The Carbon Balance of Arctic Tundra in Response to Permafrost Thawing: Using Radiocarbon to Detect the Loss of Old Soil Carbon

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ABSTRACTUp to 450 billion tons of soil carbon has accumulated in high latitude ecosystems after theretreat of the last major ice sheets. Recent studies suggest that these ecosystems may no longerbe accumulating carbon in soils, and in some cases may be losing stored carbon to theatmosphere. This study will use measurements of radiocarbon isotopes to ask the question: Is oldcarbon that comprises the bulk of the soil organic matter pool released in response to thawing ofpermafrost? Field measurements will center on a site in Alaska where permafrost has beenobserved to warm and melt over the past several decades. This area is unique for addressingquestions at the time scales relevant for change in arctic ecosystems.This project has broad significance for changes in the global carbon cycle. Transfer of carbonnow stored in waterlogged and frozen soils to the atmosphere could cause a significant positivefeedback to climate change due to the large size and potential reactivity of this carbon reservoir.In addition to the measurement program, this project will support an experienced journalist tospend time in the field each year as a consultant to the project. She will interface with scientistsand communicate the results of the research by producing stories for various public radio andprint outlets. These stories will share the research questions and implications of this project witha broad-based, lay audience.