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Antarctic ozone hole starts amid questions about impact of Hunga Tonga eruption

04:55 PM Aug 31, 2023 IST | Ground Report
antarctic ozone hole starts amid questions about impact of hunga tonga eruption

The monitoring of the early stages of the Ozone Hole over the South Pole during 2023 by the Copernicus Atmosphere Monitoring Service (CAMS) has detected a slightly earlier development. Lower ozone column values in comparison to the previous 43 years of satellite observations, together with other key indicators, mark an early start to the ozone hole this year.

Recent changes, CAMS forecast normalize

Yet, the changes seen in the past week and the upcoming CAMS forecast indicate that the situation is moving towards the norm. The early development might be linked to the influence of the January 2022 eruption of the Hunga-Tonga-Hunga Ha’apai volcano on the upper atmosphere's composition. It remains uncertain if this will cause more severe ozone depletion and a larger ozone hole than usual in 2023.


The Antarctic ozone hole happens annually in spring. In the Southern Hemisphere stratosphere, it begins forming in mid- to late August when the Sun rises over the South Pole, and it closes by the end of November.

The combination of ERA-5 and CAMS reanalyses offers a 43-year dataset of total column ozone (TCO3), providing context for the development of each year.


In 2023, the development began remarkably early, influenced by the lowest minimum total column ozone values for the Southern Hemisphere in the past four decades during July. As a result, its total area is currently relatively high, even though its progression has adhered to a fairly typical growth pattern.

A possible reason for this unique start to the ozone hole season could be the higher atmospheric water vapor resulting from the eruption of the Hunga Tonga volcano in December 2021 and January 2022.


Chemical processes deplete ozone on clouds

This mechanism occurs because chemical processes fuel ozone depletion on polar stratospheric clouds, which are more likely to form when water vapor levels in the stratosphere are high.

Ozone Depleting Substances (ODS), primarily from human activities, accumulate in the stratosphere, causing a notable springtime decrease in Antarctic ozone. These substances, emitted by industries since the 1960s, were curbed after the 1987 Montreal Protocol phased out new emissions. Consequently, ODS concentrations in the stratosphere decreased, showing signs of ozone layer recovery.


Remember that ODS will impact the ozone layer for many decades, as their removal from the atmosphere takes a considerable amount of time. It is anticipated that within 50 years, their concentrations in the stratosphere will revert to pre-industrial levels, and there will no longer be any ozone holes.

CAMS Director Peuch: Monitoring ozone holes

CAMS Director, Vincent-Henri Peuch, states, "Our capability to offer three-dimensional analyses and ozone forecasts for the polar regions is a robust method for actively tracking the formation of ozone holes and evaluating the primary factors influencing these observations."


This provides us with insights into how specific events impact this year's Antarctic ozone hole formation, like the eruption of Hunga Tonga-Hunga Ha’apai last year, which elevated stratospheric water vapor. It's currently an ongoing query for scientists, and CAMS will persist in offering detailed monitoring data until the ozone hole dissipates in November or December 2023."

The European Centre for Medium-Range Weather Forecasts implements the Copernicus Atmosphere Monitoring Service (CAMS) on behalf of the European Commission, with funding from the European Union. CAMS aids global endeavors to protect the ozone layer by consistently monitoring and supplying data on its present condition.

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