Thanks to the Montreal Protocol signed in 1987, the protective barrier should fully recover in the upcoming four decades. The prohibition of certain chemical substances also benefits the fight against global warming.
by Audrey Garric
The good news on the environment front is rare enough to be highlighted. The ozone layer should fully be reconstituted in the upcoming four decades and the progressive elimination of the chemical substances which destroy it contributes to limiting climate change. Even if points of vigilance remain, it is a major success for the international community. These are the conclusions of a group of experts sponsored by the United Nations, presented Monday, January 9.
This evaluation report constitutes the most successful state of scientific knowledge on ozone, like the reports of the group of intergovernmental experts on the evolution of Climate (IPCC). It is produced every four years by Scientific assessment group of the Montreal Protocol , under the aegis of the World Meteorological Organization and the United Nations Program for the ‘Environment (UNEP). This 2022 edition was written and reviewed by 230 researchers from 30 countries. “Over the past thirty-five years, the protocol has become a real spearhead of the defense of the environment,” said Meg Seki, the executive secretary of the Ozone Secretariat of the UNEP.
It all started in the 1970s, when scientists alerted to the degradation of the ozone layer, this protective barrier that filters UV from the sun. In the early 1980s, they discovered a “hole” above Antarctica, as large as the polar continent, which formed each year between July and September and closed in November. This phenomenon is caused by gases, such as chlorofluorocarbons (CFC) and dicks, which contain chlorine and bromine, capable of destroying ozone. At that time they were massively used in the manufacture of everyday products, such as refrigerators, air conditioners, aerosols or insulation foams.
The Montreal Protocol, signed in 1987 and now ratified by 198 countries, prohibited substances depleting the ozone layer (SAO) – since 1996 for developed countries and since 2010 for those in development. Due to their long lifespan (between fifty and one hundred years), they did not disappear from the stratosphere, the region of the atmosphere extending from 15 to 50 km altitude, which contains the layer D ‘ozone. The report confirms that the concentrations of chlorine and bromine continue their slow – decrease.
If current policies remain in place, the ozone layer should regain its state before 1980 by 2066 above the Antarctica, 2045 above the Arctic and from 2040 in the rest of the world. “It is a danger for humanity that has been avoided,” recalls Sophie Godin-Beekmann, research director (CNRS), president of the International Ozone Commission and one of the authors of the report. Just in the United States, the protocol should allow to avoid more than 400 million skin cancers until the end of the century .
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