despite being banned, chlorofluorocarbons continue to threaten the ozone layer

Pollution that persists. Despite being banned more than 35 years ago, chlorofluorocarbons (CFCs), known for their deleterious effects on the ozone layer, reached record levels in 2020, study reveals (link in English) posted Monday, April 3. CFCs are potent greenhouse gases that trap heat up to 10,000 times more effectively than carbon dioxide, the main contributor to global warming, according to data from the Global Carbon Project.

Widely used as refrigerants and in aerosols in the 1970s and 1980s, they were finally banned in 1987 during the Montreal Protocol, after the discovery of the hole in the ozone layer above Antarctica resulting from their use. But then why such persistence today? According to the study published in the journal Nature Geosciencethis recent increase in CFCs is likely due to leaks during the production of chemicals to replace CFCs, including hydrofluorocarbons (HFCs).

Risk of increased global warming

The Montreal agreement limits releases of ozone-depleting substances, but does not prohibit their use in the production of other chemicals as raw materials or by-products. These CFC substitutes are to be phased out over the next three decades under a recent 1987 treaty amendment. Unreported uses could also be behind the upsurge.

According to Luke Western, a researcher at the University of Bristol and co-author of the study, these emissions have so far had a modest impact on the ozone layer. But if the rapid upward trend in CFCs continues, their impact will increase both on the ozone layer and on global warming. The researchers therefore qualify their results as“early warning”.