Aspaas, Andreas Grøvan; Bievre, Grégory; Lacroix, Pascal; Langet, Nadege; Aga, Juditha & Skrede, Ingrid [Vis alle 9 forfattere av denne artikkelen] (2026). Seasonal and inter-annual evolution of the deformation of two Arctic landslides. Earth Surface Dynamics. ISSN 2196-6311. 14(5), s. 729–761. doi: 10.5194/esurf-14-729-2026. Fulltekst i vitenarkiv Vis sammendrag
Landslides in glacial and periglacial environments are increasingly affected by climate change, with sudden failures reported in high mountain regions and the Arctic. The complex mechanisms behind these events are often poorly understood due to a lack of dense in situ data. We investigate two slow-moving landslides in Arctic Norway (70° N), the Jettan and Gámanjunni landslides, located approximately 10 km apart: Jettan, a complex slide in micaschist and calcite marble situated below the permafrost boundary, and Gámanjunni, a rotational slide in micaschist situated above the permafrost boundary. Using over a decade of multi-physics observations, including geodetic, borehole, seismic, and hydrological data, we examine surface and subsurface deformation. Both landslides display similar seasonal surface velocity patterns, with peaks in spring and autumn, likely influenced by pore-water infiltration. At Jettan, twelve years of inclinometer data in boreholes reveal a transition from steady state to seasonal deformation in two shear zones. Since 2020, spring accelerations have intensified in years coinciding with deeper snowpacks and associated melt. These observations, together with statistical modeling, suggest that the shear-zones are becoming increasingly localized and sensitive to pore-water pressure. Conversely, autumn acceleration is not seen in localized shear zones but manifests as distributed volumetric deformation. Seismic velocity variations within the landslide body also exhibit seasonal patterns that correspond with geodetic velocity, interpreted as changes in landslide rigidity due to water infiltration. This integrated analysis of surface and subsurface data offers new insights into the evolving deformation of Arctic landslides, emphasizing the influence of hydrological forcings on both seasonal and long-term deformation processes.
Ishikawa, Mamoru; Westermann, Sebastian; Jambaljav, Yamkhin; Dashtseren, Avirmed; Hiyama, Tetsuya & Endo, Nobuhiko [Vis alle 7 forfattere av denne artikkelen] (2024). Transient Modeling of Permafrost Distribution From 1986 to 2016 in Mongolia. Permafrost and Periglacial Processes. ISSN 1045-6740. 35(3), s. 326–339. doi: 10.1002/ppp.2231. Fulltekst i vitenarkiv
Popescu, Răzvan; Filhol, Simon; Etzelmüller, Bernd; Vasile, Mirela; Pleșoianu, Alin & Vîrghileanu, Marina [Vis alle 16 forfattere av denne artikkelen] (2024). Permafrost Distribution in the Southern Carpathians, Romania, Derived From Machine Learning Modeling. Permafrost and Periglacial Processes. ISSN 1045-6740. 35(3), s. 243–261. doi: 10.1002/ppp.2232. Fulltekst i vitenarkiv
Christiansen, Hanne H; Sjöberg, Y.; Blume-Werry, G.; Dorrepaal, E.; Etzelmüller, Bernd & Farnsworth, Wesley Randall [Vis alle 14 forfattere av denne artikkelen] (2024). A roadmap for developing permafrost higher education in Norden. Nordic Journal of STEM Education. 8(2), s. 18–44. doi: 10.5324/njsteme.v8i2.5127. Fulltekst i vitenarkiv Vis sammendrag
We perform a first permafrost higher education curriculum survey in Norden. Permafrost is part of the education within both bio- and geosciences and engineering, and the variation in educational activities reflect this. Five permafrost-specific geoscience and engineering permafrost courses exist, whereas there are 23 bachelor and 25 master courses with a permafrost content ranging from 1% to 50 %. The is large potential and clear needs for closer permafrost teaching collaboration. This could focus on permafrost course development, teaching methods, sharing practical experiences including fieldwork and further developing the educational offer. Such collaboration could establish: 1) An online, joint Nordic specific course on permafrost, sharing the special permafrost competences existing across the universities using digital teaching tools, 2) Nordic collaboration on developing joint, both general but also specific, PhD courses on permafrost, 3) Lifelong education in permafrost, and 4) Internships a part of active permafrost education to better meet the future employers and society’s needs. The Nordic region might also gain largely from establishing an overview-providing interdisciplinary joint Nordic course aiming to characterize the region and its diversity broadly including both natural and social sciences, and naturally covering different topics including permafrost and seasonally frozen ground. The mapping done for this paper will function as a first overall roadmap catalogue providing an overview of all offered courses on permafrost. The overall outcome of our survey shows large potential for increased and deeper inter-university collaboration for further developing joint permafrost higher education both in the form of courses and other educational activities between institutions across Norden, and potentially with ambitions for joint permafrost degrees between several institutions. Based on the presented results and the mapped different future plans for permafrost education across Norden, we discuss the implications of our results, specifically concerning the potential for increased collaboration in Nordic permafrost education. These focus on permafrost course development, teaching methods, sharing practical experiences including fieldwork and further developing the educational offer. In more detail increased collaboration could establish: 1) An online, joint Nordic-specific course on permafrost, sharing the special permafrost competences existing across the universities using digital teaching tools, 2) Nordic collaboration on developing joint PhD courses on permafrost, 3) Lifelong education in permafrost, and 4) Internships as part of active permafrost education to better meet the needs of future employers and society. The Nordic region might also gain largely from establishing an interdisciplinary joint Nordic course, aiming to characterize the region and its diversity broadly and including both natural and social sciences, and naturally covering different topics including permafrost and seasonally frozen ground.
Czekirda, Justyna; Rempel, Alan W.; Etzelmüller, Bernd & Westermann, Sebastian (2024). Spatiotemporal variations in frost cracking measures in two dimensions: A case study for rock walls in Jotunheimen, southern Norway. Geomorphology. ISSN 0169-555X. 453. doi: 10.1016/j.geomorph.2024.109112. Fulltekst i vitenarkiv
Noetzli, Jeannette; Isaksen, Ketil; Barnett, Jamie; Christiansen, Hanne H; Delaloye, Reynald & Etzelmüller, Bernd [Vis alle 22 forfattere av denne artikkelen] (2024). Enhanced warming of European mountain permafrost in the early 21st century. Nature Communications. 15, s. 1–15. doi: 10.1038/s41467-024-54831-9. Fulltekst i vitenarkiv Vis sammendrag
Mountain permafrost, constituting 30% of the global permafrost area, is sensitive to climate change and strongly impacts mountain ecosystems and communities. This study examines 21st century permafrost warming in European mountains using decadal ground temperature data from sixty-four boreholes in the Alps, Scandinavia, Iceland, Sierra Nevada and Svalbard. During 2013–2022, warming rates at 10 metres depth exceed 1 °C dec−1 in cases, generally surpassing previous estimates because of accelerated warming and the use of a comprehensive data set. Substantial permafrost warming occurred at cold and ice-poor bedrock sites at high elevations and latitudes, at rates comparable to surface air temperature increase. In contrast, latent heat effects in ice-rich ground near 0 °C reduce warming rates and mask important changes of mountain permafrost substrates. The warming patterns observed are consistent across all sites, depths and time periods. For the coming decades, the propagation of permafrost warming to greater depths is largely predetermined already.
Temuujin, Khurelbaatar; Dashtseren, Avirmed; Etzelmüller, Bernd; Undrakhtsetseg, Tsogtbaatar; Aalstad, Kristoffer & Westermann, Sebastian (2024). Spatial variability of near-surface ground temperatures in a discontinuous permafrost area in Mongolia. Frontiers in Earth Science. 12. doi: 10.3389/feart.2024.1456012. Fulltekst i vitenarkiv Vis sammendrag
In Central Asia, the ground thermal regime is strongly affected by the interplay between topographic factors and ecosystem properties. In this study, we investigate the governing factors of the ground thermal regime in an area in Central Mongolia, which features discontinuous permafrost and is characterized by grassland and forest ecosystems. Miniature temperature dataloggers were used to measure near-surface temperatures at c. 100 locations throughout the 6 km2 large study area, with the goal to obtain a sample of sites that can represent the variability of different topographic and ecosystem properties. Mean annual near-surface ground temperatures showed a strong variability, with differences of up to 8 K. The coldest sites were all located in forests on north-facing slopes, while the warmest sites are located on steep south-facing slopes with sparse steppe vegetation. Sites in forests show generally colder near-surface temperatures in spring, summer and fall compared to grassland sites, but they are warmer during the winter season. The altitude of the measurement sites did not play a significant role in determining the near-surface temperatures, while especially solar radiation was highly correlated. In addition, we investigated the suitability of different hyperspectral indices calculated from Sentinel-2 as predictors for annual average near-surface ground temperatures. We found that especially indices sensitive to vegetation properties, such as the Normalized Difference Vegetation Index (NDVI), show a strong correlation. The presented observations provide baseline data on the spatiotemporal patterns of the ground thermal regime which can be used to train or validate modelling and remote sensing approaches targeting the impacts of climate change.
Herring, Teddi; Lewkowicz, Antoni G.; Chiasson, Alexandre; Wang, Yifeng; Way, Robert G. & Young, Joseph M. [Vis alle 17 forfattere av denne artikkelen] (2024). The Canadian Permafrost Electrical Resistivity Survey (CPERS) database: 15 years of permafrost resistivity data. Arctic Science. ISSN 2368-7460. 10(4), s. 850–856. doi: 10.1139/as-2023-0058. Fulltekst i vitenarkiv Vis sammendrag
Permafrost landscapes are becoming increasingly susceptible to widespread thaw due to climate change. Collating historical and ongoing data are critical for assessing permafrost conditions and spatiotemporal changes. Electrical resistivity tomography (ERT) is a geophysical technique that has become standard practice for characterizing permafrost. However, resistivity data—particularly raw measurements—often go unpublished and unshared, resulting in missed opportunities for knowledge exchange and collaboration. To fill this gap, we created the Canadian Permafrost Electrical Resistivity Survey database and established clear guidelines for data archival and reuse. Here, we present the first release of the database, which currently houses 280 ERT datasets, including standardized metadata, collected between 2008 and 2022 in British Columbia, Labrador, Northwest Territories, Québec, Yukon, and Alaska. These data present unique opportunities to better understand spatial and temporal variability of permafrost conditions across North America.
Czekirda, Justyna; Etzelmüller, Bernd; Westermann, Sebastian; Isaksen, Ketil & Magnin, Florence (2023). Post-Little Ice Age rock wall permafrost evolution in Norway. The Cryosphere. ISSN 1994-0416. 17(7), s. 2725–2754. doi: 10.5194/tc-17-2725-2023. Fulltekst i vitenarkiv Vis sammendrag
The ground thermal regime and permafrost development have an important influence on geomorphological processes in periglacial regions and ultimately landscape development. About 10 % of unstable rock slopes in Norway are potentially underlain by widespread permafrost. Permafrost thaw and degradation may play a role in slope destabilisation, and more knowledge about rock wall permafrost in Norway is needed to investigate possible links between the ground thermal regime, geomorphological activity and natural hazards. We assess spatio-temporal permafrost variations in selected rock walls in Norway over the last 120 years. Ground temperature is modelled using the two-dimensional ground heat flux model CryoGrid 2D along nine profiles crossing instrumented rock walls in Norway. The simulation results show the distribution of permafrost is sporadic to continuous along the modelled profiles. Results suggest that ground temperature at 20 m depth in steep rock faces increased by 0.2 ∘C per decade on average since the 1980s, and rates of change increase with elevation within a single rock wall section. Heat flow direction is primarily vertical within mountains in Norway. Nevertheless, narrow ridges may still be sensitive to even small differences in ground surface temperature and may have horizontal heat fluxes. This study further demonstrates how rock wall temperature increase rates and rock wall permafrost distribution are influenced by factors such as surface air temperature uncertainties; surface offsets arising from the incoming shortwave solar radiation; snow conditions on, above and below rock walls; and rock wall geometry and size together with adjacent blockfield-covered plateaus or glaciers.
