The ozone hole over Antarctica in 2024 measured the seventh smallest since global recovery efforts began in the early 1990s, signaling continued success in mitigating ozone depletion.
According to data from NASA and NOAA, the ozone-depleted region reached a peak size of 8.5 million square miles (22.4 million square kilometers) on September 28, far smaller than the holes observed in previous decades. This reduction is a testament to the impact of the Montreal Protocol, a landmark international treaty adopted in 1987 to phase out ozone-depleting substances such as chlorofluorocarbons (CFCs).
Measuring Progress in Ozone Layer Recovery
The ozone layer, located in the stratosphere approximately 20 miles above Earth’s surface, acts as a vital shield, protecting life from harmful ultraviolet (UV) radiation. Its depletion, caused by human-made chemicals like CFCs used in refrigerants and aerosols, was first recognized as a major environmental threat in the 1970s. Since then, coordinated global action has led to a steady decrease in the presence of these harmful substances. “The gradual improvement we’ve seen in the past two decades shows that international efforts that curbed ozone-destroying chemicals are working,” said Dr. Paul Newman, chief scientist for Earth sciences at NASA’s Goddard Space Flight Center.
Despite these improvements, the ozone layer remains far from fully healed. The concentration of ozone over Antarctica reached a low of 109 Dobson Units on October 5, significantly below the pre-1979 level of 225 Dobson Units. Bryan Johnson, a NOAA research chemist, emphasized the ongoing challenge: “So there’s still a long way to go before atmospheric ozone is back to the levels before the advent of widespread CFC pollution.” The continued monitoring and reduction of CFCs remain essential to achieving complete recovery, which is projected to occur around 2066 if current trends continue.
Factors Contributing to This Year’s Reduced Ozone Hole
The smaller ozone hole observed in 2024 can be attributed to a combination of declining levels of CFCs and unusual atmospheric conditions. During the Antarctic winter, powerful circumpolar winds called the Polar Vortex trap ozone-depleting chemicals over the South Pole. As sunlight returns in the spring, these chemicals catalyze reactions that destroy ozone molecules, creating the ozone hole. However, this year, unexpected atmospheric warming events disrupted this cycle. In June, two rare “sudden stratospheric warming” events increased upper atmospheric temperatures by up to 30.6°F (17°C), weakening the Polar Vortex and allowing more ozone to flow into the region from higher latitudes.
This year’s ozone hole, though smaller, still covered an average area of nearly 8 million square miles (20 million square kilometers), about three times the size of the contiguous United States. “For 2024, we can see that the ozone hole’s severity is below average compared to other years in the past three decades,” said Stephen Montzka, a senior scientist at NOAA’s Global Monitoring Laboratory. Despite this, scientists caution against complacency, noting that full recovery is still decades away and requires continued global cooperation.
The Ongoing Impact of Ozone Depletion and Recovery Efforts
While the ozone layer is showing signs of recovery, the damage inflicted over past decades still has lasting consequences. Ozone-depleted regions allow more UV radiation to reach the Earth’s surface, increasing the risk of skin cancer, cataracts, and other health problems. It also impacts ecosystems, particularly in sensitive regions like Antarctica, where wildlife such as seals and penguins are at heightened risk of UV damage. Moreover, excess UV radiation can affect marine ecosystems by disrupting the growth of phytoplankton, the foundation of oceanic food chains.
Scientists use a combination of satellite instruments and ground-based observations, including weather balloons launched from the South Pole, to monitor ozone levels. These measurements provide a comprehensive view of the ozone hole’s size and severity each year. The data collected is crucial for understanding the effectiveness of international policies and guiding future actions to protect the ozone layer.
As the world continues to grapple with climate change and environmental challenges, the ongoing healing of the ozone layer serves as a reminder of the power of coordinated global action. The success of the Montreal Protocol demonstrates that international agreements can have a significant impact, even if the full benefits take decades to materialize. Researchers remain hopeful that with continued vigilance, the ozone layer will eventually return to its former strength, safeguarding life on Earth for generations to come.
