Begjæring om varetekt med restriksjoner : en undersøkelse av praksis

Etter sitt besøk til Norge i 2007 anmodet FNs arbeidsgruppe mot vilkårlig fengsling (UN Working Group on Arbitrary Dentenion - WGAD) om at Norge gjennomførte en oppfølger til undersøkelsen «Restriksjoner ved varetekt» som riksadvokaten foretok i 2002. Etter anmodning fra Justisdepartmentet i mars 2008 påtok Politihøgskolens forskningsavdeling seg dette oppdraget. Undersøkelsen er gjennomført av politiinspektør Jostein Bakke under forskningsmessig ledelse av professor Tor-Geir Myhrer. Politidistriktene ble bedt om å sende inn informasjon om materiale i forbindelse med alle begjæringer om varetekt med restriksjonsbruk i perioden 1. oktober 2008 til 31. mars 2009. I rapporten redegjøres det i del 2 for gjennomføringen av undersøkelsen og for en del karakteristika ved fengslingsbegjæringene og i del 3 redegjøres det mer detaljert for hvordan disse begjæringer forholder seg til de særskilte krav som stilles til restriksjonsbegjæringer. Undersøkelsen viser at restriksjonsbruken generelt er adskillig mindre omfattende nå enn i 2002, både i innhold og i omfang. Dessuten er periodene det begjæres for fremdeles korte. Riksadvokatens direktiv om særskilt begrunnelse for restriksjonskravet følges i liten grad opp. Opplysninger fremkommet under undersøkelsen har også gitt grunnlag for noen refleksjoner omkring hvor effektivt restriksjoner gjennomføres i fengslene

Reconstruction of former glacier equilibrium-line altitudes based on proglacial sites: an evaluation of approaches and selection of sites

Various approaches are used to record variations in glacier activity and equilibrium-line altitudes (ELAs) based on proglacial sites (lacustrine and terrestrial). These approaches are based on a conceptual model of glacier-meltwater induced sedimentation in which the minerogenic (nonorganic) component of the sediments is related to the occurrence of a glacier in the catchment. The principal coupling to former glacier activity and ELAs is common for these approaches. However, different methods and techniques may complement each other, and both possibilities and limitations are demonstrated. Site selection for reconstructing variations in glacier activity/ELAs is evaluated and critical factors are discussed. Rerouting of glacier meltwater streams across local watersheds in combination with proglacial sites gives a distinct on/off signal for former glacier activity/ELAs. Together with representative lateral moraines of known age, local watersheds are important for calibrating reconstructed glacier activity/ELAs based on a chain of proglacial lakes. Based on the ‘modern analogue principle’, various proxies can record whenever glaciers existed in a catchment. In a chain of proglacial lakes with different sensitivity to record variations in glacier activity/ELAs, these proxies can be calibrated against independent records. For one-site approaches, however, variations in glacier activity/ELAs depend on the interpretation and sensitivity of the proxies used

Mapping sediment–landform assemblages to constrain lacustrine sedimentation in a glacier-fed lake catchment in northwest Spitsbergen

Changes in the deposition of fine-grained rock-flour in glacier-fed lakes reflect glacier variability. This meltwater-driven signal is, however, often overprinted by other processes. To constrain the signature of lacustrine sedimentation, we mapped the catchment of glacier-fed Lake Hajeren in northwest Spitsbergen, identifying sediment sources and linking them to surface processes. To this end, we employed a combined approach of aerial image interpretation and field mapping. Our map comprises sediment–landform assemblages commonly found in pro-, peri- and paraglacial landsystems on Spitsbergen, including weathered moraines outboard Little Ice Age limits. Based on the presented map, we argue that mass-wasting does not directly impact lake sedimentation. Also, due to the scarcity of fines in historical glacial deposits, we suggest that modified glacigenic sediments only briefly affect a recorded glacier signal, following retreat. These findings highlight the value of geomorphological maps as tools to constrain catchment processes, improving the interpretation of lake sediment records.publishedVersio

Long‑term demise of sub‑Antarctic glaciers modulated by the Southern Hemisphere Westerlies

