What the ozone hole above the Arctic would have looked like in 2011 without the Montreal Protocol. Photo courtesy of The Age.
An ozone hole larger than Australia would have opened up over the Arctic if we had continued to use CFC’s for the past three decades.
New 3D computer models reveal what the ozone layer in the stratosphere would have looked like had countries not agreed to the Montreal Protocol in 1987, which restricted the production and use of ozone-depleting chemicals such as chlorine and bromine.
The models also reveal the current ozone hole above Antarctica would have grown 40 per cent larger by 2013 and UV radiation levels in the most densely populated regions of Australia and New Zealand would have increased by eight to 12 per cent.
Australia already has the highest death rate from skin cancers. Previous research has suggested these cancers would have increased worldwide by 15 per cent by 2030 without the international treaty and ensuing action.
CFCs were widely used as refrigerants in air conditioners, refrigerators and freezers, as well as propellants in spray cans, styrofoam manufacturing and various medical products.
What the Arctic ozone looked like in 2011 because of the Montreal Protocol. Photo courtesy of The Age.
One of the study’s New Zealand authors, Richard McKenzie, said concern about ozone depletion started in the 1970s, but it was the appearance of a springtime ozone hole over Antarctica in 1980 that galvanised public attention about the environmental damage of these substances.
After the protocol was signed chlorofluorocarbons (CFCs) were at first replaced with hydrochlorofluorocarbons, which did less damage to the ozone layer. Now hydrofluorocarbons, such as propane, are generally used because they don’t contain any substances that affect the ozone.
Concentrations of CFCs peaked in 1993 and have since declined, although they have long lifetimes in the atmosphere. The ozone hole above Antarctica has appeared every year since 1980, but is predicted to have fully repaired by 2050.
“There was never a corresponding ozone hole in the Arctic because wind patterns were different. However, this paper shows that if had not been for the Montreal Protocol, there would have been an Arctic ozone hole occurring for the first time in 2011,” said Dr McKenzie, an atmospheric scientist from the National Institute of Water and Atmospheric Research.
“That is serious because, unlike Antarctica, a lot of people live up there, and they would have been exposed to far higher levels of UV than normally experienced at that time of year.”
The findings were published on Wednesday in the science journal Nature Communications.
Read the article at The Age.