A new international study has warned that the recovery of the ozone layer in the atmosphere could be delayed by several years due to continued emissions of primary chemicals that are still permitted to be used as raw materials in industry.
The study was led by an international team of researchers from the Massachusetts Institute of Technology (MIT) , as well as the Swiss Research Institute "Empa", with the participation of researchers from the University of Bristol, NASA, the National Science Foundation in the United States, the Volo Foundation, the Natural Environment Research Council in the United Kingdom, and the Korea Meteorological Administration's Research and Development Program.
The results revealed that the ongoing emissions of these ozone-depleting substances, known as feedstock chemicals, have been greatly underestimated in previous international agreements.
Although the use of substances such as tetrachloromethane (CCl₄) and chlorofluorocarbons (CFCs) is banned in refrigerators and foam materials, they are still used as raw materials in industry to produce modern refrigerants and plastics.
Using global measurements from the AGAGE network, researchers found that between 3% and 4% of these materials leak into the atmosphere during production and processing operations, and their use has increased significantly in recent decades.
It was previously expected that the ozone layer would return to its original state (the state recorded in 1980) by around 2066. But new calculations, published in the journal Nature Communications, show that if emissions continue at their current levels, the date will be delayed by about 7 years, to 2073, with a margin of error of between 6 and 11 years.
When the Montreal Protocol was negotiated in the 1980s, ozone-depleting substances were banned in everyday products, but primary chemicals were exempted from the ban, based on the assumption that only 0.5% of them would leak, and that their use would decrease over time.
But the opposite happened, as the use of these materials increased significantly, especially in alternative refrigerants after the ban on chlorofluorocarbons, and in the manufacture of polymers used in electric car batteries.
Professor Matt Rigby of the University of Bristol said: "Measurements show that emissions associated with the production of fluorinated chemicals are much higher than expected, and this means a much larger leak than assumed by the Montreal Protocol, with clear implications for climate change and ozone recovery."
Stefan Reimann, the study's lead author, added: "These substances are not only ozone-depleting, but they are also very harmful to the climate. Reducing their emissions will benefit both the ozone layer and the climate."
If nothing changes, the additional emissions from these materials will reach about 300 million metric tons of carbon dioxide equivalent per year by the middle of the century, which is equivalent to the current annual emissions of a country like England or France.
The researchers conclude that reducing these emissions would have a double benefit: protecting the ozone layer and reducing global warming at the same time.
