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  • 1.
    Charpentier Ljungqvist, Fredrik
    Stockholm University, Faculty of Humanities, Department of History. Stockholm University, Faculty of Humanities, Centre for Medieval Studies.
    A new reconstruction of temperature variability in the extra-tropical Northern Hemisphere during the last two millennia2010In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 92A, no 3, p. 339-351Article in journal (Refereed)
    Abstract [en]

    A new temperature reconstruction with decadal resolution, covering the last two millennia, is presented for the extra-tropical Northern Hemisphere (90–30°N), utilizing many palaeotemperature proxy records never previously included in any large-scale temperature reconstruction. The amplitude of the reconstructed temperature variability on centennial time-scales exceeds 0.6°C. This reconstruction is the first to show a distinct Roman Warm Period c. AD 1–300, reaching up to the 1961–1990 mean temperature level, followed by the Dark Age Cold Period c. AD 300–800. The Medieval Warm Period is seen c. AD 800–1300 and the Little Ice Age is clearly visible c. AD 1300–1900, followed by a rapid temperature increase in the twentieth century. The highest average temperatures in the reconstruction are encountered in the mid to late tenth century and the lowest in the late seventeenth century. Decadal mean temperatures seem to have reached or exceeded the 1961–1990 mean temperature level during substantial parts of the Roman Warm Period and the Medieval Warm Period. The temperature of the last two decades, however, is possibly higher than during any previous time in the past two millennia, although this is only seen in the instrumental temperature data and not in the multi-proxy reconstruction itself. Our temperature reconstruction agrees well with the reconstructions by Moberg et al. (2005) and Mann et al. (2008) with regard to the amplitude of the variability as well as the timing of warm and cold periods, except for the period c. AD 300–800, despite significant differences in both data coverage and methodology.

  • 2.
    Hall, Adrian
    et al.
    University of St Andrews, Scotland, UK.
    Ebert, Karin
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Pre-glacial landform inheritance in a glaciated shield landscape2013In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 95, no 1, p. 33-49Article in journal (Refereed)
    Abstract [en]

    We seek to quantify glacial erosion in a low relief shield landscape in northern Sweden. We use GIS analyses of digital elevation models and field mapping of glacial erosion indicators to explore the geomorphology of three granite areas with the same sets of landforms and of similar relative relief, but with different degrees of glacial streamlining. Area 1, the Parkajoki district, shows no streamlining and so is a type area for negligible glacial erosion. Parkajoki retains many delicate pre-glacial features, including tors and saprolites with exposure histories of over 1 Myr. Area 2 shows the onset of significant glacial erosion, with the development of glacially streamlined bedrock hills. Area 3 shows extensive glacial streamlining and the development of hill forms such as large crag and tails and roches moutonnées.

    Preservation of old landforms is almost complete in Area 1, due to repeated covers of cold-based, non-erosive ice. In Area 2, streamlined hills appear but sheet joint patterns indicate that the lateral erosion of granite domes needed to form flanking cliffs and to give a streamlined appearance is only of the order of a few tens of metres. The inheritance of large-scale, pre-glacial landforms, notably structurally controlled bedrock hills and low relief palaeosurfaces, remains evident even in Area 3, the zone of maximum glacial erosion. Glacial erosion here has been concentrated in valleys, leading to the dissection and loss of area of palaeosurfaces. Semi-quantitative estimates of glacial erosion on inselbergs and palaeosurfaces and in valleys provide mean totals for glacial erosion of 8 ± 8 m in Area 1 and 27 ± 11 m in Area 3. These estimates support previous views that glacial erosion depths and rates on shields can be low and that pre-glacial landforms can survive long periods of glaciation, including episodes of wet-based flow.

  • 3. Hellqvist, Magnus
    et al.
    Hättestrand, Martina
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Norström, Elin
    Stockholm University, Faculty of Science, Department of Geological Sciences. Swedish Geological Survey, Sweden.
    Almgren, Elisabeth
    Johansson, Jenny N.
    Traustadóttir, Ragnheiður
    Environment and climate change during the late Holocene in Hjaltadalur, Skagafjörður, northern Iceland2020In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 102, no 1, p. 68-82Article in journal (Refereed)
    Abstract [en]

