Late-Pleistocene and Holocene mountain permafrost geomorphology of Norway and Iceland.

The combined effect of glacial and periglacial processes on landscape evolution has recently been termed the ‘cryoconditioning’ of landscapes, and largely affect the Fennoscandian landmass. Further, the distribution of permafrost both temporally and spatially during and after the last glaciation affect the overall geomorphic expression. In this thesis the product of landscape evolution is investigated in terms of the geomorphic imprint of glacial and periglacial processes, where the interactions between glaciers and permafrost have been particularly focussed upon. Whereas the glacial variations over the Holocene are relatively well known the same is not the case for the permafrost distribution. As a starting point, inventories of landforms indicating present and former permafrost were compiled for mainland Norway and northern Iceland. The main findings from the inventories were (1) a low abundance of landforms in Norway and a high abundance of landforms in Iceland probably due to differences of bedrock competence, (2) an apparent change in processes leading to rock glacier formation occurred in mid-Holocene from a dry, periglacial regime characterizing early-Holocene to a humid, glacially-dominated regime in mid- to late-Holocene, and (3) warm and maritime permafrost regions are dominated by permafrost landforms formed by the influence of glaciers. For Iceland the occurrence of relict rock glaciers at sea level imply a possible earlier deglaciation or alternatively a less extensive Last Glacial Maximum (LGM) than commonly accepted. As a second step, modelling of permafrost variations over the Holocene was performed in depth and spatially, using a 1D heat flow model and a 2D equilibrium model (CryoGRID1.0). During the warm Holocene Thermal Maximum (HTM) the permafrost survived at high altitudes in southern Norway, whereas during the ‘Little Ice Age’ (LIA) the permafrost reached its greatest extent both in depth and spatially. From these results altitudinal zones of permafrost ages was suggested, analogous to age patterns for Arctic permafrost. From the Neoglaciation until present, the potential of glacier-permafrost interactions has been large. Thirdly, a case study of the currently very small glacier, or glacieret, Omnsbreen which formed and largely disappeared during the LIA was studied in terms of glacial geomorphic evidence for permafrost interaction. Modelled permafrost distribution for the LIA suggest permafrost presence in the Omnsbreen surroundings during its formation and decay, and the landform assemblage present at Omnsbreen is considered representative for mountain glaciers terminating into permafrost. Permafrost is currently only present sporadically in the Omnsbreen surroundings, and the glacier and permafrost underwent a parallel disintegration. The current geomorphic expression of Norway and northern Iceland is significantly affected by long-term interactions between the glacial, subglacial and ground thermal regimes

Spatial predictions of pingo, ice-wedge polygon and rock glacier occurrence across the circumpolar permafrost region for recent and future periods

This dataset contains spatial predictions of the potential environmental spaces for pingos, ice-wedge polygons and rock glaciers across the Northern Hemisphere permafrost areas. The potential environmental spaces, i.e. conditions where climate, topography and soil properties are suitable for landform presence, were predicted with statistical ensemble modelling employing geospatial data on environmental conditions at 30 arc-second resolution (~1 km). In addition to the baseline period (1950-2000), the predictions are provided for 2041-2060 and 2061-2080 using climate-forcing scenarios (Representative Concentration Pathways 4.5 and 8.5). The resulting dataset consists of five spatial predictions for each landform in GeoTIFF format. The data provide new information on 1) the fine-scale spatial distribution of permafrost landforms in the Northern Hemisphere, 2) the potential future alterations in the environmental suitability for permafrost landforms due to climate change, and 3) the circumpolar distribution of various ground ice types, and can 4) facilitate efforts to inventory permafrost landforms in incompletely mapped areas

Icelandic permafrost dynamics since the Last Glacial Maximum – model results and geomorphological implications

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

Kinematic and morphological inventories of slope movement in Northern Norway

We developed simplified ground velocity products based on Interferometric Synthetic Aperture Radar (InSAR) to inventory slope movements in a ca 7500 km2 region in Northern Norway. We used a multiple temporal baseline InSAR stacking procedure based on 2015–2019 ascending and descending snow-free Sentinel-1 images to take advantage of a large set of interferograms and exploit different detection capabilities. Moving areas were identified, 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). We updated the pre-existing inventories of rock glaciers and rockslides in the region using InSAR kinematics. Landform delineations and divisions were refined, and newly detected landforms (54 rock glaciers and 20 rockslides) incorporated into the databases. The updated inventories consist of 414 rock glacier units within 340 single- or multi-unit(s) systems and 117 rockslides. Based on InSAR, a kinematic attribute assigned to each inventoried landform documents the magnitude order of the movement

Regional Morpho-Kinematic Inventory of Slope Movements in Northern Norway

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 km2. 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

Incorporating kinematic attributes into rock glacier inventories exploiting InSAR data: preliminary results in eleven regions worldwide

Abstract. The dependence of rock glaciers on permafrost and thus their sensitivity to climatic parameters makes the spatial distribution of these landforms very important for hydrological and climate changes reasons. Inventories of rock glaciers have been produced for decades worldwide, often without an assessment of their kinematics; the availability of remote sensing data makes the inclusion of kinematic information potentially feasible, but the absence of a common methodology makes it challenging to create homogeneous inventories. In this context, the IPA Action Group on rock glacier inventories and kinematics (2018–2023), with the support of the ESA Permafrost_CCI project, is promoting the definition of standard guidelines for the inclusion of kinematic information within inventories. Here, we test the feasibility of applying common rules proposed by the Action Group in eleven regions worldwide. Satellite interferometry is used to characterize identifiable areas with slope movements related to rock glaciers; subsequently, these areas are used to assign kinematic information to rock glaciers in existing or newly compiled inventories. More than 5,000 slope movements and more than 3,600 rock glaciers are classified according to their kinematics. The analyzes conducted on the method and on the preliminary results show small irregularities related to the detection capacity of interferometry and to lack of rock glaciers without detectable movements in some regions investigated. This is the first internationally coordinated effort of rock glacier inventories. We demonstrate the feasibility of applying common rules to implement kinematic attributes within inventories at a global scale, despite the various regions and intensive manual effort