NASA NOAA Rank 2025 Ozone Hole as 5th Smallest Since 1992
In 2025, the ozone hole over Antarctica was notably smaller compared to many previous years, ranking as the fifth smallest since 1992. This assessment was reported by NASA and the National Oceanic and Atmospheric Administration (NOAA). The year 1992 marks a significant point when the international agreement to phase out ozone-depleting chemicals began to take effect. Despite its continental scale, the 2025 ozone hole’s reduced size indicates ongoing progress toward recovery.
During the peak depletion period from September 7 to October 13, the ozone hole covered an average area of approximately 7.23 million square miles (18.71 million square kilometers). This size is roughly twice that of the contiguous United States. Notably, the 2025 ozone hole began breaking up nearly three weeks earlier than the average breakup time observed over the past decade, signaling a positive trend in ozone recovery.
Details on the 2025 Ozone Hole and Its Significance
The largest extent of the ozone hole in 2025 was recorded on September 9, reaching 8.83 million square miles (22.86 million square kilometers). This maximum size was about 30% smaller than the largest ozone hole ever observed, which occurred in 2006 and measured an average area of 10.27 million square miles (26.60 million square kilometers). Paul Newman, a senior scientist at NASA’s Goddard Space Flight Center and leader of NASA’s ozone research team, explained that ozone holes have been trending smaller since the early 2000s. He noted that the holes are forming later in the season and dissipating earlier, but emphasized that full recovery to 1980s levels remains a long-term goal.
NASA and NOAA scientists attribute this gradual recovery to the controls on ozone-depleting substances established by the Montreal Protocol and its amendments. These international agreements have been effective in reducing the presence of harmful chemicals in the stratosphere, allowing the ozone layer to slowly heal. The ozone layer, located between 7 and 31 miles above Earth’s surface in the stratosphere, serves as a vital shield that protects life on Earth from harmful ultraviolet (UV) radiation. Reduced ozone levels allow more UV rays to reach the surface, which can cause crop damage and increase health risks such as skin cancer and cataracts.
Ozone Depletion Causes and Ongoing Monitoring Efforts
Ozone depletion occurs when human-made compounds containing chlorine and bromine rise into the stratosphere. These compounds, including chlorofluorocarbons (CFCs), were once commonly used in aerosol sprays, foams, air conditioners, and refrigerators. In the stratosphere, UV radiation breaks these molecules apart, releasing chlorine and bromine atoms that destroy ozone molecules. These chemicals can remain in the atmosphere for decades or even centuries.
Stephen Montzka, a senior scientist with NOAA’s Global Monitoring Laboratory, stated that since around 2000, levels of ozone-depleting substances in the Antarctic stratosphere have declined by about one-third compared to pre-ozone-hole levels. The Montreal Protocol, signed in 1987, led countries to replace these harmful substances with safer alternatives. Paul Newman highlighted that the 2025 ozone hole would have been over one million square miles larger if chlorine levels had remained as high as they were 25 years ago.
Despite these successes, banned chemicals still persist in older products like building insulation and landfills. As emissions from these legacy sources decline over time, projections indicate that the Antarctic ozone hole will fully recover around the late 2060s.
NASA and NOAA have used satellite data to track ozone levels since 1979. When considering this longer record, the 2025 ozone hole ranks as the 14th smallest in 46 years of observations. Year-to-year variations in ozone size are influenced by factors such as temperature, weather patterns, and the strength of the polar vortex—a wind system that circles Antarctica. A weaker-than-normal polar vortex in August 2025 contributed to warmer temperatures and likely helped reduce the ozone hole’s size.
Ozone monitoring is conducted using instruments aboard NASA’s Aura satellite, NOAA-20 and NOAA-21 satellites, and the Suomi National Polar-orbiting Partnership satellite, which is jointly operated by NASA and NOAA. Additionally, NOAA uses weather balloons and ground-based instruments at the South Pole Atmospheric Baseline Observatory to measure ozone levels directly. In 2025, balloon data recorded the lowest ozone concentration at 147 Dobson Units on October 6. For context, the lowest ever recorded at the South Pole was 92 Dobson Units in October 2006.
The Dobson Unit measures the total number of ozone molecules in a column of the atmosphere above a specific location. A value of 100 Dobson Units corresponds to a layer of pure ozone about 1 millimeter thick under standard conditions.
The continued monitoring and analysis by NASA and NOAA provide crucial insights into the recovery of the ozone layer. The 2025 data reinforce that international efforts to reduce ozone-depleting substances are effective, and the ozone layer remains on track to recover fully later this century.
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Source: original article.