    We present an overview of the local environmental development of the valley of Hjaltadalur, situated in Skagafjorour, northern Iceland. The aim of this study is to increase the knowledge about the valley region before and during human settlement in the ninth century. Four mires were investigated after which the Viovik peat bog was selected as the main site for evaluating changes in climate and landscape. The master core from Viovik (V-325) was dated and studied further through sediment analysis, loss-on-ignition (LOI), and pollen analysis. According to the age-depth model, based on three radiocarbon dates and analysis of two tephra layers, the 325 cm long Viovik core comprises approximately 5500 years. In the pollen percentage record, there is a decrease in birch (Betula) and an increase in grass (Poaceae) in the central part of the core, between Hekla 3 horizon at c. 2800 BP and the next dated level at c. 2000 BP. This change corresponds well with previously outlined environmental fluctuations, showing a transition from warm and dry climate to cool and humid climate at this time. Human activity is mainly reflected by a distinct peak in Lactucae pollen in the uppermost part of the core. This change in vegetation corresponds with earlier studies, showing that the vegetation changed dramatically after the colonization of Iceland in the ninth century (during Landnam period, 870-930 AD). The present study shows that a decline in birch started well before human settlement, although the subsequent Viking Age and later settlements continued the deforestation trend.

  • 4.
    Holmlund, Erik S.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography. University Centre in Svalbard, Norway.
    Holmlund, Per
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Constraining 135 years of mass balance with historic structure-from-motion photogrammetry on Storglaciaren, Sweden2019In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 101, no 3, p. 195-210Article in journal (Refereed)
    Abstract [en]

    Geodetic volume estimates of Storglaciaren in Sweden suggest a 28% loss in total ice mass between 1910 and 2015. Terrestrial photographs from 1910 of Tarfala valley, where Storglaciaren is situated, allow for an accurate reconstruction of the glacier's surface using Structure-from-Motion photogrammetry, which we used for past volume and mass estimations. The glacier's yearly mass balance gradient and net mass balance was also estimated back to 1880 using weather data from Karesuando, 170 km north-east of Storglaciaren, through neural network regression. These combined reconstructions provide a continuous mass change series between the end of the Little Ice Age and 1946, when field data become available. The resultant reconstruction suggests a state close to equilibrium between 1880 and the 1910s, followed by drastic melt until the 1970s, constituting 76% of the 1910-2015 ice loss. More favourable conditions subsequently stabilized the mass balance until the late 1990s, after which Storglaciaren started losing mass again. The 1910 reconstruction allows for a more accurate mass change series than previous estimates, and the methodology can be used on other glaciers where early photographic material exists.

  • 5.
    Holmlund, Per
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Holmlund, Erik S.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Recent climate-induced shape changes of the ice summit of Kebnekaise, Northern Sweden2019In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 101, no 1, p. 68-78Article in journal (Refereed)
    Abstract [en]

    The ice summit of Kebnekaise is slowly melting down as a consequence of climate change. In August 2018 this peak, which for a long time has been the highest in Sweden, reached an elevation a few decimetres lower than the nearby situated northern summit in solid rock. It has become a symbol of the fragility of nature. Its areal extent and shape have varied over time and its height has ranged within approximately 15 m during the twentieth century. Since the turn of the century, the ice summit has decreased to a new lower and smaller level but the changes are not uniform, and they show a complex relation between weather parameters and the shape and size of the summit. Layers in the ice include climate information of past changes. But what changes are we able to determine by examining gradually exposed dust layers, or by coring the summit. In this paper, we are analysing the late changes in shape and volume of the ice summit and we place the results into a paleo climate discussion. We have used photogrammetric methods to map the geometry of the summit at different dates when data has been available. We have also done a multiple regression to analyse the relation between the summit elevation and the net mass balance of the nearby located Storglaciaren. The correlation is good from mid 1970s until now but weak prior to that. It is herein explained by former uncertainties of the geographic position of the summit.

  • 6.
    Johnsen, Timothy F.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Alexanderson, Helena
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Fabel, Derek
    Freeman, Stewart PHT
    New 10Be cosmogenic ages from the Vimmerby moraine confirm the timing of Scandinavian Ice Sheet deglaciation in southern Sweden2009In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 91A, no 2, p. 113-120Article in journal (Refereed)
    Abstract [en]

    The overall pattern of deglaciation of the southern part of the Scandinavian Ice Sheet has been considered established, although details of the chronology and ice sheet dynamics are less well known. Even less is known for the south Swedish Upland because the area was deglaciated mostly by stagnation. Within this area lies the conspicuous Vimmerby moraine, for which we have used the terrestrial cosmogenic nuclide (10Be) exposure dating technique to derive the exposure age of six glacially transported boulders. The six 10Be cosmogenic ages are internally consistent, ranging from 14.9 ± 1.5 to 12.4 ± 1.3 ka with a mean of 13.6 ±0.9 ka. Adjusting for the effects of surface erosion, snow burial and glacio-isostatic rebound causes the mean age to increase only by c. 6% to c. 14.4± 0.9 ka. The 10Be derived age for the Vimmerby moraine is in agreement with previous estimates forthe timing of deglaciation based on radiocarbon dating and varve chronology. This result shows promise for further terrestrial cosmogenic nuclide exposure studies in southern Sweden.