Renette, Cas; Aalstad, Kristoffer; Aga, Juditha; Zweigel, Robin Benjamin; Etzelmüller, Bernd & Lilleøren, Karianne Staalesen [Vis alle 8 forfattere av denne artikkelen] (2023). Simulating the effect of subsurface drainage on the thermal regime and ground ice in blocky terrain in Norway. Earth Surface Dynamics. ISSN 2196-6311. 11(1), s. 33–50. doi: 10.5194/esurf-11-33-2023. Fulltekst i vitenarkiv Vis sammendrag
Ground temperatures in coarse, blocky deposits such as mountain blockfields and rock glaciers have long been observed to be lower in comparison with other (sub)surface material. One of the reasons for this negative temperature anomaly is the lower soil moisture content in blocky terrain, which decreases the duration of the zero curtain in autumn. Here we used the CryoGrid community model to simulate the effect of drainage on the ground thermal regime and ground ice in blocky terrain permafrost at two sites in Norway. The model set-up is based on a one-dimensional model domain and features a surface energy balance, heat conduction and advection, as well as a bucket water scheme with adjustable lateral drainage. We used three idealized subsurface stratigraphies, blocks only, blocks with sediment and sediment only, which can be either drained (i.e. with strong lateral subsurface drainage) or undrained (i.e. without drainage), resulting in six scenarios. The main difference between the three stratigraphies is their ability to retain water against drainage: while the blocks only stratigraphy can only hold small amounts of water, much more water is retained within the sediment phase of the two other stratigraphies, which critically modifies the freeze–thaw behaviour. The simulation results show markedly lower ground temperatures in the blocks only, drained scenario compared to other scenarios, with a negative thermal anomaly of up to 2.2 ∘C. For this scenario, the model can in particular simulate the time evolution of ground ice, with build-up during and after snowmelt and spring and gradual lowering of the ice table in the course of the summer season. The thermal anomaly increases with larger amounts of snowfall, showing that well-drained blocky deposits are less sensitive to insulation by snow than other soils. We simulate stable permafrost conditions at the location of a rock glacier in northern Norway with a mean annual ground surface temperature of 2.0–2.5 ∘C in the blocks only, drained simulations. Finally, transient simulations since 1951 at the rock glacier site (starting with permafrost conditions for all stratigraphies) showed a complete loss of perennial ground ice in the upper 5 m of the ground in the blocks with sediment, drained run; a 1.6 m lowering of the ground ice table in the sediment only, drained run; and only 0.1 m lowering in the blocks only, drained run. The interplay between the subsurface water–ice balance and ground freezing/thawing driven by heat conduction can at least partly explain the occurrence of permafrost in coarse blocky terrain below the elevational limit of permafrost in non-blocky sediments. It is thus important to consider the subsurface water–ice balance in blocky terrain in future efforts in permafrost distribution mapping in mountainous areas. Furthermore, an accurate prediction of the evolution of the ground ice table in a future climate can have implications for slope stability, as well as water resources in arid environments.
Peter, Maria; Andersen, Jane Lund; Nixon, Francis Chantel; Etzelmüller, Bernd; Westermann, Sebastian & Fredin, Ola (2023). Near-surface temperatures and potential for frost weathering in blockfields in Norway and Svalbard. Earth Surface Processes and Landforms. ISSN 0197-9337. 48(5), s. 940–955. doi: 10.1002/esp.5528. Fulltekst i vitenarkiv Vis sammendrag
Blockfields remain enigmatic regarding their origin, internal structure, surface processes, and glaciological implications. In Scandinavia, blockfields are found on high-elevation, low-relief mountains (plateaus) across the Arctic and Subarctic. In this study, we present a 1D numerical model that uses near-surface temperatures measured between summer 2018 and summer 2020 to calculate frost-cracking intensities (FCI) within the ground column in three different blockfields in Norway and Svalbard. Eighty-nine miniature temperature loggers were distributed on Tron Mountain (1650 m a.s.l.) in Alvdal, Gamlemsveten (780 m a.s.l.) near Ålesund in southwestern Norway and on Platåberget (460 m a.s.l.) near Longyearbyen, Svalbard. We modelled FCI by scaling the time spent in the frost cracking window (between −3 and −8°C) with the temperature gradient and a penalty function for distance to available water. At Tron and Gamlemsveten, ground temperatures never reached the frost cracking window at one third of our sites due to insulation by a thick snow cover in depressions and on the lee sides of summits. The highest FCI (0.05–0.4 K m) are obtained where the subsurface consists of boulders and stones in a matrix of relatively fine sediment (sand, silt, gravel). In contrast, very low FCI (0.003–0.02 K m) were modelled for blocky layers with large air-filled pores because of the low water availability. On Platåberget, all sensors reached the frost-cracking window during the annual temperature cycle, but FCI are extremely low (0.0004–0.15 K m) as water availability is limited due to (i) permafrost and (ii) near-surface temperatures remaining below the frost-cracking window for 3/4 of the year. This indicates that boulder-rich blockfields with air-filled hollows are preserved in very cold climates, whereas warmer, maritime settings with higher availability of fine interstitial material place blockfields in the fast lane for frost weathering.
Westermann, Sebastian; Ingeman-Nielsen, Thomas; Scheer, Johanna; Aalstad, Kristoffer; Aga, Juditha & Chaudhary, Nitin [Vis alle 24 forfattere av denne artikkelen] (2023). The CryoGrid community model (version 1.0) - a multi-physics toolbox for climate-driven simulations in the terrestrial cryosphere. Geoscientific Model Development. ISSN 1991-959X. 16(9), s. 2607–2647. doi: 10.5194/gmd-16-2607-2023. Fulltekst i vitenarkiv Vis sammendrag
The CryoGrid community model is a flexible toolbox for simulating the ground thermal regime and the ice–water balance for permafrost and glaciers, extending a well-established suite of permafrost models (CryoGrid 1, 2, and 3). The CryoGrid community model can accommodate a wide variety of application scenarios, which is achieved by fully modular structures through object-oriented programming. Different model components, characterized by their process representations and parameterizations, are realized as classes (i.e., objects) in CryoGrid. Standardized communication protocols between these classes ensure that they can be stacked vertically. For example, the CryoGrid community model features several classes with different complexity for the seasonal snow cover, which can be flexibly combined with a range of classes representing subsurface materials, each with their own set of process representations (e.g., soil with and without water balance, glacier ice). We present the CryoGrid architecture as well as the model physics and defining equations for the different model classes, focusing on one-dimensional model configurations which can also interact with external heat and water reservoirs. We illustrate the wide variety of simulation capabilities for a site on Svalbard, with point-scale permafrost simulations using, e.g., different soil freezing characteristics, drainage regimes, and snow representations, as well as simulations for glacier mass balance and a shallow water body. The CryoGrid community model is not intended as a static model framework but aims to provide developers with a flexible platform for efficient model development. In this study, we document both basic and advanced model functionalities to provide a baseline for the future development of novel cryosphere models.
Etzelmüller, Bernd; Isaksen, Ketil; Czekirda, Justyna; Westermann, Sebastian; Hilbich, Christin & Hauck, Christian (2023). Rapid warming and degradation of mountain permafrost in Norway and Iceland. The Cryosphere. ISSN 1994-0416. 17(12), s. 5477–5497. doi: 10.5194/tc-17-5477-2023. Fulltekst i vitenarkiv Vis sammendrag
Abstract. With the EU-funded PACE (Permafrost and Climate in Europe) project at the turn of this century, several deep boreholes (100 m+) were drilled in European mountain sites, including in mainland Norway, Svalbard and Sweden. During other projects from 2004 and the International Polar Year (IPY) period in 2006–2007, several additional boreholes were drilled in different sites in both Norway and Iceland, measuring temperatures along both altitudinal and latitudinal gradients. At most sites, multi-temporal geophysical soundings are available using electrical resistivity tomography (ERT). Here, we study the development of permafrost and ground temperatures in mainland Norway and Iceland based on these data sets. We document that permafrost in Norway and Iceland is warming at a high rate, including the development of taliks in both Norway and Iceland in response to global climate change during the last 20 years. At most sites, ground surface temperature (GST) is apparently increasing more strongly than surface air temperature (SAT). Changing snow conditions appear to be the most important factor for the higher GST rates. Modelling exercises also indicate that the talik development can be explained by both higher air temperatures and increasing snow depth.
Penna, Ivanna; Magnin, Florence; Nicolet, Pierrick; Etzelmüller, Bernd; Hermanns, Reginald & Böhme, Martina [Vis alle 10 forfattere av denne artikkelen] (2023). Permafrost controls the displacement rates of large unstable rock-slopes in subarctic environments. Global and Planetary Change. ISSN 0921-8181. 220, s. 104017–104017. doi: 10.1016/j.gloplacha.2022.104017. Fulltekst i vitenarkiv Vis sammendrag
Determining the link between permafrost and the displacement rates of large unstable rock-slopes (LURSs) is fundamental for understanding future hazard scenarios and establishing appropriate management strategies. From an inventory of >500 LURSs in Norway, we investigate the controls of those with available information on their displacement rates (299 LURSs), presenting the first statistical evidence of permafrost as the main driver of displacement rates of LURSs. The probability for a LURS to displace if permafrost is present now or was during the Little Ice Age (LIA) is around 2.1 times higher than if permafrost was already absent during the LIA. This probability is 1.5 times higher for LURSs with current permafrost than for LURSs with permafrost during the LIA that has since melted. Therefore, our findings enrich the classical conception that warming of permafrost increases displacement rates of LURSs, by showing that the complete thawing of permafrost can result in a decrease in displacement rate or even a complete halt of displacement.
Lilleøren, Karianne Staalesen; Etzelmüller, Bernd; Rouyet, Line; Eiken, Trond; Slinde, Gaute Aasen & Hilbich, Christin (2022). Transitional rock glaciers at sea level in northern Norway. Earth Surface Dynamics. ISSN 2196-6311. 10(5), s. 975–996. doi: 10.5194/esurf-10-975-2022. Fulltekst i vitenarkiv Vis sammendrag
Rock glaciers are geomorphological expressions of permafrost. Close to sea level in northernmost Norway, in the subarctic Nordkinn peninsula, we have observed several rock glaciers that appear to be active now or were active in the recent past. Active rock glaciers at this elevation have never before been described in Fennoscandia, and they are outside the climatic limits of present-day permafrost according to models. In this study, we have investigated whether or not these rock glaciers are active under the current climate situation. We made detailed geomorphological maps of three rock glacier areas in Nordkinn and investigated the regional ground dynamics using synthetic aperture radar interferometry (InSAR). One of the rock glaciers, namely the Ivarsfjorden rock glacier, was investigated in more detail by combining observations of vertical and horizontal changes from optical images acquired by airborne and terrestrial sensors and terrestrial laser scans (TLSs). The subsurface of the same rock glacier was investigated using a combination of electrical resistivity tomography (ERT) and refraction seismic tomography (RST). We also measured ground surface temperatures between 2016 and 2020, complemented by investigations using an infrared thermal camera, and a multi-decadal climatic analysis. We mapped the rock glaciers in the innermost parts of Store and Lille Skogfjorden as relict, while the more active ones are in the mouths of both fjords, fed by active talus in the upper slopes. Several of the rock glaciers cross over both the Younger Dryas shoreline (25 m a.s.l.) and the Early to Mid-Holocene shoreline at 13 m a.s.l. Both InSAR and optical remote sensing observations reveal low yearly movement rates (centimetres to millimetres per year). The ERT and RST suggest that there is no longer permafrost and ground ice in the rock glacier, while temperature observations on the front slope indicate freezing conditions also in summer. Based on the in situ temperature measurements and the interpolated regional temperature data, we show that the mean annual air temperature (MAAT) of the region has risen by 2 ∘C since the late 19th century to about 1.5 ∘C in the last decade. MAATs below 0 ∘C 100–150 years ago suggest that new rock glacier lobes may have formed at the end of the Little Ice Age (LIA). These combined results indicate that the Nordkinn rock glaciers are transitioning from active to relict stages. The study shows that transitional rock glaciers are still affected by creep, rock falls, snow avalanches, etc., and are not entirely dynamically dead features. Our contrasting results concerning permafrost presence and rock glacier activity show the importance of a multi-methodological approach when investigating slope processes in the edge zones of permafrost influence.
Vasile, Mirela; Vespremeanu-Stroe, Alfred; Pascal, Daniela; Braucher, Regis; Pleșoianu, Alin & Popescu, Răzvan [Vis alle 7 forfattere av denne artikkelen] (2022). Rock walls distribution and Holocene evolution in a mid-latitude mountain range (the Romanian Carpathians). Geomorphology. ISSN 0169-555X. 413. doi: 10.1016/j.geomorph.2022.108351. Fulltekst i vitenarkiv Vis sammendrag
Rock walls in high mountain areas are the expression of long–term slopes response (103–105 years) to tectonics, weathering and denudation and a major source of sediment and hazard. Controls of mountain rock walls (RW) distribution and the response to post-glacial evolution are rarely discussed in the literature at the scale of mountain ranges. Using a database of 791 RW mapped in the Romanian Carpathians, we present their distribution and morphometry in respect to lithological classes, structural features and topography and relate their exposure to post–Younger Dryas (Holocene) rock slope failure chronology. Statistical analysis results show the high significance of structural and tectonic control on RW distribution, which prevails in sedimentary units where it imposed the predominance of West and North orientations and led to the formation of RW with dimensions up to a degree higher compared to other lithologies. Morphometric data indicate that metamorphic and igneous RW (linked to a great extent to glacial valleys and cirques headwalls) are usually restricted to the highest sectors of the mountain slopes, being characterized by reduced relative heights, asymmetrically distributed, common on the North-exposed slopes and extremely rare on the South. Based on 38 in-situ produced 10Be surface exposure ages obtained on meter-sized boulders from the Southern and Eastern Carpathians, we hypothesise that metamorphic and igneous RW in the formerly glaciated Carpathian valleys were significantly shaped during Early Holocene (before 9 ka) by rock slope failures events that followed the deglaciation of the highest cirques and by intense RW permafrost degradation, which also affected some of the highest sedimentary units. We associate the long–term imprints of frost weathering to the significant North/South RW and rock glaciers distribution asymmetry, also identified in other mid-latitude mountain sites with similar topographic constraints.
