For over a century now, scientists have understood the crucial link that lies between greenhouse gases and the effect known as “Global Warming”. For decades, scientists have been focused on the role played by carbon dioxide and methane gas, the two principle polluters that are tied to human behavior and the consequences of our activities.
But now, a long-lived greenhouse gas, more potent than any other, has been discovered in the upper atmosphere by chemists at the University of Toronto. It’s known as Perfluorotributylamine (PFTBA), a gas that has a radiative efficiency of 0.86 – which is one measure of a chemical’s effectiveness at warming the climate (expressed in parts per million).
At present, the biggest contributor to climate change is carbon dioxide, mainly because its concentrations are so high — 393.1 parts per million in 2012 and growing, thanks to human activity. However, many other gases contribute to this trend – such as nitrogen trifluoride and various chloroflurocarbons (CFCs) – but are less involved in the overall warming effect because their concentrations are lower.
According to the research article, which appeared in a recent issue of Geophysics Research Letters, the concentrations of PFTBA are very small — about 0.18 parts per trillion by volume in the atmosphere (at least in Toronto, where it was detected). But even though the overall contribution of PFTBA is comparatively small, its effect is “on the same scale as some of the gases that the monitoring community is aware of.”
According to 3M, a producer of PFTBA, the chemical has been sold for more than 30 years for the purpose of cooling semiconductor processing equipment and specialized military equipment, much in the same way that CFCs have been used. It is effective at transferring heat away from electronic components, and is stable, non-flammable, non-toxic, and doesn’t conduct electricity.
The chemical has an average lifespan of about 500 years in the lower atmosphere, and also like CFC’s, it has long been known to have the potential to cause damage to the ozone layer. But up until now its ability to trap heat in the atmosphere had not been measured, nor had it been detected in the atmosphere. The reason PFTBA is so potent compared to other gases is that it absorbs heat that would normally escape from the atmosphere.
Heat, or infrared radiation comes, in different colors, and each greenhouse gas is only able to absorb certain colors of heat. PFTBA is different in that it manages to absorb colors that other greenhouse gases don’t. It was after some was discovered on the university grounds by Professor Scott Mabury that his team began to consider whether any had made it into the atmosphere as well.
Shortly thereafter, they conducted a series of tests to measure the radiative efficiency of the chemical and then began looking for samples of it in the air. This involved deploying air pumps to three locations – including the University of Toronto campus, Mt. Pleasant Cemetery and Woodbine Beach. The samples were then condensed and concentrated, and the PFTBA separated by weight.
The end result was that PFTBA was found in all samples, including those upwind from the University of Toronto, suggesting that it wasn’t just coming from the chemistry building. However, the measurements were local and therefore not representative of the global average concentrations of the chemical. Still, its discovery is an indication that dangers might exist.
According to Angela Hong, a PhD student at the UofT department of chemistry and the lead author of the paper, this danger lies in the combined effect PFTBA could have alongside other gases:
If you’re suddenly going to add a greenhouse gas and it absorbs in that region. it’s going to be very potent.
Its effect is far more intense if its effect per molecule is considered, since it is about 15 times heavier than carbon dioxide. What’s more, PFTBA survives hundreds of years in the atmosphere, which means its effects are long-lasting. Fortunately, its use has been regulated under a U.S. Environmental Protection Agency program that promotes alternatives to chemicals that deplete the ozone layer.
In addition, chemicals that deplete the ozone layer are recognized by the Kyoto Protocols. As such, it should be an easy matter (from a legal standpoint anyway) to legislate against its continued use. As 3M indicated in a recent press statement:
That regulation stipulates that PFCs [the class of chemical that PFTBA belongs to] should be used only where there are no other alternatives on the basis of performance and safety. 3M adheres to that policy globally.
It added that the company “has worked to limit the use of these materials to non-emissive applications” and emphasized that the concentration of PFTBA found in the atmosphere is very low.
Nevertheless, this represents good news and bad news when it comes to the ongoing issue of Climate Change. On the one hand, early detection like this is a good way of ensuring that gases that contribute to the problem can be identified and brought under control before they become a problem. On the other, it shows us that when it comes to warming, there are more culprits than previously expected to contributing to it.
According to the most recent IPCC report, which was filed in 2012, the likelihood of us reaching a critical tipping point – i.e. the point of no return with warming – this century is highly unlikely. But that still leaves plenty of room for the problem to get worse before it gets better. One can only hope we get our acts together before it’s too late.