A hole lotta trouble: obliterating our ozone layer

With over 15,000 new cases reported each year, Australia and New Zealand share the dubious honour of being the world’s skin cancer capitals. Ask someone why, and there’s a good chance they’ll pin it on ‘the hole in the ozone layer’ sitting above these hapless countries. Luckily for us, this is an urban myth – the chronic failure of pasty Europeans to slip, slop, and slap is the real culprit. On the other hand, the penguins in Antarctica might need some SPF 50+, because the hole in the ozone layer there stretches across twenty million square kilometres!

Cancer Council could be making a fortune with an Antarctic branch – these penguins are ready to buy.
Image by David Cook, via Flickr

Sunscreen in the sky

If you’ve ever heard of the ozone layer, you probably know that it protects our planet from the Sun’s rays. As a giant nuclear reactor, the Sun is constantly churning out excess energy as waves of radiation. Most of the radiation that escapes is harmless, but the waves with the highest energy – mainly ultraviolet (UV) rays – can irreversibly damage the DNA of living cells. Just one thing stands between us and certain death: a thin layer of ozone floating in the stratosphere, twenty kilometres above the Earth’s surface.

Ozone is just a deluxe version of the oxygen gas we breathe – instead of two oxygen atoms, ozone is made of three. But this simple difference gives ozone one very fortunate quirk: the ability to absorb the most harmful forms of UV radiation. When a UV ray crashes into an ozone molecule, its energy is sucked up into the bonds holding the ozone together. The rush of solar power ‘excites’ the bonds enough for one to break apart, and the excess energy dissipates as harmless heat. Voila! The UV ray is vanquished, and life on Earth avoids the curse of mass melanoma.

But what becomes of the ozone itself? When it breaks apart, it leaves behind a molecule of oxygen gas (O2), and a lone oxygen atom. Oxygen atoms would make fantastic cast members in a soap opera – they’re volatile, reactive, and hate being single. In a desperate bid to return to a happy marriage, they latch onto the first puff of oxygen gas that drifts by, and a new ozone molecule is born. The result is a constant cycling of oxygen particles that has allowed our ozone layer to continuously regenerate for hundreds of millions of years.

All that stands between our skin and the incredible energy of our Sun is a few tiny particles of gas.
Image by NASA Goddard Space Flight Center, via Flickr.


If our atmosphere’s built-in sunscreen can replenish itself, then why is there such an enormous hole above the South Pole? The blame – as usual – falls squarely on our shoulders.

Following the First and Second World Wars, many of the innovations developed by countries to aid their fight on the front line were transitioned into mainstream industries. Among these were an extremely unreactive group of chemicals known as chlorofluorocarbons (CFCs for short). Originally used to suppress fires in military aircraft, they gained popularity with private aviators throughout the 1930s. When less toxic CFCs were discovered in the 1950s, their use skyrocketed; at the peak of their popularity, CFCs could be found in just about every light aircraft, fire extinguisher, and spray can. They were also ubiquitous as coolants in household fridges, trademarked under the brand name Freon. But the same properties of stability that make CFCs so good at withstanding the fury of fires, and the pressure inside a spray nozzle, could also spell doom for our planet.

Old fire extinguishers like this one often contain CFCs – they were one of the largest contributors to the hole in our ozone layer!
Image by Sean Fallows
via Flickr.

CFCs are stable due to the incredibly strong bonds that hold their atoms together; they contain chlorine and fluorine, which have the strongest ‘grips’ of any element. The iron fist these elements exert on the carbon atom at their centre gives each CFC as long as a century to move through the environment without decomposing. Over several years of heavy use, CFCs began to float out of our cities and right up into our ozone layer. But the moment they move above this protective sunshield, something happens: they break up.

