Jan 9, 2023 - Science

UN report: Earth's ozone layer recovery back on course

False-color view of total ozone over the Antarctic pole on Jan. 7.
False-color view of total ozone over the Antarctic pole on Jan. 7. Photo: Nasa

The recovery of Earth's ozone layer, the vital atmospheric shield that protects the planet by absorbing most of the Sun's harmful ultraviolet radiation, is back on track, according to a new report from a panel of United Nations-backed scientists.

Why it matters: The report found that recent rogue emissions of CFC-11, an ozone-destroying chemical that was primarily being released from factories in northeastern China, have significantly declined since 2018, putting the ozone layer on course to recover within four decades.

  • Depletion of the ozone layer, which was first discovered by scientists in the 1980s, would cause increased amounts of UV radiation to reach the Earth, leading to widespread damage to life on the planet and contributing to climate change by impairing plants' ability to store carbon dioxide.
  • After large seasonal ozone losses were recorded over Antarctica, the Montreal Protocol on Substances that Deplete the Ozone Layer was signed in 1987 to restrict the production and import of ozone-depleting substances.
  • The protocol is considered the most successful environmental treaty ever enacted, becoming the first treaty in the history of the UN to achieve universal ratification.

What they're saying: “That ozone recovery is on track according to the latest quadrennial report is fantastic news," Meg Seki, the executive secretary of the United Nations Environment Programme’s Ozone Secretariat, said in a statement Monday.

  • "The impact the Montreal Protocol has had on climate change mitigation cannot be overstressed. Over the last 35 years, the Protocol has become a true champion for the environment,” Seki said.

How it works: Depletion is not a natural phenomenon but a result of the emission of chlorofluorocarbons (CFCs) and other halocarbons that break apart ozone molecules in the stratosphere, resulting in a thinner and thinner ozone layer.

  • Interactions between ozone and CFCs and halocarbons occur in the extreme cold of the Arctic and Antarctic stratosphere, which is why ozone "holes," or a thinner layer of ozone, first formed over Antarctica.
  • These thinned areas of ozone first occur in polar regions but are then mixed into the rest of the atmosphere, resulting in a net loss of ozone molecules in the atmosphere.

The big picture: The report, which was presented Monday at the American Meteorological Society’s annual meeting in Denver, is published every four years.

  • This year, it found that the phasing out of banned ozone-depleting substances has succeeded in allowing the ozone layer to make a notable recovery, leading to decreased human exposure to harmful UV light.
  • The UN-backed panel of sciences estimated that, if current policies remain in action, the ozone layer is expected to recover to 1980 values by around 2066 over the Antarctic, by 2045 over the Arctic and by 2040 for the rest of the world.

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