The ozone layer, for decades a symbol of the planet’s environmental fragility, is finally showing robust signs of recovery. In 2025, data released by the World Meteorological Organization (WMO), linked to the United Nations, reveal that the annual hole over Antarctica was the smallest in decades, marking a turning point in the fight against atmospheric destruction. This news, celebrated by scientists and environmentalists, represents not only a scientific advance, but also a triumph of international cooperation and political persistence in favor of the environment2.

The ozone layer is a band of gas located between 11 and 40 kilometers above the Earth’s surface, in the stratosphere. Its function is vital: it filters the sun’s harmful ultraviolet (UV) rays, protecting living beings from genetic mutations, skin cancer, cataracts and damage to the immune system. The destruction of this layer, which has been observed with intensity since the 1980s, was mainly caused by chlorofluorocarbons (CFCs), chemical compounds used in aerosols, refrigerators and industrial foams. The discovery of the hole over Antarctica, which forms every spring, generated an unprecedented global mobilization, culminating in the signing of the Montreal Protocol in 1987, an international treaty that gradually banned ozone-depleting substances4.

In 2024, satellites and atmospheric measuring instruments recorded a thickness of the ozone layer higher than the historical average. The ozone mass deficit over Antarctica, which calculates how much of the substance is no longer present in the atmosphere, reached 46.1 million tons — a value lower than that observed between 1990 and 2020. In addition, the hole appeared later than usual and closed quickly after reaching its peak, similar behavior to that observed between 2015 and 2019. According to the WMO report, this persistent late onset is a robust indication of the initial recovery of the ozone hole.

The recovery is not limited to Antarctica. Over the Arctic, the thickness of the layer was 14% greater in March 2024 compared to the average between 1960 and 2023. This improvement resulted in a reduction of up to 5% in the incidence of ultraviolet radiation during the summer in the northern hemisphere. The Dobson unit (DU), used to measure the total amount of ozone in the atmosphere, recorded values between 55 and 60 units above average in the Arctic, which represents a significantly thicker layer. These data indicate that the recovery is occurring globally, although with regional variations.

Science attributes this recovery to multiple factors. The greater solar activity recorded in recent years favors the formation of ozone, since solar radiation interacts with oxygen in the stratosphere to produce the gas. In addition, atmospheric dynamics such as the transport of ozone-rich air from outside the polar regions contribute to the recomposition of the layer. Recent research also points out that the initial state of ozone in the Antarctic winter and the processes of photochemical loss directly influence the extent of the hole observed in the spring.

However, the main driver of recovery remains the Montreal Protocol. Considered one of the most successful environmental treaties in history, it has been ratified by 198 countries and eliminated more than 99% of the consumption and production of ozone-depleting chemicals. The UN estimates that, if current policies are maintained, the ozone levels of the 1980s will be restored by 2066 over Antarctica, in 2045 over the Arctic, and from 2040 on the rest of the planet.

The year 2025 marks the 40th anniversary of the Vienna Convention, which gave rise to the Montreal Protocol. The date was celebrated on the International Day for the Preservation of the Ozone Layer, on September 16, with optimistic statements from world leaders and experts. António Guterres, UN Secretary-General, said that “this breakthrough reminds us that when nations listen to the warnings of science, progress is possible”. Matt Tully, leader of the WMO’s scientific advisory group on ozone, stressed that the work is not yet complete and that it is essential to maintain systematic monitoring of both stratospheric ozone and substances that deplete it3.

The recovery of the ozone layer also has positive implications for combating climate change. Many of the ozone-depleting gases are also potent greenhouse gases. The elimination of these compounds contributes to the reduction of global warming. In addition, strengthening the ozone layer improves the resilience of ecosystems, protects biodiversity, and reduces risks to human health, especially in tropical and subtropical regions, where exposure to UV rays is more intense.

Despite the advances, scientists warn of the need for continued vigilance. Substances that replace CFCs, such as hydrofluorocarbons (HFCs), although they do not deplete ozone, have a high global warming potential. The Kigali Amendment to the Montreal Protocol, adopted in 2016, aims to limit the use of these compounds and represents the next step in the global climate agenda. Effective implementation of this amendment will be crucial to ensure that gains made in ozone depletion are not compromised by new atmospheric challenges.

Brazil, in turn, has played an important role in preserving the ozone layer. The country was one of the first to ratify the Montreal Protocol and implemented policies to replace CFCs in industrial and commercial sectors. The Brazilian energy matrix, predominantly clean, also contributes to the reduction of emissions that affect the atmosphere. However, experts such as Paulo Artaxo, from the University of São Paulo, warn that it is necessary to expand monitoring and invest in environmental education to consolidate advances and avoid setbacks.

In summary, the recent news about the reduction of the ozone hole is cause for celebration and hope. They demonstrate that science, when combined with political action and international cooperation, is capable of reversing profound environmental damage. The recovery of the ozone layer is an inspiring example that it is possible to restore the ecological balance of the planet – as long as there is commitment, persistence and respect for scientific evidence. The challenge now is to stay the course, strengthen existing treaties, and ensure that future generations inherit a safer sky and a more protected Earth.