In the 1980s, scientists shockingly discovered that human pollution had dug a hole in the Earth’s protective ozone layer.
Now, almost 40 years later, scientists from the Copernicus Atmosphere Monitoring Service (CAMS) have discovered promising signs of recovery.
Latest atmospheric observations show that the ozone hole over the South Pole took longer to form this year and was smaller than expected.
On September 13, the ozone hole was 18.48 million square kilometers (7.13 million square miles) smaller than during the same period in recent years.
While scientists warn that much of this change is due to global weather patterns, there is still hope that the ozone layer will fully recover in the next forty years.
New data shows the ozone hole above the South Pole (pictured) took longer to form than in previous years
The ozone layer is a thin layer of naturally occurring ozone gas, a molecule consisting of three oxygen atoms, that absorbs almost all of the sun’s harmful UV radiation.
At ground level, this gas can cause health problems in vulnerable people suffering from lung diseases such as asthma.
However, when ozone collects in the upper atmosphere, it absorbs UV-B radiation that would otherwise be harmful to the Earth.
In 1985, research by the British Antarctic Survey discovered that a huge hole had formed in the ozone layer above the South Pole.
Each year, as spring approaches in the Southern Hemisphere, the hole opens again, allowing UV radiation to reach the Antarctic continent.
This radiation is so strong that animals in the Antarctic region, such as seals and penguins, are at greater risk of sunburn.
Every year, the ozone hole forms around August. This graph shows how the ozone hole formed later in 2024 (red) and reached a smaller size than in previous years
The ozone layer is vital because it prevents harmful UV-B radiation from reaching the Antarctic continent, harming wildlife there and further warming the melting sea ice (stock image)
Normally the hole is well filled by mid to late August and closes by late November, as part of an annual cycle.
But this year, new data shows that the ozone hole is developing significantly slower and less dramatically than in previous years.
It wasn’t until September that the hole in the ozone layer began to form. Since then, the hole has shrunk considerably.
CAMS predicts that the ozone hole will also shrink more rapidly over the remainder of the year, possibly closing completely by early December.
The ozone layer is measured using the Dobson unit, a unit that refers to the amount of ozone in an air column extending from the ground into space.
One Dobson Unit is the number of ozone molecules needed to create a layer 0.01 millimeter thick at 0°C (32°F) at sea level.
Ozone that has built up in the stratosphere normally absorbs almost all of the radiation coming from the sun.
CAMS data shows that most of the Antarctic region has remained above 220 Dobson units this year, the threshold for an ozone hole.
This is in stark contrast to 2023, when the ozone hole reached 26 million square kilometers (10 million square miles) in size on September 10.
Laurence Rouil, Director of CAMS, says: ‘From volcanoes to climate change, there are numerous factors that play a direct or indirect role in the formation of the ozone hole over Antarctica.
‘However, none of these substances are as harmful as the man-made substances that damage the ozone layer.’
Man-made compounds called CFCs or chlorofluorocarbons, used in aerosol sprays and refrigerators, were responsible for destroying huge amounts of ozone on Earth.
Although the use of CFCs was banned by the 1987 Montreal Protocol, the damage had already been done.
Previous studies have shown that the late recovery of the ozone hole (November-December, below) means more UV radiation reaches Antarctic waters – and during the peak breeding season for many seabirds, mammals and plants.
The ozone layer is depleted by chemical reactions driven by solar energy that involve the byproducts of man-made chemicals. This diagram shows how the thickness of the ozone layer changes with altitude
In winter, circling winds called the polar vortex concentrate the remaining CFCs and ozone-depleting substances in a small area above the South Pole.
In August, when spring begins in the Southern Hemisphere, solar radiation and low temperatures cause these substances to erode a hole in the ozone layer.
While the ban on CFCs has prevented the hole in the ozone layer from widening, experts do not believe this year’s slower ozone formation is necessarily a sign of recovery.
This is more likely to be the result of a disruption of the polar vortex, caused by natural changes in temperature and wind patterns.
In June, a pair of rare “sudden stratospheric warming events” occurred in Antarctica, raising temperatures in the upper atmosphere by 15ºC (59ºF) and 17ºC (63ºF) respectively.
In September of this year, the ozone hole (shown in blue) was 18.48 million square kilometers (7.13 million square miles) smaller than during the same period in recent years.
This year’s thicker ozone layer (shown in orange and red) is largely due to a weakening of the polar vortex that concentrates ozone-depleting substances over the Antarctic.
Those spikes stretched the polar vortex into a long, thin column that did not produce the fast winds that normally damage the ozone layer.
In a blog post, CAMS wrote: ‘Just as a period of colder than normal weather is not indicative of long-term climate trends, a slow onset of an ozone hole cannot automatically be attributed to ozone recovery.’
While this is not a definitive sign that the ozone layer is recovering, experts remain hopeful.
Mr Rouil said: ‘The Montreal Protocol and subsequent amendments have created ample room for recovery of the ozone layer. We can expect to see further signs of recovery over the next forty years.
“This shows how humanity, through international cooperation and science-based decision-making, has the power to transform our impact on the planet’s atmosphere.”