{"id":355866,"date":"2025-12-11T08:59:45","date_gmt":"2025-12-11T08:59:45","guid":{"rendered":"https:\/\/eodatahub.com\/index.php\/2025\/12\/11\/observer-antarctic-ozone-hole-closes-early-indicating-signs-of-recovery\/"},"modified":"2025-12-11T08:59:45","modified_gmt":"2025-12-11T08:59:45","slug":"observer-antarctic-ozone-hole-closes-early-indicating-signs-of-recovery","status":"publish","type":"post","link":"https:\/\/eodatahub.com\/index.php\/2025\/12\/11\/observer-antarctic-ozone-hole-closes-early-indicating-signs-of-recovery\/","title":{"rendered":"OBSERVER: Antarctic ozone hole closes early, indicating signs of recovery"},"content":{"rendered":"

OBSERVER: Antarctic ozone hole closes early, indicating signs of recovery
\nenora@ALSOcons\u2026<\/span><\/span><\/p>\n

Data from the Copernicus Atmosphere Monitoring Service<\/a> (CAMS) confirmed the closure of the 2025 Antarctic ozone hole on 1 December, marking the weakest and shortest\u2011lived ozone hole in five years. For the second year in a row, the average extent and duration of the ozone hole were notably less compared to the very large, long\u2011lasting holes observed between 2020 and 2023. These recent developments indicate global progress on ozone layer recovery efforts under the Montreal Protocol<\/a> and its amendments. Since it entered into force in January 1989, the Protocol has led to the phase\u00a0out of 99% of ozone\u2011depleting substances (ODS)\u2013synthetic compounds used in refrigeration, air conditioning, foams, and aerosol sprays which significantly accelerate the depletion of the ozone layer when they reach the stratosphere. By tracking ODS and monitoring the ozone hole, CAMS plays a critical role in the ongoing recovery efforts, turning scientific evidence into coordinated action to protect the ozone layer. In this Observer, we examine how this year\u2019s ozone hole developed, what recent variability tells us about long-term recovery, and how new observational capabilities such as Sentinel-5 contribute to understanding these trends.<\/h5>\n

\u00a0<\/p>\n

A smaller and shorter\u2011lived ozone hole in 2025<\/h3>\n

In 2025, the Antarctic ozone hole developed relatively early in mid\u2011August and reached a maximum area of around 21.08 million km\u00b2 in early September, significantly below the 26.1 million km\u00b2 recorded in 2023. It gradually reduced to an area between 15 and 20 million km\u00b2 in September and remained fairly stable until the end of October, followed by a rapid decline in November. Indicators pointed to the possibility of a very early closure in November, but a persistent small area of low ozone delayed the closure until 1 December. Nevertheless, the 1 December closure marked the earliest since 2019.<\/p>\n\n

\n\"Chart
Charts showing the evolution over time of the minimum detected total column ozone values (left) and the estimated amount of ozone removed from the atmosphere (right) from July to December. Credit:<\/em>\u00a0European Union, CAMS\/ECMWF.<\/em><\/figcaption><\/figure>\n

\u00a0<\/p>\n

Alongside the reduced area and duration, CAMS analyses show higher\u2011than\u2011usual minimum values of the ozone column and lower ozone mass deficit values compared with recent years.<\/p>\n\n

\n\"Charts
Charts showing the evolution over time of the minimum detected total column ozone values (left) and the estimated amount of ozone removed from the atmosphere (right) from July to December. Credit:<\/em>\u00a0European Union, CAMS\/ECMWF.<\/em><\/figcaption><\/figure>\n

\u00a0<\/p>\n

The ozone hole is generally defined as the area where total column ozone, the integrated amount of ozone in a vertical column of air above the surface, falls below 220\u00a0Dobson Units<\/a> (DU). One DU is a unit used to describe total column ozone and corresponds to a 0.01-millimetre-thick layer of pure ozone at the Earth\u2019s surface under\u00a0standard conditions<\/a>. This threshold allows scientists to compare the size and severity of the ozone hole consistently from year to year.<\/p>\n

