New analysis finds increased emissions of several ozone-depleting chemicals even though their production is banned for most uses under the Montreal Protocol — and a loophole in the rules is likely responsible.
Research published today in Natural Earth Sciences Led by the University of Bristol and the National Oceanic and Atmospheric Administration (NOAA), the rise is due in part to chemicals, known as CFCs or CFCs, used to make other ozone-friendly alternatives to CFCs. This is an exception allowed under the Montreal Protocol, but it runs counter to its broader goals.
Lead author Dr Luke Western, Research Fellow at the University of Bristol and researcher at NOAA’s Global Monitoring Laboratory (GML) said, “We’re paying attention to these emissions now because of the success of the Montreal Protocol. CFC emissions are from most uses.” The prevalence that is now banned has fallen to levels so low that CFC emissions from previously secondary sources are now more on our radar and under scrutiny.”
According to the researchers, emissions from these CFCs do not currently significantly threaten ozone recovery. But because they are such powerful greenhouse gases, they still affect the climate.
Combined, their emissions are equal to carbon dioxide2 Western said the emissions in 2020 are for a smaller developed country like Switzerland. This is equivalent to about one percent of all greenhouse gas emissions in the United States.
The international study was conducted by a team of scientists from the United Kingdom, the United States, Switzerland, Australia and Germany.
Chlorofluorocarbons are chemicals known to destroy the Earth’s protective ozone layer. Once widely used in the manufacture of hundreds of products including aerosol sprays, as foam blowing agents, packaging materials, solvents and in refrigeration, CFC production for these uses was banned under the Montreal Protocol in 2010.
However, the international treaty did not eliminate the creation of CFCs during the production of other chemicals including HFCs or HFCs, which were developed as second-generation alternatives to CFCs.
This study focused on five CFCs with little or no current uses—CFC-13, CFC-112a, CFC-113a, CFC-114a, and CFC-115—that have atmospheric lives ranging from 52-640 years. In terms of their impact on the ozone layer, these emissions were equivalent to about a quarter of the recently discovered increase in emissions of CFC-11, a substance controlled under the Montreal Protocol, and believed to be caused by the new, unreported production.
In this study, the team used measurements from the Advanced Global Atmospheric Gases Experiment (AGAGE), in which the University of Bristol plays a pivotal role, as well as other measurements made by Forschungszentrum Jülich, in Germany, the University of East Anglia, and NOAA. in the United States. These were combined with an atmospheric transition model to show that the global atmospheric abundance and emissions of these CFCs increased after their production was phased out for most uses in 2010.
The researchers determined that for the three CFCs they studied — CFC-113a, CFC-114a and CFC-115 — the increased emissions may be due in part to their use in the production of two common HFCs used primarily in refrigeration and air conditioning. The drivers of increased emissions of CFC-13 and CFC-112a remain less certain.
Although the team found a rise in global emissions, they were unable to pinpoint specific locations.
said study co-author Dr Johannes Loeb, from the Institute for Energy and Climate Research (IEK) at the Forschungszentrum Jülich.
According to the researchers, if emissions of the five CFCs continue to rise, their impact could negate some of the benefits gained under the Montreal Protocol. The study indicated that these emissions could be reduced or avoided by minimizing leakages associated with HFC production and by properly destroying any co-produced CFCs.
“The basic idea is that the production process of some CFC replacement chemicals may not be completely ozone-friendly, even if the replacement chemicals themselves are,” concluded Dr. Western.
Luke Western, Global Increase in Ozone-Depleting CFCs from 2010 to 2020, Available here. Natural Earth Sciences (2023). DOI: 10.1038/s41561-023-01147-w. www.nature.com/articles/s41561-023-01147-w
the quote: Research Finds Global Emissions of Several Ozone-Destroying Chemicals Are Increasing (2023, April 9) Retrieved April 9, 2023 from https://phys.org/news/2023-04-global-emissions-ozone-destroying-chemicals. html
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