The UN says that human efforts to save the ozone layer have produced the expected results and could recover in just decades.
The 1987 international agreement to end the use of harmful chemicals that damaged the layer was a success, says the main assessment.
The ozone layer is the thin part of the Earth’s atmosphere that absorbs most of the ultraviolet radiation from the sun.
Once exhausted, this radiation can reach the surface, causing potential harm to humans and other living things.
Ultraviolet rays can damage DNA and cause sunburn, increasing the long-term risk of problems such as skin cancer.
The ozone layer began to deplete in the 1970s.
Chlorofluorocarbons (CFCs), which were commonly found in aerosol cans, refrigerators, insulation foams and air conditioners, have been blamed for ozone depletion.
A gaping hole in the layer was discovered by scientists in 1985. Only two years later, the Montreal Protocol was signed, in which 46 countries committed to phase out harmful chemicals.
The agreement later became the first UN treaty to receive universal ratification, and almost 99% of the banned substances that deplete the ozone layer have already been phased out.
The Antarctic ozone hole continued to expand until 2000, after which its surface area and depth began to slowly improve.
Now, a joint report by UN, US and EU agencies says the Montreal Protocol is working as expected.
He says that if the current policy is maintained, the ozone layer will be restored to its 1980 values - before the ozone hole appeared – at various points in various places:
2066 over Antarctica, where ozone depletion was worst
2045 over the Arctic
around two decades’ time everywhere else
Although ozone depletion is harmful due to solar radiation, it is not the main cause of climate change.
However, the report suggests that saving the ozone layer has had a positive impact on global warming, as some of the harmful chemicals that have been phased out are powerful greenhouse gases.
This phasing out will prevent up to 1°C of warming by mid-century – compared to a 3% increase in their use a year, the researchers said.
While the report has been hailed as good news – and proof that swift, international action to avert environmental crises can work – it warns that further progress on the ozone layer cannot be guaranteed.
For example, proposals to limit global warming by sending millions of tons of sulfur dioxide into the upper atmosphere – known as aerosol injection into the stratosphere – could drastically reverse the recovery of the ozone layer.