Climate warming is causing significant changes in the Arctic, leading to increased temperatures and permafrost instability. The active layer has been shown to be affected by climate change, where warmer ground surface temperatures result in progressive permafrost thaw and a deepening active layer. This study assessed the effects of thermal modeling parameters on permafrost ground response to climate warming using the fifth phase of the Coupled Model Intercomparison Project (CMIP5) and TEMP/W software. We analyzed how variations in depth, water content, and soil type affect predictions of future active layer depths and settlement under various climate scenarios using the soil characteristics along Hudson Bay Railway corridor. The results indicate that, for finegrained soils, the depth of the model is a more significant parameter than for coarse-grained soils. The water content of all soil types is a critical factor in determining the time at which permafrost thaws and the depth at which the active layer is located, as higher water content leads to larger active layer changes and more settlement in most cases. Our findings have important implications for infrastructure and land use management in the Arctic region.

Arctic regions are highly impacted by the global temperature rising and its consequences and influences on the thermo-hydro processes and their feedbacks. Theses processes are especially not very well understood in the context of river-permafrost interactions and permafrost degradation. This paper focuses on the thermal characterization of a river-valley system in a continuous permafrost area (Syrdakh, Yakutia, Eastern Siberia) that is subject to intense thawing, with major consequences on water resources and quality. We investigated this Yakutian area through two transects crossing the river using classical tools such as in-situ temperature measurements, direct active layer thickness estimations, unscrewed aerial vehicle (UAV) imagery, heat transfer numerical experiments, Ground-Penetrating Radar (GPR), and Electrical Resistivity Tomography (ERT). Of these two transects, one was closely investigated with a long-term temperature time series from 2012 to 2018, while both of them were surveyed by geophysical and UAV data acquisition in 2017 and 2018. Thermodynamical numerical simulations were run based on the long-term temperature series and are in agreement with river thermal influence on permafrost and active layer extensions retrieved from GPR and ERT profiles. An electrical resistivity-temperature relationship highlights the predominant role of water in such a complicated system and paves the way to coupled thermo-hydro-geophysical modeling for understanding permafrost-river system evolution.

Simulations with a one-dimensional heat transfer model (TONE) were performed to reproduce the near surface ground temperature regime in the four main types of soil profiles found in Narsajuaq River Valley (Nunavik, Canada) for the period 1990-2100. The permafrost thermal regime was simulated using climate data from a reanalysis (1948-2002), climate stations (1989-1991, 2002-2019) and simulations based on climate warming scenarios RCP4.5 and RCP8.5 (2019-2100). The model was calibrated based on extensive field measurements made between 1989 and 2019. The results were used to estimate when soil thermal contraction cracking will eventually stop and to forecast the melting of ice wedges due to active-layer thickening. For the period 1990-2019, all soil profiles experienced cracking every year until 2006, when cracking became intermittent during a warm period before completely stopping in 2009-2010, after which cracking resumed during colder years. Ice-wedge tops melted from 1992 to 2010 as the active layer thickened, indicating that top-down ice-wedge degradation can occur simultaneously with cracking and growth in width. Our predictions show that ice wedges in the valley will completely stop cracking between 2024 and 2096, first in sandy soils and later in soils with thicker organic horizons. The timing will also depend on greenhouse gas concentration trajectories. All ice wedges in the study area will probably experience some degradation of their main body before the end of the century, causing their roots to become relict ice by the end of the 21st century.

A physically based one-dimensional sharp-interface model of active layer evolution and permafrost thaw is presented. This computationally efficient, semianalytical, nonequilibrium solution to soil freeze-thaw problems in partially saturated media is proposed as a component of hydrological models to describe seasonal ground ice, active layer evolution, and changes in permafrost temperature and extent. The model is developed and validated against the analytical Stefan solution and a finite volume coupled heat and mass transfer model of freeze-thaw in unsaturated porous media. Unlike analytic models, the interface model provides a nonequilibrium solution to the heat equation while permitting a wide range of temporally variable boundary conditions and supporting the simulation of multiple interfaces between frozen and unfrozen soils. The model is implemented for use in discontinuous permafrost peatlands where soil properties are highly dependent on soil ice content and infiltration capacity is high. It is demonstrated that the model is suitable for the representation of variably saturated active layer and permafrost evolution in cases both with and without a talik.

It is essential to monitor the ground temperature over large areas to understand and predict the effects of climate change on permafrost due to its rapid warming on the Qinghai-Tibet Plateau (QTP). Land surface temperature (LST) is an important parameter for the energy budget of permafrost environments. Moderate Resolution Imaging Spectroradiometer (MODIS) LST products are especially valuable for detecting permafrost thermal dynamics across the QTP. This study presents a comparison of MODIS-LST values with in situ near-surface air temperature (T-a), and ground surface temperature (GST) obtained from 2014 to 2016 at five sites in Beiluhe basin, a representative permafrost region on the QTP. Furthermore, the performance of the thermal permafrost model forced by MODIS-LSTs was studied. Averaged LSTs are found to strongly correlated with T-a and GST with R-2 values being around 0.9. There is a significant warm bias (4.43-4.67 degrees C) between averaged LST and T-a, and a slight warm bias (0.67-2.66 degrees C) between averaged LST and GST. This study indicates that averaged MODIS-LST is supposed to be a useful data source for permafrost monitoring. The modeled ground temperatures and active-layer thickness have a good agreement with the measurements, with a difference of less than 1.0 degrees C and 0.4 m, respectively.

