What is ozone?
We are talking about a gas that is found in the stratosphere between 20 and 40 kilometers high, and forms a layer that protects us against ultraviolet solar radiation, which seriously affects the health of living beings.
The thinning of the ozone layer
In the 1980s, a reduction in the thickness of the ozone layer began to be detected. In addition, in 1987 NASA confirmed the existence of a huge hole located on Antarctica, which occupied a surface similar to that of the United States of America and a depth comparable to the height of Everest . Later, in 1991, the existence of another hole in the northern hemisphere was confirmed.
Causes of the hole in the ozone layer
The main agents that destroy the ozone layer are the famous CFCs or chlorofluorocarbons, compounds present in cleaning materials, insulation and foam packaging, air conditioners, aerosols and refrigeration appliances. In the upper layers of the atmosphere they become active and destroy ozone: it is estimated that each molecule of chlorine they release can destroy one hundred thousand ozone molecules.
Other chemical compounds that destroy the ozone layer with hydrochlorofluorocarbons, halons, methyl bromide and carbon tetrachloride.
Effects of the weakening of the ozone layer
The increase in ultraviolet radiation has many effects on the organisms that inhabit the planet, for example, it reduces the photosynthesis carried out by plants and marine phytoplankton, which causes imbalances in the trophic networks.
Among the effects on human health, the increase in skin cancers and eye diseases such as cataracts stands out.
The Montreal Protocol
Scientific confirmation of the weakening of the ozone layer prompted the international community to take steps to protect it. The Montreal Protocol was signed on September 16, 1987, and for this reason the International Day for the Preservation of the Ozone Layer is celebrated every year.
The signatory countries pledged to take measures to control the total production and consumption of substances that attack the ozone layer, with special attention to CFCs and halons.
As the United Nations explains on its website, “the implementation of the Montreal Protocol has progressed well in developed and developing countries. All the elimination schedules have been respected in most cases, some even ahead of schedule ”. In light of the steady progress made under the Protocol, as early as 2003, former Secretary-General Kofi Annan declared: ” Perhaps the most successful international agreement to date has been the Montreal Protocol .”
In this video NASA shows the effect of the application of the Montreal Protocol on the ozone layer:
The hole in the ozone layer today
Although the fight against the hole in the ozone layer is one of the clearest examples of how the measures taken to alleviate environmental problems are effective, nowadays the bells can not be thrown to the flight either.
Although several studies have estimated that ozone will have returned to 1980 levels by 2060, a work published in early 2018 in the journal Atmospheric Chemistry and Physics revealed that, although the hole in the ozone layer over Antarctica is closing and the stratospheric ozone of the upper layers is recovering, the tendency to decrease prevails in the lower layers.
What are the causes, if the CFC concentration is decreasing? Experts point, on the one hand, to the irruption of new compounds in the atmosphere such as VSLS (“very short-lived substances”) which, according to a study published in the journal Nature Geoscience, would have an effect very similar to CFCs, and on the other, to the not yet well known effects of climate change on the Brewer-Dobson circulation, an atmospheric circulation model that explains how CFCs end up in polar latitudes.
In any case, and despite current threats, the United Nations Environment Program estimates that, if the Montreal Protocol had not been signed, by the year 2050 the hole in the ozone layer would increase tenfold with compared to the 1980s.
To see the ozone layer in real time
Maps and the latest ozone measurements can be seen on the NASA Ozone Watch website.
Photo: The maximum that the hole in the ozone layer over Antarctica reached in 2000 is shown. Credit: NASA / Goddard Space Flight Center Scientific Visualization Studio
