EVERY YEAR, DURING THE AUSTRAL SPRING, A PHENOMENON IS OBSERVED IN THE ATMOSPHERE OVER ANTARCTICA: THE OPENING OF “OZONE HOLE”. DESPITE THE PROGRESS ACHIEVED THANKS TO THE MONTREAL PROTOCOL, THE PHENOMENON CONTINUES TO BE A MATTER OF GREAT CONCERN AND COULD CONTINUE FOR DECADES
What is the ozone hole?
The seasonal decrease in ozone concentration in the stratosphere, known as “ozone hole” it is a phenomenon that occurs mainly between 10 and 50 kilometers above the earth’s surface. This atmospheric layer plays a crucial role in the protection of the planet from ultraviolet (UV) rays emitted by the Sun.
In particular, stratospheric ozone is essential for absorbing most UV-B rays, which, if not filtered, can cause serious damage. Among them harmful effects Associated with excessive exposure to these rays are increased risk of skin cancer, development of cataracts, and impaired immune system in humans, as well as deleterious effects on flora and fauna.
In the 1980s, the scientific community began to understand the causes of this decrease, discovering that some gases, in particular chlorofluorocarbons (CFCs), emitted by human activities, were contributing to the degradation of stratospheric ozone, O₃.
In 1985, the situation worsened following the evidence of the formation of a huge hole over Antarctica, a phenomenon that caused worldwide concern.
In response to this environmental crisis, the Montreal Protocolan international agreement that has banned the use of CFCs and other harmful gases such as hydrofluorocarbons (HFCs), which are also potent greenhouse gases.
Despite the Protocol’s significant success, the problem has not been completely resolved. The gases that destroy this layer have a long persistence in the atmosphere; therefore, even if they are no longer produced, they will continue to damage it for decades. As a result, it will continue to widen for at least another forty years, although with a progressively reduced severity compared to the past.
What are the effects of this phenomenon on the climate and the economy?
Climate change and ozone depletion: two interconnected problems
Each spring, the thinning of the ozone layer has a direct impact on atmospheric patterns in the Southern Hemisphere. The latter, which include complex climate patterns such as temperatures, winds and precipitation, are significantly affected.
Results? The effects may hit already vulnerable regions, such as Australia and Latin America, with significant consequences for agriculture and water supplies.
For example, the strengthening of the westerly winds, known as Roaring Forties (Sailors call latitudes between 40 and 50 degrees south of the equator the Roaring Forties) in the middle latitudes has contributed to increased melting of ice shelves in Antarctica. This dangerous interaction not only alters the regional climate, but also has global repercussions.
In New Zealand and Australia, for example, there are significant changes in summer precipitation and temperature patterns. These changes not only affect the natural environment, but can also compromise agriculture and water security, exacerbating existing challenges related to climate change.
At the same time, the accumulation of greenhouse gases such as carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O) alters the chemical composition of the stratosphere, making the natural regeneration of ozone more complex. In this context, the fight against climate change becomes a categorical imperative.
But the story doesn’t end here.
Emerging threats: fires, rockets and space debris
Despite progress, new threats continually emerge. An example is the impact of mega forest fireslike those that hit Australia in 2019. These fires release large amounts of smoke and aerosols into the upper atmosphere, potentially contributing to ozone depletion.
As temperatures rise, fueling these increasingly frequent and intense events, additional emissions pose an additional threat.
Also the increase in the number of space rocket launches and the increase in space debris re-entering the atmosphere pose an increasing threat to the O₃ layer. These, in fact, burning during their returncontribute to these harmful chemical reactions. While, during takeoff, the spacecraft release gases and aerosols into the air which, when they reach the upper atmosphere, can chemically interact with ozone, accelerating its depletion process.
But what exactly is the upper atmosphere? These are the outermost layers of the gaseous envelope that envelops the Earth, in particular the stratosphere and the mesosphere, which extend from around 10-50 kilometers above sea level up to over 80 kilometres. The ozone layer is located precisely in the stratosphere. What to do? The first solution that comes to mind is to adopt strategies aimed at reducing global temperatures. And here the donkey falls…
Controversial proposals: solar geoengineering
One of the most controversial measures in the fight against global warming is the proposals of solar geoengineering. This technique involves injecting aerosols into the stratosphere with the intent of reflecting some of the solar radiation, thus temporarily lowering global temperatures. Although the idea may seem like an ingenious remedy to mitigate the effects of climate change, it raises numerous questions and concerns among the scientific community.
One of the main fears concerns the unpredictability of the consequences. The reflection of sunlight on a large scale could in fact alter atmospheric dynamics in an uncontrollable way, with the risk of causing unexpected local climate changes, disrupting global weather patterns and worsening the already critical situation of the ozone layer. The injected aerosols could chemically interact with ozone molecules, accelerating their destruction and leaving Earth more exposed to harmful ultraviolet rays.
Furthermore, the side effects of such interventions could have large-scale repercussions on natural ecosystems, altering fundamental climate and environmental cycles, such as monsoon rains and ocean winds. These potentially unpredictable changes risk producing devastating consequences for biodiversity and vital sectors such as agriculture, which strictly depend on climate balance.
People’s daily lives could also be affected, with unexpected changes in rainfall patterns or a decreased availability of essential natural resources, such as water and crops, which could threaten the food and water security of entire regions.
Before adopting any geoengineering intervention, therefore, it is essential to conduct in-depth analyzes of long-term risks and evaluate the global implications. There are also other more feasible proposals, such as reducing greenhouse gas emissions through sustainable technologies, the use of renewable energyenergy efficiency and the restoration of natural ecosystems. These strategies, while requiring global commitment, pose significantly fewer risks than geoengineering and offer lasting benefits for the planet.