\u00a0<\/p>\n

CAMS monitoring critical to ozone surveillance<\/h3>\n

CAMS, implemented by the\u00a0European Centre for Medium\u2011Range Weather Forecasts<\/a> (ECMWF), plays a central role in monitoring the ozone layer. The Service maintains a dedicated\u00a0ozone monitoring page<\/a> which provides daily maps, charts, and animations showing the evolution of the Antarctic ozone hole every year. These products include forecasts and analyses of total column ozone, as well as ozone concentrations at different altitudes in the atmosphere, both globally and over the polar regions, up to five days ahead.<\/p>\n

CAMS combines a state\u2011of\u2011the\u2011art numerical model of the atmosphere with a wide range of satellite observations. By assimilating these observations into the\u00a0ECMWF Integrated Forecasting System<\/a> (IFS), CAMS generates a consistent, high\u2011resolution picture of ozone and related variables. These forecasts and analyses are regularly evaluated against independent in situ observations, such as\u00a0ozonesondes<\/a> launched on weather balloons from several Antarctic stations, to ensure accuracy and reliability.<\/p>\n

In 2023, CAMS further increased its capabilities by incorporating a detailed representation of stratospheric chemistry in its global modelling system based on the\u00a0Belgian Assimilation System for Chemical Observations<\/a> (BASCOE). Developed by the\u00a0Royal Belgian Institute for Space Aeronomy<\/a>, BASCOE introduces 57 additional chemical species into the ECMWF IFS, allowing CAMS to forecast key species which influence ozone depletion.<\/p>\n\n

\n\"Animation
Animation of ozone depleting substances contributing to the onset of the Antarctic ozone hole since 1 July 2025. Credit: European Union, CAMS\/ECMWF. \u00a0Watch the full video <\/em>here<\/em><\/a>.<\/em><\/figcaption><\/figure>\n

\u00a0<\/p>\n

Sentinel-5: a new view of the 2025 ozone hole<\/h3>\n

The\u00a0publication<\/a> of the first Copernicus Sentinel\u20115A images at the end of November marked a new milestone for European atmospheric monitoring. One of the images shows the 2025 ozone hole on 13 October, marking a clearly defined region with total column ozone values below 220 DU.\u00a0<\/p>\n\n

\n\"Data
This Copernicus Sentinel-5A image acquired on 13 October shows the Antarctic ozone hole.\u00a0Credit: European Union, Copernicus Sentinel-5 data (2025), modified and processed by\u00a0<\/em>ESA<\/em><\/a>\/<\/em>S&T<\/em><\/a>\/<\/em>TriOpSys<\/em><\/a>\/<\/em>BIRA<\/em><\/a>.<\/em><\/figcaption><\/figure>\n

\u00a0<\/p>\n

The Sentinel\u20115 instrument, part of the Copernicus Sentinel family, was\u00a0launched<\/a> aboard the first EUMETSAT Meteorological Operational Second Generation (MetOp) satellite in August. Developed by a consortium of companies from 15 European countries led by Airbus in Germany, Sentinel\u20115 is an Ultraviolet Visible Near\u2011infrared Short\u2011wave infrared (UVNS) spectrometer designed to strengthen Europe\u2019s capabilities in atmospheric composition monitoring, weather forecasting, and climate services. Sentinel\u20115 feeds data into the\u00a0Copernicus Data Space Ecosystem<\/a>, strengthening the information base available to CAMS and the\u00a0Copernicus Climate Change Service<\/a> (C3S).<\/p>\n

Following a polar, sun\u2011synchronous orbit at an altitude of about 832 kilometres, Sentinel\u20115 completes 14 to 16 orbits per day and provides daily global coverage with high spatial resolution, including detailed information over the polar region where the Antarctic ozone hole develops. It also measures a range of other trace gases including nitrogen dioxide, formaldehyde and methane, as well as aerosols. These measurements are important for monitoring air pollution, solar energy potential, and the\u00a0radiative forcing<\/a> of the atmosphere.<\/p>\n

\u00a0<\/p>\n

The science behind the ozone hole and why variability persists<\/h3>\n

The ozone layer is located in the stratosphere, which extends from roughly 7 to 20 kilometres altitude, depending on latitude, season, and weather, and up to around 50 kilometres. It acts as a protective shield by absorbing most of the Sun\u2019s harmful ultraviolet radiation. In the 1970s and 1980s, scientists discovered that certain widely used synthetic compounds containing chlorine, bromine, and fluorine were depleting this layer. The effect was most dramatic over Antarctica, where severe ozone loss led to the emergence of the ozone hole, triggering urgent international action.<\/p>\n

