A Class of Ozone-Depleting Chemicals is Declining, Thanks to the Montreal Protocol

By research.noaa.gov.

New research by a team including current and former NOAA-affiliated scientists has shown that atmospheric concentrations of a class of ozone-depleting chemicals used as refrigerants, foam blowing agents and solvents peaked in 2021 and are now beginning to decline as nations comply with restrictions called for by the Montreal Protocol.

The research, led by a scientist at the University of Bristol in England and published in Nature Climate Change focused on a class of industrial chemicals called hydrochlorofluorocarbons (HCFCs). HCFCs were created as first-generation alternatives to more-damaging chlorofluorocarbons, or CFCs, which were responsible for creating the springtime hole in the ozone layer above Antarctica. HCFCs also deplete ozone and trap heat in the atmosphere, but to a lesser degree than the CFCs they replace.

Lead author Luke Western, Marie Curie Research Fellow at Bristol University’s School of Chemistry, said the results underscore the value of establishing and following international agreements like the Montreal Protocol on Substances that Deplete the Ozone Layer.

Without the Montreal Protocol, this success would not have been possible, so it’s a resounding endorsement of multilateral commitments to combat the impacts of human-induced climate change,” said Western, who initiated this work while he was a research fellow with NOAA’s Global Monitoring Laboratory.

Trend revealed by long-term global atmospheric  monitoring

Using high-precision measurements of air samples provided by NOAA’s Global Greenhouse Gas Reference Network and the Advanced Global Atmospheric Gases Experiment obtained at their globally distributed atmospheric observatories, the researchers were able to determine that both the ozone-depleting impact and heat-trapping impact of HCFCs had peaked five years earlier than projections.

Agreed to in 1987, the Montreal Protocol is a multilateral environmental agreement that introduced controls on the production of ozone-depleting substances like CFCs. CFCs were once widely used in the manufacture of hundreds of products, including aerosol sprays, cooling devices, blowing agents for foams and packaging, and solvents.