The ozone layer, which protects the earth from harmful solar radiation, could recover within four decades. “The elimination of nearly 99% of banned ozone-depleting substances has helped preserve the ozone layer and has been instrumental in its recovery in the upper stratosphere and in reducing human exposure to harmful ultraviolet (UV) radiation from the sun,” scientists note which publish their quarterly estimate under the aegis of the UN.
The ozone hole was caused by man-made pollution, particularly chlorofluorocarbons (CFCs), which were once emitted by many refrigerators. In recent decades, however, global cooperation has given the ozone layer a chance to recover, notably through the Montreal Protocol (Canada), signed in 1987 and ratified by 195 countries, which has greatly reduced the amount of CFCs in the atmosphere. According to UN estimates, the ozone layer seemed to be able to fully recover.
“If current guidelines remain in place, the ozone layer is expected to recover to 1980 levels (before the ozone hole appeared) by around 2066 over Antarctica, 2045 over the Arctic, and 2040 in the rest of the world,” it said UN environment. In 2016, the Kigali Agreement also provided for the phase-out of hydrofluorocarbons (HFCs), extremely climate-damaging gases used in refrigerators and air conditioners. Experts already estimate that if the agreement is adhered to, it could reduce global warming by 0.5°C by 2100.
The dangers of geoengineering
However, the latter was also the first to address the potential impact of geoengineering projects on ozone, designed to limit global warming, and warned of their undesirable effects.
The idea would be to intentionally add aerosols to the stratosphere to reflect some of the sun’s rays. One such project would be to inject billions of sulfur particles into the upper layer of the atmosphere.
Injecting particles into the atmosphere “could lead to a serious decrease in ozone levels,” warns John Pyle, co-chair of the scientific panel working on ozone on behalf of the UN. “There are a lot of uncertainties,” he said.