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| Titel |
Stable atmospheric methane in the 2000s: key-role of emissions from natural wetlands |
| VerfasserIn |
I. Pison, B. Ringeval, P. Bousquet, C. Prigent, F. Papa |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 13, no. 23 ; Nr. 13, no. 23 (2013-12-02), S.11609-11623 |
| Datensatznummer |
250085845
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| Publikation (Nr.) |
 copernicus.org/acp-13-11609-2013.pdf |
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| Zusammenfassung |
Two atmospheric inversions (one fine-resolved and one process-discriminating)
and a process-based model for land surface exchanges are brought together to
analyse the variations of methane emissions from 1990 to 2009. A focus is put
on the role of natural wetlands and on the years 2000–2006, a period of
stable atmospheric concentrations.
From 1990 to 2000, the top-down and bottom-up visions agree on the
time-phasing of global total and wetland emission anomalies. The
process-discriminating inversion indicates that wetlands dominate the
time-variability of methane emissions (90% of the total variability). The
contribution of tropical wetlands to the anomalies is found to be large,
especially during the post-Pinatubo years (global negative anomalies with
minima between −41 and −19 Tg yr−1 in 1992) and during the alternate 1997–1998
El-Niño/1998–1999 La-Niña (maximal anomalies in tropical regions
between +16 and +22 Tg yr−1 for the inversions and anomalies due to tropical
wetlands between +12 and +17 Tg yr−1 for the process-based model).
Between 2000 and 2006, during the stagnation of methane concentrations in the
atmosphere, the top-down and bottom-up approaches agree on the fact that
South America is the main region contributing to anomalies in natural wetland
emissions, but they disagree on the sign and magnitude of the flux trend in
the Amazon basin. A negative trend (−3.9 ± 1.3 Tg yr−1) is inferred by the
process-discriminating inversion whereas a positive trend (+1.3 ± 0.3 Tg yr−1)
is found by the process model. Although processed-based models have their own
caveats and may not take into account all processes, the positive trend found
by the B-U approach is considered more likely because it is a robust feature
of the process-based model, consistent with analysed precipitations and the
satellite-derived extent of inundated areas. On the contrary, the
surface-data based inversions lack constraints for South America. This result
suggests the need for a re-interpretation of the large increase found in
anthropogenic methane inventories after 2000. |
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