Quite simply, there is no life without our ozone layer. The stratospheric layer of gas absorbs the most powerful, damaging ultraviolet rays and essentially prevents living things from being killed by the power of the Sun. Unfortunately, Earth's has a major weakness.
Back in the 1980s, while measuring the amount of solar radiation reaching our planet, scientists in Antarctica discovered a hole in the planet's ozone. The reason? Human-made chemicals were mixing with ozone molecules and destroying them.
The group of chemicals found to be responsible were primarily chlorofluorocarbons or CFCs. In the 1980s, they had a large number of industrial uses, primarily as refrigerants.
Fortunately, the world paid attention. In 1987, two years after the Antarctic study was published, world leaders signed an international treaty at a summit in Montreal to phase out those ozone-depleting chemicals. It was an agreement known as the Montreal Protocol and is still considered to be the most successful environmental treaty in history.
Now, four decades on, research has shown that human activity risks putting that global achievement in jeopardy. While the ozone layer hasn’t fully healed yet, it is now on the right path.
In 2022, the world hit an ozone-recovery milestone. The overall concentration of ozone-depleting substances in the mid-latitude stratosphere had fallen back to levels observed in 1980. The US National Oceanographic and Atmospheric Administration called it “slow but steady progress”.
The latest setback has been revealed by scientists who have been keeping a close eye on the hole in the ozone layer that still appears every year over Antarctica.
Currently, an area of severe ozone depletion is opening up annually over the polar continent, primarily because of chemical reactions that occur in very low temperatures, and high atmospheric clouds. Those reactions break down ozone and essentially eat through the ozone layer.
The hole opens up, then disappears as the seasonal, stratospheric reactions peak and trough. Usually, this peaks in September and October. Fortunately, that is when most land-based plants and animals are safely tucked away under snow cover and many marine animals are protected by sea ice.
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But in recent years, the hole has remained until December, well into the Antarctic summer, which is when plants and animals are much more vulnerable.
This means that the intensity of ultraviolet radiation reaching the Antarctic continent can be similar to that seen in Sydney, Australia on a summer day. As climate change scientist Prof Sharon Robinson from the University of Wollongong told me: “That’s really quite extreme.”
The beginning of summer is also the peak breeding season for many animals, so it’s a particularly vulnerable time in their lifecycle.
We wear sunblock and sunglasses to protect ourselves from some of the Sun’s ultraviolet rays, which can increase our risk of skin cancer and cataracts. Scientists who carried out this study of Antarctic UV say the same may be true for the polar continent’s mammals and birds.
While anything covered by fur and feathers would have its skin protected scientists think the biggest risk to the Antarctic animals is damage to the eyes.
What's causing this ozone hole?
The reason for this extended period of potentially deadly ozone loss is simple: climate change.
Catastrophic global warming-fuelled wildfires in Australia, between 2019 and 2020, released clouds of particles into the atmosphere that drove more of the ozone-eating reactions that have historically done so much damage.
Somewhat ironically, there are some proposed climate-cooling experiments – so-called geoengineering techniques – that propose ‘making clouds’ by releasing sulphate particles into the upper atmosphere. This would also deplete ozone, so, as Robinson put it: “It’s a bad idea.”
We should pay attention to this wake-up call from Antarctica. It comes from a frozen continent that is surrounded by an icy sea, both of which play a vital cooling role in our global climate.
We can no longer be complacent about the healing of the ozone layer. And the biggest thing we can do to help Antarctica – and ourselves – is to act on climate change and reduce carbon emissions as quickly as possible.
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