The ozone layer is a gaseous layer around the Earth’s stratosphere (the second layer of the Earth’s atmosphere), which contains the highest concentration of ozone (O3) in the planet’s atmosphere. It protects the Earth from aggressive ultraviolet radiation linked to skin cancer, cataracts, compromised immune systems and damage to agricultural land.

The 1987 Montreal Protocol was tasked with protecting the depleting ozone layer. The landmark protocol was established to ban the production and consumption of chemicals that contribute to the depletion of the ozone layer, as well as the overall protection of the ozone layer.  

Protection of the ozone layer came after three British Antarctic Survey scientists first announced the discovery of a hole in the ozone layer in May 1985.  

Chemicals such as chlorofluorocarbons (CFCs), chlorinated solvents and hydrochlorofluorocarbons (HCFs) found in aerosols and refrigerators were controlled under the Montreal Protocol, as they not only deplete the ozone layer, but are also potent greenhouse gases.

Findings of the progress of the ozone layer come from a study by the World Meteorological Organisation, United Nations Environment Programme (Unep), US Department of Commerce, National Aeronautics and Space Administration and the European Commission.

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Titled Scientific Assessment of Ozone Depletion: 2022, the study found the ozone layer is on track to recover from depletion. The ozone layer’s top columns are expected to return to 1980 values (before the ozone hole) around 2040. In Antarctica, progress has been delayed and levels are expected to recover to 1980 levels in 2066, and around 2045 in the Arctic.  

“That ozone recovery is on track according to the latest quadrennial report is fantastic news. The impact the Montreal Protocol has had on climate change mitigation cannot be overstressed. Over the last 35 years, the protocol has become a true champion for the environment,” said Meg Seki, the executive secretary of the Unep Ozone Secretariat.  

In addition to recovering the ozone layer, the Kigali Amendment to the Montreal Protocol has also been able to eliminate about 99% of banned ozone-depleting substances.

However, there are still threats to the ozone layer. These include increases in methane, nitrous oxide and carbon dioxide concentrations, the effect of the climate crisis in tropical regions, raging wildfires and volcanic eruptions.

The panel that conducted the study also raised concerns about the climate crisis-combating technology known as Stratospheric Aerosol Injection (SAI), which adds aerosols into the stratosphere. Scientists have for the first time cautioned against using SAI as it increases sunlight reflection and can unintentionally affect stratospheric temperatures and ozone production.  

“Ozone action sets a precedent for climate action. Our success in phasing out ozone-eating chemicals shows us what can and must be done — as a matter of urgency — to transition away from fossil fuels, reduce greenhouse gases and so limit temperature increase,” said the World Meteorological Organization’s secretary-general, Petteri Taalas. DM/OBP