A research project that monitored the emission of chlorofluorocarbon gases (CFCs) of lesser-known types indicates that the emission of these compounds is increasing and, if growth continues at the same rate, could delay the recovery of the ozone layer and hinder the fight against global warming.

The conclusion came from a study by NOAA (National Oceanic and Atmospheric Agency of the USA) and the University of Bristol, in England, which monitored the planetary concentration of five gases of this class in the last ten years. The five substances chosen for the research are not being emitted by a kind of loophole allowed by the Montreal Protocol, signed in 1987 to ban CFCs and restore the stratospheric ozone that protects the planet from ultraviolet rays.

"The emission of these gases has been growing relatively fast since 2010, which is precisely the year that the Montreal Protocol set as the deadline for all CFCs to stop being emitted," Luke Western, a Bristol-based researcher who led the work, told a news conference. The fine print of the treaty, he says, opened a gap.

These gases have been banned for what we call "dispersive" uses, such as in aerosols, solvents, and refrigerators. But under the Montreal Protocol, the use of CFCs is still allowed as an intermediate product, that is, raw material to produce other compounds and chemicals.

It is in this permission, the researchers believe, that there is the margin for the hidden production now revealed. The geographical origin of these compounds, however, is not yet fully known.

"We know that the emissions are not coming from the U.S. or Europe because we have a very good monitoring network," says Stefan Reimann, a collaborator on the research at Switzerland's Federal Materials Science Laboratories. Scientists suspect that the biggest source of hidden CFCs is Asia, whose chemical industry has experienced major growth in the decade studied. But it's something that lacks proof yet.

Among the CFC variants that had been directly banned by Montreal were type 11, trichlorofluoromethane, and 12, dichlorofluoromethane, which were an integral part of refrigerator radiators. (The alphanumeric nomenclature for substances was adopted to facilitate soup notation of letters of names.) In the Bristol and NOAA study, the five subtypes covered are code 113a, 114a, 115, 13 and 112a.

For the first three, although scientists have not geographically located their emission sources, the origin is believed to be indirect use as a raw material. Some of them are used in the manufacture of HFCs (hydrofluorocarbons), gases adopted precisely as substitutes for the most harmful CFCs to ozone. That was, in a way, expected.

Mysterious origin

For the last two subtypes included in the study (13 and 112a), however, the mystery is greater, because even the reason for the emission is not understood.

"The case of CFC-13, in particular, is a bit scary, because we don't know of any kind of large-scale use for it. Still, there are emissions, and we don't know where they're coming from," says NOAA's Isaac Vimont.

The amount of gases detected, in absolute terms, is not yet large enough to compromise the Montreal Protocol. By the current projection, the hole in the ozone layer over Antarctica is expected to close around 2060.

What worries researchers most is the pace of the increase. The CFCs observed in the survey jumped from the equivalent of 1,600 tons annually in 2010 to 4,200 tons annually in 2020. It's a bit of unwanted pollution, considering it's substances that were off the radar.

"If we put in a train all the substances that we included in the measurement, it would be a freight train 2 km long, loaded with them," says Reimann.

Climate crisis

When one takes into account the impact of these gases on climate change, as agents of the greenhouse effect, the problem is further aggravated. What scientists have measured is equivalent to all the annual emissions of Switzerland, a country that is small but a relevant economy on the global stage. At a time when the entire planet is vying millimeter for its greenhouse gas emission cut targets, fleeing CFCs are bad news.

The good news is that for the gases that are escaping through HFC production, there is already an update of the Montreal agreement, the Kigali Amendment, signed in 2016, which provides for its reduction. To curb the leakage of more hidden CFCs, however, scientists advocate that there be another change to the original Protocol. To begin with, they say, one needs to know how, and where, these substances are being released.

"The continued issuance of the five CFCs in question may nullify some of the benefits gained from the Montreal Protocol if it continues to increase. In addition, the climate impact of emissions from these CFCs needs to be considered," say the scientists in the study, who advocate an expansion of the monitoring network.

Source: Um só Planeta