The accelerated melting of ice on the Antarctic Peninsula and islands in the sub-Antarctic suggests that the cryosphere is edging towards an irreversible tipping point. How unusual is this trend of ice loss within the frame of natural variability, and to what extent can it be explained by underlying climate dynamics? Here, we present new high-resolution reconstructions of long-term changes in the extents of three glaciers on the island of South Georgia (54°S, 36°W), combining detailed analyses of glacial-derived sediments deposited in distal glacier-fed lakes and cosmogenic exposure dating of moraines. We document that the glaciers of South Georgia have gradually retracted since the Antarctic cold reversal (ACR, 14.5–12.8 ka), culminating in the disappearance of at least one of the reconstructed glaciers. The glacier retreat pattern observed in South Georgia suggests a persistent link to summer insolation at 55°S, which intensified during the period from the ACR to approximately 2 ka. It also reveals multi-decadal to centennial climate shifts superimposed on this long-term trend that have resulted in at least nine glacier readvances during the last 10.5 ka. Accompanying meridional changes in the Southern Hemisphere westerlies and their interconnection with local topography may explain these glacier readvances.publishedVersio

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

Early Holocene Temperature Oscillations Exceed Amplitude of Observed and Projected Warming in Svalbard Lakes

Arctic climate is uniquely sensitive to ongoing warming. The feedbacks that drive this amplified response remain insufficiently quantified and misrepresented in model scenarios of future warming. Comparison with paleotemperature reconstructions from past warm intervals can help close this gap. The Early Holocene (11.7–8.2 ka BP) is an important target because Arctic temperatures were warmer than today. This study presents centennially resolved summer temperature reconstructions from three Svalbard lakes. We show that Early Holocene temperatures fluctuated between the coldest and warmest extremes of the past 12 ka, exceeding the range of instrumental observations and future projections. Peak warmth occurred ~10 ka BP, with temperatures 7 °C warmer than today due to high radiative forcing and intensified inflow of warm Atlantic waters. Between 9.5 and 8 ka BP, temperatures dropped in response to freshwater fluxes from melting ice. Facing similar mechanisms, our findings may provide insight into the near‐future response of Arctic climate.publishedVersio

Disentangling source of moisture driving glacier dynamics and identification of 8.2 ka event: evidence from pore water isotopes, Western Himalaya

Two atmospheric circulation patterns, the Indian Summer Monsoon (ISM) and mid-latitude Westerlies control precipitation and thus glacier variability in the Himalaya. However, the role of the ISM and westerlies in controlling climate and thus past glacier variability in the Himalaya is poorly understood because of the paucity of the ice core records. In this article, we present a new Holocene paleorecord disentangling the presence of the ISM and mid-latitude westerlies and their effect on glacier fluctuations during the Holocene. Our new record is based on high-resolution multi-proxy analyses (δ18Oporewater, deuterium-excess, grain size analysis, permeability, and environmental magnetism) of lake sediments retrieved from Chandratal Lake, Western Himalaya. Our study provides new evidence that improves the current understanding of the forcing factor behind glacier advances and retreat in the Western Himalaya and identifies the 8.2 ka cold event using the aforementioned proxies. The results indicate that the ISM dominated precipitation ~ 21% of the time, whereas the mid-latitude westerlies dominated precipitation ~ 79% of the time during the last 11 ka cal BP. This is the first study that portrays the moisture sources by using the above proxies from the Himalayan region as an alternative of ice core records.publishedVersio

Mapping of the Subglacial Topography of Folgefonna Ice Cap in Western Norway—Consequences for Ice Retreat Patterns and Hydrological Changes