The incredible power of the Sun’s UV radiation is strong enough to rip apart the bonds within these hardy molecules, sending chlorine flying into the open air. If free oxygen is an unhappy soap star, then these atoms are the mass murderers from American Horror Story. Just one chlorine atom can easily destroy one hundred thousand ozone molecules before leaving the stratosphere. With such a deep thirst for blood, it should come as no surprise that CFCs (and some related chemicals) have been named and shamed as the #1 culprits behind our sprawling ozone hole.

One of the least important uses for chlorofluorocarbons – adding weight to wax in lava lamps!
Image by Faruk Atesvia Flickr.

No hole the end goal

If we were to give CFCs free reign over our skies, the hole over Australia might not be a myth for much longer. Luckily, in a rare case of political cooperation, the rest of the world seems to agree. In 1987, just over a decade after the harmful effects of CFCs were first discovered, forty-six states signed the now-famous Montreal Protocol. Developed to restrict the use of ozone-damaging chemicals across the globe, the protocol has been described as the world’s ‘single most successful international agreement‘. Fast-forward to 2018, and an incredible 197 states are signatories to the plan. Better yet, CFC emissions have declined massively, and the hole in the ozone layer is actually closing up.

Despite our habit of ruining everything we touch, it’s clear that humanity has the power to meet lofty environmental goals. While Australians will probably never learn to apply enough sunscreen, I’m sure the cancer-free penguins waddling around Antarctica’s frosty shores will thank us in the years to come.

By the end of the 21st century, this wound in our stratosphere could be gone completely.
Image by NASA Goddard Space Flight Center, via Flickr.

On cloud nine? Read more:
1. A mysterious new CFC?
2. An unexpected culprit: the plastic foam industry!
3. What we really mean by ‘ozone hole’.

8 Responses to “A hole lotta trouble: obliterating our ozone layer”

  1. Oakley Germech says:

    Thanks Adrian! I had no idea just HOW involved the chemistry of the ozone layer was before writing this post – so I’m glad I was able to simplify some of the most important concepts!

  2. Adrian Marcato says:

    Great blog! Loved your ozone being a deluxe oxygen analogy – was quite humorous but at the same time was super simple to understand given how complex it can be! 🙂

  3. Oakley Germech says:

    Hi Hugh – current projections are hoping for total ‘closure’ by 2050-2080 (though the ozone ‘hole’ is really just a thinning of the ozone layer – you can read a little more on the third ‘read more’ link at the end of the post). Let’s keep our fingers crossed that the predictions are true 🙂

  4. Oakley Germech says:

    Hey Connor – glad you liked it! There certainly has been more news on the mysterious new CFCs – and (recently) an answer! Top detective work from some analytical chemists – there are actually two links at the bottom of my post if you’re keen to find out more 🙂

  5. Hugh Rayner says:

    Any idea when they expect the hole to close up? Had no idea about CFCs, super interesting.

  6. Great piece, Oakley! I read recently that we’ve noticed CFCs have started to be produced again somewhere, despite the Montreal Protocol. Has there been any more news on that?

  7. Oakley Germech says:

    Hey Aaron,

    Thanks for your comment! I suppose they’re two very different issues – ozone depletion probably won’t lead to rising temperatures (though, interestingly, as a pollutant in the lowest sections of our atmosphere, ozone is actually a greenhouse gas!). Repairing the ozone layer is mostly the responsibility of the industries involved in manufacturing CFCs – there’s nothing much we can do as citizens (especially now that CFCs are banned as propellants in aerosol cans in Australia and have been effectively phased out of fridges). I would argue that it’s similar to the case with climate change – there’s a lot of onus placed on the consumer, but in reality a small number of large companies are responsible for over two-thirds of the world’s greenhouse gas emissions. If we change the systems that govern our society, thenI think our lifestyles will change to reflect that 🙂

  8. Aaron Barnard says:

    Interesting read! I remember learning way back in primary school about the dangers CFCs pose to the environment. Currently though, it seems like CO2 is the big issue on scientists’ minds. Is protecting our ozone as important as controlling CO2 levels, and is there anyway we can repair the ozone ourselves?