The onset of the Antarctic ozone hole each year is driven by a combination of meteorological conditions and chemical processes over the polar stratosphere. During the Southern Hemisphere winter, strong stratospheric winds form a stable polar vortex over Antarctica. Within this vortex, temperatures fall to extremely low values, allowing polar stratospheric clouds to form.<\/p>\n

When sunlight returns in spring (from August onwards), chemical reactions on the surface of these clouds release highly reactive forms of chlorine and bromine from ozone\u2011depleting substances, which rapidly destroy ozone molecules. This triggered a substantial reduction in ozone concentrations and a marked drop in total column ozone below the 220 DU threshold. As temperatures rise and the polar vortex breaks down towards the austral summer, the summer in the Southern Hemisphere, which typically occurs between December and February, ozone\u2011rich air from lower latitudes mixes into the polar stratosphere and the ozone hole closes.\u00a0<\/p>\n

The amount of ozone\u2011depleting substances in the stratosphere is slowly declining thanks to the Montreal Protocol. At the same time, the extent and duration of the ozone hole can vary from year to year due to variability in stratospheric winds and temperatures as well as exceptional events such as major volcanic eruptions. Climate change also affects the stratosphere. As the lower atmosphere warms, the stratosphere tends to cool, which can favour conditions for ozone\u2011destroying chemical reactions.<\/p>\n\n

\n\"Data
Maximum yearly extent of the ozone hole from 1979-2025. Credit: European Union, CAMS\/ECMWF.<\/figcaption><\/figure>\n

\u00a0<\/p>\n

This phenomenon explains why the very large and long\u2011lasting ozone holes from 2020 to 2023 can coexist with the more moderate seasons of 2024 and 2025 when the overall amount of ozone\u2011depleting substances is declining. Persistent monitoring is essential to distinguish natural variability and exceptional events from the underlying long\u2011term recovery.<\/p>\n

\u00a0<\/p>\n

Global progress and EU environmental policy objectives<\/h3>\n

In March 2025, a\u00a0new study<\/a> reported that the observed recovery of the Antarctic ozone hole is primarily attributable to the reduction in ozone\u2011depleting substances following the implementation of the Montreal Protocol. Based on scientific assessments, if current trends continue, ozone over Antarctica is likely to return to a level close to its 1980 values by about 2066.<\/p>\n

For the EU, progress on ozone recovery provides important lessons for broader climate and environmental policy. It shows that early, science\u2011based and cooperative international agreements can reverse environmental damage and that robust observation and monitoring systems are essential both to trigger action and to verify that actions taken are effective. High-quality and reliable data delivered by CAMS, which is part of Copernicus under the\u00a0EU Space Programme<\/a>, together with observations from Copernicus satellite missions such as Sentinel\u20115A, are crucial to continue tracking the ozone layer\u2019s recovery and monitoring greenhouse gases and air pollutants. This sustained flow of transparent, robust information underpins EU climate and environmental objectives and helps demonstrate, in a measurable way, the impact of coordinated international policy.<\/p>\n

To learn more about the Antarctic ozone hole development,\u00a0watch this video<\/a> featuring ozone hole expert Johannes Flemming.<\/p>\n

All CAMS ozone\u2011related data products, including forecasts, analyses of ozone concentrations, stratospheric temperatures and ozone\u2011depleting substances, are freely available via the\u00a0Atmosphere Data Store<\/a>.<\/p>\n

\"Data<\/p>\n

Read More<\/a><\/p>","protected":false},"excerpt":{"rendered":"

OBSERVER: Antarctic ozone hole closes early, indicating signs of recovery enora@ALSOcons\u2026 Thu, 11\/12\/2025 – 09:59 Data from the Copernicus Atmosphere Monitoring Service (CAMS) confirmed the closure of the 2025 Antarctic ozone hole on 1 December, marking the weakest and shortest\u2011lived ozone hole in five years. For the second year in a row, the average extent…
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