摘要:We used a biogeochemistry model, the Terrestrial Ecosystem Model (TEM), to examine the methane
(CH4) exchanges between terrestrial ecosystems and the atmosphere in Northern Eurasia from
1971 to 2100. Multiple model simulations using various wetland extent datasets
and climate change scenarios were conducted to assess the uncertainty of
CH4 fluxes, including emissions and consumption. On the basis of these
simulations we estimate the current net emissions in the region to be 20–24 Tg CH4 yr − 1 (1 Tg = 1012 g),
two-thirds of which are emitted during the summer. In response to climate change over the 21st century, the
annual CH4 emissions in the region are projected to increase at a rate of
0.06 Tg CH4 yr − 1, which is an order of magnitude greater than that of annual
CH4 consumption. Further,
the annual net CH4 emissions are projected to increase by 6–51% under various wetland extent datasets and climate
scenarios by the end of the 21st century, relative to present conditions. Spatial patterns of net
CH4 emissions were determined by wetland extent. Net
CH4 emissions were dominated by wetlands within boreal forests, grasslands and wet tundra
areas in the region. Correlation analyses indicated that water table depth and
soil temperature were the two most important environmental controls on both
CH4 emissions and consumption in the region. Our uncertainty analyses indicated
that the uncertainty in wetland extent had a larger effect on future
CH4 emissions than the uncertainty in future climate. This study suggests
that better characterization of the spatial distribution and the natural
diversity of wetlands should be a research priority for quantifying
CH4 fluxes in this region.