Hydrothermal processes are key components of permafrost dynamics and hydrological and carbon cycles in northern forest ecosystems. A forest hydrology model. ForHyM, was used to evaluate these processes by determining how the depth and duration of frost penetration into the soil would vary daily over the course of several decades. This was done for chosen upland/wetland conditions within the Mackenzie Plain south of Fort Simpson, where permafrost is currently sporadic to discontinuous. The model calculations were done using daily weather records from November 1963 to 2010, starting with a hypothetical no-frost condition within the soil and subsoil. Model performance was evaluated by comparing modeled and measured temperatures at different soil depths (upland and peat plateau modelling, R-2 = 0.95 and 0.94, respectively). It was found that well-drained upland forests within the general area would experience deep and complete freeze thaw cycles each year. In contrast, poorly drained wetlands would develop gradually deepening permafrost that would at first stabilize in depth over the course of 10 to 20 y, with thaw depth limited to <1 m each year. However, recent increases in recorded air temperature (more so in winter than in summer) would destabilize the pennafrost layer, and this would especially occur in areas with insufficient surface insulation by local peat, moss, forest litter, and snow accumulations. These estimates are consistent with (i) reported thawing depths and the widening encroachment of collapse scars towards the poorly drained portions of the South Mackenzie Plain.

Permafrost can provide a containment medium for drilling wastes deposited to in-ground sumps. but tall shrubs may proliferate on covers causing snow to accumulate, active layers to deepen and the ground to thaw We evaluate these effects using a 2-dimensional heat transfer model to simulate the thermal evolution of sumps in warm (-3 0 degrees C mean annual ground temperatures (MAGT)) and cold (-6 0 degrees C MAGT) permafrost under varying snow and climate conditions characteristic of the Mackenzie Delta region Application of climate and snow normals for Inuvik, Northwest Territories, south of treeline, and Tuktoyaktuk, on coastal tundra, maintained wastes within frozen ground at temperatures below -1 5 degrees C in warm permafrost and -3 0 degrees C in cold permafrost. respectively A gradual increase in snow depth from 017 m to 1.5 m simulating the effect of shrub growth on snow accumulation, caused thawing by the third decade In the absence of shrub growth and increasing snow, moderate climate warming (0 09 degrees C/year) also caused sump thawing after 35 years for the warm scenario, but for the cold scenario wastes remained below - 2 degrees C through to year 40 Climate warming and increasing snow depths hasten thermal degradation Modeling results indicating sump degradation due to deepening snow were corroborated by snow and ground temperature measurements, observations of collapsed shrub covered sumps in the Mackenzie Delta region and the local absence of permafrost where deep snow accumulates over mineral soils. Although thawing increases the mobility of sump contents, the associated subsidence of the sump and adjacent areas may inhibit lateral movement of the wastes Several factors combine to influence the integrity of sumps in permafrost indicating the need for a long-term management strategy. Crown Copyright (C) 2010 Published by Elsevier BV All rights reserved

Significant climate warming, as observed over the past decades and projected by global climate models, would inevitably cause permafrost degradation in the Arctic regions. Several studies have been conducted to assess geothermal response to climate change in natural conditions; no study, however, has been observed yet to examine the potential response of the permafrost geothermal regime in a building environment. This paper presents a methodology and the results of a case study in the community of Inuvik. Canada of the spatio-temporal dynamics simulation of the geothermal regime under climate change scenarios in a building environment. A process-based, surface-coupled, 3-dimensional geothermal model was used for the simulation. The results suggest that the permafrost under the study would deteriorate under all the three climate change scenarios assessed, and the rate of the deterioration would depend on geotechnical properties of subsurface materials and climate change scenarios. Two patterns of the geothermal dynamics were revealed from the simulation results: spatially, there are significant differences in the rate of increase in active layer thickness underneath vs. around a building; and temporally, there is an abrupt rise in the active layer thickness around the middle of this century. Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved.

We modeled the sensitivity of six ice-cemented slope deposits from the western McMurdo Dry Valleys, Antarctica to failure by shallow, thaw-induced planar sliding. The deposits examined have purportedly remained physically stable, without morphologic evidence for downslope movement, for millions of years. Could they fail in the near future from greenhouse-induced warming? To address this question, we first prescribed various increases in mean summertime soil surface temperature (MSSST) and modeled numerically the resultant changes in soil thaw depths using a one-dimensional heat diffusion equation (including the effects of latent heat of fusion). Second, we calculated the minimum thaw depths required to facilitate failure by shallow planar sliding for each deposit, for all numerical simulations, we maintained present soil-moisture conditions and used a Mohr-Coulomb-based equation of safety factor. Third, we calculated the rate of subsurface meltwater flow assuming Darcy's Law. Our results show that although most deposits contain sufficient subsurface ice to induce sliding upon thawing, lateral rates of water flow of as much as similar to 40 m/day for some colluvial deposits prohibit the build-up of requisite pore pressures for failure. On the other hand, silty deposits, that contain gravimetric water >= 15%, occur on slopes > 20 degrees, and possess low hydraulic conductivities (similar to 30-60 cm/day), common in the Dry Valleys region, could fail if MSSST, and by inference mean summertime atmospheric temperatures, increase by 4 to 9 degrees C. This temperature increase is similar to that predicted to occur from greenhouse-induced wart-ning in Antarctica over the next century. (c) 2007 Elsevier B.V. All rights reserved.