🌐 Antarctic Ozone Hole Grew Earlier Than Usual in 2023

In 2023, the Antarctic ozone hole began expanding earlier than traditionally observed, a shift scientists attribute to the Hunga Tonga–Hunga Haʻapai volcanic eruption in January 2022.

The ozone hole over Antarctica is a recurring atmospheric phenomenon, usually appearing each spring in the Southern Hemisphere. Ordinarily, the depletion starts to manifest from mid-to-late August, as sunlight returns to the South Pole, and gradually diminishes towards the end of November.

However, this year’s development diverges from the norm. The Southern Hemisphere witnessed some of the lowest minimum total column ozone levels in July, unmatched in the preceding 43 years. Consequently, the total area of the ozone hole is substantially larger at this point in the season.

Experts from the Copernicus Atmosphere Monitoring Service suggest that this early onset may be linked to elevated water vapour levels in the atmosphere due to the Hunga Tonga volcanic eruption in December 2021 and January 2022. The connection lies in the chemistry of ozone depletion: polar stratospheric clouds, a key player in ozone layer reduction, are more likely to form when the stratosphere has higher water vapour content.

The Hunga Tonga–Hunga Haʻapai eruption was the most powerful explosion ever detected in the atmosphere using modern instruments, surpassing any volcanic event or nuclear bomb test from the 20th century. It is believed that only the 1883 eruption of Krakatoa has caused a comparable level of atmospheric disturbance in recent centuries.

Most long-lasting substances that contribute to ozone depletion, concentrated in the stratosphere, can be traced back to human activities—particularly industrial emissions dating from the 1960s. The Montreal Protocol of 1987, aimed at phasing out new emissions of ozone-depleting substances, has successfully curtailed their concentrations in the stratosphere, leading to measurable signs of ozone layer recovery.

Nevertheless, these substances will continue to damage the ozone layer for several decades, given their longevity in the atmosphere. Researchers predict that it may take up to 50 years for concentrations of these substances in the stratosphere to return to pre-industrial levels, heralding the eventual end of the appearance of ozone holes.

Elia Kabanov is a science writer covering the past, present and future of technology (@metkere)

Illustration: Elia Kabanov feat. MidJourney. NB: AI-generated images may not accurately represent reality.

Animation: Copernicus Atmosphere Monitoring Service.