Abstract
Long-term sequestration of carbon in Alaskan Arctic tundra ecosystems was reversed by warming and drying of the climate in the early 1980s, resulting in substantial losses of terrestrial carbon1,2. But recent measurements suggest that continued warming and drying has resulted in diminished CO2 efflux, and in some cases, summer CO2 sink activity3,4. Here we compile summer CO2 flux data for two Arctic ecosystems from 1960 to the end of 1998. The results show that a return to summer sink activity has come during the warmest and driest period observed over the past four decades, and indicates a previously undemonstrated capacity for ecosystems to metabolically adjust to long-term (decadal or longer) changes in climate. The mechanisms involved are likely to include changes in nutrient cycling, physiological acclimation, and population and community reorganization. Nevertheless, despite the observed acclimation, the Arctic ecosystems studied are still annual net sources of CO2 to the atmosphere of at least 40 g C m-2 yr-1, due to winter release of CO2, implying that further climate change may still exacerbate CO2 emissions from Arctic ecosystems.
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Acknowledgements
We thank the Alaska Department of Natural Resources, US Bureau of Land Management, North Slope Borough Department of Industrial Development, ARCO Alaska, Inc., and BP Exploration for access to the North Slope study sites. Field assistance from R. Ault, P. Bryant and M. Vourlitis, and technical expertise from T. Crawford, T. Meyers, R. McMillen and Y. Harazono are acknowledged. We also thank A. D. McGuire, T. Christensen and S. Verma for commenting on earlier versions of the manuscript. This work was supported by the National Science Foundation, Arctic Systems Science, Land-Atmosphere-Ice-Interactions Program and Division of Environmental Biology, Joint Program on Terrestrial Ecology and Global Change, and by the US Department of Energy, Office of Health and Environmental Research. Logistic support was provided by the Northern Arctic Research Laboratory, the Polar Ice Coring Office (PICO), University of Alaska, Fairbanks (1994), PICO-University of Nebraska, Lincoln (1995–97), Institute of Arctic Biology, University of Alaska, Fairbanks, Piquniq Management Corporation and the North Slope Borough Department of Wildlife Management.
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Oechel, W., Vourlitis, G., Hastings, S. et al. Acclimation of ecosystem CO2 exchange in the Alaskan Arctic in response to decadal climate warming. Nature 406, 978–981 (2000). https://doi.org/10.1038/35023137
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DOI: https://doi.org/10.1038/35023137
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