Bertone, Aldo; Barboux, Chloé; Bodin, Xavier; Bolch, Tobias; Brardinoni, Francesco & Caduff, Rafael [Vis alle 18 forfattere av denne artikkelen] (2022). Incorporating InSAR kinematics into rock glacier inventories: insights from 11 regions worldwide. The Cryosphere. ISSN 1994-0416. 16(7), s. 2769–2792. doi: 10.5194/tc-16-2769-2022. Fulltekst i vitenarkiv Vis sammendrag
Rock glaciers are landforms related to permafrost creep that are sensitive to climate variability and change. Their spatial distribution and kinematic behaviour can be critical for managing water resources and geohazards in periglacial areas. Rock glaciers have been inventoried for decades worldwide, often without assessment of their kinematics. The availability of remote sensing data however makes the inclusion of kinematic information potentially feasible, but requires a common methodology in order to create homogeneous inventories. In this context, the International Permafrost Association (IPA) Action Group on rock glacier inventories and kinematics (2018–2023), with the support of the European Space Agency (ESA) Permafrost Climate Change Initiative (CCI) project, is defining standard guidelines for the inclusion of kinematic information within inventories. Here, we demonstrate the feasibility of applying common rules proposed by the Action Group in 11 regions worldwide. Spaceborne interferometric synthetic aperture radar (InSAR) was used to characterise identifiable moving areas related to rock glaciers, applying a manual and a semi-automated approach. Subsequently, these areas were used to assign kinematic information to rock glaciers in existing or newly compiled inventories. More than 5000 moving areas and more than 3600 rock glaciers were classified according to their kinematics. The method and the preliminary results were analysed. We identified drawbacks related to the intrinsic limitations of InSAR and to various applied strategies regarding the integration of non-moving rock glaciers in some investigated regions. This is the first internationally coordinated work that incorporates kinematic attributes within rock glacier inventories at a global scale. The results show the value of designing standardised inventorying procedures for periglacial geomorphology.
Smith, Noah D.; Burke, Eleanor J.; Aas, Kjetil Schanke; Althuizen, Inge; Boike, Julia & Christiansen, Casper Tai [Vis alle 13 forfattere av denne artikkelen] (2022). Explicitly modelling microtopography in permafrost landscapes in a land surface model (JULES vn5.4_microtopography). Geoscientific Model Development. ISSN 1991-959X. 15(9), s. 3603–3639. doi: 10.5194/gmd-15-3603-2022. Fulltekst i vitenarkiv Vis sammendrag
Microtopography can be a key driver of heterogeneity in the ground thermal and hydrological regime of permafrost landscapes. In turn, this heterogeneity can influence plant communities, methane fluxes, and the initiation of abrupt thaw processes. Here we have implemented a two-tile representation of microtopography in JULES (the Joint UK Land Environment Simulator), where tiles are representative of repeating patterns of elevation difference. Tiles are coupled by lateral flows of water, heat, and redistribution of snow, and a surface water store is added to represent ponding. Simulations are performed of two Siberian polygon sites, (Samoylov and Kytalyk) and two Scandinavian palsa sites (Stordalen and Iškoras). The model represents the observed differences between greater snow depth in hollows vs. raised areas well. The model also improves soil moisture for hollows vs. the non-tiled configuration (“standard JULES”) though the raised tile remains drier than observed. The modelled differences in snow depths and soil moisture between tiles result in the lower tile soil temperatures being warmer for palsa sites, as in reality. However, when comparing the soil temperatures for July at 20 cm depth, the difference in temperature between tiles, or “temperature splitting”, is smaller than observed (3.2 vs. 5.5 ∘C). Polygons display small (0.2 ∘C) to zero temperature splitting, in agreement with observations. Consequently, methane fluxes are near identical (+0 % to 9 %) to those for standard JULES for polygons, although they can be greater than standard JULES for palsa sites (+10 % to 49 %). Through a sensitivity analysis we quantify the relative importance of model processes with respect to soil moisture and temperatures, identifying which parameters result in the greatest uncertainty in modelled temperature. Varying the palsa elevation between 0.5 and 3 m has little effect on modelled soil temperatures, showing that using only two tiles can still be a valid representation of sites with a range of palsa elevations. Mire saturation is heavily dependent on landscape-scale drainage. Lateral conductive fluxes, while small, reduce the temperature splitting by ∼ 1 ∘C and correspond to the order of observed lateral degradation rates in peat plateau regions, indicating possible application in an area-based thaw model.
Etzelmüller, Bernd; Czekirda, Justyna; Magnin, Florence; Duvillard, Pierre-Allain; Ravanel, Ludovic & Malet, Emanuelle [Vis alle 20 forfattere av denne artikkelen] (2022). Permafrost in monitored unstable rock slopes in Norway – new insights from temperature and surface velocity measurements, geophysical surveying, and ground temperature modelling. Earth Surface Dynamics. ISSN 2196-6311. 10(1), s. 97–129. doi: 10.5194/esurf-10-97-2022. Fulltekst i vitenarkiv Vis sammendrag
Abstract. The warming and subsequent degradation of mountain permafrost within alpine areas represent an important process influencing the stability of steep slopes and rock faces. The unstable and monitored slopes of Mannen (Møre and Romsdal county, southern Norway) and Gámanjunni-3 (Troms and Finnmark county, northern Norway) were classified as high-risk sites by the Norwegian Geological Survey (NGU). Failure initiation has been suggested to be linked to permafrost degradation, but the detailed permafrost distribution at the sites is unknown. Rock wall (RW) temperature loggers at both sites have measured the thermal regime since 2015, showing mean rock surface temperatures between 2.5 and −1.6 ∘C depending on site and topographic aspect. Between 2016 and 2019 we conducted 2D and 3D electrical resistivity tomography (ERT) surveys on the plateau and directly within the rock wall back scarp of the unstable slopes at both sites. In combination with geophysical laboratory analysis of rock wall samples from both sites, the ERT soundings indicate widespread permafrost areas, especially at Gámanjunni-3. Finally, we conducted 2D thermal modelling to evaluate the potential thermal regime, along with an analysis of available displacement rate measurements based on Global Navigation Satellite System (GNSS) and ground- and satellite-based interferometric synthetic aperture radar (InSAR) methods. Surface air and ground temperatures have increased significantly since ca. 1900 by 1 and 1.5 ∘C, and the highest temperatures have been measured and modelled since 2000 at both study sites. We observed a seasonality of displacement, with increasing velocities during late winter and early spring and the highest velocities in June, probably related to water pressure variations during snowmelt. The displacement rates of Gámanjunni-3 rockslide co-vary with subsurface resistivity and modelled ground temperature. Increased displacement rates seem to be associated with sub-zero ground temperatures and higher ground resistivity. This might be related to the presence of ground ice in fractures and pores close to the melting point, facilitating increased deformation. The study demonstrates and discusses the possible influence of permafrost, at least locally, on the dynamics of large rock slope instabilities.
Zweigel, Robin Benjamin; Westermann, Sebastian; Nitzbon, Jan; Langer, M; Boike, Julia & Etzelmüller, Bernd [Vis alle 7 forfattere av denne artikkelen] (2021). Simulating Snow Redistribution and its Effect on Ground Surface Temperature at a High‐Arctic Site on Svalbard. Journal of Geophysical Research (JGR): Earth Surface. ISSN 2169-9003. 126(3). doi: 10.1029/2020JF005673. Fulltekst i vitenarkiv Vis sammendrag
In high-latitude and mountain regions, local processes such as redistribution by wind, snow metamorphism, and percolation of water produce a complex spatial distribution of snow depths and snow densities. With its strong control on the ground thermal regime, this snow distribution has pronounced effects on ground temperatures at small spatial scales which are typically not resolved by land surface models (LSMs). This limits our ability to simulate the local impacts of climate change on, for example, vegetation and permafrost. Here, we present a tiling approach combining the CryoGrid permafrost model with snow microphysics parametrizations from the CROCUS snow scheme to account for subgrid lateral exchange of snow and water in a process-based way. We demonstrate that a simple setup with three coupled tiles, each representing a different snow accumulation class with a specific topographic setting, can reproduce the observed spread of winter-time ground surface temperatures (GST) and end-of-season snow distribution for a high-Arctic site on Svalbard. For the 3-year study period, the three-tile simulations showed substantial improvement compared to traditional single-tile simulations which naturally cannot account for subgrid variability. Among others, the representation of the warmest and coldest 5% of the observed GST distribution was improved by 1–2°C, while still capturing the average of the distribution. The simulations also reveal positive mean annual GSTs at the locations receiving the greatest snow cover. This could be an indication for the onset of localized permafrost degradation which would be obscured in single-tile simulations.
Martin, Leo Celestin Paul; Nitzbon, Jan; Scheer, Johanna; Aas, Kjetil Schanke; Eiken, Trond & Langer, Moritz [Vis alle 9 forfattere av denne artikkelen] (2021). Lateral thermokarst patterns in permafrost peat plateaus in northern Norway. The Cryosphere. ISSN 1994-0416. 15(7), s. 3423–3442. doi: 10.5194/tc-15-3423-2021. Fulltekst i vitenarkiv Vis sammendrag
Subarctic peatlands underlain by permafrost contain significant amounts of organic carbon. Our ability to quantify the evolution of such permafrost landscapes in numerical models is critical for providing robust predictions of the environmental and climatic changes to come. Yet, the accuracy of large-scale predictions has so far been hampered by small-scale physical processes that create a high spatial variability of thermal surface conditions, affecting the ground thermal regime and thus permafrost degradation patterns. In this regard, a better understanding of the small-scale interplay between microtopography and lateral fluxes of heat, water and snow can be achieved by field monitoring and process-based numerical modeling. Here, we quantify the topographic changes of the Šuoššjávri peat plateau (northern Norway) over a three-year period using drone-based repeat high-resolution photogrammetry. Our results show thermokarst degradation is concentrated on the edges of the plateau, representing 77 % of observed subsidence, while most of the inner plateau surface exhibits no detectable subsidence. Based on detailed investigation of eight zones of the plateau edge, we show that this edge degradation corresponds to an annual volume change of 0.13±0.07 m3 yr−1 per meter of retreating edge (orthogonal to the retreat direction). Using the CryoGrid3 land surface model, we show that these degradation patterns can be reproduced in a modeling framework that implements lateral redistribution of snow, subsurface water and heat, as well as ground subsidence due to melting of excess ice. By performing a sensitivity test for snow depths on the plateau under steady-state climate forcing, we obtain a threshold behavior for the start of edge degradation. Small snow depth variations (from 0 to 30 cm) result in highly different degradation behavior, from stability to fast degradation. For plateau snow depths in the range of field measurements, the simulated annual volume changes are broadly in agreement with the results of the drone survey. As snow depths are clearly correlated with ground surface temperatures, our results indicate that the approach can potentially be used to simulate climate-driven dynamics of edge degradation observed at our study site and other peat plateaus worldwide. Thus, the model approach represents a first step towards simulating climate-driven landscape development through thermokarst in permafrost peatlands.
Schmidt, Juditha; Etzelmüller, Bernd; Schuler, Thomas; Magnin, Florence; Boike, Julia & Langer, Moritz [Vis alle 7 forfattere av denne artikkelen] (2021). Surface temperatures and their influence on the permafrost thermal regime in high-Arctic rock walls on Svalbard. The Cryosphere. ISSN 1994-0416. 15(5), s. 2491–2509. doi: 10.5194/tc-15-2491-2021. Fulltekst i vitenarkiv Vis sammendrag
Abstract. Permafrost degradation in steep rock walls and associated slope destabilization have been studied increasingly in recent years. While most studies focus on mountainous and sub-Arctic regions, the occurring thermo-mechanical processes also play an important role in the high Arctic. A more precise understanding is required to assess the risk of natural hazards enhanced by permafrost warming in high-Arctic rock walls. This study presents one of the first comprehensive datasets of rock surface temperature measurements of steep rock walls in the high Arctic, comparing coastal and near-coastal settings. We applied the surface energy balance model CryoGrid 3 for evaluation, including adjusted radiative forcing to account for vertical rock walls. Our measurements comprise 4 years of rock surface temperature data from summer 2016 to summer 2020. Mean annual rock surface temperatures ranged from −0.6 in a coastal rock wall in 2017/18 to −4.3 ∘C in a near-coastal rock wall in 2019/20. Our measurements and model results indicate that rock surface temperatures at coastal cliffs are up to 1.5 ∘C higher than at near-coastal rock walls when the fjord is ice-free in winter, resulting from additional energy input due to higher air temperatures at the coast and radiative warming by relatively warm seawater. An ice layer on the fjord counteracts this effect, leading to similar rock surface temperatures to those in near-coastal settings. Our results include a simulated surface energy balance with shortwave radiation as the dominant energy source during spring and summer with net average seasonal values of up to 100 W m−2 and longwave radiation being the main energy loss with net seasonal averages between 16 and 39 W m−2. While sensible heat fluxes can both warm and cool the surface, latent heat fluxes are mostly insignificant. Simulations for future climate conditions result in a warming of rock surface temperatures and a deepening of active layer thickness for both coastal and near-coastal rock walls. Our field data present a unique dataset of rock surface temperatures in steep high-Arctic rock walls, while our model can contribute towards the understanding of factors influencing coastal and near-coastal settings and the associated surface energy balance.
