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Animal and plant remains, some associated with prehistoric artefacts, were collected in freezing caverns (glacieres) of northern Yukon Territory. Radiocarbon dates show that the oldest remains are Middle Wisconsinan (ca. 38 000 BP). The absence of material of Late Wisconsinan age likely indicates that the caves were infilled by ice during this cold period. Climate warming and ice melting during the Holocene allowed animals and prehistoric hunters to regularly visit these caves. Ice plugs were evidently smaller during the early Holocene than they are now.
High-latitude regions store large quantities of organic carbon (C) in permafrost soils and peatlands, accounting for nearly half of the global belowground C pool. Projected climate warming over the next century will likely drive widespread thawing of near-surface permafrost and mobilization of soil C from deep soil horizons. However, the processes controlling soil C accumulation and loss following permafrost thaw are not well understood. To improve our understanding of these processes, I examined the effects of permafrost thaw on soil C dynamics in forested upland and peatland ecosystems of Alaska's boreal region. In upland forests, soil C accumulation and loss was governed by the complex interaction of wildfire...
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High-latitude regions store large quantities of organic carbon (C) in permafrost soils and peatlands, accounting for nearly half of the global belowground C pool. Projected climate warming over the next century will likely drive widespread thawing of near-surface permafrost and mobilization of soil C from deep soil horizons. However, the processes controlling soil C accumulation and loss following permafrost thaw are not well understood. To improve our understanding of these processes, I examined the effects of permafrost thaw on soil C dynamics in forested upland and peatland ecosystems of Alaska's boreal region. In upland forests, soil C accumulation and loss was governed by the complex interaction of wildfire...
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Northern peatlands provide important global and regional ecosystem services (carbon storage, water storage, and biodiversity). However, these ecosystems face increases in the severity, areal extent, and frequency of climate-mediated (e.g., wildfire, drought) and land-use change (e.g., drainage, flooding, and mining) disturbances that are placing the future security of these critical ecosystem services in doubt. Here we provide the first detailed synthesis of autogenic hydrological feedbacks that operate within northern peatlands to regulate their response to changes in seasonal water deficit and varying disturbances. We review, synthesize, and critique the current process-based understanding and qualitatively assess...
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Air and surface temperatures were measured for one year at five sites with different permafrost conditions near Mayo, Yukon Territory, to examine the behaviour of freezing and thawing n-factors and the relations between air and surface temperatures. During the freezing season, surface temperatures were lower where the snow cover was thin. Where snow covers were similar, surface temperatures were lower where permafrost was present. The freezing n-factor is controlled primarily by snow, but also by subsurface thermal conditions. During the thawing season, surface temperatures were higher where the near-surface thermal diffusivity allowed for rapid descent of the frost table. The thawing n-factor is primarily controlled...
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The influence of permafrost growth and thaw on the evolution of ice-rich lowland terrain in the Koyukuk-Innoko region of interior Alaska is fundamental but poorly understood. To elucidate this influence, the cryostratigraphy and properties of perennially frozen sediments from three areas in this region are described and interpreted in terms of permafrost history. The upper part of the late Quaternary sediments at the Koyukuk and Innoko Flats comprise frozen organic soils up to 4.5 m thick underlain by ice-rich silt characterised by layered and reticulate cryostructures. The volume of visible segregated ice in silt locally reaches 50 per cent, with ice lenses up to 10 cm thick. A conceptual model of terrain evolution...
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We used the CRU (1950-1959 and 2000-2009) and projected 5-GCM composite (2001-2010, 2051-2060, and 2091-2100) decadal climate forcing, ecotype (Jorgenson et al. 2008), soil landscape (Jorgenson et al. 2008), and snow (unpublished) maps of WRST to model the presence or absence of near-surface permafrost, temperature at the bottom of seasonal freeze-thaw layer and thickness of seasonal freeze-thaw layer within WRST. We produced permafrost temperature and active-layer and seasonally-frozen-layer thickness distribution maps through this modeling effort at a pixel spacing of 28.5 m. This is an immense improvement over the spatial resolution of existing permafrost maps on any part of Alaska, whether produced through the...
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We employed an integrated approach that combined remote sensing techniques with field measurements to predict the presence/absence of near-surface permafrost in a section of the Alaska Highway corridor. We investigated the correlative relationships among vegetation type, topography, moss thickness, tussock condition and near-surface permafrost in the study area. Analysis of moss thickness and active-layer depth in low-lying plains (slope <8?) showed an inverse relationship in different vegetation classes. The maximum likelihood classification of remotely sensed data mapped 80% of the study area as covered with vegetation. We developed an empirical-statistical (Binary Logistic Regression) model to establish the statistical...
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Lake-rich thermokarst landscapes occupy vast regions and provide important natural resources for northern communities. Recent research has shown that these lake-rich environments are sensitive to changes in climate and are in a state of transition. Old Crow Flats (OCF, Yukon, Canada) is one such thermokarst landscape where people of the Vuntut Gwitchin First Nation (VGFN) have thrived for many generations. However, local residents have observed changes in OCF during recent decades including unpredictable weather patterns, expansion of shrub coverage, and drastic lake and river water level fluctuations. Concerns that these changes may affect their traditional lifestyles fueled initiation of a multidisciplinary Government...
