Ozone Layer Restoration Progressing as Harmful Chemicals Are Eliminated

The Earth's protective layer is expected to recover within four decades, thanks to the phasing out of damaging airborne chemicals. This will help shield humans from the sun's rays and limit global warming, according to a UN-backed scientific panel.

Scientists first identified a hole in the ozone layer in 1985. This layer helps filter out ultraviolet rays from the sun. In 1987, an international agreement was reached to phase out gases that were damaging the ozone layer, including chlorofluorocarbons (CFCs). These gases were used in products such as air conditioners, refrigerators and deodorants.

A 2016 update to the Montreal Protocol also phased out hydrofluorocarbons (HFCs), which do not directly deplete ozone but have a strong climate change effect. Since the chemicals were banned, there has been a "notable recovery" in the upper layer of the stratosphere, according to the report by the Scientific Assessment Panel to the Montreal Protocol. The HFC phase-out has also avoided an estimated 0.5C of warming by 2100.

"Ozone action sets a precedent for climate action," said Professor Petteri Taalas, Secretary-General of the World Meteorological Organization. "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."

If current policies remain in place, the ozone layer is expected to recover to 1980 levels by around 2066 over the Antarctic, by 2045 over the Arctic and by 2040 for the rest of the world. The hole in the ozone layer, which is over the Antarctic, has been shrinking in area and depth since the year 2000, the report said.

Geoengineering proposals to reflect more sunlight back into space in order to reduce global warming could have unintended consequences, including delaying ozone recovery, according to a new report.

Other factors that could delay the recovery include rocket launches and more frequent, intense wildfires exacerbated by climate change. More research is needed to understand how much these and other factors will impact the recovery.

The Montreal Protocol is often cited as a success story for international environmental negotiation, and it is seen as relevant for modern efforts to cut carbon emissions and mitigate climate change, according to the UN.

"The Montreal Protocol has had a profound impact on climate change mitigation," said Meg Seki, executive secretary of the United Nations Environment Programme's Ozone Secretariat, in a press release. "Its success in reducing emissions of ozone-depleting substances has prevented the equivalent of 135 billion tonnes of carbon dioxide from being released into the atmosphere."