Evaluation of methane emissions from West Siberian wetlands based on inverse modeling

Abstract

West Siberia contains the largest extent of wetlands in the world, including large peat deposits; the wetland area is equivalent to 27% of the total area of West Siberia. This study used inverse modeling to refine emissions estimates for West Siberia using atmospheric CH4 observations and two wetland CH4 emissions inventories: (1) the global wetland emissions dataset of the NASA Goddard Institute for Space Studies (the GISS inventory), which includes emission seasons and emission rates based on climatology of monthly surface air temperature and precipitation, and (2) the West Siberian wetland emissions data (the Bc7 inventory), based on in situ flux measurements and a detailed wetland classification. The two inversions using the GISS and Bc7 inventories estimated annual mean flux from West Siberian wetlands to be 2.9 ± 1.7 and 3.0 ± 1.4 Tg yr − 1, respectively, which are lower than the 6.3 Tg yr − 1 predicted in the GISS inventory, but similar to those of the Bc7 inventory (3.2 Tg yr − 1). The well-constrained monthly fluxes and a comparison between the predicted CH4 concentrations in the two inversions suggest that the Bc7 inventory predicts the seasonal cycle of West Siberian wetland CH4 emissions more reasonably, indicating that the GISS inventory predicts more emissions from wetlands in northern and middle taiga.