The hole in the Earth's ozone layer is expected to fully heal within 50 years, climate change experts predict in a new UN report.
A fragile shield of gas around the planet, the ozone layer protects animal and plant life from the powerful ultraviolet (UV) rays of the sun. When the ozone layer is weakened, more UV rays can get through, making humans more prone to skin cancer, cataracts and other diseases.
Environment and natural resources
Scientists discovered huge damage to the layer in the 1980s and identified chlorofluorocarbons, or CFCs, as the main culprit.
CFCs used to be common in refrigerators, aerosol cans and dry-cleaning chemicals, but they were banned globally under the Montreal Protocol of 1987.
The decline in CFCs in our atmosphere as a result of those measures now mean the ozone layer is expected to have fully recovered sometime in the 2060s, according to the report by the UN Environment Programme, World Meteorological Organization, European Commission and other bodies.
In parts of the stratosphere, where most of the ozone is found, the layer has recovered at a rate of 1-3% per decade since 2000, the authors state.
The amount of ozone in the stratosphere varies naturally throughout the year, with zone depletion most pronounced in polar regions, resulting in so-called ozone holes.
At the recovery rates projected by the UN report, the northern hemisphere and mid-latitude ozone is scheduled to heal completely by the 2030s, followed by the southern hemisphere in the 2050s and polar regions by 2060.
Erik Solheim, head of UN Environment, described the Montreal Protocol as "one of the most successful multilateral agreements in history."
NASA's Paul Newman, joint chairman of the report, said that two thirds of the ozone would have been destroyed by 2065 had the measures not been implemented.
Back in May, however, scientists at the US National Oceanic and Atmospheric Administration (NOAA) reported a sharp rise in CFCs from an unknown source.
"We're raising a flag to the global community to say, 'This is what's going on, and it is taking us away from timely recovery of the ozone layer,'" NOAA scientist Stephen Montzka, the study's lead author, said in a statement at the time.
Montzka said if the source of the new emissions could be identified and contained, the damage to the ozone should be minor.
However, if it could not be remedied the already slow recovery of the atmosphere's protective layer could be further delayed.