Ozone is a naturally occurring molecule that forms a protective layer in the stratosphere between 20 and 30 kilometres above the earth’s surface. This relatively thin layer absorbs between 97-99% of the sun’s harmful ultra-violet (UV) radiation.
Though the destructive effect of chloroflurocarbons (CFCs) on ozone had already been known for a decade it was not until 1985 that a continent sized ‘hole’ in the ozone layer was discovered over Antarctica.
“What was happening over Antarctica was a wake up call, because no one had suspected that this could happen. It actually alerted the world to what was going on everywhere,” said the Co-author of the 2010 International Scientific Assessment of Ozone Depletion, Dr Matt Tully.
The discovery was startling; each spring up to two-thirds of the ozone above Antarctica was being destroyed and ozone levels across the globe were beginning to drop by a measurable percent.
The reaction by the international community was swift. In 1987, less than two years after the hole was discovered, 43 countries signed the Montreal Protocol, committing to the protection of the ozone layer.
“If the use of ozone-depleting substances had have continued at the same rate, then by 2065 over Melbourne the UV index in summer would have been reaching 35. Values over 10 are considered ‘Extreme’,” Dr Tully said.
“If you went out in the sun on a summer day you would get sunburnt in a matter of minutes.”
In an uplifting example of international unity, in 2009 the Montreal Protocol became the first and only United Nations treaty ratified by every country in the world. CFC production has almost completely been phased out internationally and the future of the ozone layer seems sealed.
“[The hole above Antarctica] still appears every year in spring-time, but hasn’t been getting any worse for quite a few years now.”
With ozone-depleting molecules such as CFCs able to cause havoc in the stratosphere for up to a century, it could be as late as 2080 before the ozone layer makes a full recovery.
The fact that the earth will take a century to repair the damage done by humans in a matter of decades should be a timely reminder that our planet works on a different timescale to us.
Yet the swift action to protect the ozone layer managed to avert an environmental disaster that would arguably have been as devastating as is currently posed by climate change. Increased exposure to UV radiation not only increases incidents of cataracts and potentially fatal skin cancers, but also damages crop yields and destroys natural ecosystems.
“It is a very positive example of the global community addressing a global problem,” Dr Tully said of the Montreal Protocol.
“It was a very timely action, very effective - people were willing to make substantial changes - and the number of countries that have got involved is without parallel.”
“Really it’s an example of how to take action on environmental problem. Firstly the agreement was made recognising the need and then progressively tightened over the next few years.”
When asked why action to protect the ozone layer was so quick and unanimous, Dr Tully has to admit that he has no definitive answer.
“One important thing was that industry was involved quite early on; particularly the big chemical manufacturing companies played a very positive role,” he said.
“With the very dramatic ozone loss over Antarctica there was a very dramatic warning and effect that people could see.”
Though the issue of ozone depletion may have cooled we now face numerous environmental issues that are still heating up.
Humanity’s action to protect the ozone layer is a standout of our history and should be a reminder that we as a species have been at a similar environmental crossroads once before.
If nothing else, the ozone layer is proof that our history is not always a lecture in our mistakes but can be a celebration of our triumphs.