Ozone hole: Why Antarctic wildlife is ‘scorched by the sun’

For Antarctic wildlife, exposure to the sun’s harmful rays has increased in recent years, scientists say.

A hole in the ozone layer – the protective gas barrier in the upper atmosphere – now remains above the frozen continent for much of the year.

A major cause of ozone loss is thought to be the amount of smoke from Australia’s unprecedented bushfires, which have been fueled by climate change.

Climate change biologist Prof Sharon Robinson told BBC News: “When I tell people I’m working on the ozone hole, they say, ‘Oh, isn’t it better now?’

Scientists working in Antarctica discovered the hole in the ozone layer in 1985 – by measuring the amount of solar radiation reaching Earth.

A large group of ozone-depleting chemicals were responsible—primarily CFCs, or chlorofluorocarbons—that were used as refrigerants. Each country agreed in 1987 to phase out a group of ozone-depleting chemicals. This was an agreement known as the Montreal Protocol and is considered the most successful environmental treaty in history.

The ozone layer is already healing. “But there is a hole – an area where the ozone layer is severely depleted – that appears every spring over Antarctica,” explained Prof Robinson.

This loss of ozone is particularly characteristic of the polar continent due to chemical reactions occurring at very low temperature and high atmospheric clouds. These reactions break down ozone – eating a hole in the layer.

The annual occurrence of this sinkhole usually peaks in September and October, when most land plants and animals are safely tucked under a blanket of snow and marine animals are protected by extensive sea ice.

Now it lasts until December – all the way to the Antarctic summer. “That’s when things will be exposed and most vulnerable,” Prof Robinson said.

Certain types of ultraviolet radiation from the Sun, called UV-B rays, increase the risk of skin cancer and cataracts in humans, but researchers don’t yet know whether the same is true for Antarctic mammals and birds.

It is likely that anything covered in fur and feathers – seals and penguins – will be protected, Prof Robinson explained.

“But probably the biggest risk to Antarctic animals is eye damage.”

In their paper, Prof. Robinson and her colleagues searched all the studies they could find on the effects of UV rays on Antarctic plants and animals.

They found evidence of Antarctic mosses synthesizing their own protective “sunscreen compounds”.

“And if they’re putting energy into sunscreen, they’re putting less energy into growth,” Prof Robinson said. “There’s always a price for sun protection.”

There is also evidence that krill – the small and abundant sea creatures that form the basis of the Antarctic food chain – are moving deeper into the ocean to avoid UV rays that can affect whales, seals, penguins and other seabirds , who feed on them.

“We also know that the phytoplankton that krill feed on will need to produce sunscreens to avoid damage,” Prof Robinson said.

One of the main reasons for the longevity of the ozone hole is the sheer scale and scale of the Australian bushfires in 2019 and 2020.

Jim Heywood, who is professor of atmospheric sciences at the University of Exeter, told BBC News that the record duration of the Antarctic ozone hole in recent years was a “wake-up call”.

“The public cannot be complacent about our track record in dealing with it,” he said.

But there are still a number of factors that slow ozone recovery, including wildfires and large volcanic eruptions — these particles release that fuel the ozone-eating reactions that have already done so much damage.

Professor Robinson explained that some proposed experiments to cool the climate – so-called geoengineering – propose “cloud-making” by releasing particles into the upper atmosphere.

“It would also destroy the ozone, so it’s a bad idea,” she said.

“The biggest thing we can do to help Antarctica is to act on climate change – to reduce carbon emissions as quickly as possible so that we have fewer forest fires and don’t put additional pressure on the restoration of the ozone layer.’