A great success from which we must draw inspiration to manage the other threats to our environment.
Usually, when the United Nations talks about climate, it is to sound the alarm about the disasters that await us around the corner. But once is not custom, the institution arrived with excellent news: the ozone layer is doing like a charm! A good opportunity to look back on a scientific adventure that commands respect, and which shows that despite its current setbacks, humanity is not necessarily a hopeless case.
Ozone is a gas that forms when solar radiation breaks the bonds between the atoms that make up oxygen. The latter then seek to recombine, because alone, they are energetically unstable. This results in the formation of ozone (O3).
When it is found in the lower layer of the atmosphere, it is bad news; in this context, it is technically a greenhouse gas that is also toxic in large quantities. But the game changes completely when you climb higher in the atmosphere.
A shield for all civilization
At a few tens of kilometers of altitude, we arrive in another layer of the atmosphere: the stratosphere. However, in the upper part of the latter, there is a relatively high concentration of ozone. You will have understood: this is the famous “ozone layer”. In terms of volume, it would be almost negligible. But it actually plays an absolutely fundamental protective role.
Indeed, ozone has the particularity of absorbing certain lengths of electromagnetic waves, in particular UV. However, these are extremely dangerous. They have a very high mutagenic power. In the event of significant exposure, they can in particular cause cancer. Life as we know it owes a great debt to the ozone layer.
But in the 1970s, researchers began to realize that ozone concentration was plummeting. An excessively worrying observation, knowing the role of shield of this natural structure.
Worse, they even observed the gradual appearance of a region almost empty of this gas: this is the famous “hole in the ozone layer” that we have all heard of. The conclusion was therefore clear: it was absolutely necessary to find the origin of this phenomenon, otherwise the number of cancers in the next generations would explode.
An unprecedented mobilization
It started with a great mobilization of the scientific community. The objective: to find the origin of this decline. Soon enough, a culprit emerged. These were chlorofluorocarbons (CFCs), a class of fluorinated gases frequently used in aerosols and refrigeration systems.
We therefore have a worrying situation, a well-identified culprit and clear courses of action. All the ingredients to solve the problem, in short. But a final element was still needed: political will. However, in the midst of the climate crisis, we are now seeing that the latter tends to be lacking when we talk about climate…
The situation could easily have degenerated. But fortunately, in the case of the ozone layer, the decision-makers of the time did not show the same wait-and-see attitude that we see today. For once, humanity has responded by directly attacking the root of the problem. An almost unique case in our modern history.
Barely months after identifying the hole in the ozone layer, hanging above Antarctica like a sword of Damocles, 24 countries organized the Vienna Convention, then the Montreal Protocol. The objective of these two series of agreements: to completely eradicate all substances that undermined the ozone layer.
These treaties, ratified in 1987, were unanimously approved by 196 States and by the European Union. A historic achievement for the UN: it is quite simply the first time that a text was adopted unanimously by all member states. A fine example of a unit with significant symbolic weight.
The ozone layer soon healed
For the next thirteen years, the hole continued to grow. But this initiative ended up paying off. Because at the dawn of the new millenniumthe researchers determined that the trend had finally reversed : the hole in the ozone layer has begun to close. Even better: Models from the time suggested he could fully heal within decades.
A huge victory for all humanity. But as always in science, it would have been very imprudent to sell the skin of the bear before having killed it. We still had to wait until we had more data and hindsight to confirm the trend. And that is precisely what the UN has done today.
The institution explains that thanks to the banishment of 99% of ozone-destroying compounds, the layer is now on the road to complete recoverye. If current protocols are maintained, it should return to its 1980 level (before the appearance of the hole) within 40 years in Antarctica, within 20 years over the Arctic and within fifteen years. years in the rest of the world.
A real textbook case to learn from
The conclusion is therefore clear: the problem of the ozone layer will soon be history. A historic success so humanity can congratulate itself. But beyond the technical and scientific aspect, it is also an eminently symbolic success that should serve as an example. Earthlings have pulled together to end a first-order existential threat, and it’s rare enough to be underlined.
But despite this gratifying success, it is clear that today, political decision-makers no longer show the same enthusiasm when it comes to the climate. Institutions like the IPCC regularly remind us that the situation is already catastrophic, and that it will only get worse (see our article). And yet, despite progress on topics such as renewable energies, the picture remains particularly bleak.
However, the history of the ozone layer is indisputable proof that when a very real emergency is identified, humans know how to give themselves the means to respond to it. Admittedly, the problem of greenhouse gas emissions is a completely different animal, and it will be much more difficult to tame; but the urgency is indisputable, and it is therefore to be hoped that the political class will be able to draw inspiration from this success to take the bull by the horns once and for all.