11th December 2013

Powerful new greenhouse gas discovered

A newly-discovered greenhouse gas, perfluorotributylamine, has over 7,000 times the heat-trapping ability of CO2 over a 100-year period.

Scientists from the University of Toronto have discovered a novel chemical lurking in the atmosphere that appears to be a long-lived greenhouse gas (LLGHG). The chemical – perfluorotributylamine (PFTBA) – is among the most radiatively efficient chemicals found to date.

Radiative efficiency describes how effectively a molecule can affect climate. This value is then multiplied by its atmospheric concentration to determine the total climate impact.

PFTBA has been in use since the mid-20th century for various applications in electrical equipment and is currently used in thermally and chemically stable liquids marketed for use in electronic testing and as heat transfer agents. It does not occur naturally; that is, it is produced by humans. There are no known processes that would destroy or remove PFTBA in the lower atmosphere so it has a very long lifetime, possibly up to 500 years, and is destroyed in the upper atmosphere.

"Global warming potential is a metric used to compare the cumulative effects of different greenhouse gases on climate over a specified time period," said Cora Young who was part of the research team, along with Angela Hong and their supervisor, Scott Mabury. 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.

Carbon dioxide (CO2) is used as the baseline for comparison, since it is the most important greenhouse gas responsible for human-induced climate change. "PFTBA is extremely long-lived in the atmosphere and has very high radiative efficiency; the result of this is a very high global warming potential. Calculated over a 100-year timeframe, a single molecule of PFTBA has the equivalent climate impact as 7,100 molecules of CO2," said Hong. "There are no policies that control its production, use, or emission. It is not being regulated by any type of climate policy."

Dr Drew Shindell, a climatologist at NASA: "This is a warning to us that this gas could have a very, very large impact on climate change – if there were a lot of it. Since there is not a lot of it now, we don't have to worry about it at present, but we have to make sure it doesn't grow and become a very large contributor to global warming."

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