Experts have reported the rise of five ozone-depleting CFCs. 

Scientists are warning that an increase in ozone-depleting chlorofluorocarbons (CFCs) could threaten the planet’s climate. 

Five of these CFCs have increased significantly in the Earth's atmosphere between 2010 and 2020, despite being banned in 2010, according to new data. 

CFCs are thousands of times more potent as greenhouse gases than carbon dioxide. While CFC emissions have declined since the 1980s to around 5 per cent of their peak, new research shows an unexpected increase. 

The researchers believe that the source of three of the CFCs is their use as feedstocks, but the origin of two remains a mystery. 

Dr Luke Western from the University of Bristol in the UK and US National Oceanic and Atmospheric Administration, and lead author of the study says; “They've been increasing relatively rapidly since 2010”. 

The Montreal Protocol, which was introduced in 1987 in response to the growing hole in the ozone layer, banned the release of ozone-depleting gases as aerosols in 2010. However, CFCs were allowed to be used as feedstocks. 

The researchers believe that the increasing emissions of three of those CFCs are associated with their use in the production of other chemicals, in particular hydrofluorocarbons. 

Hydrofluorocarbons or HFCs were intended to be more climate and ozone-friendly replacements for CFCs but the new research shows their use is problematic. 

“What we're suggesting here is that there may be some cost to ozone and climate when creating these HFCs and HFOs, as ozone-depleting CFCs may be released during the process,” Dr Western said. 

The Kigali Amendment, an international agreement ratified in 2016, aims to reduce the production of HFCs. However, atmospheric chemist Robyn Schofield from the University of Melbourne warns that this is happening very gradually. She also said that HFCs are often being replaced by hydrofluoroolefins, which have their impacts. 

“They get washed out [of the atmosphere] and they form [trifluoroacetic acid] and that can be problematic in drinking water,” Dr Schofield says. 

Professor Ian Rae from the University of Melbourne's school of chemistry said the increase in the three traceable CFCs was likely from poorly regulated industries, saying; “Not all countries are as strict in regulating their industries … in poorly regulated countries that's what happens - you put it down the drain if you don't want it”.

The overall impact on the Antarctic ozone hole is expected to be negligible if the emissions continue at their present rate. However, the more significant issue is the global warming potential of CFCs. 

“The emissions of these gases in 2020 were around the same size as the total carbon [dioxide] emissions for a country like Switzerland,” Dr Western said.

“So the climate impact is quite substantial from these gases and therefore mitigating these emissions would have a large impact on climate - about the same as a small country going carbon neutral.” 

There are some viable alternatives to using HFCs that do not produce CFCs as a by-product and are less potent greenhouse gases, however, some applications still pose a challenge. Discarded appliances and building foams remain the world's largest sources of leaking CFCs.