The Earth’s protective ozone layer is “on track” to fully recover in 43 years, according to a new assessment backed by the United Nations.
The scientific assessment, carried out once every four years, found that the Montreal Protocol, which banned 99% ozone-depleting substances, has succeeded in safeguarding the ozone layer, which protects humans against harmful ultraviolet rays.
Have first come into force in 1989, after scientists raised the alarm over a “hole” in the Earth’s ozone layer, chemicals that were found to deplete the upper stratospheric layer, such as CFCs, were banned.
Despite progress being slow, the report, presented on Monday at the American Meteorological Society convention in Denver, USA, stated that if policies remain in place, recovery is expected to reach 1980 levels – before the appearance of the hole – by around 2066 over the Antarctic, by 2045 over the Arctic, and by 2040 for the rest of the world.
Paul Newman, co-chair of the scientific assessment, added that the two chief chemicals that “munch away” at the ozone – bromine and chlorine – have “stopped growing” and levels are “coming down,” another testament to the effectiveness of the Protocol.
Meg Seki, executive secretary of the United Nations Environment Programme’s ozone secretariat, coined the Protocol a “true champion for the environment,” adding: “Ozone recovery is on track according to the latest quadrennial report [which] is fantastic news.”
In a 2016 update of the Protocol, known as the Kigali amendment, countries agreed to phase down the production and consumption of some hydrofluorocarbons or HFCs, which, similarly to CFCs, have a powerful effect on global warming.
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The new assessment said the Kigali amendment is estimated to avoid 0.3C to 0.5C of global warming by 2100.
It also says that new studies support previous assessments that the decline in emissions of ozone-depleting substances avoids an additional 0.5C to 1C of global warming by mid-century, compared with “an extreme scenario” of 3-3.5% increases in the chemicals each year.
The panel also examined the potential effects of a proposed deliberate addition of aerosols into the stratosphere – known as stratospheric aerosol injection – in order to reflect more sunlight and reduce warming.
It cautioned that the unintended consequences of this process could thin the ozone layer by as much as 20% in Antarctica.
