A recent study published in Nature Climate Change demonstrates a significant decline in atmospheric levels of hydrochlorofluorocarbons (HCFCs), which deplete the ozone layer and contribute to global warming. This progress is a result of the Montreal Protocol, which has successfully regulated the production and use of ozone-depleting substances since 1987.
New research indicates a decline in hydrochlorofluorocarbons (HCFCs) in the atmosphere, confirming the effectiveness of the Montreal Protocol in regulating substances that harm the ozone layer and contribute to global warming.
Significant progress in reducing atmospheric concentrations of chemicals harmful to Earth’s ozone layer has been revealed by a new study. It confirms the success of historic regulations limiting their production.
The findings show for the first time a notable decline in the atmospheric levels of potent ozone-depleting substances (ODS), called hydrochlorofluorocarbons (HCFCs). These HCFCs are also harmful greenhouse gases, so a reduction should also lessen global warming. The study was led by the 
This photo shows the high-altitude Integrated Carbon Observation System (ICOS) Jungfraujoch station in Switzerland, which was used to make measurements in this research. Credit: Jungfrau.ch
Ongoing Efforts and Future Outlook
Lead author Dr. Luke Western, Marie Curie Research Fellow at the University’s School of Chemistry, said: “The results are very encouraging. They underscore the great importance of establishing and sticking to international protocols.
“Without the Montreal Protocol, this success would not have been possible, so it’s a resounding endorsement of multilateral commitments to combat stratospheric ozone depletion, with additional benefits in tackling human-induced climate change.”
Measurements from the Copernicus Sentinel-5P satellite show 2023’s ozone hole over the Antarctic. Credit: Contains modified Copernicus Sentinel data (2023)/processed by DLR
Impact on Climate Change and Protocol Success
The international study shows the total amount of ozone-depleting chlorine contained in all HCFCs peaked in 2021. Because these compounds are also potent greenhouse gases, their contribution to climate change also peaked in that year. This maximum occurred five years before the most recent predictions. Although the drop between 2021 and 2023 was less than 1%, it still shows HCFC emissions are heading in the right direction.
Dr. Western said: “Their production is currently being phased out globally, with a completion date slated for 2040. In turn, these HCFCs are being replaced by non-ozone-depleting hydrofluorocarbons (HFCs) and other compounds. By enforcing strict controls and promoting the adoption of ozone-friendly alternatives, the protocol has successfully curbed the release and levels of HCFCs into the atmosphere.”
Advancements in Measurement and Environmental Monitoring
The results rely on high-precision measurements at globally distributed atmospheric observatories, using data from the Advanced Global Atmospheric Gases Experiment (AGAGE) and the National Atmospheric and Oceanic Administration (
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