Modeling ground thermal conditions and the limit of permafrost within the nearshore zone of the Mackenzie Delta, Canada

Stevens, Christopher W.; Moorman, Brian J.; Solomon, S.

doi:10.1029/2010jf001786

Cited by 12 publications

(19 citation statements)

References 35 publications

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“…Comparison of the permafrost delineation offshore of the Mackenzie mouth (Hunter et al, ) and modeled ice content give poor agreement. The Mackenzie outflow has warmer benthic temperatures than used as boundary condition in the model (Stevens et al, ), leading to an overestimation of permafrost ice content to the west within the Canadian Beaufort sector. The underestimation of permafrost ice content to the east may result from local inaccuracies in modeled glacial dynamics from CLIMBER‐2 or in sediment thermal properties.…”

Section: Discussionmentioning

confidence: 99%

Submarine Permafrost Map in the Arctic Modeled Using 1‐D Transient Heat Flux (SuPerMAP)

et al. 2019

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Offshore permafrost plays a role in the global climate system, but observations of permafrost thickness, state, and composition are limited to specific regions. The current global permafrost map shows potential offshore permafrost distribution based on bathymetry and global sea level rise. As a first‐order estimate, we employ a heat transfer model to calculate the subsurface temperature field. Our model uses dynamic upper boundary conditions that synthesize Earth System Model air temperature, ice mass distribution and thickness, and global sea level reconstruction and applies globally distributed geothermal heat flux as a lower boundary condition. Sea level reconstruction accounts for differences between marine and terrestrial sedimentation history. Sediment composition and pore water salinity are integrated in the model. Model runs for 450 ka for cross‐shelf transects were used to initialize the model for circumarctic modeling for the past 50 ka. Preindustrial submarine permafrost (i.e., cryotic sediment), modeled at 12.5‐km spatial resolution, lies beneath almost 2.5 ×106km2 of the Arctic shelf. Our simple modeling approach results in estimates of distribution of cryotic sediment that are similar to the current global map and recent seismically delineated permafrost distributions for the Beaufort and Kara seas, suggesting that sea level is a first‐order determinant for submarine permafrost distribution. Ice content and sediment thermal conductivity are also important for determining rates of permafrost thickness change. The model provides a consistent circumarctic approach to map submarine permafrost and to estimate the dynamics of permafrost in the past.

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Section: Discussionmentioning

confidence: 99%

Submarine Permafrost Map in the Arctic Modeled Using 1‐D Transient Heat Flux (SuPerMAP)

et al. 2019

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“…Where water depth ≤ lake ice thickness, a talik develops if thaw penetration exceeds the depth of seasonal frost penetration, or active layer, in the lake bottom sediment [ Mackay , ]. Few models consider talik development under such conditions, as available field data suggest that T lb are ≤0°C [ Brewer , ; Burn , ; Arp et al , ] and that permafrost is sustained beneath shallow water that freezes to the lake bottom in early winter [ Mackay , ; Burn , ; Schwamborn et al , ; Stevens et al , ]. In this study we describe observations of talik development beneath shallow, relatively flat‐bottomed, tundra lakes that freeze to the bottom over extended areas.…”

Section: Introductionmentioning

confidence: 86%

“…This results in increased permafrost vulnerability as it shifts the limit of permafrost sustainability toward higher FDD lb /TDD lb . Permafrost sustainability beneath the bottom‐fast ice of the outer Mackenzie Delta was effectively assessed by Stevens et al [] based on these principles.…”

Section: Introductionmentioning

confidence: 99%

Near‐shore talik development beneath shallow water in expanding thermokarst lakes, Old Crow Flats, Yukon

Roy-Léveillée

Burn

2017

JGR Earth Surface

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It is generally assumed that permafrost is preserved beneath shallow lakes and ponds in the Western North American Arctic where water depth is less than about two thirds of the late‐winter lake ice thickness. Here we present field observations of talik development beneath water as shallow as 0.2 m despite a lake ice thickness of 1.5 m, in Old Crow Flats (OCF), YT. Conditions leading to the initiation and development of taliks beneath shallow water were investigated with field measurements of shore erosion rates, bathymetry, ice thickness, snow accumulation, and lake bottom temperature near the shores of two expanding lakes in OCF. The sensitivity of talik development to variations in lake bottom thermal regime was then investigated numerically. Where ice reached the lake bottom, talik development was controlled by the ratio of freezing degree days to thawing degree days at the lake bottom (FDDlb/TDDlb). In some cases, spatial variations in on‐ice snow depth had a minimal effect on annual mean lake bottom temperature (Tlb) but caused sufficient variations in FDDlb/TDDlb to influence talik development. Where Tlb was close to but greater than 0°C simulations indicated that the thermal offset allowed permafrost aggradation to occur under certain conditions, resulting in irregular near‐shore talik geometries. The results highlight the sensitivity of permafrost to small changes in lake bottom thermal conditions where the water column freezes through in early winter and indicate the occurrence of permafrost degradation beneath very shallow water in the near‐shore zone of Arctic ponds and lakes.

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“…Although terrestrial permafrost was the main focus of the IPY project, recent investigations also provided new information on the thermal state of subsea permafrost in the Mackenzie Delta region (e.g. Solomon et al 2008;Stevens et al 2010).…”

Section: Permafrostmentioning

confidence: 99%

Variability and change in the Canadian cryosphere

et al. 2012

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During the International Polar Year (IPY), comprehensive observational research programs were undertaken to increase our understanding of the Canadian polar cryosphere response to a changing climate. Cryospheric components considered were snow, permafrost, sea ice, freshwater ice, glaciers and ice shelves. Enhancement of conventional observing systems and retrieval algorithms for satellite measurements facilitated development of a snapshot of current cryospheric conditions, providing a baseline against which future change can be assessed. Key findings include: 1. surface air temperatures across the Canadian Arctic exhibit a warming trend in all seasons over the past 40 years. A consistent pan-cryospheric response to these warming temperatures is evident through the analysis of multi-decadal datasets; 2. in recent years (including the IPY period) a higher rate of change was observed compared to previous decades including warming permafrost, reduction in snow cover extent and duration, reduction in summer sea ice extent, increased mass loss from glaciers, and thinning and break-up of the remaining Canadian ice shelves. These changes illustrate both a reduction in the spatial extent and mass of the cryosphere and an increase in the temporal persistence of melt related parameters. The observed changes in the cryosphere have important implications for human activity including the close ties of northerners to the land, access to northern regions for natural resource development, and the integrity of northern infrastructure.

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Modeling ground thermal conditions and the limit of permafrost within the nearshore zone of the Mackenzie Delta, Canada

Cited by 12 publications

References 35 publications

Submarine Permafrost Map in the Arctic Modeled Using 1‐D Transient Heat Flux (SuPerMAP)

Submarine Permafrost Map in the Arctic Modeled Using 1‐D Transient Heat Flux (SuPerMAP)

Near‐shore talik development beneath shallow water in expanding thermokarst lakes, Old Crow Flats, Yukon

Variability and change in the Canadian cryosphere

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