The recovery of the Earth’s ozone layer is on track

　　A few days ago, according to the latest research report released by relevant United Nations agencies, the Earth’s ozone layer is expected to be repaired in the next 40 years. Some critics believe that the restoration of the Earth’s ozone layer will set a good precedent for global climate action.
　　For decades, Earth’s ozone layer, which protects life on Earth from the sun’s harmful ultraviolet (UV) rays, has been battered by common chemicals ranging from refrigerants to hairspray. But now the hole in the ozone layer is shrinking, thanks to decades of global efforts to repair it, the World Meteorological Organization (WMO) has confirmed.

　　Scientists first discovered a large hole over Antarctica in 1985. A few years later, countries around the world adopted the Montreal Protocol, a global environmental treaty to phase out “substances that deplete the ozone layer.”
　　Now, thanks to this work, scientists expect the ozone layer to start looking more normal and healthy within the next few decades. This reduces people’s risk of skin cancer and cataracts, as well as sun damage to plants and crops.
　　Studies have shown that for every 1% reduction in the ozone content in the atmosphere, the amount of solar ultraviolet radiation on the ground will increase by 2%, the number of people suffering from skin cancer will increase by 5% to 7%, and the number of people suffering from cataracts and respiratory diseases will also increase. ; If the ozone content in the ozone layer is reduced by 10%, the ultraviolet radiation in different areas of the ground will increase by 19% to 22%, and the incidence of skin cancer will increase by 15% to 25%.

　　A UN panel presented the findings at the annual meeting of the American Meteorological Society. The report released by the expert group said that since 2000, the size and depth of the ozone hole over Antarctica has been gradually improving.
　　If countries continue with current policies, the ozone layer over most of the world is expected to return to 1980 levels by 2040. However, the recovery of the ozone layer over the polar regions is expected to take longer, 2045 in the Arctic and 2066 in the Antarctic. Of course, this progress depends on the development of policies to limit these ozone-depleting substances.
　　Ozone molecules in the stratosphere absorb harmful UV-B radiation from the sun, blocking most UV rays from reaching it. This is part of the ongoing process of creating and destroying ozone in the atmosphere. But when certain chemicals drift there, that balance is thrown — causing more ozone to be destroyed than produced.
　　Dr. David Fahy, co-chair of the expert group, said, “The recovery of the ozone layer is on track, and because all countries have adopted effective control measures under the Montreal Protocol, the peak of global ozone layer destruction is a thing of the past.” October
　　2022 According to research results released by NASA and the National Oceanic and Atmospheric Administration, the area of ​​the ozone layer hole over Antarctica is 23.2 million square kilometers, which is “slightly smaller” than the previous year. On the whole, the void area has been shrinking in recent years. At the time, NOAA predicted that the hole in the ozone layer over Antarctica would recover around 2070.

　　In the mid-1980s, researchers discovered that the concentration of the ozone layer over Antarctica had dropped significantly. In the center of the ozone layer over the polar regions, nearly 95% of the ozone is destroyed. Observing from the ground, the high-altitude ozone layer is extremely thin. Compared with the surrounding area, it seems to form a “hole” with a diameter of thousands of kilometers, which is why the “ozone hole” got its name. It was this discovery that triggered the international community’s urgent repair of the ozone layer.
　　The formation and expansion of the hole in the ozone layer has both natural and man-made reasons. Ozone itself is a chemically very unstable substance that is prone to chemical reactions and decomposes into oxygen molecules and oxygen atoms. The chlorofluorocarbons in products such as foaming agents, fire extinguishing agents, insecticides, and refrigerants that humans have used in large quantities are the “culprit” that promotes the above-mentioned chemical reactions of ozone.
　　So far, the environmental problem of ozone depletion appears to be being effectively addressed, with more than 100 ozone-depleting compounds finally banned and phased out, including a 99% reduction in the use of chlorofluorocarbons.
　　A global agreement to protect the ozone layer would also benefit efforts to mitigate climate change. The ozone-depleting substances have been replaced by another class of chemicals that happen to be potent greenhouse gases, called hydrofluorocarbons (or HFCs).
　　In 2016, the international community passed the “Montreal Protocol on Substances that Deplete the Ozone Layer” Kigali Amendment, which also restricted the use of Freon substitutes, not only considering the damage to the ozone layer, but also the greenhouse caused by it. gas emissions.
　　Experts estimate that if the amendment is complied with, by 2100, it is expected to reduce the global warming during this period by 0.3-0.5 degrees Celsius. For context, the world has warmed by about 1.2 degrees Celsius since pre-industrial times, exacerbating many of the extreme weather hazards we live in today.
　　But the good news from WMO comes with a climate warning. “Geoengineering” – the deliberate manipulation of the climate or the atmosphere to undo some of the damage we’ve caused by burning fossil fuels – could be damaging to the ozone layer, the panel has warned. They focused in particular on a strategy called stratospheric aerosol injection (SAI).
　　Proponents argue that this strategy could help cool the planet because the aerosols might reflect some sunlight back into space. But SAI “poses significant risks and could lead to unintended consequences,” according to a recent WMO-backed report. Some climate experts have sounded the alarm about a startup’s recent attempt to release reflective sulfur particles in the stratosphere.
　　However, the phase-out of ozone-depleting chemicals is considered an example of what people can achieve when they work together to tackle the global environmental crisis. “Ozone Action has set a precedent for climate action. Our success in phasing out ozone-depleting chemicals has shown us what we can and must do. As a matter of urgency, we must wean ourselves off fossil fuels, reduce greenhouse gases, thereby limiting temperature rise,” WMO Secretary-General Taalas said in a statement.
　　Due to its good effect, “Montreal Protocol” is considered to be the most effective global environmental agreement ever. Over the past 35 years, the Montreal Protocol has become a true guardian of the environment, according to the United Nations Environment Programme.