 |
| Titel |
Global emission estimates and radiative impact of C4F10, C5F12, C6F14, C7F16 and C8F18 |
| VerfasserIn |
D. J. Ivy, M. Rigby, M. Baasandorj, J. B. Burkholder, R. G. Prinn |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 12, no. 16 ; Nr. 12, no. 16 (2012-08-22), S.7635-7645 |
| Datensatznummer |
250011408
|
| Publikation (Nr.) |
 copernicus.org/acp-12-7635-2012.pdf |
|
|
|
|
|
| Zusammenfassung |
Global emission estimates based on new atmospheric observations are presented
for the acylic high molecular weight perfluorocarbons (PFCs):
decafluorobutane (C4F10), dodecafluoropentane (C5F12),
tetradecafluorohexane (C6F14), hexadecafluoroheptane
(C7F16) and octadecafluorooctane (C8F18). Emissions are
estimated using a 3-dimensional chemical transport model and an inverse
method that includes a growth constraint on emissions. The observations used
in the inversion are based on newly measured archived air samples that cover
a 39-yr period, from 1973 to 2011, and include 36 Northern Hemispheric and 46
Southern Hemispheric samples. The derived emission estimates show that global
emission rates were largest in the 1980s and 1990s for C4F10 and
C5F12, and in the 1990s for
C6F14, C7F16 and
C8F18. After a subsequent decline, emissions have remained
relatively stable, within 20%, for the last 5 yr. Bottom-up emission
estimates are available from the Emission Database for Global Atmospheric
Research version 4.2 (EDGARv4.2) for C4F10, C5F12,
C6F14 and C7F16,
and inventories of C4F10,
C5F12 and C6F14 are reported to the United Nations'
Framework Convention on Climate Change (UNFCCC) by Annex 1 countries that
have ratified the Kyoto Protocol. The atmospheric measurement-based emission
estimates are 20 times larger than EDGARv4.2 for C4F10 and over
three orders of magnitude larger for C5F12 (with 2008 EDGARv4.2
estimates for C5F12 at 9.6 kg yr−1, as compared to
67±53 t yr−1 as derived in this study). The derived emission
estimates for C6F14 largely agree with the bottom-up estimates
from EDGARv4.2. Moreover, the C7F16 emission estimates are
comparable to those of EDGARv4.2 at their peak in the 1990s, albeit
significant underestimation for the other time periods. There are no
bottom-up emission estimates for C8F18, thus the emission rates
reported here are the first for C8F18. The reported inventories
for C4F10, C5F12 and
C6F14 to UNFCCC are five to ten times lower than those estimated in this study.
In addition, we present measured infrared absorption spectra for
C7F16 and C8F18, and estimate their radiative
efficiencies and global warming potentials (GWPs). We find that
C8F18's radiative efficiency is similar to trifluoromethyl sulfur
pentafluoride's (SF5F3) at 0.57 W m−2 ppb−1, which is
the highest radiative efficiency of any measured atmospheric species. Using
the 100-yr time horizon GWPs, the total radiative impact of the high
molecular weight perfluorocarbons emissions are also estimated; we find the
high molecular weight PFCs peak contribution was in 1997 at 24 000 Gg of
carbon dioxide (CO2) equivalents and has decreased by a factor of
three to 7300 Gg of CO2 equivalents in 2010. This 2010 cumulative
emission rate for the high molecular weight PFCs is comparable to: 0.02%
of the total CO2 emissions, 0.81% of the total hydrofluorocarbon
emissions, or 1.07% of the total chlorofluorocarbon emissions projected
for 2010 (Velders et al., 2009). In terms of the total PFC emission budget,
including the lower molecular weight PFCs, the high molecular weight PFCs
peak contribution was also in 1997 at 15.4% and was 6% of the total
PFC emissions in CO2 equivalents in 2009. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|