This study presents data from the first years of permafrost monitoring in boreholes in the French Alps that started at the end of 2009 in the framework of the PermaFrance network. Nine boreholes are instrumented, among which six monitored permafrost temperature and active layer thickness (ALT) over >10 years. Ice-poor and cold permafrost in high-elevation north-facing rock walls has warmed by up to >1(degrees)C at 10 m depth over the reference decade (2011-2020), whereas ice-rich permafrost (rock glacier) temperatures remained stable. ALT has increased at four of the five boreholes for which decadal data are available. Summer 2015 marks a turning point in ALT regime and greatest ALT values were observed in 2022 (available for six boreholes), but thawing intensity did not show an obvious change. At one site with a layer of coarse blocks about 2 m thick, ALT was stable over 2018-2022 and response to the hottest years was dampened. Linear trends suggest an ALT increase of 2 m per decade for some ice-poor rock walls, independently of their thermal state. The data reveal a variety of permafrost patterns and evolution with significant intraregional and local differences. Snow modulates the response to air temperature signal in various ways, with an important effect on near-surface temperature trends and ALT: early snow melting in spring favors an ALT increase in rock walls. Maintaining these monitoring systems and understanding the physical processes controlling heterogeneous responses to climate signals is crucial to better assess permafrost dynamics and to adapt to its consequences.

Alpine permafrost environments are highly vulnerable and sensitive to changes in regional and global climate trends. Thawing and degradation of permafrost has numerous adverse environmental, economic, and societal impacts. Mathematical modeling and numerical simulations provide powerful tools for predicting the degree of degradation and evolution of subsurface permafrost as a result of global warming. A particularly significant characteristic of alpine environments is the high variability in their surface geometry which drives large lateral thermal and fluid fluxes along topographic gradients. The combination of these topography-driven fluxes and unsaturated ground makes alpine systems markedly different from Arctic permafrost environments and general geotechnical ground freezing applications, and therefore, alpine permafrost demands its own specialized modeling approaches. In this work, we present a multi-physics permafrost model tailored to subsurface processes of alpine regions. In particular, we resolve the ice-water phase transitions, unsaturated conditions, and capillary actions, and account for the impact of the evolving pore space through freezing and thawing processes. Moreover, the approach is multi-dimensional, and therefore, inherently resolves the topography-driven horizontal fluxes. Through numerical case studies based on the elevation profiles of the Zugspitze (DE) and the Matterhorn (CH), we show the strong influence of lateral fluxes in 2D on active layer dynamics and the distribution of permafrost.

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.

This study presents the long-term temperature monitoring in the Russian Altai Mountains. In contrast to the Mongolian and Chinese parts, the modern temperature regime of the Russian Altai remains unclear. The complexity of a comprehensive understanding of permafrost conditions in the Russian Altai is related to the high dis of the terrain, the paucity of the latest observational data, and the sparse population of permafrost areas. The general objective of this study is to determine the temperature regime on the surface, in the active layer, and in the zero annual amplitude (ZAA) layer, based on the known patterns of permafrost distribution in the region. Using automatic measuring equipment (loggers), we obtained information on the temperature of frozen and thawed ground within the altitudes from 1484 to 2879 m a. s. l. during the period from 2014 to 2020. An array of 15 loggers determined the temperature regime of bare and vegetated areas within watersheds, slopes, and valleys. N-factor parameters and surface temperature are similar to those in the Mongolian Altai, but the mean annual ground temperature at the depth of 1 m has a wide range of fluctuations (more than 32 degrees C) based on research results, and we allocated it into three groups based on altitudinal zonality. Snow cover has a strong influence on the temperature regime, but the determination of the fine-scale variability requires additional study. Ground temperature regime during the observation period remained stable, but continued monitoring allows a more detailed assessment of the response to climatic changes.

In recent decades, research of the Alps, Qinghai-Tibet Plateau, and Cordillera have made great progress in understanding the phenomenon of permafrost. For the most part, this has been made possible due to temperature monitoring. However, the permafrost parameters in an area of more than 2 million square km of the mountainous regions of northeast Asia, for the most part, remain a blank spot in the scientific community. Due to the lack and insufficiency of factual materials, in 2012 the P.I. Melnikov Permafrost Institute began to take temperature measurements in the upper part of the permafrost in the central part of the Verkhoyan-Kolyma uplands, namely the Suntar-Khayat ridge. The article describes the temperature characteristics of air, surface and rocks of the active layer in the range of heights from 850 to 1821 m, in various landscape and topographic elements. For the observation period from 2012 to 2019, we obtained information on temperatures in the soils of the active layer at depths of 1 m, 3 m, 4 m, and 5 m and also air and surface temperature parameters. The availability of data on automated monitoring of rock temperatures in the active layer and the upper horizons of the layer of annual heat rotations made it possible to substantiate the most typical conditions of the temperature conditions of the permafrost zone of the characterized region. The parameters of permafrost existence and development are in favorable conditions. This is shown in the analysis of temperature data of air, surface and active layer. Soil temperatures in the active layer of annual heat rotations are most clearly represented at a depth of 1 m. Currently, on the territory of the mountain regions of Eastern Siberia, there are no more such sites for monitoring the temperature regime of soils. Information on the permafrost parameters in the region will allow us to begin the process of creating new models or checking existing forecasts and the distribution of the temperature pattern. It will also make it possible to evaluate the response of sensitive and vulnerable frozen soils of mountain regions to climate change.

