Country: World Source: World Meteorological Organization The Antarctic ozone hole in 2025 was one of the smallest in decades – testimony to the continuing success of international action to protect the Earth’s ozone layer which shields us against the sun’s harmful ultraviolet rays, according to a new report from the World Meteorological Organization (WMO). 2025 Antarctic ozone hole was one of smallest in recent decades Annual fluctuations occur despite long-term recovery trend World Ozone Day celebrates Montreal Protocol success UV radiation remains a threat to health Atmospheric monitoring is essential to inform policy In welcome news, the WMO Ozone Bulletin said that last year’s ozone hole ranked as the fourth to fifth smallest since severe depletion patterns were observed in 1992. This is the second consecutive year that both the depth and extent of the ozone hole were significantly below the 1990–2010 average. ear-to-year fluctuations are influenced by large-scale meteorological transport conditions which drive springtime ozone depletion, an event that occurs after almost every austral winter above Antarctica, and every 5 to 10 years in the northern hemisphere. In the Northern Hemisphere, total column ozone in 2025 was below average (negative anomalies) in a large region extending from Greenland and Europe to Central Asia, northern Japan and the Kamchatka Peninsula in the Russian Federation. These variations occur within the long-term trend towards the healing of the ozone layer, reflecting the success of the Montreal Protocol on Substances that Deplete the Ozone Layer , which phased out chemicals such as chlorofluorocarbons once found in refrigeration, fire-fighting foam and other common uses. “This is an environmental success story. Since 2000, the ozone layer has been recovering, and we can expect full recovery within several decades,” said WMO Secretary-General Celeste Saulo. The WMO Global Atmosphere Watch (GAW) network provides the critical, high-quality ground-based total column ozone observations required to accurately monitor ozone and ensure that long-term changes can be understood. About 90% of atmospheric ozone resides in the upper-level stratosphere. If all this ozone were brought down to the Earth’s surface, the resulting layer of pure ozone would be only approximately 3 millimetres thick. Yet, this thin layer blocks nearly all dangerous short-wave ultraviolet (UV) radiation from the Sun and protects life on Earth. While substantial progress has been made in addressing ozone depletion, measurements over the past decades show a significant increase in the number of days with high UV index values. The UV index was developed to track the depletion of the ozone layer and now serves as an international health standard for UV protection. Since the mid-1990s, UV radiation has increased by as much as 20% in some parts of Europe. Ground-based measurements show that this has been driven primarily by a reduction in cloud cover and an accompanying increase in annual sunshine duration. Higher UV exposure means a greater risk of skin cancer and other UV-related diseases among exposed populations. “In light of this trend, targeted and effective UV protection measures are of paramount importance,” says the Bulletin. World Ozone Day The WMO Ozone Bulletin was released for World Ozone Day on 16 September , which celebrates the 1987 Montreal Protocol, which successfully phased out ozone-depleting substances. This year’s theme is Global Action for a Cooler Planet, marking the tenth anniversary of the Kigali Amendment, which expanded the scope of the Montreal Protocol. The 2016 Kigali Amendment provides for a phase down of hydrofluorocarbons (HFCs), potent greenhouse gases that are used to replace ozone depleting substances. These chemicals are widely used in everyday cooling technologies such as refrigerators, air conditioners, insulating foams, and some medical and industrial equipment. Whilst they do not deplete the ozone layer, some HFCs trap thousands of times more heat than carbon dioxide, even though they remain in the atmosphere for a much shorter time. Over the past four decades, atmospheric measurements have demonstrated significant reductions in the concentrations of controlled ozone depleting substances. But there have been unexpected emissions, for instance of CFC-11 (until 2018) and HFC-23. This is why atmospheric monitoring remains essential to support targeted regulatory actions by national authorities. The Ozone Bulletin draws attention to the state of the observing system, which traditionally relied primarily on Dobson and Brewer spectrophotometers. The number of active stations has gradually decreased from around 130 in the early 2000s to 110 today – with stations often closing in areas where observations are most sparse. Next-generation array spectrometers have grown rapidly, but these focus on air quality measurements rather than stratospheric ozone monitoring. Long-term evolution of annual mean total column ozone, averaged from 60°S to 60°N. The median of available satellite and ground-based datasets is shown. The ODS-related ozone decline from the 1960s to the 1990s can be clearly seen, as can the beginning of the recovery of ozone starting in 2000. Source: Adapted from Weber et al. (2022) The World Meteorological Organization is the United Nations System’s authoritative voice on Weather, Climate and Water. Clare Nullis WMO media officer cnullis@wmo.int +41 79 709 13 97 Global Communication and Engagement Media Contact media@wmo.int
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