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The high-altitude Integrated Carbon Observation System (ICOS) Jungfraujoch station in Switzerland was one of the sampling stations used to take atmospheric measurements of hydrochlorofluorocarbons. Credit: Jungfrau.ch
Recent findings indicate significant reductions in hydrochlorofluorocarbons (HCFCs), harmful to both the ozone layer and climate. This success, stemming from the Montreal Protocol, shows that global efforts to phase out these substances are effective, with reductions exceeding earlier predictions.
A new study by an international team of researchers has revealed significant progress in the drive to reduce atmospheric levels of chemicals that destroy the Earth’s protective ozone layer, confirming the success of historic regulations limiting their production and use. Empa scientists contributed to this study with measurements from the high-alpine research station at Jungfraujoch.
Montreal Protocol and HCFCs
The study, led by researchers at the 
For Empa scientist and co-author Stefan Reimann, the study represents a “milestone in the history of measures to contain the ozone hole, in which we were able to show for the first time that even the replacement products for the even more ozone-depleting CFCs are now decreasing – and this even five years earlier than expected.” Credit: EMPA
“The results are very encouraging. They underscore the great importance of establishing and sticking to international protocols”, says lead author Luke Western from the University of Bristol’s School of Chemistry. “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.”
Decline Faster Than Anticipated
The international study shows the total amount of ozone-depleting chlorine contained in all HCFCs combined peaked in 2021. Because these compounds are also potent GHGs, their contribution to climate change also peaked in that year. This maximum occurred five years earlier than predicted in the last ozone assessment report published in 2022. Although the drop between 2021 and 2023 was less than 1%, it still shows HCFC emissions are heading in the right direction.
For Empa scientist and co-author Stefan Reimann, the study represents a “milestone in the history of measures to contain the ozone hole, in which we were able to show for the first time that even the replacement products for the even more ozone-depleting CFCs are now decreasing – and this even five years earlier than expected.” According to the Empa researcher, this was only possible thanks to the continuous tightening of international protocols and their verification with the help of atmospheric measurements, for instance on Jungfraujoch.
Ensuring Future Environmental Stability
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 (DOI: 10.1038/s41558-024-02038-7
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