The recovery of the ozone layer is also good news for climate change


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

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

Its restoration is essential for human health, food security and the planet. UV-B radiation causes cancer and eye damage in humans. It also damages plants, inhibiting their growth and limiting their ability to shop carbon dioxide that warms the planet.

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

“Action against ozone sets a precedent for climate action,” World Meteorological Organization Secretary-General Petteri Taalas said in a statement. “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 gases and thus limit the increase of the temperature.”

At this rate, the ozone layer could recover to 1980s levels across 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 steady, the scientists stressed, given natural fluctuations in ozone levels and the ozone-inhibiting influence of volcanic eruptions like the massive one from the Pacific Ocean submarine volcano Hunga Tonga there. one year old.

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

Meg Seki, executive secretary of the United Nations Environment Programme’s Ozone Secretariat, called the results “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 had been observed at higher than expected levels and attributed to China – is proof that corporations can work together to solve a puzzling environmental problem. , said Martyn Chipperfield, a professor at the University of Leeds who sits on the scientific committee.

“It turned out to be another success story,” he said. “The communities came together and the problem was solved.”

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

In the same way that UV rays eradicate pathogens like the virus responsible for covid-19, solar radiation would prevent life from thriving on Earth if it weren’t for the protection of the ozone layer. UV-B, a form of high-energy solar radiation, damages the DNA of plants and animals, disrupting a variety of biological processes and reducing the efficiency of photosynthesis.

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

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

The report, which was presented Monday morning at the American Meteorological Society’s annual meeting in Denver, finds that the world is also making progress in bringing these global-warming emissions under control.

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

Still, upcoming data on ozone levels may raise some concerns that the ozone layer may not be recovering as quickly as the report concludes, he said. Newman said he expects it to be because the Hunga Tonga eruption threw so much material into the atmosphere. Volcanic eruptions are known to accelerate the depletion of the ozone layer.

Progress would likely also be slowed if humans continued geoengineering to reverse global warming by injecting sunlight-reflecting particles into the upper atmosphere, Newman said. The panel, which examined the potential impact of this practice for the first time for Monday’s report, found that depending on the timing, frequency and amount of these injections, the particles could alter aspects of atmospheric chemistry. which are important in the development of ozone.

“The Antarctic ozone hole is the beacon child of ozone depletion,” Newman said. “Stratospheric aerosol injections are likely to make the situation a bit worse.”


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

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