New studies indicate that China may have successfully curbed production of CFC-11, an ozone-depleting refrigerant also used for foam insulation.
The chemical was banned, along with other CFCs such as R12 and R502, under the Montreal Protocol to stop the production and import of ozone depleting substances and reduce their concentration in the atmosphere. In 2018, however, reports emerged of an increase in concentrations of the gas from 2012 onwards. Scientists, industry experts, policy-makers and others duly looked for the cause.
Later in 2018, evidence emerged that 18 companies in China were using CFC-11 in the polyurethane (PU) foam insulation sector. And in 2019, Nature published high-frequency atmospheric observations that confirmed increased emissions from eastern mainland China, primarily around the northeastern provinces of Shandong and Hebei. It was thought that this could account for more than half of the global increase in CFC-11 emissions.
Although, at the time, the Chinese environment ministry refuted these findings, it also agreed to establish a monitoring network and increase penalties for companies caught producing the chemical.
Now, a pair of studies published in Nature indicate that these measures may have worked. They show an accelerated decline in the global mean CFC-11 concentration during 2019 and 2020, derived from atmospheric concentration measurements at remote sites around the world.
“We find that global CFC-11 emissions decreased by 18 ± 6 gigagrams per year (26 ± 9 per cent; one standard deviation) from 2018 to 2019, to a 2019 value (52 ± 10 gigagrams per year) that is similar to the 2008−2012 mean,” says one study.
“The decline in global emissions suggests a substantial decrease in unreported CFC-11 production. If the sharp decline in unexpected global emissions and unreported production is sustained, any associated future ozone depletion is likely to be limited, despite an increase in the CFC-11 bank (the amount of CFC-11 produced, but not yet emitted) by 90 to 725 gigagrams by the beginning of 2020.”
There are still some gaps in the data, particularly in large industrial countries such as India and Brazil. Around 40 per cent of the recent decrease is yet to be accounted for. Discussions are now under way among parties to the Montreal Protocol to expand the network of monitoring stations.