Antarctic Ozone Hole Shrinks to Smallest Since 2019, Scientists Say

For the first time in several years, the seasonal ozone hole over Antarctica has shrunk to its smallest and shortest-lived size since 2019, according to data released by U.S. and European climate monitoring agencies. Scientists say the trend offers encouraging evidence that international efforts to heal Earth’s protective atmospheric shield are working, even as uncertainty remains about how quickly full recovery will unfold.

The ozone hole forms each Southern Hemisphere spring when man-made chemicals historically depleted ozone in the upper atmosphere, reducing Earth’s shield against harmful ultraviolet radiation. In 2025, satellites and climate observatories showed that the hole was notably smaller than in recent years and began to break up earlier than average. European data show the 2025 ozone hole was the smallest and shortest-lasting since 2019.


“This year’s measurements are a reassuring sign that the ozone layer is on a path toward long-term recovery,” scientists from the Copernicus Atmosphere Monitoring Service, NASA, and the National Oceanic and Atmospheric Administration (NOAA) said in coordinated analyses released this fall.

What the Numbers Show

Using satellite observations, researchers track how much of the stratospheric ozone dips below a key threshold that defines the “ozone hole.” In 2025, the average size at peak depletion was roughly 7.23 million square miles during the Southern Hemisphere spring months, a measurement that places it among the smallest recorded since long-term monitoring began in the early 1990s.

The region also started breaking up nearly three weeks earlier than the ten-year average, a sign of faster seasonal recovery than in many recent years. This marks the second consecutive season of relatively small ozone holes after larger, persistent depletion events between 2020 and 2023.

NASA and NOAA scientists confirmed that, when ranked against the observational record dating back to 1992, the 2025 hole is the fifth smallest measured in more than three decades. Those measurements align with independent European data.

What Caused the Improvement

Experts attribute the shrinking ozone hole largely to ongoing cuts in ozone-depleting substances such as chlorofluorocarbons (CFCs) and halons, which were heavily used in refrigeration and industrial products in the 20th century. The 1987 Montreal Protocol, a landmark global treaty, has phased out most of these chemicals and has prompted follow-up agreements that tightened controls in subsequent decades.

Since the protocol entered into force, levels of human-made ozone-depleting gases in the stratosphere have dropped significantly. According to NOAA and NASA, levels of the most potent ozone-depleting substances have fallen by about a third from their peak years. That decline correlates with smaller and less persistent ozone holes over time.

Scientists caution that natural atmospheric conditions also influence ozone depletion each year. Weather patterns, stratospheric temperatures, and winds over Antarctica can either slow or accelerate ozone loss. Still, the repeated appearance of smaller ozone holes in recent years points to a broader trend driven by reduced emissions of damaging chemicals.

Why It Matters

The ozone layer sits about 7 to 31 miles above Earth’s surface and absorbs much of the Sun’s harmful ultraviolet (UV) radiation. Without ozone, more UV rays would reach the ground, increasing risks of skin cancer, cataracts, immune system suppression, and damage to crops and marine ecosystems.

Large ozone holes in the past were linked to spikes in health problems and environmental disruption. The shrinking of the 2025 ozone hole suggests that protective measures taken more than three decades ago are paying off and may spare future generations from the worst consequences of ozone depletion.

Still on the Road Ahead

Despite the good news, scientists say the ozone layer is not fully restored. Models predict that ozone levels over Antarctica may not return to 1980 baseline levels, before significant depletion occurred, until the middle of the 21st century or later. Research published by monitoring agencies suggests recovery projections near 2066 or beyond, depending on climate dynamics and future emissions.

Researchers also emphasize the need for continued vigilance. New industrial activities, such as increased rocket launches and unregulated chemical emissions, could introduce ozone-depleting substances into the stratosphere, slowing recovery.

Still, the findings this year, a smaller, short-lived ozone hole, are being hailed by scientists as a rare piece of positive climate news. They say it underscores how coordinated international action can produce measurable environmental benefits on a global scale.