Scientists discover greenhouse gas 7,100 times more potent than carbon dioxide

A team of chemists from the University of Toronto has published a study that found a gas called perfluorotributylamine (PFTBA), which has been in use for decades in electronic equipment, is the most potent greenhouse gas we know of — 7,100 times more potent than carbon dioxide.

"PFTBA is extremely long-lived in the atmosphere and it has a very high radiative efficiency; the result of this is a very high global warming potential," said Angela Hong, one of the researchers who co-authored the study, according to a UofT news release. "Calculated over a 100-year timeframe, a single molecule of PFTBA has the equivalent climate impact as 7,100 molecules of CO2."

'Radiative efficiency' is a measure of how much solar radiation a substance can affect, by volume. The total effect on the depends on this value, how much of the substance is in atmosphere, and how long it stays there for. The researchers found that PFTBA has a radiative efficiency of 0.86, compared to 0.000014 for CO2 and 0.00037 for methane. Other chemicals have slightly higher efficiency, but they only last a very short time in the atmosphere before they're broken down. Nature has no way of removing PFTBA from the lower atmosphere, so it lingers for a minimum of 500 years before it reaches the upper atmosphere and is broken down there.

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"Global warming potential is a metric used to compare the cumulative effects of different greenhouse gases on climate over a specified time period," said study co-author Cora Young said in the UofT news release. "Time is incorporated in the global warming potential metric as different compounds stay in the atmosphere for different lengths of time, which determines how long-lasting the climate impacts are."

The only good news about PFTBA is that there is only an extremely tiny amount of it in the air. The researchers measured a concentration of 0.18 parts per trillion in the Toronto area. Assuming that's typical of the global background concentration, that's less than half a billionth of the current atmospheric concentration of CO2. So, PFTBA isn't driving any of the current climate change, but its potency is the real concern.

"It is so much less than carbon dioxide, but the important thing is on a per molecule basis, it is very very effective in interacting with heat from the Earth," Hong told The Guardian. "Individually each molecule is able to affect the climate potentially and because its lifetime is so long it also has a long-lasting effect."

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This discovery is reminiscent of scientists finding out that chlorofluorocarbons (CFCs) — thought to be completely inert and harmless for over 40 years of use in refrigeration — were destroying our planet's protective layer of stratospheric ozone. The Montreal Protocol was signed and ratified by nations around the world, causing a shift away from these damaging products and on to (hopefully) safer alternatives. However, industries use many different chemicals in their day-to-day operations, and apparently the long-term climate change impacts of many of them aren't known. The researchers are recommending further study of perfluoroalkyl amines, the class of chemicals that PFTBA belongs to, but how many more industrial chemicals are we going to find that have these kinds of strong impacts?

(Photo courtesy: Getty Images)

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