Rising methane emissions in response to climate change in Northern Eurasia during the21st century

Abstract

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 from1971 to 2100. Multiple model simulations using various wetland extent datasetsand climate change scenarios were conducted to assess the uncertainty ofCH4 fluxes, including emissions and consumption. On the basis of thesesimulations 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, theannual CH4 emissions in the region are projected to increase at a rate of0.06 Tg CH4 yr − 1, which is an order of magnitude greater than that of annualCH4 consumption. Further,the annual net CH4 emissions are projected to increase by 6–51% under various wetland extent datasets and climatescenarios by the end of the 21st century, relative to present conditions. Spatial patterns of netCH4 emissions were determined by wetland extent. NetCH4 emissions were dominated by wetlands within boreal forests, grasslands and wet tundraareas in the region. Correlation analyses indicated that water table depth andsoil temperature were the two most important environmental controls on bothCH4 emissions and consumption in the region. Our uncertainty analyses indicatedthat the uncertainty in wetland extent had a larger effect on futureCH4 emissions than the uncertainty in future climate. This study suggeststhat better characterization of the spatial distribution and the naturaldiversity of wetlands should be a research priority for quantifyingCH4 fluxes in this region.