Present And Future Methane Emissions of Northern Peatland in the Global Land Surface Model ORCHIDEE

Abstract:

As peatlands are one of the most significant natural sources of atmospheric methane, we included peatland processes in the land surface model ORCHIDEE to evaluate methane emissions from peatlands in northern high latitude (>45°) at global scale.

A specific hydrology of subgrid-scale peatlands as been included in the large-scale land surface model ORCHIDEE into which the soil water freeze-thaw cycle had already been implemented. Through this specific peatland hydrology, the description of the water table changes as been improved. This leads to a better estimation of methane production, oxidation and methane emission from peatlands. These developments are then used to evaluate present and future methane emission from northern peatlands, and to quantify the relative contribution of the three main processes of emission: plants, bubbling and diffusion.

In this work, we present the results on inter-annual and decadal variation of actual northern peatland emissions at global scale. We further analyze future projections of methane emissions from peatlands depending on the future hydrological profiles in different climate change scenarios. Finally, we estimate the contribution of northern peatland methane emission on present and future atmospheric concentration of CH₄ by 2100.