Ice-free areas occupy 5 m in bedrock sites in the Antarctic Peninsula. The deepest and most variable ALTs (ca. 40 to >500 cm) were found in the Antarctic Peninsula, whereas the maximum ALT generally did not exceed 90 cm in Victoria Land and East Antarctica. Notably, found that the mean annual near-surface temperature follows the latitudinal gradient of-0.9 degrees C/deg. (R2 = 0.9) and the active layer thickness 3.7 cm/deg. (R2 = 0.64). The continuous permafrost occurs in the vast majority of the ice-free areas in Antarctica. The modelling of temperature on the top of the permafrost indicates also the permafrost presence in South Orkneys and South Georgia. The only areas where deep boreholes and geophysical surveys indicates discontinuous or sporadic permafrost are South Shet-lands and Western Antarctic Peninsula.

Air and near-surface ground temperatures were measured using dataloggers over 14 years (2006-2020) in 10 locations at 2262 to 2471 m.a.s.l. in a glacial cirque of the Cantabrian Mountains. These sites exhibit relevant differences in terms of substrate, solar radiation, orientation, and geomorphology. Basal temperature of snow (BTS) measurements and electrical resistivity tomography of the talus slope were also performed. The mean annual near-surface ground temperatures ranged from 5.1 degrees C on the sunny slope to 0.2 degrees C in the rock glacier furrow, while the mean annual air temperature was 2.5 degrees C. Snow cover was inferred from near-surface ground temperature (GST) data, estimating between 130 and 275 days per year and 0.5 to 7.1 m snow thickness. Temperature and BTS data show that the lowest part of the talus slope and the rock glacier furrow are the coldest places in this cirque, coinciding with a more persistent and thickest snow cover. The highest temperatures coincide with less snow cover, fine-grained soils, and higher solar radiation. Snow cover has a primary role in controlling GST, as the delayed appearance in autumn or delayed disappearance in spring have a cooling effect, but no correlation with mean annual near-surface ground temperatures exists. Heavy rain-over-snow events have an important influence on the GST. In the talus slope, air circulation during the snow-covered period produces a cooling effect in the lower part, especially during the summer. Significant inter-annual GST differences were observed that exhibited BTS limitations. A slight positive temperature trend was detected but without statistically significance and less prominent than nearby reference official meteorological stations, so topoclimatic conditions reduced the more global positive temperature trend. Probable existence of permafrost in the rock glacier furrow and the lowest part of the talus slope is claimed; however, future work is necessary to confirm this aspect.

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 degrees C), thick (>500 m) continuous permafrost and a mean annual air temperature of -19.7 degrees 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 degrees C for mean annual, 2.5 degrees C in summer, and 15.2 degrees 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.

Permafrost controls geomorphological dynamics in maritime Antarctic ecosystems. Here, we analyze and model ground thermal regime in bordering conditions between continuous and discontinuous permafrost to better understand its relationship with the timing of glacial retreat. In February 2017, a transect including 10 sites for monitoring ground temperatures was installed in the eastern fringe of Byers Peninsula (Livingston Island, northern Antarctic Peninsula), together with one station recording air temperatures and snow thickness. The sites were selected following the Mid-Late Holocene deglaciation of the area at a distance ranging from 0.30 to 3.15 km from the current Rotch Dome glacier front. The transect provided data on the effects of topography, snow cover and the timing of ice-free exposure, on the ground thermal regime. From February 2017 to February 2019, the mean annual air temperature was - 2.0 degrees C, which was > 0.5 degrees C higher than 1986-2015 average in the Western Antarctic Peninsula region. Mean annual ground temperature at 10 cm depth varied between 0.3 and -1.1 degrees C, similar to the modelled Temperatures on the Top of the Permafrost (TTOP) that ranged from 0.06 +/- 0.08 degrees C to -1.33 +/- 0.07 degrees C. The positive average temperatures at the warmest site were related to the long-lasting presence of snow which favoured warmer ground temperatures and may trigger permafrost degradation. The role of other factors (topography, and timing of the deglaciation) explained intersite differences, but the overall effect was not as strong as snow cover.

Mean annual ground temperature (MAGT) and active layer thickness (ALT) are key to understanding the evolution of the ground thermal state across the Arctic under climate change. Here a statistical modeling approach is presented to forecast current and future circum-Arctic MAGT and ALT in relation to climatic and local environmental factors, at spatial scales unreachable with contemporary transient modeling. After deploying an ensemble of multiple statistical techniques, distance-blocked cross validation between observations and predictions suggested excellent and reasonable transferability of the MAGT and ALT models, respectively. The MAGT forecasts indicated currently suitable conditions for permafrost to prevail over an area of 15.1 +/- 2.8 x 10(6) km(2). This extent is likely to dramatically contract in the future, as the results showed consistent, but region-specific, changes in ground thermal regime due to climate change. The forecasts provide new opportunities to assess future Arctic changes in ground thermal state and biogeochemical feedback.

The geothermal record for 1977-2014 from a 29m deep borehole in permafrost on Mont Jacques-Cartier, in southeastern Canada, shows substantial decadal fluctuations and an overall warming trend. An extremely thin winter snow cover on the wind-blown summit favours the presence of permafrost. As a consequence, the instability of the thermal regime was found to be a direct response to air temperature variations modelled from data produced by the National Center for Environmental Prediction and National Center for Atmospheric Research. At a depth of 14m, an increase of 0.4 degrees C from 1979 to 1984 was followed by a decrease of 0.7 degrees C over the next decade, and then by a marked, but irregular increase of 1 degrees C up to 2013. Since 2008, diurnal data, refined by a one-dimensional, transient heat transfer model, indicate an active layer averaging 8.6m in depth, but whose thickness is sensitive to fluctuations in annual mean ground surface temperatures. For a permafrost body already close to the thawing point, the continuation of the overall warming trend of the last 37years would lead to its rapid degradation, and the permafrost would then become relict, thinning progressively both from the base and the surface. Copyright (c) 2016 John Wiley & Sons, Ltd.

Antarctica provides natural models that are influenced exclusively by climate change and/or other natural processes because the anthropogenic effects are negligible. The key environmental components of these ecosystems consist of vegetation and the underlying permafrost. The surface energy balance and, consequently, the ground surface temperature (GST) and ground thermal regime (GTR) can be influenced by vegetation, as is well known in Arctic areas. The interactions between vegetation, GST, GTR and their potential ecological implications in Antarctica have only recently begun to develop. This paper aims to contribute towards closing the gap of knowledge of these interactions. It does so by considering different spatial (intra-site and inter-site variability) and temporal (seasonal versus annual) scales with reference to dry and wet Antarctic cryptogamic tundra. For this reason, two sites and seven plots (bare ground versus vegetated ground) were instrumented and monitored in Victoria Land (continental Antarctica) to measure the ground temperature at different depths during the summer, as well as during one complete year. Our results demonstrate for the first time for continental Antarctica that vegetation provides an insulating effect with a net cooling effect on the GST varying with the vegetation type, structure, coverage and thickness. Independently of the GST, the soil thermal characteristics constitute the driving factor in determining the thickness of the active layer. We discuss potential future implications of changes in the vegetation, ground thermal regime and permafrost in a climate change scenario, with reference to the activation of feedbacks through changes in the energy balance, in the permafrost conditions and controls over ecosystem C storage and fluxes. (C) 2009 Elsevier B.V. All rights reserved.