The ozone layer, which helps limit Earth’s exposure to harmful ultraviolet (UV) rays from the sun, is on track to recover within four decades.
A new report has confirmed the phasing out of nearly 99% of banned ozone-depleting substances has not only succeeded in a notable recovery of the ozone layer (which lies roughly 15km to 40km above Earth’s surface in the stratosphere), it has also benefited from efforts to mitigate climate change.
According to a report presented by a UN-backed panel of experts at the American Meteorological Society’s annual meeting in Denver in the US on Monday, if current policies remain in place, the ozone layer is expected to recover to 1980 values (before the appearance of the ozone hole) by about 2066 over the Antarctic, by 2045 over the Arctic and by 2040 for the rest of the world.
“Ozone action sets a precedent for climate action. 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,” said Prof Petteri Taalas, secretary-general of the World Meteorological Organization (WMO).
In its latest report, the Scientific Assessment Panel to the Montreal Protocol on Ozone Depleting Substances for the first time also examined the unintended affects on the ozone layer that may occur from the deployment novel technologies such as geoengineering.
The panel highlighted the potential effects on ozone of the intentional addition of aerosols into the stratosphere, known as stratospheric aerosol injection (SAI).
SAI, the WMO explains, has been proposed as a potential method to reduce climate warming by increasing sunlight reflection, but the panel cautions that unintended consequences of SAI “could also affect stratospheric temperatures, circulation and ozone production and destruction rates and transport”.
An additional 2016 agreement to the Montreal Protocol known as the Kigali Amendment, requiring the phase down of production and consumption of some hydrofluorocarbons (typically used for cooling and refrigeration), is estimated to avoid 0.3°C to 0.5°C of warming by 2100, the Scientific Assessment Panel said.
“That ozone recovery is on track according to the latest […] report is fantastic news. The impact the Montreal Protocol has had on climate change mitigation cannot be overstressed,” said Meg Seki, executive secretary of the UN Environment Programme’s ozone secretariat.
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