The ozone hole over Antarctica has grown to enormous proportions again. As satellite data shows, this year the depletion of the ozone layer has reached 26 million square kilometers. However, the reason for such a significant ozone loss may be a completely natural phenomenon.
The ozone layer is the part of the atmosphere 15 to 30 kilometers above the Earth’s surface where there is a high concentration of ozone. It is essential for the survival of life on Earth because it blocks excess harmful ultraviolet (UV) radiation from the Sun. Its losses occur periodically over the poles in winter, and the one recorded in 2023 over Antarctica turned out to be really huge.
A gigantic eruption
According to the European Space Agency (ESA), which monitors the state of the ozone layer using the Copernicus Sentinel-5P satellite, this year’s ozone hole over Antarctica reached its maximum size on September 16 – it amounted to 26 million square kilometers. This is an area comparable to the entire area of North America and about twice as large as Antarctica itself.
“The 2023 ozone hole appeared early and has been growing rapidly since mid-August,” Antje Inness, a researcher at the European Center for Medium-Range Weather Forecasts, said in a statement. She added that this is “one of the largest ozone holes in history.”
What is causing the huge gap? According to scientists, the eruption of the Hunga Tonga-Hunga Ha’apai volcano in January 2022 took part in its creation. 50 million tons of water were then thrown into the upper atmosphere, causing the amount of atmospheric water to increase by 10 percent. This concerned some researchers, who warned that the additional water vapor could destabilize the ozone layer by breaking up into tiny particles that react with ozone. However, as Inness explained, more research is needed to confirm this link.
Why do we see the effects of a volcanic eruption with a delay? Water vapor reached Antarctica quite late, after the end of winter at the South Pole. Water vapor also increases the likelihood of the winter formation of polar stratospheric clouds – shiny clouds that deplete ozone resources.
Refrigerators and El Nino
Ozone holes above the poles show natural variability, which may also play a role in this year’s gigantic loss. In 2019, the loss over Antarctica was a record low, due to exceptionally high temperatures that prevented the formation of polar stratospheric clouds. In the years 2020-2022, as temperatures dropped, the ozone hole increased year by year. The change in temperatures near the poles may also have been influenced by the El Nino thermal anomaly, but its impact on the ozone hole has not yet been thoroughly investigated.
In the mid-1980s, scientists discovered that large losses were occurring in the ozone layer over Earth’s polar regions. The cause of these “holes” turned out to be freons (CFCs), chemicals used at that time in the production of refrigerators, packaging and aerosols. As it turned out, they react with atmospheric ozone, reducing its concentration. When the use of CFCs was banned, the ozone layer slowly began to recover and ozone levels began to return to normal.
Although the current ozone hole is one of the largest in history, ESA scientists have reassured that there is no reason to panic. The affected area is largely uninhabited and the damage should heal within a few months. If global CFC levels remain low, the ozone layer should be fully recovered by 2050.
Main photo source: Copernicus Sentinel-5P/DLR