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| Titel |
Climate-CH4 feedback from wetlands and its interaction with the climate-CO2 feedback |
| VerfasserIn |
B. Ringeval, P. Friedlingstein, C. Koven, P. Ciais, N. Noblet-Ducoudré, B. Decharme, P. Cadule |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 8, no. 8 ; Nr. 8, no. 8 (2011-08-09), S.2137-2157 |
| Datensatznummer |
250006076
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| Publikation (Nr.) |
 copernicus.org/bg-8-2137-2011.pdf |
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| Zusammenfassung |
The existence of a feedback between climate and methane (CH4) emissions
from wetlands has previously been hypothesized, but both its sign and
amplitude remain unknown. Moreover, this feedback could interact with the
climate-CO2 cycle feedback, which has not yet been accounted for at the
global scale. These interactions relate to (i) the effect of atmospheric
CO2 on methanogenic substrates by virtue of its fertilizing effect on
plant productivity and (ii) the fact that a climate perturbation due to
CO2 (respectively CH4) radiative forcing has an effect on wetland
CH4 emissions (respectively CO2 fluxes at the surface/atmosphere
interface).
We present a theoretical analysis of these interactions, which makes it
possible to express the magnitude of the feedback for CO2 and CH4
alone, the additional gain due to interactions between these two feedbacks
and the effects of these feedbacks on the difference in atmospheric CH4
and CO2 between 2100 and pre-industrial time (respectively
ΔCH4 and ΔCO2). These gains are expressed as functions of
different sensitivity terms, which we estimate based on prior studies and
from experiments performed with the global terrestrial vegetation model
ORCHIDEE.
Despite high uncertainties on the sensitivity of wetland CH4 emissions
to climate, we found that the absolute value of the gain of the
climate-CH4 feedback from wetlands is relatively low (<30 % of
climate-CO2 feedback gain), with either negative or positive sign
within the range of estimates. Whereas the interactions between the two
feedbacks have low influence on ΔCO2, the ΔCH4
could increase by 475 to 1400 ppb based on the sign of the C-CH4
feedback gain.
Our study suggests that it is necessary to better constrain the evolution of
wetland area under future climate change as well as the local coupling
through methanogenesis substrate of the carbon and CH4 cycles – in
particular the magnitude of the CO2 fertilization effect on the wetland
CH4 emissions – as these are the dominant sources of uncertainty in our
model. |
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