The ozone layer’s recovery is good news for climate change, too

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COMMENTARY

A new assessment of Earth’s depleted ozone layer released Monday shows that efforts to repair the vital atmospheric shield are working, according to a UN-backed panel of scientists, as global emissions of ozone-depleting chemicals continue to fall.

As a result, the ozone layer – which blocks the sun’s ultraviolet rays from reaching the Earth’s surface – continues to slowly thicken.

Its restoration is key to human health, food security and the planet. UV-B radiation causes cancer and eye damage in humans. It also damages plants, stunting their growth and curbing their ability to store planet-warming carbon dioxide.

Scientists said ozone recovery should also serve as proof that societies can come together to solve environmental problems and fight climate change.

The Secretary-General of the World Meteorological Organization, Petteri Taalas, said in a statement: “Ozone action sets a precedent for climate action.” “Our success in phasing out ozone-depleting chemicals shows us what can and must be done — as a matter of urgency — to move away from fossil fuels, reduce greenhouse gases and limit temperature rise.”

At this rate, the ozone layer could recover to 1980s levels over most of the globe by the 2040s, and by 2066 in Antarctica, the report concludes. Ozone loss is most dramatic over the South Pole, with an ozone “hole” appearing there each spring.

These improvements will not be sustainable, the scientists noted, given natural fluctuations in ozone levels and the ozone-suppressing impact of volcanic eruptions such as the massive one from the Pacific Ocean’s undersea volcano Hunga Tonga a year ago.

But scientists said the latest ozone data and forecasts are nevertheless further evidence of the success of the Montreal Protocol, the 1987 global agreement to phase out the production and use of ozone-depleting substances.

Meg Seki, executive secretary of the UN Environment Programme’s Ozone Secretariat, called the findings “fantastic news” in a statement.

A recent drop in observed levels of the chemical known as CFC-11, in particular — which as recently as 2018 was observed in higher-than-expected levels and traced to China — is evidence that societies can collaborate to tackle a tangled environmental problem. , said Martyn Chipperfield, a professor at the University of Leeds who serves on the scientific panel.

“This turned out to be another success story,” he said. “Communities came together and it was addressed.”

Ozone is a molecule made up of three oxygen atoms and is spread in a layer of the stratosphere about nine to 18 miles above the earth. It can also exist at ground level, where it is a product of air pollution on hot summer days and is considered a health hazard. But in the atmosphere, it serves as an essential shield that protects life on Earth from harmful ultraviolet radiation.

In the same way that UV lights wipe out pathogens like the virus responsible for Covid-19, the sun’s radiation would make it impossible for life to thrive on Earth if not for the protection of the ozone layer. UV-B, a high-energy form of solar radiation, damages DNA in plants and animals, disrupting a variety of biological processes and reducing the efficiency of photosynthesis.

The Montreal Protocol, which has been adopted by every country in the world, protects ozone by outlawing the production and use of substances that destroy it when they come into contact with it in the atmosphere. This mainly includes a class known as chlorofluorocarbons, or CFCs, which contain ozone-depleting chlorine and were used in refrigerators, air conditioners and aerosol cans.

The treaty was expanded in 2016 through the Kigali Amendment to include hydrofluorocarbons, or HFCs, a replacement for CFCs that do not deplete the ozone but are a type of greenhouse gas that warms the planet more strongly than carbon dioxide. The US Senate ratified the amendment in September.

The report, which was presented Monday morning at the annual meeting of the American Meteorological Society in Denver, finds that the world is also making progress in curbing these planet-warming emissions.

“We can already see that HFCs are not growing as fast as we thought they would because countries are starting to implement their own controls,” said Paul Newman, one of the four co-chairs of the Montreal Protocol’s Scientific Assessment Panel.

However, it is possible that future data on ozone levels will cause some concern that the ozone layer is not recovering as quickly as the report concludes, he said. Newman said he expects this to happen because the Hunga Tonga eruption blasted so much material into the atmosphere. Volcanic eruptions are known to accelerate ozone depletion.

Progress is also likely to slow if people pursue geoengineering to reverse global warming by injecting particles that reflect sunlight into the upper atmosphere, Newman said. The panel, which examined the potential impact of the practice for the first time for Monday’s report, found that, depending on the timing, frequency and amount of such injections, the particles can alter aspects of atmospheric chemistry that are important in ozone development.

“The Antarctic ozone hole is the baby of ozone depletion,” Newman said. “Injections of stratospheric aerosol will probably make it a little worse.”

correction

An earlier version of this article incorrectly referred to hydrofluorocarbons as HCFCs. They are known as HFCs. The article has been corrected.