Modeling modern methane emissions from wetlands 1980-present

Methane is one of the important greenhouse gases and plays an important role in atmospheric chemistry. Its contribution to the current greenhouse effect is about 22%. Since the beginning of the industrialization the atmospheric methane concentration has increased by a factor of 2.5. This increase continues until present, however, since the early 1990s the growth rate has decreased. Superimposed on this trend is considerable interannual variation. Currently natural wetlands are the largest methane source, however, current estimates of the wetland source strength are still uncertain, ranging from about 145 Tg yr [Houweling et al., 1999, and references therein] to 230 Tg yr [Hein et al., 1997]. In addition, they are believed to contribute considerably to interannual variations and particular anomalies. Wetland emissions depend highly on the climate, i.e., on soil temperature and water table. In this study, the history of global wetland emissions from 1980present has been simulated using a process-based methane-hydrology model that derives methane emissions from natural wetlands as a function of soil temperature, water table, and Net Primary Productivity. ECMWF and NCEP re-analyses were used as model forcing.