The consumption of atmospheric methane by soil in a simulated future climate

Abstract

Abstract.A recently developed model for the consumption of atmospheric methane by soil (Curry, 2007) is used to investigate the global magnitude and distribution of methane uptake in a simulated future climate. In addition to solving the one-dimensional diffusion-reaction equation, the model includes a parameterization of biological CH 4 oxidation that is sensitive to soil temperature and moisture content, along with specified reduction factors for land cultivation and wetland fractional coverage. Under the SRES emission scenario A1B, the model projects an 8% increase in the global annual mean CH 4 soil sink by 2100, over and above the 15% increase expected from increased CH 4 concentration alone. While the largest absolute increases occur in cool temperate and subtropical forest ecosystems, the largest relative increases in consumption (>40%) are seen in the boreal forest, tundra and polar desert environments of the high northern latitudes. Methane uptake at mid-to high northern latitudes increases year-round in 2100, with a 68% increase over present-day values in June. This increase is primarily due to enhanced soil diffusivity resulting from lower soil moisture produced by increased evaporation and reduced snow cover. At lower latitudes, uptake is enhanced mainly by elevated soil temperatures and/or reduced soil moisture stress, with the dominant influence determined by the local climate.

Stabilization and stimulation of atmospheric methane oxidation in soil and soil biofilters by Al2O3 amendment

“…This effect may potentially be alleviated by soil homogenization to increase methane diffusivity (Blagodatsky and Smith, 2012;Tate et al, 2012). Changes in soil structure, and loss or displacement of water as water is known to be a crucial parameter for soil diffusion (Moldrup et al, 2000;Smith et al, 2003;Curry, 2009;Kolb, 2009;Blagodatsky and Smith, 2012). In the present study, sieving and repacking of spruce soil cores did not increase methane fluxes significantly relative to fluxes in intact soil cores.…”

“…The atmospheric methane concentration has increased for several decades due to an imbalance of 28e37 Tg yr À1 between methane emission and consumption Dalal et al, 2008). This imbalance is more or less equal to the annual microbial oxidation of atmospheric methane in soils which accounts for 15e45 Tg yr À1 , making atmospheric methane oxidation in soil a very important process in the global methane cycle (Dalal et al, 2008;Conrad, 2009;Curry, 2009;Kolb, 2009).…”

Present state of global wetland extent and wetland methane modelling: methodology of a model inter-comparison project (WETCHIMP)

“…More recent work has devoted much effort to improving modelling of these processes (Segers and Leffelaar, 2001;van Bodegom et al, 2001a,b;Zhuang et al, 2006) and other controls on CH 4 production such as pH (Zhuang et al, 2004). Oxidation in the oxic portion of the soil, water column, and rhizosphere has also been parameterized (Ridgwell et al, 1999;Segers and Leffelaar, 2001;Zhuang et al, 2006;Curry, 2007Curry, , 2009. Model simulations have also moved on from equilibrium-only simulations to transient simulations (Walter et al, 2001a,b;Shindell et al, 2004;Gedney et al, 2004;Zhuang et al, 2006).…”

Improved quantification of microbial CH<sub>4</sub> oxidation efficiency in arctic wetland soils using carbon isotope fractionation

“…This pathway may allow more than 90 % of the available CH 4 to be oxidized to CO 2 before it reaches the soil surface (Roslev and King, 1996;Sundh et al, 1995). The extent to which the CH 4 produced is oxidized, the CH 4 oxidation efficiency, is controlled by the key factors (1) rate of microbial oxidation (Wang et al, 2004) and (2) rate of diffusion of CH 4 (Curry, 2009;Dueñas et al, 1994). These parameters are mainly governed by the abundance and composition of methane oxidizing microbial communities and the environmental factors CH 4 and oxygen (O 2 ) availability, soil airfilled porosity and soil-water content.…”