Human actions to preserve the ozone layer have worked as hoped, and it may recover in just decades, the UN says.
A 1987 international agreement to end the use of harmful chemicals that damaged the layer was a success, the main assessment said.
The ozone layer is a thin part of the Earth’s atmosphere that absorbs most of the sun’s ultraviolet radiation.
When it is depleted, this radiation can reach the surface, causing potential harm to humans and other living things.
UV rays can damage DNA and cause sunburn, increasing the long-term risk of problems such as skin cancer.
The ozone layer began to collapse in the 1970s.
Chlorofluorocarbons (CFCs), commonly found in cans, refrigerators, foam insulation and air conditioners, have been blamed for depleting the ozone layer.
A gaping hole in the layer was discovered by scientists in 1985. Only two years later, the Montreal Protocol was signed, under which 46 countries promised to phase out harmful chemicals.
This agreement later became the first UN treaty to receive universal ratification, and almost 99% of banned ozone-depleting substances have now been phased out .
The Antarctic ozone hole continued to expand until 2000, after which its area and depth began to slowly increase.
Now, a report jointly prepared by UN agencies, the US and the EU says that the Montreal Protocol is working as hoped.
It states that, if current policies are maintained, the ozone layer will be restored to the values of the 1980s – before the appearance of the ozone hole – at different points and in different places:
- 2066 over the Antarctic, where the destruction of the ozone layer was the greatest
- 2045 over the Arctic
- about two decades later everywhere
Although the destruction of the ozone layer is harmful due to solar radiation, it is not the main cause of climate change .
But preserving the ozone layer has had a positive effect on global warming, the report says, because some of the harmful chemicals that have been phased out are powerful greenhouse gases.
This phase-out would prevent warming of 1C by mid-century – compared to their use of 3% per year, the scientists found.
While the report was hailed as good news – and proof that swift international action to avert environmental crises can work – it warns that continued progress on the ozone layer is not guaranteed.
For example, proposals to limit global warming by sending millions of tons of sulfur dioxide into the upper atmosphere are known as injection of stratospheric aerosol – can radically reverse the process of restoring the ozone layer.