Folgefonna consists of three ice caps which are rapidly retreating in response to warmer temperatures. The melting of Folgefonna has implications for meltwater drainage and hydropower production, as well as the potential for geohazards and impacts to tourism, the communities and infrastructures surrounding the glacier. To support future adaptation strategies, we need to know the subglacial topography of the ice caps to identify water divides and possible areas for geohazards. Therefore, we mapped the subglacial topography at Sørfonna, the largest of the Folgefonna ice caps, using an ice-penetrating radar (2.5 MHz antennas; 1,000 × 500 m grid). The results show a highly irregular subglacial landscape, with deep valleys and high mountain peaks. The maximum ice thickness is 570 m and the mean ice thickness is 190 m. We examined the retreat pattern of Sørfonna using the subglacial topography map in combination with a simple ice flow model and simulated the ice retreat 150 years into the future. We used two climate scenarios (one with a 1.5°C warming and a 3% increase in precipitation, and a second with a 3.5°C warming together with 15% increase in precipitation) and focused on how the glacial retreat will cause hydrological changes in the catchments surrounding the glacier. The main drainage pattern shifts during glacial retreat, with a larger proportion of southward drainage compared to the present day. The ice flow modelling also reveals that the southern part of Sørfonna is more durable during climate change whereas the thinner part of the ice cap, in the north, melts faster. We suggest that increased winter precipitation in a future warmer climate makes the southern part of Sørfonna more resilient than many other glaciers in southern Norway. The subglacial topography map and the retreat pattern also reveal areas that may accumulate water and could potentially generate a future glacial outburst flood. Sediments from distal glacier-fed lakes around Sørfonna have been used to constrain the thresholds identified on the subglacial topography map. Combining sedimentological evidence from distal glacier-fed lakes with the new subglacial topography map confirms that the retreat of specific outlet glaciers, such as Bondhusbreen, Buerbreen, and Møsevassbreen, will have a large impact on meltwater routing, as they are situated behind bedrock thresholds in the upper part of the glacier’s catchment area.publishedVersio

Reconstructing Holocene Glacier and Climate Fluctuations From Lake Sediments in Vårfluesjøen, Northern Spitsbergen

A process-based understanding of lacustrine deposited sediments in Arctic lakes is essential to set the present warming and hydroclimatic shift into perspective. From such a perspective, we can enhance our understanding of the natural climate variability in the Arctic. Here, we present work from the northern coast of Spitsbergen in which we unravel the sediment sequence from a distal glacier-fed lake, Vårfluesjøen. Utilizing recent methodological and technological developments, we base our interpretation on new tools that better visualize and characterize the sediments cores. High-resolution X-ray Computed Tomography (X-ray CT) is used to visualize the lake sediments and quantify the sand-sized particles found in the 210Pb- and radiocarbon-dated sediments, together with a multi-proxy approach including measurement of their physical, geochemical, and magnetic properties. Our findings suggest that Vårfluesjøen (6 m a.s.l.) was isolated from Woodfjorden at c. 10200 ± 260 cal. yr. BP. During the early Holocene, the glaciers in the Vårfluesjøen catchment were considerably smaller than today or had even melted completely. At the start of the Neoglacial period (c. 3500 cal. yr. BP), we find increased glacier activity in the catchment of the lake. X-ray CT reveals an increased frequency of sand-sized particles from 3500 to 1750 cal. yr. BP, suggesting greater wintertime aeolian activity. Starting c. 2250 years ago, we find a progressive increase in snowmelt runoff in the Vårfluesjøen catchment, with peak runoff from 1000 to 750 cal. yr. BP. This coincides with a drop in sand-sized particles, hence less favorable environment for aeolian activity, and implying wetter conditions. During the last 2000 years, there is evidence for high glacier activity between c. 2000 to 900 and 750–350 cal. yr. BP. In between these time spans, less activity is recorded in the periods 1900–1800, 1000–800, and 350–150 cal. yr. BP

Glare, a GIS tool to reconstruct the 3D surface of palaeoglaciers

Acknowledgements This research has been supported by the Leverhulme Trust International Network Grant IN-2012-140. Processing and collecting of ground penetrating data in Forgefonna was part of Elend Førre's master's project that was completed in 2009 at the Department of Geography, University of Bergen. We also acknowledge Dr Andreas Bauder for providing the subglacial topography data for Griessgletscher and Simone Tarquini for granting access to the high resolution TIN of Italy, a cut of which is provided to the reader to practice the tools (see Appendix). Referees Dr. Iestyn Barr, Dr. Jeremy Ely and Dr. Marc Oliva are thanked for their constructive comments and tool testing, which significantly improved the final output.Peer reviewedPostprin