Where are these fluorocarbons coming from?

Levels of hydrofluorocarbon-23 (HFC-23), which is a greenhouse gas twelve thousand times more potent than carbon dioxide, are at an all-time record high, despite claims emissions have been eliminated...

“China and India reported they had made huge cuts in the emissions of this gas, which would have led to around a 90% cut in global emissions. This would have been very detectable in atmospheric measurements,” explains Matt Rigby, an atmospheric scientist from the University of Bristol and author of a new report on HFC-23 levels. “But unfortunately, instead of reducing, they’ve grown and now they’re higher than they’ve ever been.”

These results, published in the journal Nature Communications, suggest that rather than being captured and destroyed as manufacturers are reporting, this greenhouse gas is still being vented into the atmosphere.

Greenhouse gases are able to absorb the long-wavelength infrared light that radiates from the Earth's surface. This prevents the radiation escaping into space, and traps the energy associated with that light in the Earth's atmosphere, causing the temperature to rise.

The gas in question, hydrofluorocarbon-23, or HFC-23, is a fluorine-containing gas produced as a byproduct in the manufacture of refrigerants. Its potency as a greenhouse gas comes from two factors. HFC-23 can trap much larger amounts of energy than carbon dioxide and remains in the atmosphere for up to 228 years after it has been emitted.

Only one out of every trillion molecules in the atmosphere is a molecule of HFC-23, so measuring the concentration of the gas requires special techniques. “We have to use techniques that get rid of the bulk gases in the atmosphere, like nitrogen and oxygen, from our air samples, so we have more concentrated samples of the gases that we’re interested in”, says Rigby.

“We measure at various points on the Earth’s surface. For example, we have measurement stations on the West coast of Ireland, in Barbados and Samoa, which are relatively clean environments where we can look at the change in concentration in the background atmosphere”.

This study hasn’t confirmed the sources of the HFC-23, but data from different measurement stations may provide clues in the future.

“We have a measurement station in Korea, which is quite close to some potential emission hotspots...hopefully we’ll be able to verify whether it is China that is still continuing to emit large quantities of HFC-23.”