Rouyet, Line; Lilleøren, Karianne Staalesen; Böhme, Martina; Vick, Louise Mary; Delaloye, Reynald & Etzelmüller, Bernd [Vis alle 9 forfattere av denne artikkelen] (2021). Regional Morpho-Kinematic Inventory of Slope Movements in Northern Norway. Frontiers in Earth Science. 9. doi: 10.3389/feart.2021.681088. Fulltekst i vitenarkiv Vis sammendrag
Mountain slopes in periglacial environments are affected by frost- and gravity-driven processes that shape the landscape. Both rock glaciers and rockslides have been intensively inventoried worldwide. Although most inventories are traditionally based on morphologic criteria, kinematic approaches based on satellite remote sensing have more recently been used to identify moving landforms at the regional scale. In this study, we developed simplified Interferometric Synthetic Aperture Radar (InSAR) products to inventory ground velocity in a region in Northern Norway covering approximately 7,500 km 2 . We used a multiple temporal baseline InSAR stacking procedure based on 2015–2019 ascending and descending Sentinel-1 images to take advantage of a large set of interferograms and exploit different detection capabilities. First, moving areas are classified according to six velocity brackets, and morphologically associated to six landform types (rock glaciers, rockslides, glaciers/moraines, talus/scree deposits, solifluction/cryoturbation and composite landforms). The kinematic inventory shows that the velocity ranges and spatial distribution of the different types of slope processes vary greatly within the study area. Second, we exploit InSAR to update pre-existing inventories of rock glaciers and rockslides in the region. Landform delineations and divisions are refined, and newly detected landforms (54 rock glaciers and 20 rockslides) are incorporated into the databases. The updated inventories consist of 414 rock glacier units within 340 single- or multi-unit(s) systems and 117 rockslides. A kinematic attribute assigned to each inventoried landform documents the order of magnitude of the creep rate. Finally, we show that topo-climatic variables influence the spatial distribution of the rock glaciers. Their mean elevation increases toward the continental interior with a dominance of relict landforms close to the land-sea margin and an increased occurrence of active landforms further inland. Both rock glaciers and rockslides are mostly located on west-facing slopes and in areas characterised by strongly foliated rocks, which suggests the influence of geological preconditioning factors. The study demonstrates the value of semi-quantitative InSAR products to characterise kinematic information at large scale and exploit the results for periglacial research. It highlights the complementarity of both kinematic and morphologic approaches for inventorying slope processes.
Kristensen, Lene; Czekirda, Justyna; Penna, Ivanna; Etzelmüller, Bernd; Nicolet, Pierrick & Pullarello, Jose Santiago [Vis alle 10 forfattere av denne artikkelen] (2021). Movements, failure and climatic control of the Veslemannen rockslide, Western Norway. Landslides. Journal of the International Consortium on Landslides. ISSN 1612-510X. 18, s. 1963–1980. doi: 10.1007/s10346-020-01609-x. Fulltekst i vitenarkiv Vis sammendrag
On September 5, 2019, the Veslemannen unstable rock slope (54,000 m 3 ) in Romsdalen, Western Norway, failed catastrophically after 5 years of continuous monitoring. During this period, the rock slope weakened while the precursor movements increased progressively, in particular from 2017. Measured displacement prior to the failure was around 19 m in the upper parts of the instability and 4–5 m in the toe area. The pre-failure movements were usually associated with precipitation events, where peak velocities occurred 2–12 h after maximum precipitation. This indicates that the pore-water pressure in the sliding zones had a large influence on the slope stability. The sensitivity to rainfall increased greatly from spring to autumn suggesting a thermal control on the pore-water pressure. Transient modelling of temperatures suggests near permafrost conditions, and deep seasonal frost was certainly present. We propose that a frozen surface layer prevented water percolation to the sliding zone during spring snowmelt and early summer rainfalls. A transition from possible permafrost to a seasonal frost setting of the landslide body after 2000 was modelled, which may have affected the slope stability. Repeated rapid accelerations during late summers and autumns caused a total of 16 events of the red (high) hazard level and evacuation of the hazard zone. Threshold values for velocity were used in the risk management when increasing or decreasing hazard levels. The inverse velocity method was initially of little value. However, in the final phase before the failure, the inverse velocity method was useful for forecasting the time of failure. Risk communication was important for maintaining public trust in early-warning systems, and especially critical is the communication of the difference between issuing the red hazard level and predicting a landslide.
Hilger, Paula; Hermanns, Reginald; Czekirda, Justyna; Sæterdal, Kristin Myhra; Gosse, John C. & Etzelmüller, Bernd (2020). Permafrost as a first order control on long-term rock-slope deformation in (Sub-)Arctic Norway. Quaternary Science Reviews. ISSN 0277-3791. 251. doi: 10.1016/j.quascirev.2020.106718. Fulltekst i vitenarkiv Vis sammendrag
Assessing initiation of rock-slope deformation and paleo-slip rates of rockslides is important to understand the impact of climate variability - in particular permafrost changes - on rockslide activity. Norway, with 6–6.5% permafrost cover today, continues to experience spatial and temporal variations in permafrost. We assess the timing of deformation initiation and potential late Pleistocene and Holocene sliding rates for six active gradually deforming rockslides in Norway using terrestrial cosmogenic nuclide dating. We evaluate the timing and rates of deformation considering a possible climate control by modelling the permafrost evolution since deglaciation for three rockslide locations: Mannen, Revdalsfjellet and Gamanjunni 3. Deformation at these sites started during or at the end of the Holocene Thermal Maximum (HTM), between 8 and 4.5 ka when permafrost in those regions was mostly degraded. At two low elevation sites, Oppstadhornet and Skjeringahaugane in western Norway, where permafrost remained absent during the Holocene, deformation started shortly after deglaciation. The timings suggest that the presence of permafrost in Norwegian rock slopes had a stabilizing effect over several millennia after deglaciation. Vertical transects of exposure ages along outcropping sliding surfaces indicate that pre-historical sliding rates seem to have decreased throughout the Holocene at all analysed rock-slope instabilities. However, modern measured sliding rates at four sites indicate a moderate to strong acceleration, compared to previous deformation rates. Three of these sites are located above or at the lower limit of alpine permafrost, where recent permafrost degradation may enhance slope destabilisation. The implication is that slope failures may become more frequent during accelerated warming in the Arctic and Subarctic.
Etzelmüller, Bernd; Patton, Henry; Schomacker, Anders; Czekirda, Justyna; Girod, Luc Maurice Ramuntcho & Hubbard, Alun Lloyd [Vis alle 8 forfattere av denne artikkelen] (2020). Icelandic permafrost dynamics since the Last Glacial Maximum – model results and geomorphological implications. Quaternary Science Reviews. ISSN 0277-3791. 233:106236. doi: 10.1016/j.quascirev.2020.106236. Fulltekst i vitenarkiv Vis sammendrag
Iceland’s periglacial realm is one of the most dynamic on the planet, with active geomorphologicalprocesses and high weathering rates of young bedrock resulting in high sediment yields and ongoingmass movement. Permafrost is discontinuous in Iceland’s highlands and mountains over c. 800 m a.s.l,and sporadic in palsa mires in the central highlands. During the late Pleistocene and Holocene, Iceland’speriglacial environment varied considerably in time and space, dominated by glacialfluctuations andperiglacial processes. To evaluate the dynamics of permafrost in Iceland since the last deglaciation, weuse the output of a coupled climate/ice sheet model to force a transient permafrost model (CryoGRID 2)from the Last Glacial Maximum (LGM) through to the present. Wefind that permafrost was widespreadacross the deglaciated areas of western, northern and eastern Iceland after the LGM, and that up to 20% ofIceland’s terrestrial area was underlain by permafrost throughout the late Pleistocene. This influencedgeomorphological processes and landform generation: the early collapse of the marine-based ice sheettogether with the aggradation of permafrost in these zones initiated the formation of abundant and nowrelict rock glaciers across coastal margins. Permafrost degraded rapidly after the Younger Dryas, with amarked impact on slope stability. Permafrost that formed during the Little Ice Age is again thawingrapidly, and an escalation in slope failure and mass-movement might be currently underway. Our studydemonstrates that large regions of Iceland have been underlain by permafrost for millennia, facilitatinglandform development and influencing the stability of steep slopes
Hilger, Paula; Hermanns, Reginald & Etzelmüller, Bernd (2020). A Landform Evolution Model for the Mannen Area in Romsdal Valley, Norway. I Vilimek, Vit; Wang, Fawu; Strom, Alexander; Sassa, Kyoji; Bobrowsky, Peter T. & Takara, Kaoru (Red.), Understanding and Reducing Landslide Disaster Risk Volume 5 Catastrophic Landslides and Frontiers of Landslide Science. Springer Nature. ISSN 9783030603199. s. 309–314. doi: 10.1007/978-3-030-60319-9_34. Fulltekst i vitenarkiv Vis sammendrag
The Quaternary geology of western Norway’s landscape is the result of glacial and post-glacial sedimentation and erosional processes, a significant sea-level drop and high rock-slope failure activity. All these processes are represented within a small valley section below the Mannen rock-slope instability in Romsdal valley, western Norway. Here, exposure ages, Quaternary geological mapping and geophysical investigations permit the development of a paraglacial landscape evolution model. The model contextualises at least six catastrophic rock-slope failure events within the overall sequence of fjord-valley infilling following deglaciation. A transition from a wide basin-like valley into a strongly confined valley section led to the build-up of more than 40 m thick stratified drift, which was at least partly deposited within a marine environment. The morphology of these sediments features two distinct erosional levels, which are interpreted to be connected to tidal currents during post-glacial sea-level drop. The landform evolution model illustrates the importance of catastrophic rock-slope failures and the impact of strong tidal currents on the typical sediment fill in narrow, high-relief fjord valleys.
Karjalainen, Olli; Luoto, Miska; Aalto, Juha; Etzelmüller, Bernd; Grosse, Guido & Jones, Benjamin M. [Vis alle 8 forfattere av denne artikkelen] (2020). High potential for loss of permafrost landforms in a changing climate. Environmental Research Letters. 15(10). doi: 10.1088/1748-9326/abafd5. Fulltekst i vitenarkiv Vis sammendrag
The presence of ground ice in Arctic soils exerts a major effect on permafrost hydrology and ecology, and factors prominently into geomorphic landform development. As most ground ice has accumulated in near-surface permafrost, it is sensitive to variations in atmospheric conditions. Typical and regionally widespread permafrost landforms such as pingos, ice-wedge polygons, and rock glaciers are closely tied to ground ice. However, under ongoing climate change, suitable environmental spaces for preserving landforms associated with ice-rich permafrost may be rapidly disappearing. We deploy a statistical ensemble approach to model, for the first time, the current and potential future environmental conditions of three typical permafrost landforms, pingos, ice-wedge polygons and rock glaciers across the Northern Hemisphere. We show that by midcentury, the landforms are projected to lose more than one-fifth of their suitable environments under a moderate climate scenario (RCP4.5) and on average around one-third under a very high baseline emission scenario (RCP8.5), even when projected new suitable areas for occurrence are considered. By 2061–2080, on average more than 50% of the recent suitable conditions can be lost (RCP8.5). In the case of pingos and ice-wedge polygons, geographical changes are mainly attributed to alterations in thawing-season precipitation and air temperatures. Rock glaciers show air temperature-induced regional changes in suitable conditions strongly constrained by topography and soil properties. The predicted losses could have important implications for Arctic hydrology, geo- and biodiversity, and to the global climate system through changes in biogeochemical cycles governed by the geomorphology of permafrost landscapes. Moreover, our projections provide insights into the circumpolar distribution of various ground ice types and help inventory permafrost landforms in unmapped regions.
Etzelmüller, Bernd; Guglielmin, Mauro; Hauck, Christian; Hilbich, Christin; Hoelzle, Martin & Isaksen, Ketil [Vis alle 9 forfattere av denne artikkelen] (2020). Twenty years of European mountain permafrost dynamics-the PACE legacy. Environmental Research Letters. 15(10). doi: 10.1088/1748-9326/abae9d. Fulltekst i vitenarkiv Vis sammendrag
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°N) to Svalbard (78°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 °C on Svalbard and 0.4 °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 °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.
Magnin, Florence; Etzelmüller, Bernd; Westermann, Sebastian; Isaksen, Ketil; Hilger, Paula & Hermanns, Reginald (2019). Permafrost distribution in steep rock slopes in Norway: measurements, statistical modelling and implications for geomorphological processes. Earth Surface Dynamics. ISSN 2196-6311. 7(4), s. 1019–1040. doi: 10.5194/esurf-7-1019-2019. Fulltekst i vitenarkiv Vis sammendrag
Permafrost in steep rock slopes has been increasingly studied since the early 2000s in conjunction with a growing number of rock slope failures, which likely resulted from permafrost degradation. In Norway, rock slope destabilization is a widespread phenomenon and a major source of risk for the population and infrastructure. However, a lack of precise knowledge of the permafrost distribution in steep slopes hinders the assessment of its role in these destabilizations. This study proposes the first nationwide permafrost probability map for the steep slopes of Norway (CryoWall map). It is based on a multiple linear regression model fitted with multi-annual rock surface temperature (RST) measurements, collected at 25 rock slope sites, spread across a latitudinal transect (59–69∘ N) over mainland Norway. The CryoWall map suggests that discontinuous permafrost widely occurs above 1300–1400 and 1600–1700 m a.s.l. in the north and south rock faces of southern Norway (59∘ N), respectively. This lower altitudinal limit decreases in northern Norway (70∘ N) by about 500±50 m, with a more pronounced decrease for south faces, as a result of the insolation patterns largely driven by midnight sun in summer and polar night in winter. Similarly, the mean annual RST differences between north and south faces of similar elevation range around 1.5 ∘C in northern Norway and 3.5 ∘C in southern Norway. The CryoWall map is evaluated against direct ice observations in steep slopes and discussed in the context of former permafrost studies in various types of terrain in Norway. We show that permafrost can occur at much lower elevations in steep rock slopes than in other terrains, especially in north faces. We demonstrate that the CryoWall map is a valuable basis for further investigations related to permafrost in steep slopes in terms of both practical concerns and fundamental science.