This paper reviews and analyses the past 20 years of change and variability of European mountain permafrost in response to climate change based on time series of ground temperatures along a south-north transect of deep boreholes from Sierra Nevada in Spain (37 degrees N) to Svalbard (78 degrees N), established between 1998 and 2000 during the EU-funded PACE (Permafrost and Climate in Europe) project. In Sierra Nevada (at the Veleta Peak), no permafrost is encountered. All other boreholes are drilled in permafrost. Results show that permafrost warmed at all sites down to depths of 50 m or more. The warming at a 20 m depth varied between 1.5 degrees C on Svalbard and 0.4 degrees C in the Alps. Warming rates tend to be less pronounced in the warm permafrost boreholes, which is partly due to latent heat effects at more ice-rich sites with ground temperatures close to 0 degrees C. At most sites, the air temperature at 2 m height showed a smaller increase than the near-ground-surface temperature, leading to an increase of surface offsets (SOs). The active layer thickness (ALT) increased at all sites between c. 10% and 200% with respect to the start of the study period, with the largest changes observed in the European Alps. Multi-temporal electrical resistivity tomography (ERT) carried out at six sites showed a decrease in electrical resistivity, independently supporting our conclusion of ground ice degradation and higher unfrozen water content.

Permafrost plays an important role in numerous environmental processes at high latitudes and in high mountain areas. The identification of mountain permafrost, particularly in the discontinuous permafrost regions, is challenging due to limited data availability and the high spatial variability of controlling factors. This study focuses on mountain permafrost in a data-scarce environment of northern Mongolia, at the interface between the boreal forest and the dry steppe mid-latitudes. In this region, the ground temperature has been increasing continuously since 2011 and has a high spatial variability due to the distribution of incoming solar radiation, as well as seasonal snow and vegetation cover. We analyzed the effect of these controlling factors to understand the climate-permafrost relationship based on in situ observations. Furthermore, mean ground surface temperature (MGST) was calculated at 30-m resolution to predict permafrost distribution. The calculated MGST, with a root mean square error of +/- 1.4 degrees C, shows permafrost occurrence on north-facing slopes and at higher elevations and absence on south-facing slopes. Borehole temperature data indicate a serious wildfire-induced permafrost degradation in the region; therefore, special attention should be paid to further investigations on ecosystem resilience and climate change mitigation in this region.

The past four decades have seen extensive development of the winter sport industry in the French Alps and several hundred ropeway transport systems have been installed in areas where mountain permafrost may be present. Due to current climatic change and the ensuing permafrost degradation, the vulnerability of these infrastructures to destabilization may increase. Therefore, there is a real potential for instabilities to develop on ropeway transport systems in the Alps, requiring a better understanding of these processes. This study investigates the relation between permafrost and infrastructure stability in the French Alps, seeking to understand the evolution of this phenomenon over the past decades. This was done by following a two-step analysis. At first, the infrastructure elements built on modeled permafrost-affected areas were inventoried at the scale of the French Alps in order to get an overview of the possible vulnerabilities. Then, our study presents a detailed historical inventory of damage to infrastructure over the past three decades in different geomorphologic contexts. Overall, in the French Alps, there are almost 1000 infrastructure elements located in permafrost areas among which 12 (i.e., 24 infrastructure elements) were identified to have been subject to repeated instances of disruption and deterioration and most of the damages recorded were in areas where permafrost degradation is fully expected (ice-rich terrain). Infrastructure recovery costs may be significantly high, making this issue a relevant consideration to be included in the design process.

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.

Knowledge of the thermal state of mountain permafrost has greatly increased since 2007 with the establishment of numerous new monitoring stations around the world. Data collected at these sites have pointed to longer-term changes in ground temperatures, which seem to have increased during the last two to three decades in cold permafrost, while in ground close to 0 degrees C the near-surface ice content has restricted warming and similar trends are not apparent. Modelling of mountain permafrost has developed greatly, driven by general circulation models or gridded temperature maps, through both predictive methods and spatial equilibrium and transient approaches. The spatial resolution of climate parameters, which is normally much coarser than the spatial heterogeneity of alpine environments, presents a major problem for modelling studies. This is a fundamental challenge for future research. Copyright (c) 2013 John Wiley & Sons, Ltd.