Good news in the environmental field is rare, but it does exist. For example, a new study by an international team of researchers shows the decline in chemicals that destroy the ozone layer. The Montreal Protocol of 1987 appears to be a success.
On June 11, 2024, a study led by researchers from the University of Bristol was published in the journal «Nature Climate Change», showing for the first time a remarkable decrease in the atmospheric content of ozone-depleting substances, the so-called hydrochlorofluorocarbons (HCFCs). These HCFCs are also potent greenhouse gases, so that their reduction should also reduce global warming. According to the international team of researchers, the study thus confirms the success of international regulations to limit the production and use of such pollutants. Central measurements were carried out by Empa scientists at the Jungfraujoch high-alpine research station, among others.
Production and use of HCFCs to be reduced to zero by 2040
In 1987, the Montreal Protocol was agreed to control the production and use of ozone-depleting substances that were previously widely used in the manufacture of hundreds of products such as refrigerators, aerosol sprays, foams and packaging. HCFCs were developed as a replacement for the chlorofluorocarbons (CFCs) previously used. While the production of CFCs has been banned worldwide since 2010, the production and use of HCFCs is currently still being phased out worldwide. This process should be completed by 2040. They will be replaced by non-ozone-depleting hydrofluorocarbons (HFCs) and other compounds.
International protocols are important
«The results are very encouraging. They underline the importance of establishing and adhering to international protocols», says the lead author of the study, Luke Western from the University of Bristol. And he continues: «Without the Montreal Protocol, this success would not have been possible. It is therefore a confirmation of multilateral commitments to combat stratospheric ozone depletion, which also has an impact on combating man-made climate change.»
Decline faster than expected
The international study shows that the total amount of ozone-depleting chlorine in all HCFCs peaked in 2021. As these compounds are also potent greenhouse gases, their contribution to climate change also peaked this year. However, this peak occurred five years earlier than predicted in the last ozone report in 2022. Although the decrease between 2021 and 2023 was only less than 1%, it shows that HCFC emissions are moving in the right direction. For Empa scientist and co-author Stefan Reimann, the study also 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 substitute products of the even more ozone-depleting CFCs are now decreasing - and even five years earlier than expected». This was only possible thanks to the continuous tightening of international protocols and their verification with the help of atmospheric measurements, for example on the Jungfraujoch.
Reliability of observations must be guaranteed worldwide
The results are based on high-precision measurements at globally distributed atmospheric observatories that use data from the Advanced Global Atmospheric Gases Experiment (AGAGE) and the National Atmospheric and Oceanic Administration (NOAA), including the high alpine research station on the Jungfraujoch, where Empa scientists carry out their atmospheric investigations of numerous air pollutants. «We use highly sensitive measurement techniques and careful measurement protocols to ensure the reliability and comparability of these observations worldwide», says co-author Martin Vollmer, atmospheric researcher at Empa.
Co-author and NOAA scientist Isaac Vimont added: «This study underscores the need to remain vigilant and proactive in environmental monitoring to ensure that other ozone-depleting substances and greenhouse gases follow a similar trend, which will help protect our planet for future generations.»
