TY - JOUR
T1 - Carbon Thaw Rate Doubles When Accounting for Subsidence in a Permafrost Warming Experiment
AU - Rodenhizer, Heidi
AU - Ledman, Justin
AU - Mauritz, Marguerite
AU - Natali, Susan M.
AU - Pegoraro, Elaine
AU - Plaza, César
AU - Romano, Emily
AU - Schädel, Christina
AU - Taylor, Meghan
AU - Schuur, Edward
N1 - Funding Information:
This work was based in part on support provided by the following programs: U.S. Department of Energy, Office of Biological and Environmental Research, Terrestrial Ecosystem Science (TES) Program, Award DE-SC0006982 and updated with DE-SC0014085; National Science Foundation CAREER program, Award 0747195; National Parks Inventory and Monitoring Program; National Science Foundation Bonanza Creek LTER program, Award 1026415; National Science Foundation Office of Polar Programs, Award 1203777; and NNA: LTREB: The Arctic Carbon and Climate (ACCLIMATE) Observatory: Tundra Ecosystem Carbon Balance and Old Carbon Loss as a Consequence of Permafrost Degradation (Award 1754839). The National Park Service and Denali National Park, particularly Joel Cusick and Britta Schroeder, contributed their time, technical expertise, and GPS equipment. Jamie Hollingsworth at the Bonanza Creek LTER generously contributed GPS equipment. Many field technicians and graduate students, including Elizabeth Webb and Fay Belshe, made the collection of so many GPS data points possible. Katie Heard and Pat Burns, among many others, contributed to troubleshooting errors in the GPS data. All data are currently available on the Bonanza Creek LTER Data Catalog (http://www.lter.uaf.edu/data/data-catalog). See citations within section 3 for links to specific data sets.
Funding Information:
This work was based in part on support provided by the following programs: U.S. Department of Energy, Office of Biological and Environmental Research, Terrestrial Ecosystem Science (TES) Program, Award DE‐SC0006982 and updated with DE‐SC0014085; National Science Foundation CAREER program, Award 0747195; National Parks Inventory and Monitoring Program; National Science Foundation Bonanza Creek LTER program, Award 1026415; National Science Foundation Office of Polar Programs, Award 1203777; and NNA: LTREB: The Arctic Carbon and Climate (ACCLIMATE) Observatory: Tundra Ecosystem Carbon Balance and Old Carbon Loss as a Consequence of Permafrost Degradation (Award 1754839). The National Park Service and Denali National Park, particularly Joel Cusick and Britta Schroeder, contributed their time, technical expertise, and GPS equipment. Jamie Hollingsworth at the Bonanza Creek LTER generously contributed GPS equipment. Many field technicians and graduate students, including Elizabeth Webb and Fay Belshe, made the collection of so many GPS data points possible. Katie Heard and Pat Burns, among many others, contributed to troubleshooting errors in the GPS data. All data are currently available on the Bonanza Creek LTER Data Catalog ( http://www.lter.uaf.edu/data/data-catalog ). See citations within section 3 for links to specific data sets.
Publisher Copyright:
©2020. American Geophysical Union. All Rights Reserved.
PY - 2020/6/1
Y1 - 2020/6/1
N2 - Permafrost thaw is typically measured with active layer thickness, or the maximum seasonal thaw measured from the ground surface. However, previous work has shown that this measurement alone fails to account for ground subsidence and therefore underestimates permafrost thaw. To determine the impact of subsidence on observed permafrost thaw and thawed soil carbon stocks, we quantified subsidence using high-accuracy GPS and identified its environmental drivers in a permafrost warming experiment near the southern limit of permafrost in Alaska. With permafrost temperatures near 0°C, 10.8 cm of subsidence was observed in control plots over 9 years. Experimental air and soil warming increased subsidence by five times and created inundated microsites. Across treatments, ice and soil loss drove 85–91% and 9–15% of subsidence, respectively. Accounting for subsidence, permafrost thawed between 19% (control) and 49% (warming) deeper than active layer thickness indicated, and the amount of newly thawed carbon within the active layer was between 37% (control) and 113% (warming) greater. As additional carbon thaws as the active layer deepens, carbon fluxes to the atmosphere and lateral transport of carbon in groundwater could increase. The magnitude of this impact is uncertain at the landscape scale, though, due to limited subsidence measurements. Therefore, to determine the full extent of permafrost thaw across the circumpolar region and its feedback on the carbon cycle, it is necessary to quantify subsidence more broadly across the circumpolar region.
AB - Permafrost thaw is typically measured with active layer thickness, or the maximum seasonal thaw measured from the ground surface. However, previous work has shown that this measurement alone fails to account for ground subsidence and therefore underestimates permafrost thaw. To determine the impact of subsidence on observed permafrost thaw and thawed soil carbon stocks, we quantified subsidence using high-accuracy GPS and identified its environmental drivers in a permafrost warming experiment near the southern limit of permafrost in Alaska. With permafrost temperatures near 0°C, 10.8 cm of subsidence was observed in control plots over 9 years. Experimental air and soil warming increased subsidence by five times and created inundated microsites. Across treatments, ice and soil loss drove 85–91% and 9–15% of subsidence, respectively. Accounting for subsidence, permafrost thawed between 19% (control) and 49% (warming) deeper than active layer thickness indicated, and the amount of newly thawed carbon within the active layer was between 37% (control) and 113% (warming) greater. As additional carbon thaws as the active layer deepens, carbon fluxes to the atmosphere and lateral transport of carbon in groundwater could increase. The magnitude of this impact is uncertain at the landscape scale, though, due to limited subsidence measurements. Therefore, to determine the full extent of permafrost thaw across the circumpolar region and its feedback on the carbon cycle, it is necessary to quantify subsidence more broadly across the circumpolar region.
KW - Arctic
KW - carbon
KW - climate change
KW - permafrost
KW - tundra
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U2 - 10.1029/2019JG005528
DO - 10.1029/2019JG005528
M3 - Article
AN - SCOPUS:85086892359
SN - 2169-8953
VL - 125
JO - Journal of Geophysical Research: Biogeosciences
JF - Journal of Geophysical Research: Biogeosciences
IS - 6
M1 - e2019JG005528
ER -