The ozone layer is Earth’s natural defence against the effects of ultraviolet radiation from the Sun. Found between 12 and 31 miles (20 and 50km) up in the planet’s stratosphere, this layer of colourless gas absorbs the harmful components of ultraviolet B or UV-B. But just like the threat of climate change the ozone is damaged and each year for the past few decades, a hole has been opening above Antarctica, thanks in no small part to the emission of CFC chemicals into the atmosphere.
The Antarctic ozone hole forms each year between September and December.
But a European mission studying the hole has announced this week the hole has already reached its maximum size for 2020.
According to the World Meteorological Organization (WMO), the hole rapidly expanded from mid-August and peaked in early October.
At its peak, the hole expanded to a worrying 9.2 million square miles (24 million square kilometres).
And as of October 6, the hole has reached its 2020 maximum of nearly 8.9 million square miles (23 million square km).
The WMO tweeted on Tuesday: “The #ozone hole over the #Antarctic is one of the largest and deepst in recent years, per @CopernicusECMWF, @NASAEarth, @envrironmentca and WMO’s Global Atmosphere Watch network.
“Analyses show the hole has reached its maximum size for the year.”
The ozone hole is being monitored by the Copernicus Atmospheric Monitoring Service in cooperation with NASA, Environment and Climate Change Canada as well as the WMO’s Global Atmosphere Watch.
Vincent-Henri Peuch, director of the Copernicus Atmosphere Monitoring Service, said: “There is much variability in how far ozone hole events develop each year.
“The 2020 ozone hole resembles the one from 2018, which also was a quite large hole, and is definitely in the upper part of the pack of the last fifteen years or so.”
In 2019, scientists announced the ozone hole has shrunk to the smallest size on record.
At the time, the hole shrunk from a maximum of 6.3 million square miles (16.4 million square km) in September to just 3.9 million square miles (10 million square km) until the end of October.
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Dr Peuch said: “With the sunlight returning to the South Pole in the last weeks, we saw continued ozone depletion over the area.
“After the unusually small and short-lived ozone hole in 2019, which was driven by special meteorological conditions, we are registering a rather large one again this year, which confirms that we need to continue enforcing the Montreal Protocol banning emissions of ozone-depleting chemicals.”
The Montreal Protocol or The Montreal Protocol on Substances that Deplete the Ozone Layer is an international treaty banning the use of CFS.
CFS or chlorofluorocarbons and their derivatives are chemicals containing chlorine and bromine that collect in the atmosphere.
CFS have been most commonly found in refrigerators and propellant devices and can persist in the air for years or even decades.
When they reach the stratosphere, ultraviolet radiation breaks the bonds holding the chemicals together, releasing chlorine atoms that can destroy the ozone.
Ozone depletion is also directly related to temperatures and this year’s hole has been driven by a strong and stable, cold polar vortex.
The vortex kept the ozone hole over Antarctica steadily cold, below -78C (-108F), allowing stratospheric clouds to form.
In 2018, the WMO said the Antarctic ozone hole appeared to be on track for recovery by 2060.
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