Despite being banned more than 35 years ago, record levels of chlorofluorocarbons (CFCs), known to have harmful effects on the ozone layer , were recorded in 2020, according to a study published Monday.

CFCs are a powerful greenhouse gas that traps 10,000 times more heat than carbon dioxide, the major global warming gas, according to data from the Global Carbon Project.

After the widespread use of CFCs as a refrigerant in the seventies and eighties of the twentieth century, they were banned in 1987 under the Montreal Protocol, following the discovery of a hole in the ozone layer over Antarctica resulting from the use of this substance.

While this hole is slowly shrinking, the United Nations Environment Program expects it to disappear within four decades.

The study, published in the journal Nature Geoscience, which analyzed five CFCs between 2010 and 2020, indicated that the recent increase in CFC levels is likely to result from leaks during the production of chemicals that are alternatives to these compounds, including HFCs. (HFCs).

The Montreal Convention states that the release of ozone-depleting and dispersible substances must be reduced, but it does not prohibit their use as raw materials or by-products in the production of other chemical compounds. It is assumed that CFCs will cease to be used within the next three decades under a recent amendment to the 1987 treaty.

The increase in CFC levels may be due to unauthorized uses.
Luke Western of the University of Bristol and the Global Monitoring Laboratory, one of the study's authors, pointed out that these emissions have had a minimal impact to date on the ozone layer, and are equivalent to carbon dioxide emissions in Switzerland for the year 2020, or about 1% of the total greenhouse gas emissions in the world. United State.

But if the rapid upward trend of CFCs continues, their impact on the ozone layer and global warming will increase.

The researchers called their findings an "early warning."

And in 2018, a group of scientists determined that the rate at which CFCs slowed down had halved compared to the previous five years.

At the time, the researchers said, the causative agents were factories in eastern China. Once CFC production stopped in this area, CFC levels fell again.

The study, published on Monday, confirmed the need for further research to find out the source of the recent increase in CFC emissions.

"Putting out CFCs would be an easy win in terms of reducing greenhouse gas emissions," Western noted.