Climate Change Drives Widespread and Rapid Thermokarst Development in Very Cold Permafrost in the Canadian High Arctic

Farquharson, Louise M.; Romanovsky, V. E.; Cable, William; Walker, Donald A.; Kokelj, Steven V.; Nicolsky, Dmitry

doi:10.1029/2019gl082187

Cited by 209 publications

(156 citation statements)

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“…Our results support the importance of considering the spatial organization and density of IW troughs within a landscape as the magnitude of the impacts of IW degradation on vegetation communities, soil moisture, snow distribution, and the ground thermal regime can differ within a small area. This idea merits further study, particularly with recent observations in widespread IW degradation (Farquharson et al, 2019;Fraser et al, 2018;Frost et al, 2018;Jorgenson et al, 2006;Jorgenson & Grosse, 2016;Liljedahl et al, 2016) and future thermokarst generated by climate change. The spatial importance of these impacts varies depending on the surface cover density of IW troughs within an area (Figure 8).…”

Section: Iw Polygon Landscapesmentioning

confidence: 99%

“…Active IW systems (particularly in the high Arctic where vegetation and organic protection is lacking) are in dynamic equilibrium with climate, where the top of the IW is positioned at the active layer‐permafrost interface in a quasi‐stable situation (Pollard et al, ). An increase in the active layer thickness can melt some of the ice at the top of the wedge, leading to deeper troughs (Farquharson et al, ). Rapid degradation of IWs has been observed in recent decades (Farquharson et al, ; Fraser et al, ; Frost et al, ; Jorgenson et al, ; Jorgenson & Grosse, ; Liljedahl et al, ), as IW degradation has been accelerated with climate change.…”

Section: Introductionmentioning

confidence: 99%

“…An increase in the active layer thickness can melt some of the ice at the top of the wedge, leading to deeper troughs (Farquharson et al, ). Rapid degradation of IWs has been observed in recent decades (Farquharson et al, ; Fraser et al, ; Frost et al, ; Jorgenson et al, ; Jorgenson & Grosse, ; Liljedahl et al, ), as IW degradation has been accelerated with climate change. Their widespread distribution in the Arctic means that these systems will generate environmental changes and feedback that will likely increase in significance.…”

Section: Introductionmentioning

confidence: 99%

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Impacts of Degrading Ice‐Wedges on Ground Temperatures in a High Arctic Polar Desert System

2020

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Ice‐wedge ice is the most widespread type of massive ice found in the continuous permafrost zone. Polygonal networks of ice‐wedges drive environmental changes and feedback that will likely be exacerbated with future climate change. Recent decadal‐scale observations have shown that ice‐wedges are degrading rapidly within the entire Circum‐Arctic Region but observations of feedback associated with ground temperature regimes are still lacking in many areas. We present over a year's worth of field observations from an area with cold (−16.5°C), thick (>500 m) continuous permafrost and a mean annual air temperature of −19.7°C in the Canadian high Arctic. Topographic surveys, thaw depths, vegetation cover, soil moisture, and annual shallow (12 cm) ground temperature measurements were collected for seven ice‐wedge troughs and two polygon centers in a high‐centered polygon system. We show that geomorphic changes caused by ice‐wedge degradation generate new responses in soil moisture, vegetation cover, and snow distribution that create a mosaic of ground temperatures that range by 5.1°C for mean annual, 2.5°C in summer, and 15.2°C in winter between polygon‐centers and ice‐wedge troughs. Our results show that snow redistribution due to wind induces the cooling of polygon centers, thus promoting new thermal contraction cracking and ice‐wedge formation. We provide an example based on high‐resolution remote sensing data on how these ice‐wedge trough densities vary spatially in our study area. Capturing these fine scale geomorphic differences and resulting ground temperatures will be critical to accurately assess future changes of these common Arctic landscapes.