    Download full text (pdf)
    Johnsen et al. 2009 - New 10Be cosmogenic ages from the Vimmerby moraine
  • 7.
    Klingbjer, Per
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Recurring jökulhlaups in Sälka, northern Sweden2004In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 86, no 2, p. 169-179Article in journal (Refereed)
    Abstract [en]

    An ice-dammed lake at the margin of the glacier Slkaglaciren, in the Kebnekaise Mountains in northern Sweden, drained suddenly in July 2003 producing a flood with a measured peak discharge of 9.5±0.25 m3s-1. The total lake volume of 4.55×105 million3 drained within two days. The hydrograph of this event is characteristic of a jökulhlaup controlled by a single basal ice tunnel that enlarges due to melting. The jökulhlaup had an exponential rise to a peak discharge, and following the peak, a very steep fall in discharge as the water supply to the drainage system ceased. A similar jökulhlaup was observed in August 1990 with an estimated release of 8.05×105 m3 water. Jökulhlaups at Slkaglaciren are recurring events and have been indirectly observed since the 1950s.

  • 8.
    Lidmar-Bergström, Karna
    Stockholm University, Faculty of Science, Department of Physical Geography.
    The major landforms of the bedrock of Sweden - with a view on the relationships between physical geography and geology2020In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 102, no 1, p. 1-11Article in journal (Refereed)
    Abstract [en]

    This paper presents the result of my research in Sweden and my view on the relationships between physical geography (here mainly geomorphology) and geology. I developed a method for identification and mapping denudation surfaces formed in the Precambrian basement. South Sweden turned out to be a key area with cover rocks of different age directly on the basement. The relief differences in the basement are connected to the different sedimentary covers with a flat and inclined sub-Cambrian surface and a hilly and inclined sub-Cretaceous surface. The crosscutting horizontal South Smaland Plain was classified as a peneplain, as it is a surface graded to a distinct base level. Besides the basement forms and remnant cover rocks, saprolite remnants are important for the identification of denudation surfaces. The mapping method was ultimately labeled Stratigraphic Landscape Analysis (SLA) and used for conclusion on tectonics (uplift/subsidence and faulting). I obtained, as a physical geographer, a broad holistic knowledge on the relief differentiation of the basement rocks of Fennoscandia and on Swedish regional geology. This gave me the tool to identify denudation surfaces with the aid of the new digital elevation data and new geological knowledge of the surrounding continental shelf. The Swedish knowledge on the relationships between relief in the basement and its cover rocks is unique in the world. Maybe the relationship between denudation surfaces, cover rocks and tectonics ought to be a part of geology. Results of measurements, by different new techniques, are nowadays often analyzed based on hypotheses/theories. Observations of field conditions have become difficult to perform both within geology and geomorphology and seem to be considered as unscientific. Further, regional analysis, typical for geography, does not exist anymore.

  • 9.
    Lundqvist, Jan
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    DEPOSITS FROM LANDSLIDES AND AVALANCHES TRIGGERED BY SEISMIC ACTIVITY IN SWEDISH LAPLAND2010In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 92A, no 3, p. 411-420Article in journal (Refereed)
    Abstract [en]

    In the mountain area of Swedish Lapland, landforms with semicircular or horse-shoe ridges encircling hummocky ground occur They are interpreted as landslide or avalanche deposits directly upon, from or adjacent to down-wasting ice Since they are restricted to the vicinity of fault scarps in the Parvie fault system the releasing factor is suggested to be displacement of bedrock blocks or related seismic activity.

  • 10.
    Lyon, Steve W.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography. Stockholm University, Faculty of Science, Stockholm University Baltic Sea Centre, Baltic Nest Institute.
    Jantze, Elin J.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Dahlke, Helen E.
    Jaramillo, Fernando
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Winterdahl, Mattias
    Stockholm University, Faculty of Science, Department of Physical Geography.
    WHY MONITOR CARBON IN HIGH-ALPINE STREAMS?2016In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 98, no 3, p. 237-245Article in journal (Refereed)
    Abstract [en]

    In this short communication, we report on dissolved organic and inorganic carbon concentrations from a summer stream monitoring campaign at the main hydrological catchment of the Tarfala Research Station in northern Sweden. Further, we place these unique high-alpine observations in the context of a relevant subset of Sweden's national monitoring programme. Our analysis shows that while the monitoring programme (at least for total organic carbon) may have relatively good representativeness across a range of forest coverages, alpine/tundra environments are potentially underrepresented. As for dissolved inorganic carbon, there is currently no national monitoring in Sweden. Since the selection of stream water monitoring locations and monitored constituents at the national scale can be motivated by any number of goals (or limitations), monitoring at the Tarfala Research Station along with other research catchment sites across Fennoscandia becomes increasingly important and can offer potential complementary data necessary for improving process understanding. Research catchment sites (typically not included in national monitoring programmes) can help cover small-scale landscape features and thus complement national monitoring thereby improving the ability to capture hot spots and hot moments of biogeochemical export. This provides a valuable baseline of current conditions in high-alpine environments against which to gauge future changes in response to potential climatic and land cover shifts.

