 |
| Titel |
Integrating a Methane Emission Tool into the Land Component JSBACH |
| VerfasserIn |
M. Tomasic, T. Vesala, M. Raivonen, S. Smolander, T. Holtta, V. Brovkin, R. Schuldt, A. Valdebenito, T. Kleinen, C. Reick |
| Konferenz |
EGU General Assembly 2012
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250060504
|
|
|
|
|
|
| Zusammenfassung |
| Northern peatlands in the northern hemisphere are a very large carbon storage pool and act as
a carbon sink due to the greater primary production than substrate decomposition over the last
6000 years [7]. This accumulation resulted in a global storage capacity between
220 and 445 GT [2]. Between 15to 22 $ of the global terrestrial carbon [3, 2] are
stored in these wetland ecosystems. They are one of the largest individual source of
emission on the global methane budget. Estimates of total emission vary between
100 - 231 Tg a-1 [4] which respresents about 15 - 20% of the overall contribution
[1, 5].  Calculating global methane budgets and emission patterns will depend
especially on the developments in this area. Temperature is expected to rise and the
following increase in anaerobic microbial activity has a very large significance for
detrimental changes in the global climate. Accurate observations and description of the
processes related to methanogenesis and emission is of fundamental necessity. We
are using two approaches to reach this goal:Â On one hand we perform continuous
measurements of ecosystem emissions of methane at our wetland site, a boreal
fen in southern Siikaneva close to Hyytyälä Forest Station in Southern Finland
[6]. As a second approach we are developing a methane emission scheme for the
JSBACH land and vegeation tool of the Max-Planck Earthsystem Model (MPI-ESM).
A stand alone version for comparison with the local site in Siikaneva will be the
follow up once the global tool has been calibrated and tested. Â Methane emissions
involve the interaction of different gases and thus has to be described with different
subprocesses:
1) Production of CH4 in correlation with the biomass substrate available 2) Oxidation of
CH4 among the different layers leading to CO2 2)Transport of methane up to the lower
boundary layer of the atmosphere via a) Diffusion in peat layer, b) Ebullition and c) Plant
enhancement . 4) Oxygen transport from the atmosphere downward to the roots and
aswell in the different layers 5) Transport of CO2 to the lower boundary layer of the
atmosphere
Several of the most important pathways of methane release have been described
by the modelling study by Wania et al. [8]. We are using this as a starting point
of our model development. An improved description of the transport process via
the plant aerenchyma is described in the model in comparison with the approach
taken by Wania and the transport and emission of CO2 as a process of oxidation of
methane is not being neglected. We are currently in the phase of calibrating and
testing the model so that we can start running comparison studies with previous
works [8]. First results of this modeling studies will be presented at the 2012 EGU
session.
References
[1]Â Â Â I. Aselmann and P. J. Crutzen. Global distribution of natural freshwater wetlands and
rice paddies, their net pri- mary productivity, seasonality and possible methane emissions.
Journal of Atmospheric Chemistry, 8:307–358, 1989. 10.1007/BF00052709.1
[2]Â Â Â E. Gorham. Northern peatlands: Role in the carbon cycle and probable response to
climate warming. Ecol. Monogr. 1, page 182195, 1991.
[3]Â Â Â P. Reich H. Eswaran, E. Van den Berg and J. Kimble. Global soil carbon resources.
Advances in Soil Science: Soils and Global Change, page 2743, 1995.
[4]Â Â Â A. Chidthaisong P. Ciais P. M. Cox R. E. Dickinson D. Hauglustaine C. Heinze E.
Holland D. Jacob U. Lohmann S. Rmachandran P. L. da Silva Dias S. C. Wofsy K. L.
Denman, G. Brasseur and X. Zhang. chapter Couplings between changes in the climate
system and biogeochemistry,In Solomon et al. [2007], chapter 7„ pages 499–588. John
Wiley, New York, 2007.
[5]Â Â Â E. Matthews and Inez Fung. Methane emission from natural wetlands: Global
distribution, area, and environmental characteristics of sources. Global Biogeochem. Cycles,
1:61– 86, 1987.
[6]Â Â Â J. Rinne, T. Riutta, M. Pihlatie, M. Aurela, S. Haapanala, J.-P. Tuovinen, E.-S. Tuittila,
and T. Vesala. Annual cycle of methane emission from a boreal fen measured by the eddy
covariance technique. Tellus B, 59(3):449457, 2007.
[7]Â Â Â J. M. Waddington and N. T. Roulet. Carbon balance of a boreal patterned peatland.
Global Change Biology, 6(1):8797, 2000.
[8]Â Â Â R. Wania, I. Ross, and I. C. Prentice. Integrating Peatlands and Permafrost into a
dynamic global vegetation model: 1. Evaluation and sensitivity of physical land surface
processes. Global Biogeochem. Cycles, 23, 2009. |
|
|
|
|
|
|