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Section: Iw Polygon Landscapesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Impacts of Degrading Ice‐Wedges on Ground Temperatures in a High Arctic Polar Desert System

2020

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“…In the past 30 years, increased air temperatures associated with climate change (Overland et al, ; Schuur et al, ) have spurred an abrupt acceleration in the onset of ice wedge melting throughout the Arctic (Farquharson et al, ; Fraser et al, ; Jorgenson et al, , ; Liljedahl et al, ; Raynolds et al, ). Once melting initiates, however, the relationship between summer severity and rates of ice wedge degradation is nonlinear, as thermokarst is influenced by an array of competing feedbacks (Jorgenson et al, ; Kanevskiy et al, ).…”

Section: Introductionmentioning

confidence: 99%

Feedbacks Between Surface Deformation and Permafrost Degradation in Ice Wedge Polygons, Arctic Coastal Plain, Alaska

et al. 2020

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In the past three decades, an abrupt, pan‐Arctic acceleration of ice wedge melting has transformed tundra landscapes, spurring the formation of hummock‐like features known as high‐centered polygons (HCPs). This rapid geomorphic transition profoundly alters regional hydrology and influences surface emissions of CO2 and CH4. In Arctic Alaska, most recent instances of ice wedge degradation have arrested within 15–20 years of inception, stabilizing HCP microtopography. However, feedbacks between ground surface deformation and permafrost stability are incompletely understood, limiting our capacity to predict trajectories of landscape evolution in a still warmer future. Here, we use field data from a site near Prudhoe Bay, Alaska, to develop a modeling‐based framework for assessing the strength of positive (i.e., exacerbating) feedbacks on ice wedge degradation, focusing on the importance of heterogeneity in surface drainage and microtopographic conditions. Our simulations suggest that, when troughs are narrow, positive feedbacks on ice wedge melting (associated with thermokarst pool formation) are relatively weak. Positive feedbacks are markedly stronger beneath wide troughs, such as those that form above older, larger ice wedges. Seasonal thaw abruptly accelerates once a talik begins to form beneath wide and deep thermokarst pools. Once a talik initiates, winter severity and snowpack thickness increase in importance as predictors of thaw intensity in summer. Our results indicate that meter‐scale heterogeneity in polygonal microtopography potentially exerts strong, nonlinear controls on thermokarst trajectories. These findings are useful for predicting future thermokarst dynamics and for interpreting the results from coarser‐resolution land surface models operating at greater spatial and temporal scales.

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“…Warming causes permafrost thaw through the gradual deepening of the active layer and increasing soil mass wasting processes (Arctic Monitoring and Assessment Programme, 2017). The active layer will continue to deepen and ice‐rich zones will thaw, which will promote slope instability, rapid mass movement (e.g., landslides and active layer failures) and enhanced rates of solifluction activity (Biskaborn et al, 2019; Farquharson et al, 2019; Lewkowicz & Way, 2019). These climate‐driven changes will impact the hydrological and related hydrochemical fluxes to aquatic ecosystems (Lafreniére & Lamoureux, 2019).…”

Section: Introductionmentioning

confidence: 99%

Biofilm Growth in Two Streams Draining Mountainous Permafrost Catchments in NE Greenland

2020

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The objective of this study was to evaluate how stream water nutrient concentrations influence biofilm accrual in streams draining mountainous permafrost headwaters. We selected six stream locations in the Zackenberg area (NE Greenland, 74°N) subjected to a gradient in the areal contribution of different geomorphological units in the watersheds and channel stability. We used nutrient diffusing substrates to evaluate biofilm growth (autotrophic and total biomass). We found elevated stream nitrate concentrations in samples from upstream reaches draining larger areas of solifluction sheets and bare rock and with higher channel instability. Nitrate had the highest standardized effect on autotrophic biofilm growth on control disks. However, stream biofilm growth was not nutrient limited as shown by the absence of an increase in biofilm biomass as a response to the experimental nutrient additions. The response to nutrient additions via diffusing substrates depended on the altitude gradient. Overall, our results showed stream nitrogen availability to be one of the main drivers of algal biofilm accrual in high‐Arctic streams, suggesting that the predicted changes in nutrient exports induced by climate change will have strong impacts on the biogeochemistry and ecological functioning of high‐Arctic streams.

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Climate Change Drives Widespread and Rapid Thermokarst Development in Very Cold Permafrost in the Canadian High Arctic

Cited by 209 publications

References 37 publications

Impacts of Degrading Ice‐Wedges on Ground Temperatures in a High Arctic Polar Desert System

Impacts of Degrading Ice‐Wedges on Ground Temperatures in a High Arctic Polar Desert System

Feedbacks Between Surface Deformation and Permafrost Degradation in Ice Wedge Polygons, Arctic Coastal Plain, Alaska

Biofilm Growth in Two Streams Draining Mountainous Permafrost Catchments in NE Greenland

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