Soil temperature response to global warming: implications for carbon content from thawing permafrost soils in North America

Abstract

Changes in the observed depth of the active layer in Northern regions and the projected changes in soil temperatures over the next century have recently raised questions on the fate of carbon stored in frozen soils should these soils thaw. Of particular concern are peatland soils that have a much higher carbon concentration then mineral soil but also have unique thermal and hydrological characteristics that insulate deeper peat soil from the atmosphere and dampen the response of soil temperatures to changes in air temperature.

We used a thermodynamic soil temperature model to predict 21st century changes in the soil temperatures across northern North America, and implications of these changes for the active layer depth and the amount of carbon that could potentially interact with the atmosphere or hydrosphere. Taking into account the spatial distribution of peatlands and their depths in Alaska and Canada, we estimate the volume of newly thawed peatland soils and mineral soils and the amount of carbon that potentially changes from being relatively inert (frozen) to seasonally biogeochemically active in these soils. Results indicate a moderate decrease in the peatland area underlain by permanently frozen soils, and a steady increase in the volume of soil that will seasonally thaw during the 21st century for both mineral and peatland soils, although the degradation of permafrost in peatland areas is delayed. We report volumes of thawed soils and estimate carbon content in those volumes based on reported carbon concentrations.

Department

Earth Sciences, Earth Systems Research Center

Publication Date

1-2011

Journal Title

North American Carbon Program Meeting

Publisher

North American Carbon Program

Document Type

Conference Proceeding

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