The ozone layer is a region of concentration of ozone (O3) molecules in the Earth’s atmosphere. This layer is located at an altitude between 19 and 30 km. Its function is to protect all living species that inhabit the earth from the ultraviolet rays of the sun. Scientists have discovered a new hole, larger than any currently known.
In the 1980s, the scientific community began to warn of a new environmental threat. The question of a huge hole in the ozone layer over Antarctica became entrenched in society from 1985, and especially throughout the following two decades.
New terms related to the hole in the ozone layer have begun to resonate around the world: “chlorofluorocarbons”, “global warming” or “climate change”, although many are still completely unaware of their meaning and even deny them.
Regarding human health, the population is beginning to learn about its possible consequences: melanoma, cataracts, skin cancer and weakening of the immune system. And to make heavy use of sunscreen, which in turn generates other types of pollutants and skin problems.
The ozone cheat
The ozone layer is located in the lower region of the stratosphere and has a more or less diffuse zone, without clear boundaries like the other layers of the atmosphere.
What characterizes this area, as its name suggests, is its high concentration of ozone gas, a molecule made up of three oxygen atoms, with the ability to absorb ultraviolet radiation. Indeed, it absorbs between 97 and 99% of high frequency ultraviolet radiation from the sun.
In low-lying regions, ozone is produced by electrical storms, and when its concentration is too high, it can be a pollutant. Indeed, it is a highly reactive and very oxidizing substance.
holes in the ozone layer
The expression “hole in the ozone layer” is not literal. The problem is a thinning of the thickness of this layer produces the lower concentration of ozone gas. In turn, this thinning and loss of density is variable and usually fluctuates with the seasons of the year.
This thinning of the ozone layer is produced mainly by the presence of pollutants which react with the ozone by decomposing it. Among them, stratospheric aerosols derived from sulfur produced by volcanoes, which have a point influence, stand out.
But there are other man-made compounds that cause sustained decreases in ozone concentration over time, halocarbons and chlorine-derived gases, particularly chlorofluorocarbons (CFCs). These molecules, used as propellants and coolants, remain stable in the atmosphere for up to 200 years; when they reach the stratosphere, the ultraviolet radiation, which is stronger up there, dissociates the molecule, releasing chlorine which, by reacting with the ozone, breaks it down.
The reduction in the amount of ozone in the stratosphere allows the passage of ultraviolet light with greater intensity, which causes greater release of chlorine from CFCs. This ends in a negative feedback in which ozone depletion leads to further ozone depletion.
To prevent this from happening in eternityIn recent decades, CFCs have been replaced by other less hazardous compounds, such as hydrofluorocarbons (HFCs) for refrigeration or isobutane as a propellant. But all those that have been released for more than half a century remain in the atmosphere, causing this degradation.
A new hole, a new threat
The hole in the ozone layer in Antarctica is already well known. Its dynamics have already been studied by scientists: during the austral summer and autumn, ozone levels partially recover, but the winter cold favors a greater concentration of chlorinated compounds, and each year, at spring, the hole re-forms.
There are others of smaller dimensions, above the North Pole, and another hole above Tibet, observed in 2006 and 2011.
But a new scientific publication in AIP Advances conducted by the team of scientists from the University of Waterloo in Ontario, Canada warns of a hole in the ozone layer that had gone unnoticed until now, and is now more than 20 years old.
Unlike the Antarctic hole, which only appears in the spring, this one remains all year round, forming a band between the tropics. The magnitude of the hole is similar to that of Antarctica, but its size is seven times larger.
The large year-round tropical O3 hole could be of major global concern because it can lead to increased ultraviolet radiation at ground level and affect 50% of the Earth’s surface, which is home to around 50% of Earth’s surface. population.
The depletion of the ozone layer implies a weaker filter of ultraviolet radiation which reaches the surface more easily and in greater quantity. It is more than proven that ultraviolet radiation has negative effects on the health of people and other living beings; that affect terrestrial and aquatic ecosystems and become the cause of biodiversity loss.
Dunbar, J. 2001. The Ozone Layer. JAR.
Farman, JC et al. 1985. Significant losses of total ozone in Antarctica reveal a seasonal ClOx/NOx interaction. Nature, 315(6016), 207-210. DOI: 10.1038/315207a0
Lu, Q.-B. 2022. Observing large, all-season ozone losses over the tropics. Advances AIP, 12(7), 075006. DOI: 10.1063/5.0094629