The ozone hole above Antarctica this year reached its maximum extent. And, more broadly, it has once again taken on large dimensions, both in terms of depth and area. The alarm has been raised by the European climate monitoring service Copernicus, according to which "stratospheric ozone concentrations have been observed to have dropped to values close to zero over Antarctica at around 20–25 kilometres altitude, with the depth of the layer just below 100 Dobson units (roughly one third of the average value)".

Ozone values close to zero over Antarctica at 20–25 km altitude

Scientists have specified that the phenomenon was caused by a particularly strong, stable and cold polar vortex in the area. "Chlorine- and bromine-containing substances," the European service explains, "accumulate inside the polar vortex, where they remain chemically inactive in the dark. Temperatures in the vortex can drop to -78 degrees Celsius and ice crystals can form in polar stratospheric clouds. When the sun rises above the Pole, its energy releases chemically active chlorine and bromine atoms into the vortex, which rapidly destroy ozone molecules, leading to the formation of the hole."

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Copernicus Atmosphere Monitoring Service (CAMS) confirms maximum extent of the ozone hole over Antarctica in recent years. @CopernicusEU

➡️bit.ly/ozone-extent

♥ 16 6 ott 2020 · Apri su X →

"The way changes in the ozone hole develop each year is highly variable," said Vincent-Henry Peuch, director of the Copernicus Atmosphere Monitoring Service. "The 2020 hole resembles that of 2018, which was also quite large and among the top-ranked of the past fifteen years."

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2020's #OzoneHole is both larger and deeper than most in recent years. This is being driven by a strong, stable and cold polar vortex, with all signs pointing to continued ozone depletion in the coming days.

#Ozone monitoring➡️bit.ly/2P3nXIb

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"We must continue to apply the Montreal Protocol"

The expert adds that "with sunlight having returned towards the South Pole in recent weeks, we have witnessed a continued reduction in ozone over the area. After the unusually small and short-lived hole in 2019, favoured by special meteorological conditions, we are therefore recording a rather large one this year too. This confirms that we must continue to apply the Montreal Protocol, which bans emissions of chemical substances that deplete the ozone layer."

The data were obtained through computer models of the atmosphere combined with satellite and on-site measurements, in order to closely monitor the evolution of the phenomenon. "Since the stratospheric ozone layer acts as a shield, protecting against potentially harmful ultraviolet radiation," the Copernicus service underlines, "it is of the utmost importance to monitor its changes."