The ozone layer, which protects the Earth from dangerous solar radiation, is “on track” to fully recover within the next 40 years, but geoengineering projects aimed at limiting global warming could jeopardize that progress, scientists say.

“Phasing out almost 99% of banned ozone-depleting substances has helped preserve the ozone layer and has greatly contributed to its recovery in the upper stratosphere and limiting human exposure to harmful ultraviolet (UV) radiation from helium,” experts say. in the report they compile every four years under the auspices of the UN.

The ozone hole was formed due to anthropogenic pollution, especially chlorofluorocarbons (CFCs), which used to be emitted by many refrigerators. In recent decades, thanks to global cooperation, the ozone layer has been able to recover.

The Montreal Protocol, signed in 1987 and ratified by 195 countries, has significantly reduced the amount of CFCs in the atmosphere, and the UN estimates that the ozone layer is likely to recover completely.

Forecast up to 2066

“If current policies are maintained, the ozone layer should recover to 1980 values ​​(before the hole appeared) by about 2066 over Antarctica, 2045 over the Arctic and 2040 over the rest of the world,” the UN Environment Agency said in a statement. .

In 2016, the Kigali Agreement also called for the phase-out of hydrofluorocarbons (HFCs), highly climate-damaging gases used in refrigerators and air conditioners. Experts estimate that if the agreement is maintained, it could limit global warming by 0.5°C by 2100. But at the same time, for the first time, they studied the possible impact on ozone of geoengineering projects aimed at limiting climate change, and highlighted their undesirable side effects. One idea is to deliberately add aerosols to the stratosphere to reflect some of the solar radiation. One of these plans involves introducing billions of sulfur particles into the upper atmosphere. Such an injection could seriously damage the ozone layer, warned John Pyle, co-chair of a group of scientists working on behalf of the UN. “There are many concerns,” he stressed.

Source: APE-MPE, AFP.