Ice wedges: Growth, thaw transformation, and palaeoenvironmental significance

Harry, D. G.; Goździk, Jan

doi:10.1002/jqs.3390030107

Cited by 123 publications

(96 citation statements)

References 30 publications

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“…Wet and dry phases can then be explained by a feedback between sediment accumulation, controlled by the input of organic and mineral material, and the upward growth of ice-wedges, which is limited by the rate of sediment accumulation (Harry & Gozdzik 1988;Mackay 2000). Wet phases may correspond to periods when the amplitude between a polygon's ridges and centre is relatively large (higher values for Q g , Q s and P) although upward growth of icewedges, and the continued development of ridges, will gradually slow or cease, to be resumed only when sufficient sediments have accumulated in the polygon centre.…”

Section: Figmentioning

confidence: 99%

Long‐term sensitivity of a High Arctic wetland to Holocene climate change

Ellis

Rochefort

2005

Journal of Ecology

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Summary 1The response of peat-rich permafrost soils to human-induced climate change may be especially important in modifying the global C-flux. We examined the Holocene developmental record of a High Arctic peat-forming wetland to investigate its sensitivity to past climate change and aid understanding of the likely effects of future climate warming on high-latitude ecosystems. 2 The microhabitat of mosses was quantified in the present-day polygon-complex at Bylot Island (73 ° N, 80 ° W) and used to interpret the radiocarbon-dated macrofossil record of three cores, comprising c. 3500 years of wetland development. Recurrent wet and dry phases in the reconstructed palaeohydrological record indicated pronounced temporal variability. Wet and dry phases were compared between cores and with palaeoclimatic proxy values, measured as percentage melt and δ 18 O in nearby ice cores. 3 Periodic wet and dry phases appear unrelated to past climate over c. 50% of the combined stratigraphic records, and are attributable instead to geomorphological mechanisms. At other times, association of wet and dry phases with significantly lower and higher values of percentage melt and δ 18 O indicate a possible effect of past climate change on polygon hydrology and vegetation, although inconsistencies between cores suggest that local geomorphological processes continued to modify a regional climatic effect. However, during a period incorporating the Little Ice Age ( c. 305-530 cal. years  ), reconstructed moisture and vegetation change is pronounced and consistent among all three cores. 4 The results provide strong evidence for the sensitivity of a High Arctic terrestrial ecosystem to past climate change during the Holocene. The estimated magnitude of changes in soil moisture between wet and dry phases is sufficient to imply recurrent shifts in wetland function, periodically impacted upon by pronounced climatic variability, although controlled principally by autogenic processes. The structure and function of such wetlands may therefore be susceptible to predicted, human-induced climate warming.

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Section: Figmentioning

confidence: 99%

Long‐term sensitivity of a High Arctic wetland to Holocene climate change

Ellis

Rochefort

2005

Journal of Ecology

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“…This situation can lead to development of thermokarst terrain. Rapid backwards niveo-fluvial erosion of ice wedges has been demonstrated to create small valleys or large gullies in polygonal terrain (Svensson, 1982(Svensson, , 1988Harry and Gozdzik, 1988). In Svalbard such small valleys are up to 20-30 m long and 4-5 m deep and have developed relatively rapidly in sediments deposited during the last 3000 years.…”

Section: Ice Wedge Formation and Decay In Relation To Climate Changementioning

confidence: 99%

“…In most cases, ice wedges thaw from above (Harry and Gozdzik, 1988) due to increasing active layer thickness or because of local geomorphological activity such as alas lake development. Since ice wedge growth and decay are slow, little is known of the nature of the thaw transformation process both in different materials, geomorphological settings and relationships to climatic change.…”

Section: Ice Wedge Formation and Decay In Relation To Climate Changementioning

confidence: 99%

“…Since ice wedge growth and decay are slow, little is known of the nature of the thaw transformation process both in different materials, geomorphological settings and relationships to climatic change. Most studies of partial thaw of ice wedges are based on stratigraphical sections (Harry and Gozdzik, 1988), and they indicate small-scale faulting with subsidence and slumping in the thawed zone above the ice wedge, affecting the stability of the terrain surface. This situation can lead to development of thermokarst terrain.…”

Section: Ice Wedge Formation and Decay In Relation To Climate Changementioning

confidence: 99%

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Permafrost and climate in Europe: Monitoring and modelling thermal, geomorphological and geotechnical responses

