For decades, we used chemicals called clorofluorocarbons (CFCs) in aerosol cans and refridgerators, unaware of the effect they had on the environment. In the 1970s, scientists began to realize that the CFCs we'd been releasing into the atmosphere were staying there, slowly eroding the ozone layer that protects us from harmful ultraviolet rays. In response, the world’s nations signed the Montreal Protocol in 1987, which slowly phased out CFCs over the subsequent two decades.
Since about 2010, the world has all but stopped using CFCs and replaced them with cleaner, safer products. The ozone layer has since come a long way toward fully recovering in one of the greatest success stories of the environmental movement. But shows that somehow, CFCs are still making their way into the atmosphere.
The National Oceanic and Atmospheric Administration maintains a number of stations around the world that constantly sample the air for all kinds of chemicals. Since a peak in the mid 1990s, CFC levels have been steadily decreasing, which is great news for our planet. But since about 2012, that decrease has been slowing down, which means more CFCs are entering the atmosphere.
There are a handful of possible sources for these additional CFCs, including legacy aerosol cans made before the ban or demolishing old buildings with CFC materials in them. But neither really account for the scale of the problem, so the researchers conclude that the only explanation that makes sense is that someone is making more of the stuff.
This is potentially a serious problem. Whoever is doing this is violating international law and potentially delaying the recovery of the ozone layer by decades. Currently, there’s not enough evidence to determine where these excess CFCs are coming from, but if the research holds up it could spark an investigation into the source.
This is also mysterious because there’s no real reason why anyone should be manufacturing CFCs anymore. Safer, cheaper alternatives have existed for decades, so even if there weren’t a ban on making them there’s no practical use for them anymore. Perhaps soon, we might finally get some answers and some accountability.