New analysis has found increasing emissions of several ozone-depleting chemicals despite their production being banned for most uses under the Montreal Protocol – and a loophole in the rules is likely responsible. The University of Bristol and National Oceanic and Atmospheric Administration (NOAA) research, which was published Monday in Nature Geoscience, attributes the spike in part to the chemicals, known as chlorofluorocarbons or CFCs, being used to create other ozone-friendly alternatives to CFCs. The Montreal Protocol permits this exception, but it runs counter to the Protocol's larger objectives. "We're paying attention to these emissions now because of the success of the Montreal Protocol," said lead author Luke Western, a Global Monitoring Laboratory (GML) researcher and Research Fellow at the University of Bristol. CFC emissions from more common uses that are currently prohibited have decreased to such low levels that emissions from formerly unimportant sources are now more under our notice and examination. The researchers found that the ozone recovery is not now seriously threatened by emissions from these CFCs. Yet, they still have an impact on the climate because they are strong greenhouse gases. Their combined emissions are comparable to those of Switzerland, a less industrialised nation, for 2020, according to Western. According to Western, that amounts to around 1% of all greenhouse gas emissions in the United States. The international study was conducted by a team of scientists from the UK, US, Switzerland, Australia, and Germany. CFCs are chemicals known to destroy Earth's protective ozone layer. Once widely used in the manufacture of hundreds of products including aerosol sprays, such as blowing agents for foams and packing materials, solvents, and in refrigeration, CFC production for such uses was banned under the Montreal Protocol in 2010. However, the international treaty didn't eliminate the creation of CFCs during production of other chemicals including hydrofluorocarbons or HFCs, which were developed as second-generation replacements for CFCs. This study focused on five CFCs with few, or no, known current uses—CFC-13, CFC-112a, CFC-113a, CFC-114a, and CFC-115—and that have atmospheric lifetimes ranging from 52-640 years. In terms of their impact on the ozone layer, these emissions were equivalent to around one quarter of a recently detected rise in emissions of CFC-11, a substance controlled under the Montreal Protocol, thought to be due to unreported new production. The researchers determined that for three CFCs they studied – CFC-113a, CFC-114a and CFC-115 – the increased emissions may be partly due to their use in the production of two common HFCs used primarily in refrigeration and air conditioning. The drivers behind increasing emissions of the other two CFCs, CFC-13 and CFC-112a, are less certain. Although the team found rising global emissions, they weren't able to identify particular locations. According to the researchers, if emissions of these five CFCs continue to rise, their impact may negate some of the benefits gained under the Montreal Protocol. The study noted these emissions might be reduced or avoided by reducing leakages associated with HFC production and by properly destroying any co-produced CFCs.