Harris

Arenson

Christiansen³

et al. 2009

Earth-Science Reviews

575

361

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We present a review of the changing state of European permafrost within a spatial zone that includes the continuous high latitude arctic permafrost of Svalbard and the discontinuous high altitude mountain permafrost of Iceland, Fennoscandia and the Alps. The paper focuses on methodological developments and data collection over the last decade or so, including research associated with the continent-scale network of instrumented permafrost boreholes established between 1998 and 2001 under the European Union PACE project. Data indicate recent warming trends, with greatest warming at higher latitudes. Equally important are the impacts of shorter-term extreme climatic events, most immediately reflected in changes in active layer thickness. A large number of complex variables, including altitude, topography, insolation and snow distribution, determine permafrost temperatures. The development of regionally calibrated empiricalstatistical models, and physically based process-oriented models, is described, and it is shown that, though more complex and data dependent, process-oriented approaches are better suited to estimating transient effects of climate change in complex mountain topography. Mapping and characterisation of permafrost depth and distribution requires integrated multiple geophysical approaches and recent advances are discussed. We report on recent research into ground ice formation, including ice segregation within bedrock and vein ice formation within ice wedge systems. The potential impacts of climate change on rock weathering, permafrost creep, landslides, rock falls, debris flows and slow mass movements are also discussed. Recent engineering responses to the potentially damaging effects of climate warming are outlined, and risk assessment strategies to minimise geological hazards are described. We conclude that forecasting changes in hazard occurrence, magnitude and frequency is likely to depend on process-based modelling, demanding improved understanding of geomorphological process-response systems and their impacts on human activity. We present a review of the changing state of European permafrost within a spatial zone that includes the continuous high latitude arctic permafrost of Svalbard and the discontinuous high altitude mountain permafrost of Iceland, Fennoscandia and the Alps. The paper focuses on methodological developments and data collection over the last decade or so, including research associated with the continent-scale network of instrumented permafrost boreholes established between 1998 and 2001 under the European Union PACE project. Data indicate recent warming trends, with greatest warming at higher latitudes. Equally important are the impacts of shorter-term extreme climatic events, most immediately reflected in changes in active layer thickness. A large number of complex variables, including altitude, topography, insolation and snow distribution, determine permafrost temperatures. The development of regionally calibrated empiricalstatistical models, and physically based ...

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“…In any discussion of the origin of the polygon network, one of the key elements to establish is whether the fissures are or were underlain by ice-wedges, by ice-wedge pseudomorphs (Harry and Gozdzik, 1988), by permafrost sand wedges (Péwé, 1959), by active layer ground wedges (Harry and Gozdzik, 1988), or by seasonal frost wedges (Dionne, 1978).…”

Section: Origin Of the Polygonsmentioning

confidence: 99%

Deeply Dissected Tundra Polygons on a Glacio-Fluvial Outwash Plain, Northern Ungava Peninsula, Québec

Gray¹,

Seppälä²

2007

gpq

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ABSTRACTDeeply dissected tundra polygons are described from the continuous permafrost environment of northernmost Ungava. They are developed on a glacial outwash plain, formed subsequent to déglaciation of the site about 7,500 BP. The exposed surfaces of the polygons are sparsely vegetated and aeolian deflation has removed their sandy matrix material. The furrows between the polygons attain depths of 0.5-2 m. From the base of one. a 0.25 m wide wedge of peat and sandy material penetrates to a minimum depth of 0.7 m (the frost table depth). Radiocarbon dates of 1650 ± 60 BP and 740 ± 80 BP indicate that progressive filling of this fissure accompanied decay of a preexisting ice-wedge. The present low mean annual air temperature at the site ( - 70C) suggests that thawing of the ice-wedges may be related more to local dynamic factors, such as deflation and improved local drainage associated with fluvial dissection, than to regional climatic amelioration. Wedge ice is believed to still underlie the polygon furrows.

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Ice wedges: Growth, thaw transformation, and palaeoenvironmental significance

Cited by 123 publications

References 30 publications

Long‐term sensitivity of a High Arctic wetland to Holocene climate change

Long‐term sensitivity of a High Arctic wetland to Holocene climate change

Permafrost and climate in Europe: Monitoring and modelling thermal, geomorphological and geotechnical responses

Deeply Dissected Tundra Polygons on a Glacio-Fluvial Outwash Plain, Northern Ungava Peninsula, Québec

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