The Earth’s ozone layer—the thin shield that protects life from harmful ultraviolet (UV) radiation—is healing. According to the 2024 WMO Ozone Bulletin, the ozone hole last year was smaller than in recent years, signaling continued progress toward full recovery by mid-century.
The report, released on World Ozone Day (16 September) and marking the 40th anniversary of the Vienna Convention, celebrates one of humanity’s greatest environmental success stories. It highlights how science-guided policies, notably the Montreal Protocol, have reversed decades of ozone depletion caused by human-made chemicals.
UN Secretary-General António Guterres hailed the achievement:
“Forty years ago, nations came together to take the first step in protecting the ozone layer—guided by science, united in action. Today, the ozone layer is healing. This reminds us that when nations heed the warnings of science, progress is possible.”
The Montreal Protocol has eliminated over 99% of ozone-depleting substances (ODS) once widely used in refrigeration, aerosols, firefighting foam, and even hairspray. This global pact has not only helped restore the ozone layer but also averted millions of cases of skin cancer, cataracts, and ecosystem damage.
The Bulletin noted that the Antarctic ozone hole in 2024 was smaller than the 1990–2020 average.
The maximum ozone mass deficit (OMD) was 46.1 million tonnes—below recent peaks.
Onset of ozone depletion was delayed, followed by a faster-than-usual recovery.
Global ozone cover was higher than in recent years, particularly across the Northern Hemisphere.
These trends, while influenced by natural variability, are increasingly recognized as robust signals of ozone layer recovery.
The Bulletin emphasizes that the road to recovery is not automatic. Ongoing systematic monitoring of ozone and ODS levels is crucial to ensure compliance and detect emerging risks.
The Global Atmosphere Watch Programme, led by WMO, provides global standards for measurements, calibration, and data sharing. This network—built on collaboration and open science—has been key to the Montreal Protocol’s success.
The Kigali Amendment (2016) expanded the scope of the Montreal Protocol by committing nations to phase down hydrofluorocarbons (HFCs), potent greenhouse gases that replaced ODS. Already ratified by 164 countries, this action is projected to avoid up to 0.5°C of global warming by 2100.
This dual benefit—protecting ozone and tackling climate change—shows how international treaties can deliver co-benefits across multiple environmental challenges.
The latest Scientific Assessment of Ozone Depletion (2022) projects:
Recovery to 1980 levels by 2040 for most of the world.
By 2045 over the Arctic.
By 2066 over Antarctica.
The next scientific assessment is due in 2026, but current evidence suggests the world remains firmly on track—if vigilance and cooperation continue.
WMO Secretary-General Celeste Saulo noted that the theme of World Ozone Day—“From Science to Global Action”—mirrors WMO’s ethos of “Science for Action.” The ozone story offers a vital reminder: when scientific evidence guides policymaking, and nations act collectively, global crises can be reversed.
Protecting the ozone layer has also advanced multiple UN Sustainable Development Goals (SDGs):
Good Health (SDG 3) through reduced UV-related diseases.
Climate Action (SDG 13) via the Kigali Amendment.
Zero Hunger (SDG 2) and Life on Land (SDG 15) by shielding crops and ecosystems from excessive UV radiation.
Despite the historic success of the Montreal Protocol, scientists warn against complacency. The fight is not over—continuous monitoring, enforcement, and vigilance against substitute chemicals remain essential.
The ozone story stands as proof of what multilateral cooperation can achieve. At a time of geopolitical tension and climate challenges, it offers hope: global problems demand global solutions—and science must lead the way.