Industrial emissions of feedstock chemicals are hindering recovery of ozone layer

Emissions of certain ozone-depleting chemicals used in industry could delay the recovery of the Earth’s ozone layer by as much as 11 years, according to researchers. Lowering these emissions would help both the ozone layer to heal and reduce the climate heating impacts of such chemicals.

The 1987 Montreal Protocol banned the global production and use of ozone-depleting chemicals – such as hydrochlorofluorocarbons (HCFCs) – for refrigeration and as foaming agents. However, there are no restrictions on the use of such chemicals as feedstocks to make other molecules. This applies to HCFCs, carbon tetrachloride, chlorofluorocarbons (CFCs) and other long-lived chlorinated and brominated compounds.

Industrial experts assumed that only 0.5% of these feedstock chemicals would escape into the atmosphere and that the use of these substances by the chemical industry would decline. ‘[However], feedstock chemicals are now being released in increased quantities during production, transport and further processing,’ said Stefan Reimann, an atmospheric scientist at the Swiss Federal Laboratories for Materials Science and Technology. ‘And the volumes currently being produced are significantly larger than was assumed 30 years ago.’

Reimann and his team have now found that 4% of these feedstock chemicals are released to the atmosphere, and that industrial use of these compounds has increased by 160% since 2000. The team predicts that the use of these chemicals will continue to rise until 2100.

Earlier estimates suggested that the stratospheric ozone layer would fully recover in 2066, but the researchers say that these industrial emissions could delay the recovery by six to 11 years.

These ozone-depleting chemicals are also powerful greenhouse gases, with some HCFCs being nearly 2000 times more potent than carbon dioxide. Analysis suggested that continuing to release these chemicals at the same rate will lead to around 300 million tonnes of equivalent CO₂ emissions by 2050. This is around 1% of anthropogenic CO₂ emissions in 2024 – equivalent to France’s annual CO₂ emissions.

‘The Montreal protocol was successful because science, politics and industry worked closely together,’ says Reimann. ‘Such cooperation is crucial again today to address new challenges.’