Analysis of the global atmospheric methane budget using ECHAM-MOZ simulations for present-day, pre-industrial time and the Last Glacial Maximum

• Main Authors: Basu, A., Schultz, M. G., Schröder, S., François, Louis, Zhang, X., Lohmann, G., Laepple, T.
• Format: Article in Journal/Newspaper
• Language: English
• Published: European Geosciences Union 2014
• Subjects: methane; wetlands; budget; global; model; Physical; chemical; mathematical & earth Sciences; Earth sciences & physical geography; Physique; chimie; mathématiques & sciences de la terre; Sciences de la terre & géographie physique; ice core
• Online Access: https://orbi.uliege.be/handle/2268/162550; https://doi.org/10.5194/acpd-14-3193-2014

peer reviewed Atmospheric methane concentrations increased considerably from pre-industrial (PI) to present times largely due to anthropogenic emissions. However, firn and ice core records also document a notable rise of methane levels between the Last Glacial Maximum (LGM) and the pre-industrial era, the exact cause of which is not entirely clear. This study investigates these changes by analyzing the methane sources and sinks at each of these climatic periods. Wetlands are the largest natural source of methane and play a key role in determining methane budget changes in particular in the absence of anthropogenic sources. Here, a simple wetland parameterization suitable for coarse-scale climate simulations over long periods is introduced, which is derived from a high- resolution map of surface slopes together with various soil hydrology parameters from the CARAIB vegetation model. This parameterization was implemented in the chem- istry general circulation model ECHAM5-MOZ and multi-year time slices were run for LGM, PI and present-day (PD) climate conditions. Global wetland emissions from our parameterization are 72 Tg yr