University of Oulu

Pedron, S. A., Welker, J. M., Euskirchen, E. S., Klein, E. S., Walker, J. C., Xu, X., & Czimczik, C. I. (2022). Closing the winter gap—Year-round measurements of soil CO2 emission sources in Arctic tundra. Geophysical Research Letters, 49, e2021GL097347.

Closing the winter gap : year-round measurements of soil CO₂ emission sources in Arctic tundra

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Author: Pedron, Shawn A.1; Welker, J. M.2,3,4; Euskirchen, E. S.5;
Organizations: 1Department of Earth System Science, University of California, Irvine, CA, USA
2Department of Biological Sciences, University of Alaska Anchorage, Anchorage, AK, USA
3University of Oulu, Oulu, Finland
4UArctic, Rovaniemi, Finland
5Institute of Arctic Biology, University of Alaska, Fairbanks, AK, USA
6Department of Geological Sciences, University of Alaska Anchorage, Anchorage, AK, USA
7A. E. Lalonde AMS Laboratory, Ottawa, ON, Canada
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.4 MB)
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Language: English
Published: American Geophysical Union, 2022
Publish Date: 2022-09-08


Non-growing season CO₂ emissions from Arctic tundra remain a major uncertainty in forecasting climate change consequences of permafrost thaw. We present the first time series of soil and microbial CO₂ emissions from a graminoid tundra based on year-round in situ measurements of the radiocarbon content of soil CO₂ (Δ¹⁴CO₂) and of bulk soil C (Δ¹⁴C), microbial activity, and temperature. Combining these data with land-atmosphere CO₂ exchange allows estimates of the proportion and mean age of microbial CO₂ emissions year-round. We observe a seasonal shift in emission sources from fresh carbon during the growing season (August Δ¹⁴CO₂ = 74 ± 4.7‰, 37% ± 3.4% microbial, mean ± se) to increasingly older soil carbon in fall and winter (March Δ¹⁴CO₂ = 22 ± 1.3‰, 47% ± 8% microbial). Thus, rising soil temperatures and emissions during fall and winter are depleting aged soil carbon pools in the active layer and thawing permafrost and further accelerating climate change.

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Series: Geophysical research letters
ISSN: 0094-8276
ISSN-E: 1944-8007
ISSN-L: 0094-8276
Volume: 49
Issue: 6
Article number: e2021GL097347
DOI: 10.1029/2021GL097347
Type of Publication: A1 Journal article – refereed
Field of Science: 1171 Geosciences
1172 Environmental sciences
Funding: The authors thank the Toolik Field Station Science Support and Environmental Data Center teams, D. Helmig (CU Boulder), and the KCCAMS staff and C. McCormick (UCI) for their logistical and technical support. Funding was provided by the U.S. National Science Foundation OPP (#1649664 to C. I. Czimczik, #1650084 to J. M. Welker and E. S. Klein, #1649792 to E. Euskirchen).
Copyright information: © 2022. The Authors. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivsLicense, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.