Holocene glacier variability and Neoglacial hydroclimate at Ålfotbreen, western Norway

Glaciers and small ice caps respond rapidly to climate perturbations (mainly winter precipitation, and summer temperature), and the mass-balance of glaciers located in western Norway is governed mainly by winter precipitation (Pw). Records of past Pw can offer important insight into long-term changes in atmospheric circulation, but few proxies are able to accurately capture winter climate variations in Scandinavia. Reconstructions of equilibrium-line-altitude (ELA) variations from glaciers that are sensitive to changes in Pw therefore provide a unique opportunity to quantify past winter climate in this region. Here we present a new, Holocene glacier activity reconstruction for the maritime ice cap Ålfotbreen in western Norway, based on investigations of distal glacier-fed lake sediments and modern mass balance measurements (1963–2010). Several lake sediment cores have been subject to a suite of laboratory analyses, including measurements of physical parameters such as dry bulk density (DBD) and loss-on-ignition (LOI), geochemistry (XRF), surface magnetic susceptibility (MS), and grain size distribution, to identify glacial sedimentation in the lake. Both radiocarbon (AMS 14C) and 210Pb dating were applied to establish age-depth relationships in the sediment cores. A novel approach was used to calibrate the sedimentary record against a simple ELA model, which allowed reconstruction of continuous ELA changes for Ålfotbreen during the Neoglacial (when Ålfotbreen was present, i.e. the last ∼1400 years). Furthermore, the resulting ELA variations were combined with an independent summer temperature record to calculate Neoglacial Pw using the ‘Liestøl equation’. The resulting Pw record is of higher resolution than previous reconstructions from glaciers in Norway and shows the potential of glacier records to provide high-resolution data reflecting past variations in hydroclimate. Complete deglaciation of the Ålfotbreen occurred ∼9700 cal yr BP, and the ice cap was subsequently absent or very small until a short-lived glacier event is seen in the lake sediments ∼8200 cal yr BP. The ice cap was most likely completely melted until a new glacier event occurred around ∼5300 cal yr BP, coeval with the onset of the Neoglacial at several other glaciers in southwestern Norway. Ålfotbreen was thereafter absent (or very small) until the onset of the Neoglacial period ∼1400 cal yr BP. The ‘Little Ice Age’ (LIA) ∼650–50 cal yr BP was the largest glacier advance of Ålfotbreen since deglaciation, with a maximum extent at ∼400–200 cal yr BP, when the ELA was lowered approximately 200 m relative to today. The late onset of the Neoglacial at Ålfotbreen is suggested to be a result of its low altitude relative to the regional ELA. A synthesis of Neoglacial ELA fluctuations along the coast of Norway indicates a time-transgressive trend in the maximum extent of the LIA, which apparently seems to have occurred progressively later as we move northwards. We suggest that this trend is likely due to regional winter precipitation differences along the coast of Norway.publishedVersio

Modeling Protective Forests for Gravitational Natural Hazards and How It Relates to Risk-Based Decision Support Tools

Simulation tools and their integrated models are widely used to estimate potential starting, transit and runout zones of gravitational natural hazards such as rockfall, snow avalanches and landslides (i.e., gravitational mass flows [GMFs]). Forests growing in areas susceptible to GMFs can influence their release and propagation probabilities (i.e., frequency and magnitude of an event) as well as their intensity. If and how well depends on the GMF type, the topography of the terrain and the forests’ structure. In this chapter, we introduce basic concepts of computer models and state-of-the-art methods for modeling forest interactions with rockfall, snow avalanches and landslides. Furthermore, an example of a protective forest routine embedded in the runout angle-based GMF simulation tool Flow-Py will be presented together with its parameterization for forest-GMF interactions. We applied Flow-Py and two custom extensions to model where forests protect people and assets against GMFs (the protective function) and how forests reduce their frequency, magnitude and/or intensity (the protective effect). The goal of this chapter is to describe protective forest models, so that practitioners and decision makers can better utilize them and their results as decision support tools for risk-based protective forest and ecosystem-based integrated risk management of natural hazards

Experience in using a Learning Management System (Göteborgs Universitets Lärplattform - GUL) for integrated course design

Integrated course design needs a developed structure based on pedagogic principles in order to keep track of learning outcomes, assignments, learning resources and lectures. A Learning Management System (LMS) is tested for the learning outcome experience of 24 students that took a Quaternary Geology course at University of Gothenburg. A student survey with a questionnaire and a personal feedback session were analyzed in order to receive objective criteria to evaluate the usefulness of the LMS for the distribution of learning resources. As a key finding students will need to be exposed in hands-on exercises to the LMS in order to take full advantage of the offered online information and resources

Remote Identification, Characterization and Monitoring of Erosional Processes

Remote sensing techniques and geophysical techniques have enabled the collection of vital information on geotechnical, hydrogeological, and environmental processes. These techniques may offer improvements over traditional data collection techniques or may provide data not readily available using conventional instrumentation. An assessment of various remote sensing and geophysical techniques, used to collect parameters of interest to the Multi-scale Erosion Risk under Climate Change (MERRIC) project, is provided in this technical note. This technical note is a deliverable of the MERRIC work package 4 on "Warning, monitoring, and non-physical mitigation measures". A list of 11 key parameters for coastal erosion studies was established and matched with appropriate remote sensing techniques (including microwave, laser, and optical techniques) and on- and off-shore (or near-shore) geophysical techniques. The characteristics of each of the techniques is listed and background material is provided. The maturity of these techniques is described through examples in the literature and the potential for application within the scope of MERRIC is discussed. Many of the more mature techniques described in this technical note (for example, terrestrial lidar scanning [TLS], or electrical resistivity tomography [ERT]) are already routinely used in NGI projects, and thus, their relevance for MERRIC is well understood. Other emerging techniques (for example, terrestrial radar interferometry, or multi-beam echo sounding [MBES]) are less commonly applied, but may nonetheless prove to be indispensable for future projects related to MERRIC. It is, therefore, recommended that the potential of emergent remote sensing and geophysical techniques will be further investigated using the resources available at NGI

