ASSESSING THE CARBON BALANCE OF CIRCUMPOLAR ARCTIC TUNDRA USING REMOTE SENSING AND PROCESS MODELING

Authors

  • Stephen Sitch,

    1. Potsdam Institute for Climate Impact Research (PIK), P.O. Box 601203, 14412 Potsdam, Germany
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    • A. David McGuire,

      1. U.S. Geological Survey, Alaska Cooperative Fish and Wildlife Research Unit, 214 Irving I Building, University of Alaska, Fairbanks, Alaska 99775 USA
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    • John Kimball,

      1. Flathead Lake Biological Station, Division of Biological Sciences, 311 BioStation Lane, University of Montana, Polson, Montana 59860-9659 USA
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    • Nicola Gedney,

      1. Met Office, Hadley Centre for Climate Prediction and Research (JCHMR), Maclean Building, Crowmarsh-Gifford, Wallingford, OX10 8BB, UK
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    • John Gamon,

      1. Center for Environmental Analysis (CEA-CREST) and Department of Biological Sciences, 5151 State University Drive, California State University, Los Angeles, California 90032 USA
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    • Ryan Engstrom,

      1. Department of Geography, George Washington University, 1957 E Street NW, Suite 512, Washington, D.C. 20052 USA
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    • Annett Wolf,

      1. Abisko Scientific Research Station, 981 07 Abisko, Sweden and Department of Physical Geography and Ecosystem Analysis, Sölvegatan 12, Lund University, 22362 Lund, Sweden
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      • Qianlai Zhuang,

        1. The Ecosystems Center, Marine Biological Laboratory, 7 MBL Street, Woods Hole, Massachusetts 02543 USA
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        • Joy Clein,

          1. Institute of Arctic Biology, 214 Irving I Building, University of Alaska, Fairbanks, Alaska 99775 USA
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        • Kyle C. McDonald

          1. Water and Carbon Cycles Group, Mail Stop 300-233, Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109-8099 USA
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        • Corresponding editor: M. L. Goulden.

        Abstract

        This paper reviews the current status of using remote sensing and process-based modeling approaches to assess the contemporary and future circumpolar carbon balance of Arctic tundra, including the exchange of both carbon dioxide and methane with the atmosphere. Analyses based on remote sensing approaches that use a 20-year data record of satellite data indicate that tundra is greening in the Arctic, suggesting an increase in photosynthetic activity and net primary production. Modeling studies generally simulate a small net carbon sink for the distribution of Arctic tundra, a result that is within the uncertainty range of field-based estimates of net carbon exchange. Applications of process-based approaches for scenarios of future climate change generally indicate net carbon sequestration in Arctic tundra as enhanced vegetation production exceeds simulated increases in decomposition. However, methane emissions are likely to increase dramatically, in response to rising soil temperatures, over the next century. Key uncertainties in the response of Arctic ecosystems to climate change include uncertainties in future fire regimes and uncertainties relating to changes in the soil environment. These include the response of soil decomposition and respiration to warming and deepening of the soil active layer, uncertainties in precipitation and potential soil drying, and distribution of wetlands. While there are numerous uncertainties in the projections of process-based models, they generally indicate that Arctic tundra will be a small sink for carbon over the next century and that methane emissions will increase considerably, which implies that exchange of greenhouse gases between the atmosphere and Arctic tundra ecosystems is likely to contribute to climate warming.

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