The ozone hole is closing. A result achieved through cooperation between states and the implementation of environmental agreements. An example to follow.
The ozone hole is closing. The historic announcement comes from the United Nations (UN): the report Scientific assessment of ozone depletion 2022 takes stock of the environmental challenge that humanity has been waging against the ozone hole since the 1980s. After various preliminary indications in recent years, the good news has finally arrived — and it is definitive: by 2045 the hole in the ozone layer above the Arctic will have fully recovered, returning to pre-1980 levels.
The ozone layer is the layer of the atmosphere in which the majority of ozone is concentrated: ozone retains and absorbs part of the energy coming directly from the Sun, in particular the ultraviolet rays that are harmful to life on Earth. The ozone layer is therefore a fundamental shield for living beings. Given the circulation of air across the planet, this gas accumulates more at high altitudes and at the poles.
It was precisely by studying the poles, and in particular the South Pole, that scientists discovered how this layer was thinning year by year, to the point that the expression "ozone hole" was coined. Without the protection of the ozone layer, the risk is that of receiving higher levels of harmful solar radiation, increasing the risk of developing skin cancers, accelerating skin ageing and generally disrupting the immune system of all living beings.
The first person to speak of an "ozone hole" was the American scientist Frank Sherwood Rowland, who in 1995 received the Nobel Prize in Chemistry for his work on atmospheric chemistry. His best-known contribution is the 1974 discovery that chlorofluorocarbons (CFCs) contribute to the thinning of the ozone layer. Further research followed, and in 1985 another scientist, Joseph Charles Farman, confirmed the alarming finding: ozone was disappearing above the South Pole. That same year, during the Vienna Convention, the United Nations recognised the fundamental importance of preventing damage to the stratospheric ozone layer.
International meetings, treaties and new rules followed: just two years later, in 1987, 46 countries signed the Montreal Protocol, which imposed a progressive reduction in the production of CFCs — the powerful greenhouse gases that warm the atmosphere up to 7,000 times more than CO2, long used as refrigerants in fridges, as solvents, and as propellants in aerosol cans.
In 1988 the phenomenon began to appear above the North Pole too, a discovery that led, in 1990, to more than 90 countries signing up to a suspension of CFC production. Over more than 30 years, another historic step forward in combating the ozone hole (and, more broadly, climate change) has been the banning of another dangerous chemical compound: hydrofluorocarbons (HFCs), greenhouse gases 14,000 times more potent than CO2. The agreement was reached by the same nations that had signed the Montreal Protocol, at the 28th summit of the parties, held in Kigali, Rwanda, in 2016.
Research today tells us that the ozone hole above the Arctic will close and the ozone layer will return to the levels that existed before 1980. This will happen between 2040 and 2045, while the hole above the South Pole will take longer (2066 is the figure being cited). Despite the good news, the UN points out that, while ozone in the upper bands of the stratosphere is improving, it is worth noting that in the lower bands it has so far shown no signs of recovery — a signal that efforts still need to be made.
The hole in the ozone layer is not considered a primary driver of global warming. However, many of the substances responsible for the thinning, such as CFCs and HFCs, contribute to rising temperatures at the Earth's surface. Moreover, the ban on hydrofluorocarbons has only come about recently. As we know, CO2 is not the only greenhouse gas responsible for global warming, and therefore any action taken for the good of the atmosphere — including measures to counter the ozone hole — can only have beneficial effects on mitigating the impacts of climate change.
At the time of the ozone hole, there was no shortage of deniers: various scientists and institutions maintained that the phenomenon was driven exclusively by natural causes, such as volcanic eruptions. But thorough studies demonstrated the determining role of human-made chemical compounds, until, thanks to the ban on CFC production, MIT announced in 2016 that the hole had shrunk by approximately 4 million square kilometres compared to the year 2000, when the thinning reached its greatest extent.
For this reason, the news that the ozone hole is healing is proof that environmental agreements, when enforced, work. This experience allows us to draw an interesting parallel with the ongoing climate crisis: in 1990, after a large number of states decided to cooperate at a global level, it still took a further decade before the environmental problem in question reached its peak. In other words, there were no guarantees of success, yet the states that stopped producing CFCs listened to the voice of scientists.
A sign of hope for the future: the next targets in terms of reducing climate-altering gases and achieving climate neutrality can only be reached when all states begin to cooperate in earnest, implementing the agreements they have entered into. It would be worth drawing on this experience before the next COP.
