As is customary in this column and in this newspaper, once a year in this part of the calendar we review the current state and historical perspective of the ozone “hole” that forms annually in the first half of our spring of the year. much of the south of the planet.
To put things in perspective, we need to insist on the basics: the ozone “hole” is not permanent, nor is it a hole.
I explain: the layer of ozone, a gas made up of oxygen atoms, occupies a part about 20 kilometers high in the stratosphere. This gas reflects almost 100% of some form of ultraviolet radiation that hits Earth from the Sun and returns it to space. This is high-frequency UV radiation. If it didn’t exist, there wouldn’t be life as we know it. Therefore, it is a matter of life and death to make it stable. Ozone is very useful in the stratosphere but toxic at ground level. Paradoxical.
Well, the hole isn’t like that either. Neither in time nor in the textual concept of a hole.
It turns out that certain gases that we produce in the industrial processes that evolution brought us, when released into the atmosphere, begin to rise up and end up in the stratosphere, destroying ozone molecules with the help of sunlight. Because of the way air circulates at high altitude and the seasonal cycle that increases the number of daylight hours above the Arctic Circle towards the beginning of spring; Once sunlight illuminates the ozone, gases that can destroy it begin to do so with the help of sunlight. Starting in August and peaking between September and October, ozone-depleting gases therefore reduce the concentration of the gas in the atmosphere. They won’t go away. Therefore, it is better to talk about thinning, but not about the hole in the ozone layer.
Then the weight loss process ends and everything returns to normal by the end of the year.
In 2023, ozone depletion reached its peak, with nearly 25 million km2 of the planet’s southern atmosphere showing ozone loss within a fortnight in September. Now it is less than 16 million km2.
In the last three years, the weight loss was greater than the average seen in the last decade.
Actions taken to end the problem in the future, banning the release of ozone-depleting gases, are working very slowly, but they appear to be working, according to data from NOAA, which regularly monitors the worrisome problem. In fact, the greatest thinning – over 28 million km2 – was observed in 2000.
