29 Aug 2022
29 Aug 2022
Status: this preprint is currently under review for the journal BG.

Using atmospheric observations to quantify annual biogenic carbon dioxide fluxes on the Alaska North Slope

Luke D. Schiferl1,2, Jennifer D. Watts3, Erik J. L. Larson4, Kyle A. Arndt5,6, Sébastien C. Biraud7, Eugénie S. Euskirchen8, John M. Henderson9, Kathryn McKain10,11, Marikate E. Mountain9, J. William Munger2, Walter C. Oechel5,12, Colm Sweeney10, Yonghong Yi13,14, Donatella Zona5,15, and Róisín Commane1,16 Luke D. Schiferl et al.
  • 1Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York, USA
  • 2Harvard John A. Paulson School of Engineering and Applied Sciences, Cambridge, Massachusetts, USA
  • 3Woodwell Climate Research Center, Falmouth, Massachusetts, USA
  • 4Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, USA
  • 5Department of Biology, San Diego State University, San Diego, California, USA
  • 6Earth Systems Research Center, Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, New Hampshire, USA
  • 7Lawrence Berkeley National Laboratory, Berkeley, California, USA
  • 8Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, Alaska, USA
  • 9Atmospheric and Environmental Research, Inc., Lexington, Massachusetts, USA
  • 10Global Monitoring Laboratory, Earth System Research Laboratories, NOAA, Boulder, Colorado, USA
  • 11Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA
  • 12Department of Geography, University of Exeter, Exeter, United Kingdom
  • 13Joint Institute for Regional Earth System Science and Engineering, University of California, Los Angeles, California, USA
  • 14College of Surveying and Geo-Informatics, Tongji University, Shanghai, China
  • 15Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield, United Kingdom
  • 16Department of Earth and Environmental Sciences, Columbia University, New York, New York, USA

Abstract. The continued warming of the Arctic could release vast stores of carbon into the atmosphere from high-latitude ecosystems, especially from thawing permafrost. Increasing uptake of carbon dioxide (CO2) by vegetation during longer growing seasons may partially offset such release of carbon. However, evidence of significant net annual release of carbon from site-level observations and model simulations across tundra ecosystems has been inconclusive. To address this knowledge gap, we combined top-down observations of atmospheric CO2 concentrations from aircraft and a tall tower, which integrate ecosystem exchange over large regions, with bottom-up observed CO2 fluxes from tundra environments and found that the Alaska North Slope is not a consistent net source or net sink of CO2 to the atmosphere (ranging from –6 to +6 TgC yr–1 for 2012–2017). Our analysis suggests that significant biogenic CO2 fluxes from unfrozen terrestrial soils, and likely inland waters, during the early cold season (September–December) are major factors in determining the net annual carbon balance of the North Slope, implying strong sensitivity to the rapidly warming freeze-up period. At the regional level, we find no evidence for previously reported large late cold season (January–April) CO2 emissions to the atmosphere during the study period. Despite the importance of the cold season CO2 emissions to the annual total, the interannual variability of the net CO2 flux is driven by the variability in growing season fluxes. During the growing season, the regional net CO2 flux is also highly sensitive to the distribution of tundra vegetation types throughout the North Slope. This study shows that quantification and characterization of year-round CO2 fluxes from the heterogeneous terrestrial and aquatic ecosystems in the Arctic using both site-level and atmospheric observations is important to accurately project the earth system response to future warming.

Luke D. Schiferl et al.

Status: open (until 17 Oct 2022)

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Luke D. Schiferl et al.

Luke D. Schiferl et al.


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Short summary
As the Arctic rapidly warms, vast stores of thawing permafrost could release carbon dioxide (CO2) into the atmosphere. We combined observations of atmospheric CO2 concentrations from aircraft and a tower with observed CO2 fluxes from tundra ecosystems and found that the Alaskan North Slope in not a consistent source or sink for CO2. Our study shows the importance of using both site-level and atmospheric measurements to constrain regional net CO2 fluxes and improve biogenic processes in models.