19
Hydrofluorocarbons (HFCs) are powerful
factory-made greenhouse gases used
primarily in air conditioning, refrigeration,
foam-blowing, fire suppression, solvents,
and aerosols. Their use is growing
because they are being widely adopted as
replacements for O
3
-depleting substances
(ODS), including chlorofluorocarbons
(CFCs) and hydrochlorofluorocarbons
(HCFCs), which are being phased out
under the Montreal Protocol on Substances
that Deplete the Ozone Layer.
The mix of HFCs in current use, weighted by
usage (tonnage), has an average atmospheric
lifetime of 15 years (Velders G.J.M.
et al.
2009). Although they currently represent
only a small fraction of the total greenhouse
gases (less than 1%), they are among the
fastest-growing ones (in percentage) in
many countries, including the United States,
the European Union, China, and India.
Emissions of high-global warming potential
(GWP) HFCs are rising very quickly at 8%
or more per year (UNEP 2011b).
A recent study concluded that replacing
high-GWP HFCs with low-GWP
alternatives could avoid 0.1°C of warming
by 2050 (Xu Y.
et al
. 2013).
08
Hydrofluorocarbons