Terrestrial processes affecting unlithified coastal erosion disparities in central fjords of Svalbard

Terrestrial influences of coastal cliff morphology and hydrological impact on coastal erosion in unlithified cliff sediments in the inner fjords of Svalbard are assessed. Differential global positioning system measurements have been taken annually over the past two to four years at four field sites in central Svalbard. Measurements were combined with aerial imagery using ArcGIS and the Digital Shoreline Analysis System to calculate rates of erosion in varying geomorphological cliff types. A total of 750 m of coast was divided into two main cliff types: ice-poor and ice-rich tundra cliffs and further divided based on their sediment depositional character and processes currently acting upon sediments. The results show that the most consistent erosion rates occur in the ice-poor cliffs (0.34 m/yr), whereas the most irregular and highest rates occur in ice-rich cliffs (0.47 m/yr). Throughout the study, no waves were observed to reach cliff toes, and therefore erosion rates are considered to reflect an effect of terrestrial processes, rather than wave action. Terrestrial hydrological processes are the driving factors for cliff erosion through winter precipitation for ice-poor cliffs and summer precipitation for ice-rich cliffs. Sediment removal from the base of the cliffs appears to be mainly conducted by sea ice and the ice foot during break up as waves did not reach the base of the studied cliffs during the observed period. Keywords:Terrestrial-sourced hazards, coastal erosion, coastal geomorphology, Digital Shoreline Analysis System, Svalbard.publishedVersio

Carbon 14 age dating of wood samples from the Alps

Glacially deformed pieces of wood, organic lake sediments and clasts of reworked peat have been collected in front of Alpine glaciers since AD 1990. The palaeoglaciological interpretation of these organic materials is related to earlier phases of glacier recession surpassing that of today's shrunken glaciers and to tree growth and peat accumulation in the valleys now occupied by the glaciers. Glacial transport of the material is indicated by wood anatomy, incorporated silt, sand and gravel particles, missing bark and deformed treerings. A total of 65 samples have been radiocarbon dated so far, and clusters of dates provide evidence of eight phases of glacier recession: 9910-9550, 9010-7980, 7250-6500, 6170-5950, 5290-3870, 3640-3360, 2740-2620 and 1530-1170 calibrated years BP. Allowing for the timelag between climatic fluctuations, glacier response and vegetation colonization, these recession phases may lag behind climatic changes by 100-200 years

Terrestrial processes affecting unlithified coastal erosion disparities in central fjords of Svalbard

Terrestrial influences of coastal cliff morphology and hydrological impact on coastal erosion in unlithified cliff sediments in the inner fjords of Svalbard are assessed. Differential global positioning system measurements have been taken annually over the past two to four years at four field sites in central Svalbard. Measurements were combined with aerial imagery using ArcGIS and the Digital Shoreline Analysis System to calculate rates of erosion in varying geomorphological cliff types. A total of 750 m of coast was divided into two main cliff types: ice-poor and ice-rich tundra cliffs and further divided based on their sediment depositional character and processes currently acting upon sediments. The results show that the most consistent erosion rates occur in the ice-poor cliffs (0.34 m/yr), whereas the most irregular and highest rates occur in ice-rich cliffs (0.47 m/yr). Throughout the study, no waves were observed to reach cliff toes, and therefore erosion rates are considered to reflect an effect of terrestrial processes, rather than wave action. Terrestrial hydrological processes are the driving factors for cliff erosion through winter precipitation for ice-poor cliffs and summer precipitation for ice-rich cliffs. Sediment removal from the base of the cliffs appears to be mainly conducted by sea ice and the ice foot during break up as waves did not reach the base of the studied cliffs during the observed period

Constraining the chronology of Pleistocene glaciations on Svalbard: Kapp Ekholm re-visited

The Kapp Ekholm site, in central Spitsbergen, shows alternating units of glaciomarine sandy silt and diamicton representing three glacial cycles and is key in reconstructing the Late Pleistocene glacial history of Svalbard. Part of the site is reinvestigated here by focusing on re-dating two units (B and F) interpreted as interglacial/interstadial glaciomarine deposits, in order to constrain the controversial chronology. A combination of Optical Stimulated Luminescence (OSL) on quartz, infrared stimulated luminescence with a 50 °C readout temperature (IRSL50) and post infrared-infrared stimulated luminescence (pIR), both on feldspar, was applied. While Formation B was beyond the dateable range of OSL, IRSL50 and pIR ages lead to the conclusion that this unit represents the Last Interglacial, Marine Isotope Stage (MIS) 5e, and the underlying diamicton the MIS 6 glacial. Formation F yielded ages implying that the formation represents the MIS 5a interstadial and the underlying diamicton is interpreted to represent the MIS 5b stadial. This agrees with conclusions drawn concerning the Pleistocene glaciations elsewhere on Svalbard