Martin, Leo Celestin Paul; Nitzbon, Jan; Aas, Kjetil Schanke; Etzelmüller, Bernd; Kristiansen, Håvard & Westermann, Sebastian (2019). Stability Conditions of Peat Plateaus and Palsas in Northern Norway. Journal of Geophysical Research (JGR): Earth Surface. ISSN 2169-9003. 124(3), s. 705–719. doi: 10.1029/2018JF004945. Fulltekst i vitenarkiv Vis sammendrag
Peat plateaus and palsas are characteristic morphologies of sporadic permafrost, and the transition from permafrost to permafrost‐free ground typically occurs on spatial scales of meters. They are particularly vulnerable to climate change and are currently degrading in Fennoscandia. Here we present a spatially distributed data set of ground surface temperatures for two peat plateau sites in northern Norway for the year 2015–2016. Based on these data and thermal modeling, we investigate how the snow depth and water balance modulate the climate signal in the ground. We find that mean annual ground surface temperatures are centered around 2 to 2.5 °C for stable permafrost locations and 3.5 to 4.5 °C for permafrost‐free locations. The surface freezing degree days are characterized by a noticeable threshold around 200 °C.day, with most permafrost‐free locations ranging below this value and most stable permafrost ones above it. Freezing degree day values are well correlated to the March snow cover, although some variability is observed and attributed to the ground moisture level. Indeed, a zero curtain effect is observed on temperature time series for saturated soils during winter, while drained peat plateaus show early freezing surface temperatures. Complementarily, modeling experiments allow identifying a drainage effect that can modify 1‐m ground temperatures by up to 2 °C between drained and water accumulating simulations for the same snow cover. This effect can set favorable or unfavorable conditions for permafrost stability under the same climate forcing.
Karjalainen, Olli; Aalto, Juha; Luoto, Miska; Westermann, Sebastian; Romanovsky, Vladimir E & Nelson, Frederick E. [Vis alle 8 forfattere av denne artikkelen] (2019). Data Descriptor: Circumpolar permafrost maps and geohazard indices for near-future infrastructure risk assessments. Scientific Data. 6. doi: 10.1038/sdata.2019.37. Fulltekst i vitenarkiv Vis sammendrag
Ongoing climate change is causing fundamental changes in the Arctic, some of which can be hazardous to nature and human activity. In the context of Earth surface systems, warming climate may lead to rising ground temperatures and thaw of permafrost. This Data Descriptor presents circumpolar permafrost maps and geohazard indices depicting zones of varying potential for development of hazards related to near-surface permafrost degradation, such as ground subsidence. Statistical models were used to predict ground temperature and the thickness of the seasonally thawed (active) layer using geospatial data on environmental conditions at 30 arc-second resolution. These predictions, together with data on factors (ground ice content, soil grain size and slope gradient) affecting permafrost stability, were used to formulate geohazard indices. Using climate-forcing scenarios (Representative Concentration Pathways 2.6, 4.5 and 8.5), permafrost extent and hazard potential were projected for the 2041–2060 and 2061–2080 time periods. The resulting data (seven permafrost and 24 geohazard maps) are relevant to near-future infrastructure risk assessments and for targeting localized geohazard analyses.
Biskaborn, Boris K.; Smith, Sharon L.; Noetzli, Jeannette; Matthes, Heidrun; Vieira, Gonçalo & Streletskiy, Dmitry A. [Vis alle 48 forfattere av denne artikkelen] (2019). Permafrost is warming at a global scale. Nature Communications. 10. doi: 10.1038/s41467-018-08240-4. Fulltekst i vitenarkiv Vis sammendrag
Permafrost warming has the potential to amplify global climate change, because when frozen sediments thaw it unlocks soil organic carbon. Yet to date, no globally consistent assessment of permafrost temperature change has been compiled. Here we use a global data set of permafrost temperature time series from the Global Terrestrial Network for Permafrost to evaluate temperature change across permafrost regions for the period since the International Polar Year (2007–2009). During the reference decade between 2007 and 2016, ground temperature near the depth of zero annual amplitude in the continuous permafrost zone increased by 0.39 ± 0.15 °C. Over the same period, discontinuous permafrost warmed by 0.20 ± 0.10 °C. Permafrost in mountains warmed by 0.19 ± 0.05 °C and in Antarctica by 0.37 ± 0.10 °C. Globally, permafrost temperature increased by 0.29 ± 0.12 °C. The observed trend follows the Arctic amplification of air temperature increase in the Northern Hemisphere. In the discontinuous zone, however, ground warming occurred due to increased snow thickness while air temperature remained statistically unchanged.
Czekirda, Justyna; Westermann, Sebastian; Etzelmüller, Bernd & Jóhannesson, Tómas (2019). Transient Modelling of Permafrost Distribution in Iceland. Frontiers in Earth Science. 7(130). doi: 10.3389/feart.2019.00130. Fulltekst i vitenarkiv Vis sammendrag
Warming and degradation of permafrost during the ongoing climate change is of growing concern. Recently, permafrost thawing has been recognized as a new factor triggering landslides in Iceland. Therefore, there is an increased need for a more thorough understanding of permafrost distribution and the temporal evolution of the ground thermal regime in this region. This study focuses on regional modelling of ground temperature evolution in Iceland for the last six decades (1960–2016) by employing the transient permafrost model CryoGrid 2 at 1-km spatial resolution. To account for the strong wind redistribution of snow in Iceland, we ran three realizations of the model, by forcing the embodied snow water equivalent model with 50, 100, and 150% of gridded precipitation. The modelled permafrost extent strongly depends on snow depth, with around 3–15 times more cells indicating permafrost in the halved-precipitation run in comparison to the other two precipitation runs. A three- to four-decade-long warming trend has led to warming or degradation of permafrost in some areas of Iceland. We roughly estimate that ~11 and 7% of the land area of Iceland was underlain by permafrost during the periods 1980–1989 and 2010–2016, respectively. Model validation with ground temperature measurements and the distribution of permafrost-related landforms, such as active rock glaciers and stable ice-cored moraines, together with palsas and peat plateaus, shows good agreement. The simulation results may be further used as a baseline for modelling of future permafrost evolution at a regional scale or for identification of landslide-susceptible areas in Iceland.
Myhra, Kristin Sæterdal; Westermann, Sebastian & Etzelmüller, Bernd (2019). Modelling conductive heat flow between steep rock walls and talus slopes–thermal processes and geomorphological implications. Frontiers in Earth Science. 7, s. 1–14. doi: 10.3389/feart.2019.00192. Fulltekst i vitenarkiv Vis sammendrag
The thermal regime in steep and snow-free rock slopes is crucial for understanding rock slope stability, frost weathering and the associated material production in steep mountain areas. In this study, we model heat flow and explore the hypothesis that strong thermal gradients are maintained in transition areas between snow-free rock walls and snow-covered talus slopes. The results of our 2D heat transfer modeling experiments indicate that, under the assumption of snow-free steep rock walls, conductive heat flow can cool the upper parts of an adjacent talus slope with low conductivity and induce strong thermal gradients in the solid bedrock. The modeled conductive cooling effect may be relevant for both frost weathering processes and subsequent geomorphological implications and for the thermal regime of complex surface material in rock wall-talus systems in alpine areas.
Obu, Jaroslav; Westermann, Sebastian; Bartsch, Annett; Berdnikov, Nikolai M.; Christiansen, Hanne H & Dashtseren, Avirmed [Vis alle 21 forfattere av denne artikkelen] (2019). Northern Hemisphere permafrost map based on TTOP modelling for 2000–2016 at 1 km2 scale. Earth-Science Reviews. ISSN 0012-8252. 193, s. 299–316. doi: 10.1016/j.earscirev.2019.04.023. Fulltekst i vitenarkiv Vis sammendrag
Permafrost is a key element of the cryosphere and an essential climate variable in the Global Climate Observing System. There is no remote-sensing method available to reliably monitor the permafrost thermal state. To estimate permafrost distribution at a hemispheric scale, we employ an equilibrium state model for the temperature at the top of the permafrost (TTOP model) for the 2000–2016 period, driven by remotely-sensed land surface temperatures, down-scaled ERA-Interim climate reanalysis data, tundra wetness classes and landcover map from the ESA Landcover Climate Change Initiative (CCI) project. Subgrid variability of ground temperatures due to snow and landcover variability is represented in the model using subpixel statistics. The results are validated against borehole measurements and reviewed regionally. The accuracy of the modelled mean annual ground temperature (MAGT) at the top of the permafrost is ±2 °C when compared to permafrost borehole data. The modelled permafrost area (MAGT <0 °C) covers 13.9 × 106 km2 (ca. 15% of the exposed land area), which is within the range or slightly below the average of previous estimates. The sum of all pixels having isolated patches, sporadic, discontinuous or continuous permafrost (permafrost probability >0) is around 21 × 106 km2 (22% of exposed land area), which is approximately 2 × 106 km2 less than estimated previously. Detailed comparisons at a regional scale show that the model performs well in sparsely vegetated tundra regions and mountains, but is less accurate in densely vegetated boreal spruce and larch forests.
Kjellman, Sofia E.; Axelsson, Pia E.; Etzelmüller, Bernd; Westermann, Sebastian & Sannel, A. Britta K. (2018). Holocene development of subarctic permafrost peatlands in Finnmark, northern Norway. The Holocene. ISSN 0959-6836. 28(12), s. 1855–1869. doi: 10.1177/0959683618798126. Fulltekst i vitenarkiv Vis sammendrag
Subarctic permafrost peatlands are important soil organic carbon pools, and improved knowledge about peat properties and peatland sensitivity to past climate change is essential when predicting future response to a warmer climate and associated feedback mechanisms. In this study, Holocene peatland development and permafrost dynamics of four subarctic peat plateaus in Finnmark, northern Norway have been investigated through detailed analyses of plant macrofossils and geochemical properties. Peatland inception occurred around 9800 cal. yr BP and 9200 cal. yr BP at the two continental sites Suossjavri and Iskoras. Younger basal peat ages were found at the two coastal locations Lakselv and Karlebotn, at least partly caused by the time lag between deglaciation and emergence of land by isostatic uplift. Here, peatland development started around 6150 cal. yr BP and 5150 cal. yr BP, respectively. All four peatlands developed as wet fens throughout most of the Holocene. Permafrost aggradation, causing frost heave and a shift in the vegetation assemblage from wet fen to dry bog species, probably did not occur until during the last millennium, ca. 950 cal. yr BP in Karlebotn and ca. 800 cal. yr BP in Iskoras, and before ca. 150 cal. yr BP in Lakselv and ca. 100 cal. yr BP in Suossjavri. In Karlebotn, there are indications of a possible earlier permafrost phase around 2200 cal. yr BP due to climatic cooling at the late Subboreal to early Subatlantic transition. The mean long-term Holocene carbon accumulation rate at all four sites was 12.3 +/- 4.1 gC m-2 yr-1 (+/- SD) and the mean soil organic carbon storage was 97 +/- 46 kgC m-2.
Hilger, Paula; Hermanns, Reginald; Gosse, John C; Jacobs, B; Etzelmüller, Bernd & Krautblatter, Michael (2018). Multiple rock-slope failures from Mannen in Romsdal Valley, western Norway, revealed from Quaternary geological mapping and 10Be exposure dating. The Holocene. ISSN 0959-6836. 28(12), s. 1841–1854. doi: 10.1177/0959683618798165. Fulltekst i vitenarkiv Vis sammendrag
Oversteepened valley walls in western Norway have high recurrences of Holocene rock-slope failure activity causing significant risk to communities and infrastructure. Deposits from six to nine catastrophic rock-slope failure (CRSF) events are preserved at the base of the Mannen rock-slope instability in the Romsdal Valley, western Norway. The timing of these CRSF events was determined by terrestrial cosmogenic nuclide dating and relative chronology due to mapping Quaternary deposits. The stratigraphical chronology indicates that three of the CRSF events occurred between 12 and 10 ka, during regional deglaciation. Congruent with previous investigations, these events are attributed to the debuttressing effect experienced by steep slopes following deglaciation, during a period of paraglacial relaxation. The remaining three to six CRSF events cluster at 4.9 ± 0.6 ka (based on 10 cosmogenic 10Be samples from boulders). CRSF events during this later period are ascribed to climatic changes at the end of the Holocene thermal optimum, including increased precipitation rates, high air temperatures and the associated degradation of permafrost in rock-slope faces. Geomorphological mapping and sedimentological analyses further permit the contextualisation of these deposits within the overall sequence of post-glacial fjord-valley infilling. In the light of contemporary climate change, the relationship between CRSF frequency, precipitation, air temperature and permafrost degradation may be of interest to others working or operating in comparable settings.
