According to Luke Western, the lead author of the paper and a researcher from NOAA's Global Monitoring Laboratory and the University of Bristol, the Montreal Protocol's success has caused us to pay attention to emissions. "The CFC emissions from more widespread uses that are now banned have declined to such an extent that emissions from lesser-known sources have become noticeable," he states. The study, undertaken by a group of scientists from NOAA, the University of Bristol, Empa, CSIRO, the University of East Anglia, the University of California San Diego, the University of Colorado, Boulder, and Forschungszentrum Julich, was recently released in Nature Geoscience.
There is not an imminent danger to the ozone layer, however, a considerable greenhouse effect is present.
The researchers indicated that, though CFCs are not presently a big concern for ozone recovery, their rate of emission is such that they could eventually become a major source of ozone-depleting materials. Moreover, given the potency of these gases as greenhouse gases, their collective emissions are comparable to Switzerland's CO2 emissions in 2020. This is equivalent to approximately one percent of the US' total greenhouse gas emissions, or one thousandth of the global total.
The ozone layer, a protective shield for the Earth, is being damaged by CFCs. These chemicals were once used in multiple commercial applications such as propellants, foam-blowing agents, solvents, and refrigerants, until the Montreal Protocol in 2010 stopped the production of CFCs for these purposes.
The international treaty didn't outlaw the manufacture and utilization of CFCs while producing other compounds like hydrofluorocarbons (HFCs) and the more recent hydrofluoroolefins (HFOs), which were both created to substitute CFCs.
The concentration of five CFCs—CFC-13, CFC-112a, CFC-113a, CFC-114a, and CFC-115—with few or no known current uses and lifetimes in the atmosphere ranging from 52 to 640 years were the focus of this study. When it comes to ozone depletion, the amount of emissions from these five CFCs is similar to one tenth of the emissions of CFC-11, the most abundant of this group of chemicals which are currently regulated by the Montreal Protocol.
An unprecedented number of instances
In this research, the team studied atmospheric gases and emissions of CFCs at 14 sites around the world. They included the AGAGE-managed station at Jungfraujoch and an atmospheric transport model. The results showed a rise in global abundances and emissions after the phase-out of most uses of CFCs in 2010. In 2020, the amounts reached an all-time high.
For CFC-113a, CFC-114a and CFC-115, the researchers inferred that the increased emissions may be a result of their involvement in the manufacturing of two widely employed HFCs utilized mainly in air conditioning and refrigeration. Martin Vollmer of Empa, a collaborator of the research, commented, "Given the estimated production of some of these modern fluorocarbon products, there are worries concerning the rising emissions of these CFCs."
The motivations for the rising emissions of CFC-13 and CFC-112a are less certain. According to Vollmer, "No chemical fluorocarbon process is known to us involving these two substances either as intermediates or resulting products."
Could it be time to refine the Montreal Protocol?
The researchers were unable to find out the origins of the emissions; they recorded the escalating worldwide emissions yet were not able to locate the precise locations. Stefan Reimann from Empa, another contributor to the study, gave an explanation for this, saying there are a lot of "blind spots" in the global monitoring network: "Even though this research combined data from a few networks and teams, there are numerous areas of the world, including those with the biggest worldwide fluorocarbon productions, that are inadequately surveyed."
The researchers point out that if the emissions of the five CFCs increase, it would eliminate some of the positive aspects of the Montreal Protocol and would also add significantly to the global warming. It is possible to reduce these emissions or avoid them by decreasing the leakages related to HFC production and by effectively destroying the CFCs produced. Johannes Laube of the Forschungszentrum Julich suggested that it is time to review the Montreal Protocol more closely. Luke Western also noted that the production process of the replacement CFCs might not be completely secure for the ozone layer, even if the chemicals themselves are.
In a study published in Nat Geosci, Western et al. found that the concentration of ozone-depleting chlorofluorocarbons had significantly increased from 2010 to 2020. Their DOI is 10.1038/s41561-023-01147-w.
Post a Comment