Experts: Recovery of the ozone layer is on track

A UN-sponsored panel of experts has said the ozone layer is expected to recover over the next four decades and the global phase-out of ozone-damaging chemicals is already contributing to the climate change mitigation.

Presenting their findings at the 103rd Annual Meeting of the American Meteorological Society, however, these experts warned of the adverse effects that innovative technologies such as geo-engineering could have on the ozone layer.

The United Nations-sponsored Montreal Protocol Scientific Assessment Panel’s Quadrennial Assessment Report on Substances that Deplete the Ozone Layer confirms that phasing out nearly 99% of banned substances that destroy the Ozone has helped preserve the ozone layer and contributed significantly to its recovery in the upper stratosphere and to a reduction in human exposure to harmful ultraviolet (UV) radiation from the sun.

If current policies remain in place, the ozone layer is expected to recover to 1980 values ​​(before the ozone hole appeared) by about 2066 above Antarctica, 2045 above of the Arctic and 2040 in the rest of the world.

Variations in the size of the hole in the ozone layer over Antarctica, especially between 2019 and 2021, have been largely influenced by weather conditions. Nevertheless, the area and depth of the ozone hole over Antarctica has been slowly shrinking since the year 2000.

In this regard, Meg Seki, Executive Secretary of the Ozone Secretariat of the United Nations Environment Program (UNEP), points out that “according to the last quadrennial report, the recovery of the ozone layer is on track, which is fantastic news. The impact of the Montreal Protocol on mitigating climate change cannot be overstated. Over the past 35 years, the Protocol has become a veritable spearhead in the defense of the environment”.

“The analyzes and reviews undertaken by the Scientific Assessment Panel remain an essential component of the work associated with the Protocol that helps inform policy and decision makers,” she adds.

Impacts on climate change

The tenth report of the Scientific Assessment Panel confirms the positive impact the Treaty has already had on the climate. An additional agreement concluded in 2016, the Kigali Amendment to the Montreal Protocol requires the progressive reduction of the production and use of certain hydrofluorocarbons (HFCs).

While not directly depleting ozone, HFCs are potent greenhouse gases. According to the Scientific Assessment Panel, this amendment should prevent a warming of 0.3 to 0.5°C by 2100 (not counting the contributions of HFC-23 emissions).

According to Petteri Taalas, Secretary General of the World Meteorological Organization (WMO), “the measures taken on ozone set a precedent for climate action. The success in phasing out ozone-depleting chemicals shows us what can and must be done – urgently – to phase out fossil fuels, reduce greenhouse gases and limit rising temperatures “.

The latest assessment was based on extensive studies, research and data collected by a large international group of experts, many of them from WMO, UNEP, the United States Oceans and Atmosphere (NOAA), the United States Aeronautics and Space Administration (NASA) and the European Commission.


For the first time, the Scientific Assessment Panel considered the potential effects on ozone of Stratospheric Aerosol Injection (SAI). SAI is a method considered by some to reduce global warming by increasing the reflection of sunlight. However, the expert group warns against the unintended consequences of this practice which “could also influence the temperatures, circulation and rates of production and destruction of ozone in the stratosphere as well as its transport”.

Montreal Protocol

The Montreal Protocol is a global agreement to protect the Earth’s ozone layer by phasing out chemicals that deplete it. This landmark text, which entered into force in 1989, is one of the world’s most successful environmental agreements. Thanks to the collaboration of nations around the world, the ozone layer is recovering and many positive environmental and economic benefits have been recorded.

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