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Long-Lived Greenhouse Gas Discovered: Highest Global-Warming Impact
of Any Compound to Date
Scientists
from U of T's Department of Chemistry have discovered a novel
chemical lurking in the atmosphere that appears to be a long-lived
greenhouse gas (LLGHG). The chemical -- perfluorotributylamine
(PFTBA) -- is the most radiatively efficient chemical found to date,
breaking all other chemical records for its potential to impact
climate.
9
December, 2013
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 hundreds of 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 U of T 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 it
has a 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 7100
molecules of CO2," said Hong.
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