Earth's Ozone Layer Is Healing, Bringing Some Good News on Global Wind Movement -


The ozone layer above Antarctica has recovered so much, it's actually stopped many worrying changes in the Southern Hemisphere's atmosphere. If you're looking for someone to thank, try the world at large.

A new study suggests the Montreal Protocol - the 1987 agreement to stop producing ozone depleting substances (ODSs) - could be responsible for pausing, or even reversing, some troubling changes in air currents around the Southern Hemisphere.
Then, a decade or so after the protocol was signed, that migration suddenly stopped. Was it a coincidence?
In other words, the impact of the Montreal Protocol appears to have paused, or even slightly reversed, the southern migration of the jet stream. And for once, that's actually good news.

"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," says Ian Rae, organic chemist from the University of Melbourne who was not involved in the study.
"If the ozone layer is recovering, and the circulation is moving north, that's good news on two fronts (pun not intended)."
Last year, the Antarctic ozone hole hit its smallest annual peak on record since 1982, but the problem isn't solved, and this record may have something to do with unusually mild temperatures in that layer of the atmosphere.
What's more, in recent years, there's been a surge in ozone-depleting chemicals, coming from industrial regions in China.
"We term this a 'pause' because the poleward circulation trends might resume, stay flat, or reverse," says atmospheric chemist Antara Banerjee from the University of Colorado Boulder.

"It's the tug of war between the opposing effects of ozone recovery and rising greenhouse gases that will determine future trends."
The Montreal Protocol is proof that if we take global and immediate action we can help pause or even reverse some of the damage we've started. Yet even now, the steady rise in greenhouse gas emissions is a reminder that one such action is simply not enough.
The study was published in Nature.

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