The monitoring of the hole in the ozone layer over the South Pole during 2023 by the Copernicus Atmosphere Monitoring Service (CAMS) has detected a formation or appearance of this cyclical phenomenon slightly earlier -in time- than what is usual.
The lowest column ozone values compared to the previous 43 years of satellite observations, along with other key indicators, mark an early start to the ozone hole this year. However, the evolution observed during the last week and the CAMS forecasts for the coming days show that the situation is close to the average, indicates the balance presented on August 31 by this European Union climate program.
"The early formation of the ozone hole in this part of the Earth is possibly related to the impact that the January 2022 eruption of the Hunga-Tonga volcano had on the composition of the upper atmosphere," Copernicus said. However, it is not yet clear whether this late appearance will lead to further depletion of the ozone layer and a larger-than-usual ozone hole by the global balance of 2023, experts have indicated.
The ozone hole in Antarctica is an atmospheric phenomenon that occurs during the spring of each year. Under normal conditions in the southern hemisphere stratosphere, the hole begins to form between mid and late August, when the Sun rises over the South Pole, and closes towards the end of November. The combination of the ERA-5 and CAMS reanalyses provides a 43-year total column ozone (TCO3) dataset that provides context to each year's development. In 2023, development began unusually early after some of the lowest total ozone column minimum values for the Southern Hemisphere in four decades throughout the month of July. Because of this, its total area is currently relatively high, although its progression has followed a fairly typical growth pattern.
One of the possible reasons that could explain this unusual start of the ozone hole season is the increase in water vapor brought into the atmosphere by the eruption of the Hunga Tonga volcano in December 2021 and January 2022. This mechanism occurs because ozone layer depletion is fueled. by chemical processes that occur in polar stratospheric clouds, which are more likely to form when water vapor levels in the stratosphere are high.
The long-lived ozone-depleting substances (ODS) that have accumulated in the stratosphere and cause a drastic decline in ozone concentration over Antarctica each spring each year are primarily of human origin and have been emitted by a variety of of industries since the 1960s.
Since the adoption of the Montreal Protocol in 1987, which phased out new emissions, ODS concentrations (particularly chlorinated, fluorinated or brominated hydrocarbons such as CFCs and HCFCs) in the stratosphere have been reduced and there are significant signs of recovery the ozone layer, recalls Copernicus. It is important to note that ODS will affect the ozone layer for many decades as it takes a long time to remove them from the atmosphere. It is expected that within 50 years their concentrations in the stratosphere will have returned to pre-industrial levels and ozone holes will no longer be experienced.
