Ozone-destroying CFC chemicals are on the rise again despite ban

The concentrations of some ozone-depleting chlorofluorocarbons (CFCs) in the atmosphere are increasing rapidly, scientists warn, despite the production of these chemicals having been banned globally since 2010.

CFCs were commonly used in refrigerants, aerosol propellants and solvents until they were discovered to be the driving force behind the destruction of the ozone layer. Under the Montreal Protocol, their production was phased out from 1989 to 2010.

But Luke Western at the University of Bristol, UK, and his colleagues have uncovered a sharp increase in global atmospheric concentrations of five CFC chemicals between 2010 and 2020, which could suggest they are still being illicitly produced in some factories.

Using data from 14 measurement sites around the world, the researchers found that concentrations of CFC-112a, CFC-113, CFC-113a, CFC-114a and CFC-115 have increased since 2010, reaching a record high abundance in the atmosphere in 2020.

The jump in emissions isn’t likely to significantly hamper the recovery of the ozone layer, which is expected to heal completely by the 2060s, but the planet-warming impact of CFC gases means the findings are a concern, said Western at a press briefing.

He told reporters that the findings should act as an “early warning” for countries to crack down on illicit or negligent production of the chemicals.

The amount of these gases emitted in 2020 would have an equivalent warming effect to the total carbon emissions for a country like Switzerland, he said. “So the climate impacts are still quite substantial.”

Some of the increase in emissions can be explained by a jump in the production of hydrofluorocarbons (HFCs), which are widely used as a replacement for CFCs. The production of HFCs sometimes leads to the production and release of CFCs as a by-product.

But two CFCs in particular, CFC-112a and CFC-113, have no known legal uses and researchers aren’t sure what is causing the increase in emissions. “That’s really a bit scary,” said Stefan Reimann at the Swiss Federal Laboratories for Materials Science and Technology during the same briefing.

Western suggested it could be that factories are using CFC-112a illegally to produce fluorovinyl ether or solvents, for example. “We have no evidence to suggest that’s what is going on,” he said. “But that’s one of the only previously known uses of CFC-112a.”

Likewise, the researchers aren’t sure where the emissions are coming from. “We are pretty certain it’s not coming from Europe or the US,” said team member Isaac Vimont at the National Oceanic and Atmospheric Administration in the US. But, beyond that, it isn’t yet clear which countries are the source of the emissions, he said.

In 2018, factories in China were found to be the source of a spike in CFC-11 emissions. Previous research has identified East Asia as a source of CFC-113a and CFC-115 emissions, and more monitoring is needed across the region to help pinpoint the source of the current increase in emissions, the study authors wrote in their paper.

Under the Kigali Amendment to the Montreal Protocol, which was ratified in 2016, countries agreed to reduce the production and consumption of HFCs. These are harmless to the ozone layer, but drive climate change.

Western said action under this amendment should help to tackle CFC emissions as well. Reducing HFC and CFC emissions would be an “easy win” for the climate, he added.