A group of scientists have worked as a veritable atmospheric detective agency and dug into a new mystery of more ozone-damaging substances. Two years ago, they identified rogue sources of ozone-depleting chemicals. In a new study out Monday they found sources of new potentially damaging chemicals while highlighting just how crucial vigilance and early detection can be.
While the newly identified chemicals are less damaging to the ozone layer than others, they have no known use, which means they’re doing damage for no reason. And the findings, published in the Proceedings of the National Academy of Sciences, also show how far scientists have come in identifying the smallest traces of dangerous substances in the atmosphere and the value of developing an even more comprehensive monitoring network.
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Since 1978, a handful of sites scattered around the world have been used to measure trace gases in the atmosphere. For the current study, scientists looked at 14 sites that are part of or affiliated with the network, and are in operation from the frigid Arctic island of Svalbard to a site on the outskirts of densely populated Beijing. The observatories measure a host of gases from familiar ones like methane to ones with more unwieldy names and scientific abbreviations that nevertheless are vital to keep an eye on.
“We are monitoring many ‘known’ compounds, and are on the search for more hitherto unknown compounds,’ Martin Vollmer, the lead author on the new paper and researcher at the Swiss Federal Laboratories, said in an email. “We even built a new instrument, which can virtually scan the atmosphere for compounds, and take a ‘fingerprint’ or ‘DNA’ of the atmosphere.”
For the current study, scientists looked at hydrochlorofluorocarbons or more simply, HCFCs. The compounds can be used for a variety of purposes from cooling to solvents. There are a number of them, but scientists looked specifically at HCFC-132b, HCFC-133a, and HCFC-31 (don’t worry if you mix them up, there won’t be a quiz later). All three have no known use as an end product, but they are tied to the production of other chemical compounds.
While they’re reported on the ground by factories, the new study uses the network of monitors and models of global air circulation to track them from the top-down. The results show that the compounds started to appear in the atmosphere in the 1990s and have risen steadily since then.
The modelling allowed the researchers to pinpoint the biggest source to a few regions. HCFC-132b and HCFC-133a both predominantly came from eastern China, though from different regions. China was also the culprit in the earlier whodunit solved by the researchers. The researchers also found Europe was another likely source, but the concentrations in the atmosphere tied to the continent dropped off significantly in 2017 around the time a chemical plant in Lyon, France shut down.
These HCFCs aren’t as damaging as the chlorofluorocarbons — or CFCs — the researchers detected in their previous study. They do less damage to the ozone layer, and unlike some HCFCs, they don’t contribute to global warming. The relatively early detection of the chemicals also means scientists are measuring them in fractions of parts per trillion as opposed to parts per billion or million used to measure other ozone- and climate-wrecking chemicals.
Obviously, any type of pollution is bad, but the study does contain a kernel of good news given the relatively moderate impact the HCFCs have on the ozone layer and atmosphere. It shows the power of early detection and scientists maintaining vigilance. While more work will need to be done to pinpoint the exact source of the chemicals, the findings are another proof of concept for how top-down monitoring from satellites to air flasks taking samples around the world can be used to monitor dangerous compounds and gases in the atmosphere.
“This is like an important independent check,” Vollmer said, noting that it also points to the need to expand the network to fill in gaps in coverage.
In the case of these HCFCs with no known use, the work is invaluable to help clean up an extremely pointless form of pollution. As the world looks to draw down a number of emissions from CFCs to carbon dioxide to hydrofluorocarbons, this type of detective work will take on added importance to make sure countries are meeting their pledges and enforcing the regulations they put in place to do so.
Update, 1/25/21, 3:17 p.m.: This post has been updated with comments from Martin Vollmer.