The World Meteorological Organization has issued its annual WMO Ozone and UV Bulletin, on the occasion of World Ozone Day on 16 Sept, 2024.
Key facts
- The world’s ozone layer is on “the road to long-term recovery” despite a destructive volcanic eruption in the South Pacific after efforts to phase out ozone-depleting chemicals.
- On current trends, the ozone layer is on track to recover to 1980 levels by around 2066 over the Antarctic, 2045 over the Arctic and 2040 for the rest of the world.
- Though the volcanic eruption near Tonga in early 2022 led to a short period of accelerated depletion of ozone above Antarctica last year, driven by higher levels of atmospheric water vapour, overall losses were limited.
- Volcanic eruptions produce large amounts of tiny particles called aerosols (different from consumer products also known as aerosols). These aerosols increase chlorine’s effectiveness at destroying ozone. The aerosols in the stratosphere create a surface on which CFC-based chlorine can destroy ozone. However, the effect from volcanoes is short-lived.
- The ozone layer protects the earth from the sun’s ultraviolet radiation, which is linked to skin cancer and other health risks.
- The Montreal Protocol, which came into effect in 1989, agreed to phase out chlorofluorocarbons and other ozone-depleting substances, and its success “stands out as a powerful symbol of hope” at a time when multilateral cooperation has come under strain.
- CFCs have been largely replaced by hydrofluorocarbons, which do not cause ozone depletion but are a powerful climate-warming greenhouse gas. Countries are now implementing the 2016 Kigali amendment to Montreal, which will phase down HFC production, and could avoid around 0.5 degrees Celsius of warming by 2100.
- China remains the world’s biggest HFC producer, with current capacity the equivalent of nearly 2 billion metric tons of carbon dioxide. About a quarter is exported.
- Most atmospheric ozone is concentrated in a layer in the stratosphere, about 9 to 18 miles (15 to 30 km) above the Earth’s surface.
- Ozone is a molecule that contains three oxygen atoms. Ozone depletion is not limited to the area over the South Pole.
- One example of ozone depletion is the annual ozone “hole” over Antarctica that has occurred during the Antarctic spring since the early 1980s. This is not really a hole through the ozone layer, but rather a large area of the stratosphere with extremely low amounts of ozone.
- Research has shown that ozone depletion occurs over the latitudes that include North America, Europe, Asia, and much of Africa, Australia, and South America.
- Not all chlorine and bromine sources contribute to ozone layer depletion.