Hjort, Jan; Karjalainen, Olli; Aalto, Juha; Westermann, Sebastian; Romanovsky, Vladimir E & Nelson, Frederick E. [Vis alle 8 forfattere av denne artikkelen] (2018). Degrading permafrost puts Arctic infrastructure at risk by mid-century. Nature Communications. 9. doi: 10.1038/s41467-018-07557-4. Fulltekst i vitenarkiv Vis sammendrag
Degradation of near-surface permafrost can pose a serious threat to the utilization of natural resources, and to the sustainable development of Arctic communities. Here we identify at unprecedentedly high spatial resolution infrastructure hazard areas in the Northern Hemisphere’s permafrost regions under projected climatic changes and quantify fundamental engineering structures at risk by 2050. We show that nearly four million people and 70% of current infrastructure in the permafrost domain are in areas with high potential for thaw of near-surface permafrost. Our results demonstrate that one-third of pan-Arctic infrastructure and 45% of the hydrocarbon extraction fields in the Russian Arctic are in regions where thaw-related ground instability can cause severe damage to the built environment. Alarmingly, these figures are not reduced substantially even if the climate change targets of the Paris Agreement are reached.
Gisnås, Kjersti; Etzelmüller, Bernd; Lussana, Cristian; Hjort, Jan; Sannel, Britta & Isaksen, Ketil [Vis alle 11 forfattere av denne artikkelen] (2017). Permafrost Map for Norway, Sweden and Finland. Permafrost and Periglacial Processes. ISSN 1045-6740. 28(2), s. 359–378. doi: 10.1002/ppp.1922. Fulltekst i vitenarkiv
Borge, Amund Frogner; Westermann, Sebastian; Solheim, Ingvild & Etzelmüller, Bernd (2017). Strong degradation of palsas and peat plateaus in northern Norway during the last 60 years. The Cryosphere. ISSN 1994-0416. 11(1), s. 1–16. doi: 10.5194/tc-11-1-2017. Fulltekst i vitenarkiv Vis sammendrag
Solheim, Ingvild og Etzelmuller, Bernd er ikke (P)-personer. Fikset ms 26/9
Westermann, Sebastian; Peter, Maria; Langer, Moritz; Schwamborn, Georg; Schirrmeister, Lutz & Etzelmüller, Bernd [Vis alle 7 forfattere av denne artikkelen] (2017). Transient modeling of the ground thermal conditions using satellite data in the Lena River delta, Siberia. The Cryosphere. ISSN 1994-0416. 11(3), s. 1441–1463. doi: 10.5194/tc-11-1441-2017. Fulltekst i vitenarkiv Vis sammendrag
Permafrost is a sensitive element of the cryosphere, but operational monitoring of the ground thermal conditions on large spatial scales is still lacking. Here, we demonstrate a remote-sensing-based scheme that is capable of estimating the transient evolution of ground temperatures and active layer thickness by means of the ground thermal model CryoGrid 2. The scheme is applied to an area of approximately 16 000 km2 in the Lena River delta (LRD) in NE Siberia for a period of 14 years. The forcing data sets at 1 km spatial and weekly temporal resolution are synthesized from satellite products and fields of meteorological variables from the ERA-Interim reanalysis. To assign spatially distributed ground thermal properties, a stratigraphic classification based on geomorphological observations and mapping is constructed, which accounts for the large-scale patterns of sediment types, ground ice and surface properties in the Lena River delta. A comparison of the model forcing to in situ measurements on Samoylov Island in the southern part of the study area yields an acceptable agreement for the purpose of ground thermal modeling, for surface temperature, snow depth, and timing of the onset and termination of the winter snow cover. The model results are compared to observations of ground temperatures and thaw depths at nine sites in the Lena River delta, suggesting that thaw depths are in most cases reproduced to within 0.1 m or less and multi-year averages of ground temperatures within 1–2 °C. Comparison of monthly average temperatures at depths of 2–3 m in five boreholes yielded an RMSE of 1.1 °C and a bias of −0.9 °C for the model results. The highest ground temperatures are calculated for grid cells close to the main river channels in the south as well as areas with sandy sediments and low organic and ice contents in the central delta, where also the largest thaw depths occur. On the other hand, the lowest temperatures are modeled for the eastern part, which is an area with low surface temperatures and snow depths. The lowest thaw depths are modeled for Yedoma permafrost featuring very high ground ice and soil organic contents in the southern parts of the delta. The comparison to in situ observations indicates that transient ground temperature modeling forced by remote-sensing data is generally capable of estimating the thermal state of permafrost (TSP) and its time evolution in the Lena River delta. The approach could hence be a first step towards remote detection of ground thermal conditions and active layer thickness in permafrost areas.
Girod, Luc Maurice Ramuntcho; Nuth, Christopher; Kääb, Andreas; Etzelmüller, Bernd & Kohler, Jack (2017). Terrain changes from images acquired on opportunistic flights by SfM photogrammetry. The Cryosphere. ISSN 1994-0416. 11(2), s. 827–840. doi: 10.5194/tc-11-827-2017. Fulltekst i vitenarkiv Vis sammendrag
Acquiring data to analyse change in topography is often a costly endeavour requiring either extensive, potentially risky, fieldwork and/or expensive equipment or commercial data. Bringing the cost down while keeping the precision and accuracy has been a focus in geoscience in recent years. Structure from motion (SfM) photogrammetric techniques are emerging as powerful tools for surveying, with modern algorithm and large computing power allowing for the production of accurate and detailed data from low-cost, informal surveys. The high spatial and temporal resolution permits the monitoring of geomorphological features undergoing relatively rapid change, such as glaciers, moraines, or landslides. We present a method that takes advantage of light-transport flights conducting other missions to opportunistically collect imagery for geomorphological analysis. We test and validate an approach in which we attach a consumer-grade camera and a simple code-based Global Navigation Satellite System (GNSS) receiver to a helicopter to collect data when the flight path covers an area of interest. Our method is based and builds upon Welty et al. (2013), showing the ability to link GNSS data to images without a complex physical or electronic link, even with imprecise camera clocks and irregular time lapses. As a proof of concept, we conducted two test surveys, in September 2014 and 2015, over the glacier Midtre Lovénbreen and its forefield, in northwestern Svalbard. We were able to derive elevation change estimates comparable to in situ mass balance stake measurements. The accuracy and precision of our DEMs allow detection and analysis of a number of processes in the proglacial area, including the presence of thermokarst and the evolution of water channels.
Myhra, Kristin Sæterdal; Westermann, Sebastian & Etzelmuller, Bernd (2017). Modelled Distribution and Temporal Evolution of Permafrost in Steep Rock Walls Along a Latitudinal Transect in Norway by CryoGrid 2D. Permafrost and Periglacial Processes. ISSN 1045-6740. 28(1), s. 172–182. doi: 10.1002/ppp.1884. Fulltekst i vitenarkiv
Westermann, Sebastian; Langer, Moritz; Boike, Julia; Heikenfeld, Max; Peter, Maria & Etzelmuller, Bernd [Vis alle 7 forfattere av denne artikkelen] (2016). Simulating the thermal regime and thaw processes of ice-rich permafrost ground with the land-surface model CryoGrid 3. Geoscientific Model Development. ISSN 1991-959X. 9(2), s. 523–546. doi: 10.5194/gmd-9-523-2016. Fulltekst i vitenarkiv
Berthling, Ivar Thoralf & Etzelmüller, Bernd (2016). The changing cryosphere. I Beylich, Achim A.; Dixon, John C. & Zbigniew, Zwoliński (Red.), Source-to-Sink Fluxes in Undisturbed Cold Environments. Cambridge University Press. ISSN 9781107068223. s. 13–29. Fulltekst i vitenarkiv
Steiger, Céline; Etzelmüller, Bernd; Westermann, Sebastian & Myhra, Kristin Sæterdal (2016). Modelling the permafrost distribution in steep rock walls in Norway. Norsk Geologisk Tidsskrift. ISSN 0029-196X. 96(4), s. 1–13. doi: 10.17850/njg96-4-04. Fulltekst i vitenarkiv
Gisnås, Kjersti; Westermann, Sebastian; Schuler, Thomas; Melvold, Kjetil & Etzelmüller, Bernd (2016). Small-scale variation of snow in a regional permafrost model. The Cryosphere. ISSN 1994-0416. 10(3), s. 1201–1215. doi: 10.5194/tc-10-1201-2016. Fulltekst i vitenarkiv
Westermann, Sebastian; Østby, Torbjørn; Gisnås, Kjersti; Schuler, Thomas & Etzelmuller, Bernd (2015). A ground temperature map of the North Atlantic permafrost region based on remote sensing and reanalysis data. The Cryosphere. ISSN 1994-0416. 9(3), s. 1303–1319. doi: 10.5194/tc-9-1303-2015. Fulltekst i vitenarkiv
Aas, Kjetil Schanke; Berntsen, Terje Koren; Boike, Julia; Etzelmuller, Bernd; Kristjansson, Jon Egill & Maturilli, Marion [Vis alle 9 forfattere av denne artikkelen] (2015). A comparison between simulated and observed surface energy balance at the Svalbard Archipelago. Journal of Applied Meteorology and Climatology. ISSN 1558-8424. 54(5), s. 1102–1119. doi: 10.1175/JAMC-D-14-0080.1. Fulltekst i vitenarkiv
Gisnås, Kjersti; Westermann, Sebastian; Schuler, Thomas; Melvold, Kjetil & Etzelmuller, Bernd (2015). Small-scale variation of snow in a regional permafrost model. The Cryosphere Discussions. 9, s. 6661–6696. doi: 10.5194/tcd-9-6661-2015. Fulltekst i vitenarkiv Vis sammendrag
The strong winds prevalent in high altitude and arctic environments heavily redistribute the snow cover, causing a small-scale pattern of highly variable snow depths. This has profound implications for the ground thermal regime, resulting in highly variable near-surface ground temperatures on the metre scale. Due to asymmetric snow distributions combined with the nonlinear insulating effect of snow, the spatial average ground temperature in a 1 km2 area cannot be determined based on the average snow cover for that area. Land surface or permafrost models employing a coarsely classified average snow depth will therefore not yield a realistic representation of ground temperatures. In this study we employ statistically derived snow distributions within 1 km2 grid cells as input to a regional permafrost model in order to represent sub-grid variability of ground temperatures. This improves the representation of both the average and the total range of ground temperatures. The model reproduces observed sub-grid ground temperature variations of up to 6 °C, and 98 % of borehole observations match the modelled temperature range. The mean modelled temperature of the grid cell reproduces the observations with an accuracy of 1.5 °C or better. The observed sub-grid variations in ground surface temperatures from two field sites are very well reproduced, with estimated fractions of sub-zero mean annual ground surface temperatures within ±10 %. We also find that snow distributions within areas of 1 km2 in Norwegian mountain environments are closer to a gamma than to a lognormal theoretical distribution. The modelled permafrost distribution seems to be more sensitive to the choice of distribution function than to the fine-tuning of the coefficient of variation. When incorporating the small-scale variation of snow, the modelled total permafrost area of mainland Norway is nearly twice as large compared to the area obtained with grid-cell average snow depths without a sub-grid approach.
Jarsve, Erlend Morisbak; Krøgli, Svein Olav; Etzelmuller, Bernd & Gabrielsen, Roy (2014). Automatic identification of topographic surfaces related to the sub-Cambrian peneplain (SCP) in southern Norway - Surface generation algorithms and implications. Geomorphology. ISSN 0169-555X. 211, s. 89–99. doi: 10.1016/j.geomorph.2013.12.032. Fulltekst i vitenarkiv
Hipp, Tobias Florian; Etzelmuller, Bernd & Westermann, Sebastian (2014). Permafrost in Alpine Rock Faces from Jotunheimen and Hurrungane, Southern Norway. Permafrost and Periglacial Processes. ISSN 1045-6740. 25(1), s. 1–13. doi: 10.1002/ppp.1799. Fulltekst i vitenarkiv
Hjort, Jan; Ujanen, Joonas; Parviainen, Miia; Tolgensbakk, Jon & Etzelmuller, Bernd (2014). Transferability of geomorphological distribution models: Evaluation using solifluction features in subarctic and Arctic regions. Geomorphology. ISSN 0169-555X. 204, s. 165–176. doi: 10.1016/j.geomorph.2013.08.002. Fulltekst i vitenarkiv
Gisnås, Kjersti; Westermann, Sebastian; Schuler, Thomas; Litherland, Tobias; Isaksen, Ketil & Boike, Julia [Vis alle 7 forfattere av denne artikkelen] (2014). A statistical approach to represent small-scale variability of permafrost temperatures due to snow cover. The Cryosphere Discussions. 8, s. 509–536. doi: 10.5194/tcd-8-509-2014. Fulltekst i vitenarkiv Vis sammendrag
In permafrost environments exposed to strong winds, drifting snow can create a small-scale pattern of strongly variable snow heights, which has profound implications for the thermal regime of the ground. Arrays of 26 to more than 100 temperature loggers were installed to record the distribution of ground surface temperatures within three study areas across a climatic gradient from continuous to sporadic permafrost in Norway. A variability of the mean annual ground surface temperature of up to 6°C was documented within areas of 0.5 km2. The observed variation can, to a large degree, be explained by variation in snow height. Permafrost models, employing averages of snow height for grid cells of, e.g., 1 km2, are not capable of representing such sub-grid variability. We propose a statistical representation of the sub-grid variability of ground surface temperatures and demonstrate that a simple equilibrium permafrost model can reproduce the temperature distribution within a grid cell based on the distribution of snow heights.
