The recovery of the ozone layer is on track thanks to the success of the Montreal Protocol

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But the group also warned of the unintended effects on the ozone layer of new technologies such as geoengineering.

In a report published every four years on the progress of the Montreal Protocol, the panel confirmed the phase-out of nearly 99 percent of banned substances that deplete the ozone layer.

Signed in September 1987, the Montreal Protocol is a major multilateral environmental agreement that regulates the consumption and production of nearly 100 man-made chemicals, or “ozone-depleting substances” (ODS).

The overall phase-out has led to the remarkable recovery of the protective ozone layer in the upper stratosphere and reduced human exposure to the sun’s harmful ultraviolet (UV) rays.

“The impact of the Montreal Protocol on climate change mitigation cannot be overemphasized,” said Meg Seki, executive secretary of the UN Environment Program Ozone Secretariat (UNEP).

“Over the past 35 years, the Protocol has become a true champion for the environment. The reviews and assessments conducted by the scientific review panel continue to be an essential part of the protocol’s work helping to inform policy makers and decision makers.”

Ozone recovery

The discovery of a hole in the ozone layer was first announced by three scientists from the British Antarctic Survey in May 1985.

According to the panel’s report, the low is expected to recover to 1980 values ​​by 2040 if current policies remain in place.

This recovery is expected around 2066 over Antarctica and around 2045 over the North Pole.

Variations in the size of the Antarctic ozone hole, particularly between 2019 and 2021, were largely caused by meteorological conditions.

Nevertheless, the Antarctic ozone breakthrough has been slowly improving in area and depth since the year 2000.

Consequences for climate change

The Montreal Protocol has already benefited from climate change mitigation efforts, preventing global warming by an estimated 0.5°C.

The report reaffirms the positive impact the treaty has had on climate.

In 2016, an additional agreement to the Montreal Protocol, known as the Kigali Amendment, required a phase-out of the production and consumption of some hydrofluorocarbons (HFCs).

HFCs do not directly affect the ozone layer, but are potent gases that contribute to global warming and accelerated climate change.

The panel said it is estimated that the amendment will prevent another 0.3 to 0.5°C of warming by 2100.

“Ozone action sets a precedent for climate action. Our success in phasing out ozone-eating chemicals shows us what can and must be done – urgently – to move away from fossil fuels, reduce greenhouse gas emissions and thus limit temperature rise,” said WMO Secretary General Petteri Taalas.

Warning new technology

The panel cautioned against using a potential method of mitigating global warming by increasing the reflection of sunlight.

For the first time, they examined the potential effects on ozone arising from the deliberate addition of aerosols into the stratosphere, known as a stratospheric aerosol injection (SAI).

But they warned that an “unintended consequence” of SAI was that it “could also affect stratospheric temperatures, circulation and ozone production and destruction rates and transport.”



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