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ABSTRACT: Wetlands exist in a transition zone between aquatic and terrestrial environments which can be altered by subtle changes in hydrology. Twentieth century climate records show that the United States is generally experiencing a trend towards a wetter, warmer climate; some climate models suggest that this trend will continue and possibly intensify over the next 100 years. Wetlands that are most likely to be affected by these and other potential changes (e.g., sea-level rise) associated with atmospheric carbon enrichment include permafrost wetlands, coastal and estuanne wetlands, peat lands, alpine wetlands, and prairie pothole wetlands. Potential impacts range from changes in community structure to changes...
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Long-term lake area change has previously been measured to detect the temporal rate and spatial extent of permafrost degradation. However, the natural intra- and interannual variability of lake areas has not been considered explicitly and quantitatively, which can substantially interfere with the detection of long-term lake area change associated with permafrost degradation. In order to better understand the natural background variability of lake areas, we used Landsat 7 images obtained on 11 dates from 1999 to 2002 to quantify the intra- and interannual lake area variability for a 4224 km2 study area within the Yukon Flats, Alaska. Total lake areas ranged from 179 km2 (22 August 1999) to 326 km2 (6 June 2000)....
map background search result map search result map Permafrost degradation and ecological changes associated with a warming climate in central Alaska Investigating the Hydrology of a Thermokarst Landscape (Old Crow Flats, Yukon, Canada) Using Water Isotope Tracers The effects of permafrost degradation on soil carbon dynamics in Alaska's boreal region N-factors and the relations between air and surface temperature in discontinuous permafrost near Mayo, Yukon Territory The Importance of Natural Variability in Lake Areas on the Detection of Permafrost Degradation: A Case Study in the Yukon Flats, Alaska Dissolved Organic Carbon in Alaskan Boreal Forest: Sources, Chemical Characteristics, and Biodegradability Rapid runoff via shallow throughflow and deeper preferential flow in a boreal catchment underlain by frozen silt (Alaska, USA) Stream dissolved organic matter bioavailability and composition in watersheds underlain with discontinuous permafrost Remote sensing and field-based mapping of permafrost distribution along the Alaska Highway corridor, interior Alaska Cryostratigraphy and Permafrost Evolution in the Lacustrine Lowlands of West-Central Alaska The thermal regime of a retrogressive thaw slump near Mayo, Yukon Territory High-Resolution Permafrost Modeling in Wrangell-St.Elias National Park and Preserve Hydrological feedbacks in northern peatlands The influence of fire and permafrost on sub-arctic stream chemistry during storms Faunal and Archaeological Remains as Evidence of Climate Change in Freezing Caverns, Yukon Territory, Canada Herbivory-Mediated Responses of Selected Boreal Forests to Climatic Change Thermokarst rates intensify due to climate change and forest fragmentation in an Alaskan boreal forest lowland A remote assessment of ice-rich permafrost loss across a~ 500m elevation gradient in the Mackenzie and Selwyn Mountains, Canada Rapid runoff via shallow throughflow and deeper preferential flow in a boreal catchment underlain by frozen silt (Alaska, USA) The influence of fire and permafrost on sub-arctic stream chemistry during storms Investigating the Hydrology of a Thermokarst Landscape (Old Crow Flats, Yukon, Canada) Using Water Isotope Tracers The thermal regime of a retrogressive thaw slump near Mayo, Yukon Territory Stream dissolved organic matter bioavailability and composition in watersheds underlain with discontinuous permafrost Thermokarst rates intensify due to climate change and forest fragmentation in an Alaskan boreal forest lowland N-factors and the relations between air and surface temperature in discontinuous permafrost near Mayo, Yukon Territory Permafrost degradation and ecological changes associated with a warming climate in central Alaska Dissolved Organic Carbon in Alaskan Boreal Forest: Sources, Chemical Characteristics, and Biodegradability Remote sensing and field-based mapping of permafrost distribution along the Alaska Highway corridor, interior Alaska Faunal and Archaeological Remains as Evidence of Climate Change in Freezing Caverns, Yukon Territory, Canada The Importance of Natural Variability in Lake Areas on the Detection of Permafrost Degradation: A Case Study in the Yukon Flats, Alaska The effects of permafrost degradation on soil carbon dynamics in Alaska's boreal region High-Resolution Permafrost Modeling in Wrangell-St.Elias National Park and Preserve Cryostratigraphy and Permafrost Evolution in the Lacustrine Lowlands of West-Central Alaska A remote assessment of ice-rich permafrost loss across a~ 500m elevation gradient in the Mackenzie and Selwyn Mountains, Canada Herbivory-Mediated Responses of Selected Boreal Forests to Climatic Change Hydrological feedbacks in northern peatlands