of ozone layer depletion. This is due to extremely cold temperatures in the stratosphere. When temperatures plummet below -78°C, polar stratospheric clouds form, making ozone depletion worse.

The Montreal Protocol: A Game-Changing Agreement

Back in 1987, something extraordinary happened, as the world united to sign the Montreal Protocol, a global agreement designed to save the Earth’s ozone layer. This protocol aimed to phase out chemicals like CFCs and HCFCs that were poking a hole in the ozone layer above Antarctica.

Since 1987, there has been impressive progress in reducing the use of ODS worldwide, largely due to the Montreal Protocol’s influence. This protocol has been hailed as one of the most successful environmental agreements in history.

In September 2000, the ozone hole hit its largest extent ever recorded, covering an enormous 28.4 million square kilometers. That’s nearly seven times the size of the European Union! Fast forward to late September 2022, the Antarctic ozone hole stretched across 24.5 million square kilometers, resembling the ones in 2020 and 2021.

The Road to Recovery: What’s Next?

The good news is that the ozone layer is on a path to recovery. Scientists estimate that by the 2060s, the hole in the ozone layer will be no more. However, complete recovery is a challenge due to changes in the atmosphere caused by factors like global warming.

While we’ve made great progress, the journey isn’t over. Some chemicals, like nitrous oxide, known to harm the ozone layer, are still not under the Montreal Protocol’s control. There’s work to be done.

Protecting the ozone layer means safeguarding all life on Earth. Ecosystems, human health, agriculture, and wildlife are all beneficiaries. Without the ozone layer, harmful UVB radiation could cause harm to humans as well as other living organisms on planet Earth.

The Montreal Protocol’s success provides hope and vital lessons for tackling climate change and other global environmental issues. It required innovative measures and global cooperation across various sectors. This approach can serve as a blueprint for addressing future challenges.