Closing the Winter Gap—Year‐Round Measurements of Soil CO2 Emission Sources in Arctic Tundra

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 conte...

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Bibliographic Details
Published in:Geophysical Research Letters
Main Authors: Pedron, Shawn A, Welker, JM, Euskirchen, ES, Klein, ES, Walker, JC, Xu, X, Czimczik, CI
Format: Article in Journal/Newspaper
Language:unknown
Published: eScholarship, University of California 2022
Subjects:
Climate Action
carbon flux
permafrost
radiocarbon
respiration
winter
vulnerability
Meteorology & Atmospheric Sciences
Climate change
Tundra
Online Access:https://escholarship.org/uc/item/0md7p85h
https://escholarship.org/content/qt0md7p85h/qt0md7p85h.pdf
https://doi.org/10.1029/2021gl097347
Description
Summary: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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