The ozone layer is on course to recover within four decades in an environmental success story that has also limited global warming, the UN said.
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The reversal of damage to the Earth’s protective layer is progressing well, reflecting the effectiveness of global agreements to phase out harmful chemicals, the UN’s Scientific Assessment Panel of the Montreal Protocol said on Monday.
“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 limit temperature increase.”
Under the current policies, the ozone layer is expected to recover to 1980 levels by 2066 over the Antarctic, by 2045 over the Arctic and by 2040 in the rest of the world.
The assessment is the latest edition of a report that’s published every four years to assess the impact of the 1987 Montreal Protocol, which banned substances that damage the Earth’s protective shield, posing a risk to humans and the environment.
The rare universal agreement, ratified by 197 states and the EU, phased out gases including chlorofluorocarbons (CFCs), which were used in products such as air conditioners, refrigerators and deodorants but were breaking down ozone in the upper atmosphere once released, allowing more harmful UV-B rays to pass through. A 2016 update to the agreement also phased out hydrofluorocarbons (HFCs), which had been used in their place and do not directly deplete ozone but have a strong climate change effect.
There has since been a “notable recovery” in the upper layer of the stratosphere, the report found. The HFC phase-out has also avoided an estimated 0.5C of warming by 2100.
However, proposals to use geoengineering in the atmosphere to reduce global warming by reflecting more sunlight into space could have unintended consequences, including delaying ozone recovery and deepening the Antarctic ozone hole, the report warns.
Other factors including rocket launches and more frequent intense wildfires exacerbated by climate change could also affect the recovery, and more research is needed to understand how much.
Often held up as a success story for international environmental negotiation, the Montreal Protocol has relevance for modern efforts to cut carbon emissions and mitigate climate change, the UN said.
“The impact the Montreal Protocol has had on climate change mitigation cannot be overstressed,” Meg Seki, executive secretary of the United Nations Environment Programme’s Ozone Secretariat in a press release.