The latest scientific assessment of ozone depletion conducted by the World Meteorological Organization and the United Nations Environment Program (UNEP) shows that in some parts of the stratosphere the ozone layer has recovered to a rate of 1 to 3% per decade since the year 2000.
Thanks to its recovery and the protection it offers us against ultraviolet radiation that comes from the sun, a high percentage of life as we know it is assured, although this is only one of the phenomena that could contribute to it, since climate change today It has clear challenges, explained researchers from the National Autonomous University of Mexico.
Doctor Telma Castro Romero, from the Atmospheric Aerosols Group of the Institute of Atmospheric Sciences and Climate Change, explains that in 1987 197 countries signed the Montreal Protocol on substances that damage the ozone layer, a gas that is permanent in the earth’s atmosphere and its highest concentration is located in the stratosphere. It is approximately 100 kilometers high and one way to study it is through the temperature profile. “This was a pivotal moment to start reversing the problem.”
What is the ozone layer?
Castro Romero explained that stratospheric ozone is formed in the atmosphere when ultraviolet radiation reaches the lower stratosphere and dissociates atomic oxygen molecules, which rapidly combine with other oxygen molecules (O2) to form ozone. This process has been going on for thousands of years and forms a layer that surrounds the entire planet. This shield absorbs ultraviolet light from the sun and does not allow that radiation to reach the surface completely. Without this protection, life as we know it would not exist. by the penetration of this variation.
If this shield were weakened, life would be in danger and that happened for a few years, but upon realizing what was happening, the international community began to take action. “In the 1970s, Sherwood Rowland and Mario Molina, at a scientific conference in London, raised the idea that the chlorofluorocarbons (CFCs) used in the refrigeration process and aerosols are products with very stable chemistry and that over time they change very little, so they had to accumulate somewhere.”
This is how it became known that widespread use significantly damaged the ozone layer surrounding the Earth’s layer, leading to the formation of what we now call the ozone hole over Antarctica, which is still present today. but it has been recovering.
The 2019 observations by NASA researchers, who measure this hole with instruments on board satellites, revealed that the ozone hole was 9.3 million square kilometers, less than the one reported in 1998 when it averaged 25.9 million square kilometers.
“With the Montreal protocol, a global problem regarding the ozone layer was solved at that time, but it was achieved with elements that now affect the earth’s climate along with other greenhouse gases such as carbon dioxide or methane” . For this reason, in October 2016, the Kigali Amendment was adopted, an international agreement to gradually reduce the consumption and production of gases emitted in refrigeration and consumption processes. These are hydrogens that include mainly chlorine and bromine, in addition to halocarbons.
What does it mean for the ozone layer to recover?
“If actions had not been carried out through the Montreal Protocol, life on earth would be much more complicated and with irreversible damage,” says Dr. Amparo Martínez Arroyo.
He said that this was the first international environmental protocol that had specific goals, financial and technological support, in addition to a compliance schedule. It achieved the involvement of governments with industry and the scientific sector, as well as raising awareness among citizens at the national level. worldwide, because they began to stop consuming certain products and demand stamps indicating that the ozone layer was not damaged. “That was very important to be able to reach the results.”
The destruction of the ozone layer was caused by substances produced by human beings, it was technology from the 1920s. At the time it seemed like a great solution because it was non-toxic, flammable, cheap and had many uses, but if it had been there If the investigation was left, we would not have realized in the 70s about the damage to the environment.
The two researchers, together with Dr. Carlos Gay García, agree that at that time these products had great commercial value, so accepting any damage was very delicate, but it was achieved somehow. “Without this process of more than 30 years today we would not have the positive results and it is estimated that if progress continues in this direction in 2060 the levels of the ozone layer will have already been recovered.”
Actions from Mexico
Our country was one of the first to sign the Montreal protocol and one of the first to ratify it. Since the 1990s, more than 120 investment projects have been developed to eliminate the consumption of substances that deplete stratospheric ozone, especially in the refrigeration industry, air conditioning, polyurethane foams, fire extinguishers, aerosols, in agricultural processes, solvents, which has implied projects for institutional strengthening, training and technical assistance at the same time.
In 2005 Mexico eliminated the use of CFCs definitively thanks to the promotion of the use of alternative propellants, but since 1997 the conversion began, especially in domestic refrigerators. The researchers say that even so there is still much to be done to eradicate the consumption of substances and destruction of CFCs completely. “The final lesson is that short-termism that only addresses immediate and urgent problems for voters can create the illusion that problems are being fixed, but if continuity, surveillance, and scientific and citizen monitoring measures are not taken, this can have repercussions on a short term, therefore it is important to continue the research and improve the technologies”.