Gisnås, Kjersti; Westermann, Sebastian; Schuler, Thomas; Litherland, Tobias; Isaksen, Ketil & Boike, Julia [Vis alle 7 forfattere av denne artikkelen] (2014). A statistical approach to represent small-scale variability of permafrost temperatures due to snow cover. The Cryosphere. ISSN 1994-0416. 8, s. 2063–2074. doi: 10.5194/tc-8-2063-2014. Fulltekst i vitenarkiv

Se alle arbeider i NVA

Aspaas, Andreas Grøvan; Lacroix, Pascal; Langet, Nadege; Sena, Clara; Kristensen, Lene & Etzelmüller, Bernd [Vis alle 7 forfattere av denne artikkelen] (2023). What causes creep bursts in the Åknes landslide, Norway. Fulltekst i vitenarkiv
Åkesson, Henning; Kjellin, Simen; Hirsti, Linn Katrine; Etzelmüller, Bernd & Lilleøren, Karianne Staalesen (2023). Utstilling: Arven etter Esmark – Fra oppdagelsen av istiden til dens betydning for dagens forskning. Fulltekst i vitenarkiv
Etzelmüller, Bernd; Lilleøren, Karianne Staalesen; Conrad, Clinton Phillips; Åkesson, Henning & Lund, Martin (2023). GeoOnsdag Spesial "Arven etter Esmark" - Sjå opptak frå foredraget. [Internet]. https://www.mn.uio.no/geo/om/organisasjon/geohyd/aktuelt/geo. Fulltekst i vitenarkiv
Snook, Paula; Hermanns, Reginald Leonhard Manfred; Czekirda, Justyna; Sæterdal, Kristin Myhra; Gosse, John C. & Etzelmüller, Bernd (2023). Permafrost controls long-term displacement activity of large unstable rock slopes in subarctic Norway. Fulltekst i vitenarkiv
Åkesson, Henning; Etzelmüller, Bernd; Lund, Erik Martin; Conrad, Clinton Phillips & Lilleøren, Karianne Staalesen (2023). Arven etter Esmark - GeoOnsdag Spesial. Fulltekst i vitenarkiv Vis sammendrag
Arven etter Esmark, Bernd Etzelmüller/Karianne Lilleøren Imagining Esmark’s Lost Scandinavian Ice, Clint Conrad Gårsdagens is - fremtidens fasit, Henning Åkesson Wind of change, Martin Lund
Filhol, Simon; Vasile, Mirela; Sîrbu, Flavius; Onaca, Alexandru; Etzelmüller, Bernd & Westermann, Sebastian (2023). Climate Downscaling in the Southern Carpathians for Climate Analysis and Permafrost Conditions Change (1950-2020). Fulltekst i vitenarkiv
Rouyet, Line; Lilleøren, Karianne Staalesen; Etzelmüller, Bernd; Kääb, Andreas Max; Christiansen, Hanne H. & Humlum, Ole [Vis alle 9 forfattere av denne artikkelen] (2022). SAR satellite remote sensing for mapping and monitoring Norwegian rock glaciers. Fulltekst i vitenarkiv
Aspaas, Andreas Grøvan; Renard, Francois; Lacroix, Pascal; Kristensen, Lene & Etzelmüller, Bernd (2022). What causes transient deformations in the Åknes landslide, Norway? Fulltekst i vitenarkiv
Hilger, Paula; Hermanns, Reginald & Etzelmüller, Bernd (2022). Fjellskredaktivitet i Norge siden den siste istida. Naturen. ISSN 0028-0887. 146(2-3), s. 94–106. doi: 10.18261/naturen.146.2-3.4. Fulltekst i vitenarkiv
Hilger, Paula; Hermanns, Reginald; Czekirda, Justyna; Sæterdal, Kristin Myhra; Gosse, John C. & Etzelmüller, Bernd (2020). Is permafrost a first order control on rock-slope deformation in Norway? Fulltekst i vitenarkiv
Aspaas, Andreas Grøvan; Krautblatter, Michael; Renard, Francois & Etzelmüller, Bernd (2019). Effects of glimmer rich rocks on the failure criterion of ice-filled permafrost rock joints. Fulltekst i vitenarkiv
Etzelmüller, Bernd; Patton, Henry; Schomacker, Anders; Hubbard, Alun Lloyd; Czekirda, Justyna & Westermann, Sebastian (2019). Permafrost dynamics in Iceland between 18 ka BP and today – model results and geomorphological implications. Fulltekst i vitenarkiv Vis sammendrag
Periglacial processes and the dynamics of permafrost is a decisive factor for slope stability locally, and for understanding landscape development over longer time scales. Iceland has a highly dynamic landscape because of young bedrock and associated high geomorphological process rates, leading to large material production and frequent gravitational processes in the present periglacial realm. At present, permafrost in Iceland is widespread in mountain settings over c. 800 m a.s.l. and sporadically in palsa mires in the central Highlands. However, during the late Pleistocene and Holocene, the periglacial environment in Iceland must have varied strongly in time and space, with subsequent imprint in the landscape. To evaluate the dynamics of permafrost in Iceland since the onset of the last deglaciation, we used the forcing and output of a 3D, time-integrated ice sheet model to run a transient permafrost model (CryoGRID 2) between the onset of the last deglaciation (c. 18 ka BP) until today. The permafrost model was forced by either modeled sub-glacial temperatures if ice-covered, or air temperatures if the area was deglaciated. The results give insights into the possible age of permafrost in Iceland, distinguish areas with wide-spread paleo-permafrost and let us determine the persistence of permafrost in the different areas. The presentation discusses these results in the light of periglacial processes, landforms and landscape development
Hilger, Paula; Hermanns, Reginald; Gosse, John C. & Etzelmüller, Bernd (2019). Dating large landslides - opportunities and challenges using terrestrial cosmogenic nuclides. Fulltekst i vitenarkiv
Hilger, Paula; Hermanns, Reginald; Magnin, Florence; Myhra, Kristin Sæterdal; Etzelmüller, Bernd & Gosse, John C. (2018). Destabilisation and deformation patterns of rock-slope instabilities in northern and western Norway. Fulltekst i vitenarkiv
Hilger, Paula; Hermanns, Reginald; Gosse, John C.; Myhra, Kristin Sæterdal; Magnin, Florence & Etzelmüller, Bernd (2018). Initial failure timing of gradually moving rockslides in northern and western Norway. Fulltekst i vitenarkiv
Hilger, Paula; Hermanns, Reginald; Etzelmüller, Bernd; Myhra, Kristin Sæterdal; Magnin, Florence & Gosse, John C. (2018). Do deformation patterns and initial failure timing of rock-slope instabilities in Norway relate to permafrost dynamics? Fulltekst i vitenarkiv
Hilger, Paula; Hermanns, Reginald; Myhra, Kristin Sæterdal; Gosse, John C.; Ivy-Ochs, Susan & Etzelmüller, Bernd (2017). Rock-slope failure activity and geological crises in western Norway. Fulltekst i vitenarkiv
Hilger, Paula; Myhra, Kristin Sæterdal; Hermanns, Reginald; Magnin, Florence; Etzelmüller, Bernd & Gosse, John C. (2017). Post-glacial timing of rock-slope destabilisation. Fulltekst i vitenarkiv
Hilger, Paula; Hermanns, Reginald; Myhra, Kristin Sæterdal; Gosse, John C. & Etzelmüller, Bernd (2017). Temporal distribution of rock-slope failure activity in western and northern Norway. Fulltekst i vitenarkiv
Myhra, Kristin Sæterdal; Etzelmuller, Bernd & Westermann, Sebastian (2016). The Influence of Steep Rock Walls on the Thermal Regime of Talus Slopes. Fulltekst i vitenarkiv
Girod, Luc Maurice Ramuntcho; Nuth, Christopher; Kääb, Andreas; Etzelmüller, Bernd & Kohler, Jack (2016). Terrain changes from images acquired on opportunistic flights by SFM photogrammetry. Fulltekst i vitenarkiv
Westermann, Sebastian; Langer, Moritz; Østby, Torbjørn Ims; Peter, Maria; Boike, Julia & Gisnås, Kjersti [Vis alle 12 forfattere av denne artikkelen] (2016). Mapping the thermal state of permafrost through modeling and remote sensing. Fulltekst i vitenarkiv
Hilger, Paula; Hermanns, Reginald; Gosse, John C. & Etzelmüller, Bernd (2016). Evaluation of rock-slope failures and rockslides in steep permafrost slopes using 10Be- and 36Cl-dating. Fulltekst i vitenarkiv
Hilger, Paula; Hermanns, Reginald; Etzelmüller, Bernd & Magnin, Florence (2016). Climate factors as triggering mechanism for rock-slope failures and rockslides in Norway. Fulltekst i vitenarkiv
Hilger, Paula; Hermanns, Reginald; Etzelmüller, Bernd; Westermann, Sebastian; Krautblatter, Michael & Gosse, John C. [Vis alle 8 forfattere av denne artikkelen] (2016). Evaluation of rock-slope failures in steep permafrost slopes in Norway - first insights in the geological history of the Mannen unstable rock slope in Møre og Romsdal. Fulltekst i vitenarkiv
Myhra, Kristin Sæterdal; Etzelmuller, Bernd & Westermann, Sebastian (2014). The Sensitivity of Rock Wall Temperatures Along a Latitudinal Transect in Norway. Fulltekst i vitenarkiv
Myhra, Kristin Sæterdal; Etzelmuller, Bernd & Westermann, Sebastian (2014). Sensitivity of Rock Slope Stability in Relation to Thermal Regime - a Study From Norway. Fulltekst i vitenarkiv
Westermann, Sebastian; Langer, Moritz; Peter, Maria; Boike, Julia & Etzelmuller, Bernd (2014). Large-scale monitoring of ground thermal conditions in permafrost areas using satellite-derived LST. Fulltekst i vitenarkiv
Peter, Maria; Langer, Moritz; Boike, Julia; Westermann, Sebastian; Schwamborn, Georg & Etzelmuller, Bernd (2014). Modeling the regional differences in permafrost temperatures of the Lena River Delta in northern Siberia based on remote sensing products. Fulltekst i vitenarkiv
Peter, Maria; Langer, Moritz; Boike, Julia; Westermann, Sebastian & Etzelmuller, Bernd (2014). Transient permafrost modeling of the Lena River Delta, Siberia. Fulltekst i vitenarkiv
Aas, Kjetil Schanke; Berntsen, Terje Koren; Boike, Julia; Etzelmuller, Bernd; Gisnås, Kjersti & Westermann, Sebastian (2014). Simulating the surface energy balance on Svalbard with the Weather Research and Forecasting model. Fulltekst i vitenarkiv
Westermann, Sebastian; Langer, Moritz; Peter, Maria; Boike, Julia; Gisnås, Kjersti & Aas, Kjetil Schanke [Vis alle 8 forfattere av denne artikkelen] (2014). Permafrost models and permafrost landscapes – is there a connection? Fulltekst i vitenarkiv
Westermann, Sebastian; Langer, Moritz; Peter, Maria; Boike, Julia; Schuler, Thomas & Etzelmuller, Bernd (2014). Large-scale monitoring of ground thermal conditions through data fusion of remote sensing products. Fulltekst i vitenarkiv
Westermann, Sebastian; Boike, Julia; Etzelmuller, Bernd; Gisnås, Kjersti; Langer, Moritz & Peter, Maria [Vis alle 8 forfattere av denne artikkelen] (2014). Ground temperature mapping from space. Fulltekst i vitenarkiv
Gisnås, Kjersti; Westermann, Sebastian; Schuler, Thomas & Etzelmuller, Bernd (2014). Towards Inclusion of Sub-grid Variability of Snow in Distributed Permafrost Models. Fulltekst i vitenarkiv
Gisnås, Kjersti; Westermann, Sebastian; Etzelmuller, Bernd; Schuler, Thomas; Isaksen, Ketil & Litherland, Tobias [Vis alle 7 forfattere av denne artikkelen] (2014). A probabilistic approach to represent small-scale variability of permafrost temperatures due to snow cover. Fulltekst i vitenarkiv
Gisnås, Kjersti; Etzelmuller, Bernd; Christiansen, Hanne H; Elberling, Bo; Engström, Jonas & Hjort, Jan [Vis alle 10 forfattere av denne artikkelen] (2014). A First Nordic Permafrost Map for Norway, Sweden and Finland. Fulltekst i vitenarkiv
Østby, Torbjørn; Westermann, Sebastian; Gisnås, Kjersti; Etzelmuller, Bernd; Schuler, Thomas & Aas, Kjetil Schanke (2014). Towards a spatial model of ground thermal regime for theSvalbard archipelago. Fulltekst i vitenarkiv
Berthling, Ivar Thoralf & Etzelmuller, Bernd (2014). Glacier/permafrost interaction, alpine landscape development and paleic surfaces. Fulltekst i vitenarkiv Vis sammendrag
Glacier/permafrost interaction, alpine landscape development and paleic surfaces Berthling, Ivar1; Etzelmüller, Bernd 1Department of Geography, Norwegian University of Science and Technology, Trondheim, Norway; ivar.berthling@svt.ntnu.no 2 Department of Geosciences, University of Oslo, Oslo, Norway; bernde@geo.uio.no The high-altitude low relief surfaces of southern Norway are traditionally explained by ancient peneplanation and more recent uplift (e.g. Lidmar Bergström et al., 2000), and survival during Pleistocene glaciations under cold-based ice (Fjellanger and Sørbel, 2007). This account is defied by a model where a glacial buzzsaw effect as well as periglacial and fluvial processes have shaped these surfaces (Nielsen et al., 2009). In some areas, they coexist with alpine landscape and blockfields. We show that field relationships between these elements challenge both models. A glacial buzzsaw origin implies that blockfields postdate erosion; however blockfield distribution is at odds with climate and weathering regimes. A preglacial blockfield origin and subsequent preservation beneath cold based ice is the common interpretation (e.g. Strømsøe and Paasche, 2011). Conversely, if cold-based ice sheets protected pre-glacial surfaces and sediments, why not the glacial sediments related to cirque erosion in the same areas? Permafrost/glacier interactions may explain this paradox. Ground ice will respond to the stresses of a growing glacier above it by deformation, which may cause large-scale sediment deformation and entrainment. This is conceptualized as cryo-conditioned landscape development (Berthling & Etzelmüller 2011). Berthling, I. and Etzelmuller, B., 2011. The concept of cryo-conditioning in landscape evolution. Quaternary Research 75, 378-384. DOI 10.1016/j.yqres.2010.12.011 Fjellanger, J. and Sørbel, L., 2007. Origin of the palaeic landforms and glacial impact on the Varanger Peninsula, northern Norway: Norwegian Journal of Geology 87, p. 223-238. Lidmar Bergström, K. et al., 2000. Landforms and uplift history of southern Norway: Global and Planetary Change 24, p. 211-231. Nielsen, S. B., et al., 2009. The evolution of western Scandinavian topography: A review of Neogene uplift versus the ICE (isostasy-climate-erosion) hypothesis: Journal of Geodynamics 47, p. 72-95. Strømsøe, J. R., and Paasche, O., 2011, Weathering patterns in high-latitude regolith: Journal of Geophysical Research-Earth Surface, 116.