  • 11.
    Margold, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Treml, Vaclav
    Petr, Libor
    Nyplova, Petra
    Snowpatch hollows and pronival ramparts in the krkonoše mountains, Czech Republic: distribution, morphology and chronology of formation2011In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 93A, no 2, p. 137-150Article in journal (Refereed)
    Abstract [en]

    Two types of landforms attributed to the geomorphological effects of long-lasting snow accumulations, snowpatch hollows and pronival ramparts, were studied in the Krkonose Mountains, Czech Republic. Factors influencing the distribution and morphology of snowpatch hollows were examined using statistical analysis of field-measured and DEM-modelled snowpatch hollow characteristics. Snowpatch hollows were classified into two groups. The first group comprises hollows developed mainly in erosional incisions from streams on low-relief summit planation surfaces. The hollows of this group are relatively small and display signs of recent activity, with development during the Holocene. The second group consists of larger snowpatch hollows developed in debris-covered slopes of the highest summits, closely related to the cryoplanation terraces occurring in the area. The hollows of this group are suggested to have developed in the periglacial environment of the glacial periods. The age and degree of activity of pronival ramparts, occurring only at two sites in the study area, were determined using several methods (Schmidt hammer, lichenometry, pollen analysis, and radiocarbon dating). The appearance of these pronival ramparts differs between the two sites as a result of the different geological setting. Both the ramparts in the Harrachova jama cirque, consisting of coarse granite debris, and the rampart in the Upska jama cirque, developed of mica-schist clasts, have been active during the late Holocene and are considered to be active even today.

  • 12. Sugden, David E.
    et al.
    Hall, Adrian M.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Phillips, William M.
    Stewart, Margaret A.
    Plucking enhanced beneath ice sheet margins: evidence from the Grampian Mountains, Scotland2019In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 101, no 1, p. 34-44Article in journal (Refereed)
    Abstract [en]

    Concentrations of boulders are a common feature of landscapes modified by former mid-latitude ice sheets. In many cases, the origin of the boulders can be traced in the up-ice direction to a cliff only tens to hundreds of metres distant. The implication is that a pulse of plucking and short boulder transport occurred beneath thin ice at the end of the last glacial cycle. Here we use a case study in granite bedrock in the Dee Valley, Scotland, to constrain theory and explore the factors involved in such a late phase of plucking. Plucking is influenced by ice velocity, hydrology, effective ice pressure, the extent of subglacial cavities and bedrock characteristics. The balance between these factors favours block removal beneath thin ice near a glacier margin. At Ripe Hill in the Dee Valley, a mean exposure age of 14.2 ka on blocks supports the view that the boulder train formed at the end of ice sheet glaciation. The late pulse of plucking was further enhanced by ice flowing obliquely across vertical joints and by fluctuations in sub-marginal meltwater conditions. An implication of the study is that there is the potential for a wave of ice-marginal plucking to sweep across a landscape as an ice sheet retreats.

  • 13.
    Sundqvist, Hanna S.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Baker, A
    Holmgren, Karin
    Luminescence in fast growing stalagmites from Uppsala, Sweden2005In: Geografiska Annaler. Series A, Physical Geography, ISSN 0435-3676, E-ISSN 1468-0459, Vol. 87, no 4, p. 539-548Article in journal (Refereed)
    Abstract [en]

    Two fast-growing stalagmites from a cellar vault in Uppsala, southeast Sweden, are ana-lysed for their luminescent properties. The results

    indicate that variations in luminescence intensity in the stalagmites are annual. Due to problems in find-ing a suitable absolute dating method this assump-tion cannot yet be firmly tested; however, results from radiocarbon dating of one of the stalagmites do not contradict the proposal that the laminae are annual. If so, the speleothems have been growing for 10-15 years with a growth rate of 3-8 mm per year, which is a similar rate to other fast-growing speleothems in Great Britain that have formed from the reaction of lime mortar and carbon dioxide. It is likely that the assumed annual laminae of the lumi-nescence record represent a flush of organic mate-rial.

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