HFC-23: potent greenhouse gas emissions rise

HFC-23 is a gas produced as a byproduct while manufacturing refrigerants. It’s also an extremely potent greenhouse gas, thousands of times more powerful than carbon dioxide. Leading manufacturers have been under pressure to reduce their HFC emissions, which they claim they’ve done - but bizarrely, atmospheric scientists are seeing a quite different picture. Megan McGregor spoke to the University of Bristol’s Matt Rigby...

Matt - We saw reports from China and from India, which showed that they had completely cut down emissions of a very potent greenhouse gas called HFC-23. This gas has been growing fairly consistently in the atmosphere for a few decades now and about one tonne of emissions of this gas is equivalent to somewhere between 12 and 15,000 tonnes of emissions of carbon dioxide. So what we wanted to do is we wanted to then take a look at the data and see if that cut had actually played out in the atmospheric record. But unfortunately, what we seem to be finding is quite the opposite has happened. That actually instead of emissions reducing, they've grown and they're now are higher than they've ever been.

Megan - You wanted to keep an eye on the level of HFCs. How did you go about measuring their concentration in the atmosphere?

Matt - We use very sophisticated techniques, essentially they're methods to try and separate the air into its various component parts. And the concentrations of these HFCs are really challenging to measure. They're down at the levels of parts per trillion. So we have to use extremely sensitive instruments and we have to use techniques that essentially try and get rid of the bulk gases in the atmosphere. So things like nitrogen and oxygen. Sowe find ways of essentially removing those from our air samples and just leaving us with the more concentrated samples of the gases that we're interested in. And what we do is that we measure the concentration of a whole range of gases, at various points on the Earth's surface. For example, we have a measurement station on the West coast of Ireland and we have measurement stations in Barbados and Samoa. They tend to be in relatively clean environments where we can look at the change in concentration in the background atmosphere.

Megan - Is there any way using your measurement technique that you could figure out what's going on with, for example, more targeted measurements?

Matt - Yes. So that's going to be the next step. We have a measurement station in Korea which was not used in this paper. This station, instead of being far away from emission sources in the background atmosphere, is actually quite close to some potential emission hotspots. So, for example, it sees air arriving from the East coast of China. And so in the past we've used measurements from that station to be able to identify emission sources from China and the Korean peninsula. So hopefully we'll be able to verify whether it is China that is still continuing to emit large quantities of HFC-23.

Megan - So what would you say to someone in the UK who is trying to reduce their carbon emissions - they're cycling everywhere, they don't eat any meat - while this kind of thing is going on in the background, given that it's such a potent gas?

Matt - It's still important for all of us to think about how we live and how we can live more sustainably. But at the same time, yeah, we do need to keep up the pressure on the chemical industry because they do have a disproportionate impact on the climate and on the ozone layer. So hopefully, you know, with the two together, with enforcement action on chemical manufacturers, and action by billions of individuals, then we'll move towards a more sustainable economy.