Scientists discovered the ozone layer, particularly over the Antarctic region and as far up as Australia, had depleted in the 1970s. The ozone layer is a layer of the atmosphere which sits about 10 kilometres above the Earth’s surface and protects life from ultraviolet radiation from the Sun.
As the ozone layer began to thin, more lifeforms, including humans, were exposed to stronger solar rays which increase the likelihood of cancer.
The researchers put the restrengthening of the ozone layer down to the 1987 Montreal Protocol which was an international treaty that banned chemicals such as chlorofluorocarbons (CFCs) and other ozone-depleting substances (ODSs) which were found to be weakening the atmospheric layer.
Now the ozone layer has recovered to such an extent that it is helping in the battle against climate change.
The depletion of the ozone layer had affected the jet streams – high altitude fast air currents – pushing them further down, disturbing rainfall patterns and ocean currents which hampers the planet’s delicate ecosystem.
For example, the lowering of the jet stream increased the risk of droughts throughout Australia, but if the ozone layer fully recovers, which, it is important to add, has not yet, then the rains over Australia could return.
But the recovering ozone later is allowing for the jet stream over the Antarctic to move further up in the atmosphere, according to new computer simulations from the University of Colorado Boulder.
Ian Rae, an organic chemist from the University of Melbourne who was not involved in the study, said: “The ‘weather bands’ that bring our cold fronts have been narrowing towards the south pole, and that’s why southern Australia has experienced decreasing rainfall over the last thirty years or so.
“If the ozone layer is recovering, and the circulation is moving north, that’s good news on two fronts (pun not intended).”
However, the team warn the recovery of the ozone layer might be temporary, with a sharp uptake in ODSs in China in recent years such as evidence of an increase in CFC-11 – an ozone-depleting chemical – from eastern Asia since 2012.
Atmospheric chemist Antara Banerjee from the University of Colorado Boulder: “We term this a ‘pause’ because the poleward circulation trends might resume, stay flat, or reverse.
“It’s the tug of war between the opposing effects of ozone recovery and rising greenhouse gases that will determine future trends.”
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