HFC-23, 13,000 times more potent than CO2, was thought to be in sharp decline. Instead, according to a study, it has reached record levels in the atmosphere.
International conferences, reports from research institutes and NGO campaigns often focus on carbon dioxide (CO2) emissions — the primary greenhouse gas of anthropogenic origin, in terms of the quantity dispersed into the Earth's atmosphere. But the process of warming the latter is also driven by other substances. One of these is HFC-23.
Few people are familiar with it, partly because it was believed to have been largely eliminated in recent years. Contrary to all expectations, however, concentrations of trifluoromethane in the Earth's atmosphere have grown to record levels, according to a study published on 21 January by the scientific journal Nature.
This is dramatic news, given that HFC-23 — a necessary by-product in the manufacture of HCFC-22, found in air conditioners worldwide (but particularly in developing countries) — has a climate-altering potential 13,000 times greater than CO2. And it persists in the atmosphere for more than two centuries.
The study highlights how the problem is concentrated primarily in China and India, despite the two nations having pledged drastic reductions. "From 2015 onwards," write the scientists who authored the paper, "the two Asian states that dominate the production of HCFC-22, and are therefore also responsible for the by-product HFC-23, had drawn up ambitious programmes. These should have led to a fall of 87 per cent, at the global level, by 2017."
However, the researchers' analysis continues, "given the magnitude of the gap between expected and observed emissions, it is likely that the declared reduction targets were not actually met. Or that there exists significant undeclared production of HCFC-22, capable of explaining the unaccounted-for emissions of HFC-23." While the cause of the problem remains to be understood, what is clear is that achieving the targets set by the Paris Agreement is becoming ever more difficult.
