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| Titel |
Methane emissions from wetlands and its role on the global methane budget over the last millenium |
| VerfasserIn |
Bruno Ringeval, Sophie Szopa, Pierre Friedlingstein, Juliette Lathière, Jerome Servonnat, Myriam Khodri, Jérôme Chappellaz, Nathalie De-Noblet, Philippe Ciais |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250042722
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| Zusammenfassung |
| More than methane (CH4) atmospheric concentration, the contribution of each source to the
global budget does present strong variations with time over the last millennium. This is
proved by large variations in ice-core record of stable carbon isotope measurements in
atmospheric CH4 (δ13CH4) [Etheridge et al., 1998; MacFarling Meure et al., 2006].
Uncertainties remain about how to explain these observed variations and two major
hypotheses have been put forward to explain the measurements [Ferretti et al., 2005;
Houweling, 2008]. Even if these hypotheses are based mainly on the role played by biomass
burning and anthropogenic sources emergence, they also suggest a decrease in natural sources
during the Little Ice Age (LIA) but at different magnitude [Houweling et al., 2008]. Thus
better constraint on CH4 emissions from wetlands during the LIA could help us to choose
among these hypotheses and to better understand the global CH4 budget over the last
millenium.
Here, we present results of a modelling approach over the 800-1800 period using the
ORCHIDEE model [Krinner et al., 2005] accounting for CH4 emissions by wetlands. The
TOPMODEL approach [Beven and Kirkby, 1979; Decharme and Douville, 2006] and a
modification of the process-based model by Walter et al. [2001] are included in
ORCHIDEE to compute the wetland dynamic and related CH4 fluxes [Ringeval et
al., submitted]. The model was forced with climate fields from a last millennium
simulation performed with the IPSL-CM4 coupled ocean-atmosphere general circulation
model.
The simulated CH4 wetland emissions for key periods (Medieval Warm Optimum and
LIA) are then transported in the atmosphere with LMDz-INCA, a global three-dimensional
chemistry-climate model [Hauglustaine et al., 2004]. Emissions of volatile organic
compounds computed by ORCHIDEE [Lathiere et al., 2005] are also provided to
LMDz-INCA as well as mean 800-1800 estimates of other sources. This allows us to estimate
the relative roles of wetland emissions vs. atmospheric chemistry in controlling the changes
in CH4 concentration during the last millennium. |
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