Lilleøren, Karianne Staalesen; Gärtner-Roer, Isabelle & Etzelmuller, Bernd (2013). Permafrost landforms in the Tröllaskagi peninsula, northern Iceland – implications for the deglaciation pattern. Fulltekst i vitenarkiv
Lilleøren, Karianne Staalesen; Etzelmuller, Bernd; Gisnås, Kjersti; Humlum, Ole & Schuler, Thomas (2013). Relative age and Holocene distribution of permafrost in Norway. Fulltekst i vitenarkiv
Lunde, Albert; Dannevig, Halvor; Etzelmüller, Bernd; Isaksen, Ketil; Løseth, Kristin & Njå, Ove (2026). Klimarisiko i Jotunheimen 2023 – 2026. Rapport frå prosjektet «Klimarisiko i Jotunheimen». Nasjonalt kompetansesenter for fjellredning. ISSN 9788293906117. Fulltekst i vitenarkiv Vis sammendrag
Fjellturismen i Jotunheimen er særleg utsett for konsekvensane av eit varmare klima, gjennom raske landskapsendringar og fleire akutte geofarehendingar. Samstundes endrar sjølve fjellturismen seg, med meir trafikk, nye typar turistar og fleire med svak fjellkompetanse. Dette gir høgare eksponering for krevjande ferdselsforhold, fleire uønskte hendingar og meir komplekse oppdrag for fjellredningstenesta. Det utfordrar heile fjellturismesystemet – frå næringa og forvaltninga til redningsberedskapen. Prosjektet «Klimarisiko i Jotunheimen» undersøker korleis dette systemet kan forhalda seg til fysisk klimarisiko. Arbeidspakke 1 dokumenterer at permafrost og brear er i rask endring. Høgoppløyselege permafrostkart for Juvflye, støtta av boreholsdata, viser kor tining kan svekkje skråningar langs mykje brukte ruter. Etter ekstremvêret «Hans» er det kartlagt skredhendingar, og det er gjennomført avanserte modelleringar av eit dødeleg steinsprang under Besseggen. Andre observasjonar peikar på risiko for isskred frå hengande brear og stein- og flaumskred frå ustabile iskjernemorener, særleg ved ein iskjernemorene ovanfor Spiterstulen (Spiterhømorena). Ei analyse av 22 steinsprang- og steinskredulykker (2005–2020) viser at langvarig varme er den viktigaste utløysande faktoren, og at risikoen over 2000 moh er tett knytt til tinande permafrost. Arbeidspakke 2, basert på intervju med hyttevertar, guidar, aktivitetsbedrifter og naturforvaltarar, skildrar ein fjellheim der kjende ruter vert utrygge eller ufarbare. Normalvegen til Falketind via Koldedalen vert frårådd, og fleire klassiske bre- og fjellskiruter er blitt for risikable på grunn av bresmelting og ustabile morenar. Samstundes ser aktørane ein tydeleg auke i mindre erfarne turistar, både norske og utanlandske, som ofte undervurderer risiko og jagar spektakulære motiv til sosiale medium. Framtidsscenario for redningstenesta byggjer på denne kunnskapen. Ein ventar fleire alvorlege steinsprangulykker, nokre med potensial for masseskade, større steinskred som kan råke stigar, vatn og infrastruktur, mogelege isskred i bratt breterreng og fleire sørpe- og jordskred ved raske skifte i temperatur og nedbør. Eit meir krevjande terreng vil òg kunne gje fleire fallulykker og hendingar der folk står fast. Ein systemteoretisk studie av sikkerheitsstyring (AP 4) viser at det i dag finst ein struktur for vern av natur, men ikkje for aktiv ivaretaking av tryggleik for fjellturistar. Det er ikkje avklart kven som har ansvar og myndigheit til å styre sikkerheit i fjellturismen. Forfattarane tilrår at ein byggjer vidare på eksisterande uformelle praksisar, som Besseggenpatruljen, og etablerer ei formell organisering av fjellturismesystemet. Eit lokalt klimafareforum vert føreslått som arena for deling av kunnskap, samordning av ansvar og løypande tilpassing til klimaskapte endringar i Jotunheimen.
Peter, Maria; Nixon, Francis Chantel; Etzelmüller, Bernd & Fredin, Ola (2024). Constraining frost weathering potential, formation history and subsurface processes of blockfields in Norway and Svalbard. Norges teknisk-naturvitenskapelige universitet. ISSN 9788232683734. Fulltekst i vitenarkiv Vis sammendrag
Norsk sammendrag Blokkmark dekker platå-fjelltopper med svakt relieff og slake skråninger i periglasiale områder i for eksempel Skandinavia, Canada og Russland. De har en spesiell og enestående stratigrafi med store blokker og stein med luft-fylte porer som dekker et lag med finkornet sediment og mindre blokker. Blokkmarker er en gåtefull landform - deres dannelseshistorie og utvikling, samt implikasjonene av deres utbredelse for omfanget av tidligere innlandsiser, er fortsatt svært omdiskutert i det geovitenskapelige miljøet. I denne avhandlingen nærmer jeg meg disse spørsmålene ved å analysere det såkalte «frostforvitringspotensialet» som et mål på motstand mot erosjon og dermed alder av denne landform, ved hjelp av en numerisk frostsprengningsmodell basert på temperaturmålinger som er anvendt på tre ulike feltlokaliteter: Platåberget på Svalbard med svært kaldt og tørt klima og permafrostforhold, Tron, et fjell ved Alvdal med kontinentalt klima og varm til forsvinnende permafrost i Sørøst-Norge og Gamlemsveten-toppen på Vestlandet i et maritimt klima uten permafrost. Avhandlingen analyserer også dannelseshistorien og bevegelsene i undergrunnen til de ulike komponentene i blokkmarkens stratigrafi (blokker og finkornede sedimenter) og bakketemperaturrelaterte prosesser som frostheving og frostmiksing ved hjelp av kosmogene nuklid- og geokjemiske analyser samt satellittbaserte fjernmålinger. Resultatene viser at blokkmarksplatåer er stabile overflater med svært lav frostforvitring og dermed ekstremt lav erosjon, hvis de utsettes for et kaldt og tørt klima og permafrostforhold som på Platåberget på Svalbard. Når de utsettes for vått og varmt klima som på Gamlemsveten på Vestlandet, blir frostforvitringspotensialet 10 til 100 ganger høyere. Blokkmark kan være en utbredelses-indikator for kaldbaserte breer og isdekker, men resultatene viser at de også kan ha eksistert under kalde og isfrie forhold med minimal erosjon for lange perioder. Resultatene også tyder på at dannelsestidspunktet og utgangsmateriale kan være forskjellig for hver blokkmark, avhengig av tidligere breerosjon, posisjon under isdekkene og desglasiasjonstidspunkt, samt klimaforholdene under de isfrie periodene i kvartær og holocen.
Hilger, Paula; Hermanns, Reginald; Etzelmüller, Bernd & Gosse, John C. (2019). Rock-slope failures in Norway - temporal development and climatic conditioning. Universitetet i Oslo. Fulltekst i vitenarkiv Vis sammendrag
In previously glaciated mountain regions rock-slope failure processes contribute significantly to landscape development and may pose a direct or indirect threat to the population and infrastructure in inhabited areas. In Norway, most of the population lives along fjords and valleys which are highly exposed to rock-slope failures and potential secondary effects, such as displacement waves and catastrophical flooding due to the breaching of landslide dams. To minimise potential consequences, it is important to understand the preparatory factors destabilising rock slopes before they fail catastrophically. Rock-slope destabilisation in paraglacial landscapes is driven by several internal and external factors, adding to the structural pre-conditions, which are a significant component in crystalline rocks. In this thesis, it is demonstrated that the temporal distribution of catastrophic rock-slope failures (CRSF) in Norway is strongly linked to climatic factors, such as ground temperatures and permafrost, as well as to debuttressing effects after deglaciation. For the age determination of rock-slope failure events, terrestrial cosmogenic nuclide (TCN) dating techniques were applied, which was complemented with Quaternary geological mapping. As a first step, uncertainty of inheritance was evaluated on a recent rock avalanche in Patagonia (Chile), determining the amount of inherited 10Be concentrations in each sample. The analysis showed that CRSF boulders are likely to by affected by inheritance, leading to a general age overestimation. The effect, however, is dependent on the real exposure age and the exposure and burial history of the pre-failure surface. In northern and western Norway, the failure timing of several pre-historic CRSFs at Rombakstøtta in Nordland, at Mannen in Møre og Romsdal and at Ramnanosi in Sogn og Fjordane was determined. During the last decades, 10Be dating has become increasingly popular for dating such rock-slope failure deposits. In this thesis, the approach was taken one step further, targeting near vertical sliding surfaces of actively deforming rock-slope instabilities for surface exposure dating. This allows for an estimation of the timing of initial failure and the subsequent rates of progressive deformation. The deformation history of six rock-slope instabilities was analysed, including Skjeringahaugane, Oppstadhornet and Mannen in western Norway, and Revdalsfjellet 1, Revdalsfjellet 2 and Gamanjunni 3 in northern Norway. To set this into the context of climatic variations, the results of three temperature and precipitation reconstructions are analysed using one of them as forcing for a long-term reconstruction of the permafrost distribution in rock-walls. The temporal distribution of CRSF events in Norway generally peaks shortly after deglaciation. At five sites, rock-slope failure activity was observed to follow the deglaciation closely, including the initial failure timing of at least two rock-slope instabilities. This early destabilisation is most likely related to debuttressing effects, when the glacial ice as counterweight was removed from the oversteepened rock slopes. At the Mannen site, a ‘stability crisis’ was identified, where the same slope failed 3-6 times within a few hundred years. Climatic conditions related to permafrost degradation and increased precipitation may have added to the sudden slope destabilisation 4.9±0.6 ka ago. The initial failure timing of four rock-slope instabilities fall into the period of the Holocene thermal maximum (HTM). At Mannen (62◦N, 1295 m asl.) and Revdalsfjellet 2 (69◦N, 650 m asl.), the modelled ground temperatures were close to or above 0◦C, when deformation started early in the HTM. Late permafrost degradation at Gamanjunni 3 (69◦N, 1200 m asl.), which is located close to Revdalsfjellet, explains a time lag of over two millennia before initial failure. The results of this thesis strengthen the hypothesis that climatic variability and related permafrost fluctuations have an effect on rock-slope stability in Norway. The temporal distribution generally reflects the results of other independent studies, with a peak shortly after deglaciation, high rock-slope failure activity during the HTM and a third period of activity between 5 and 2 ka ago.

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Publisert 10. des. 2013 21:17 - Sist endret 6. mai 2025 14:42

Bernd Etzelmüller

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Bernd Etzelmüller

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