Jan. 21 (UPI) -- Scientists had expected the levels of HFC-23, a type of hydrofluorocarbon and a potent greenhouse gas, to drop in the latest global survey of greenhouse gas emissions. Instead, atmospheric concentrations of HFC-23 are rising.
HFC-23 is the byproduct of the production of HCFC-22, another hydrofluorocarbon that is commonly used in cooling systems in developing economies. India and China are two of the largest emitters of HFC-23, but in 2015, the two nations promised to rapidly reduce their HFC-23 emissions.
After making the pledge, officials in China and India reported tremendous progress with their HFC-23 abatement program, with the expectation that HFC-23 emissions would drop to nearly zero by 2017.
A new study, published Tuesday in the journal Nature Communications, suggests the opposite has happened.
Authors of the new study assumed China and India's reported progress was real, and would lead to reduced concentration of HFC-23 in the atmosphere.
"We had no particular reason to distrust the reports. We were motivated to write the paper because the reported reductions were so dramatic," study co-author Matthew Rigby, an atmospheric chemist at the University of Bristol in Britain, told UPI in an email. "Based on the reported values, we were expecting to see global atmospheric concentrations stabilize, following decades of growth. So it was a surprise to see them continue to grow, and in fact, grow at a faster rate than ever before."
Rigby is a member of the Advanced Global Atmospheric Gases Experiment, UGAGE, which measure greenhouse gas concentrations in the atmosphere at test sites around the globe.
The latest findings revealed a significant global rise in HFC-23 in 2017, but the data doesn't pinpoint the exact source of the increase. Rigby and his colleagues acknowledged that their study doesn't prove China and India failed to execute their HFC-23 abatement programs.
"From our analysis, we cannot definitively say that China and India have not achieved their reported emission reductions," lead study author Kieran Stanley, a post-doctoral researcher at the Goethe University Frankfurt in Germany, told UPI. "However, seeing as China and India account for 75 percent of the total global HCFC-22 production in 2017, it is highly likely that China's reported emissions reductions haven't taken place."
Because India's HCFC-22 production accounts for just 7 percent of global production, it's harder to guess how much progress the country has made in its efforts to reduce HFC-23 emissions.
According to Stanley, had China and India truly made the emissions reduction progress they reported, that would mean large amounts of illegal, unreported HCFC-22 were manufactured in 2017. If that had happened, Stanley said the hydrocarbon's price should have dropped. It didn't.
After the ozone-eating gases, chlorofluorocarbons, or CFCs, were banned by the Montreal Protocol, most industries adopted a variety of alternative gases -- hydrofluorocarbons. While most of theses gases are less harmful to the ozone layer, some feature a greenhouse gas effect.
In 2016, parties to the Montreal Protocol signed the Kigali Amendment, aiming to reduce the warming impact of HFCs.
HFC-23's greenhouse gas effect is particularly potent. Just 1 metric ton of HFC-23 is equivalent to the greenhouse gas effect of 12,000 metric tons of carbon dioxide.
This isn't the first time scientists have found concentrations of a gas regulated by the Montreal Protocol and its amendments. In 2018, scientists found evidence of a dramatic rise in the ozone-eating gas CFC-11. Investigations revealed China's foam industry as the primary driver of the emissions increase.
"These two findings do suggest that monitoring of the chemical industry may need to be improved in China," Rigby said. "In light of the finding of new emissions of CFC-11 from China, the government has announced additional monitoring initiatives focused on ozone depleting substances. Hopefully, they will also be able to look into these continuing emissions of the greenhouse gas, HFC-23."