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  • 1.
    Aggemyr, Elsa
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Cousins, Sara A. O.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Landscape structure and land use history influence changes in island plant composition after 100 years2012In: Journal of Biogeography, ISSN 0305-0270, E-ISSN 1365-2699, Vol. 39, no 9, p. 1645-1656Article in journal (Refereed)
    Abstract [en]

    Aim We investigated how current and historical land use and landscape structure affect species richness and the processes of extinction, immigration and species turnover. Location The northern part of the Stockholm archipelago, Baltic Sea, Sweden. We resurveyed 27 islands ranging from 0.3 to 33 ha in area. Methods We compared current plant survey data, cadastral maps and aerial photographs with records obtained from a survey in 1908, using databases and a digital elevation model to examine changes in plant community dynamics in space and time. We examined the effects of local and landscape structure and land use changes on plant species dynamics by using stepwise regression in relation to eight local and three landscape variables. The eight local variables were area, relative age, shape, soil heterogeneity, bedrock ratio, number of houses, forest cover change, and grazing 100 years ago. The three landscape variables were distance to mainland, distance to closest island with a farm 100 years ago, and structural connectivity. Hanskis connectivity measure was modified to incorporate both connectivity and fragmentation. Results The investigated islands have undergone drastic changes, with increasing forest cover, habitation, and abandonment of grassland management. Although the total species richness increased by 31% and mean island area by 23%, we found no significant increase in species richness per unit area. Local variables explain past species richness (100 years ago), whereas both local and landscape variables explain current species richness, extinctions, immigrations and species turnover. Grazing that occurred 100 years ago still influences species richness, even though grazing management was abandoned several decades ago. The evidence clearly shows an increase in nitrophilous plant species, particularly among immigrant species. Main conclusions This study highlights the importance of including land use history when interpreting current patterns of species richness. Furthermore, local environment and landscape patterns affect important ecological processes such as immigration, extinction and species turnover, and hence should be included when assessing the impact of habitat fragmentation and land use change. We suggest that our modified structural connectivity measure can be applied to other types of landscapes to investigate the effects of fragmentation and habitat loss.

  • 2.
    Aggemyr, Elsa
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Cousins, Sara A. O.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Plant species richness and composition, changes over a 100 year period in the Swedish archipelago - a landscape study2010In: The Future of Biodiversity: Genes, Species, Ecosystems: 40th Anniversary Conference / [ed] Volkmar Wolters, Janine Groh, Franziska Peter, Rainer Waldhardt, Giessen: Justus Liebig University Giessen , 2010, p. 118-118Conference paper (Refereed)
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    FULLTEXT01
  • 3. Ahlkrona, Josefin
    et al.
    Lötstedt, Per
    Kirchner, Nina
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Zwinger, Thomas
    Dynamically coupling the non-linear Stokes equations with the shallow ice approximation in glaciology: Description and first applications of the ISCAL method2016In: Journal of Computational Physics, ISSN 0021-9991, E-ISSN 1090-2716, Vol. 308, p. 1-19Article in journal (Refereed)
    Abstract [en]

    We propose and implement a new method, called the Ice Sheet Coupled Approximation Levels (ISCAL) method, for simulation of ice sheet flow in large domains during long time-intervals. The method couples the full Stokes (FS) equations with the Shallow Ice Approximation (SIA). The part of the domain where SIA is applied is determined automatically and dynamically based on estimates of the modeling error. For a three dimensional model problem, ISCAL computes the solution substantially faster with a low reduction in accuracy compared to a monolithic FS. Furthermore, ISCAL is shown to be able to detect rapid dynamic changes in the flow. Three different error estimations are applied and compared. Finally, ISCAL is applied to the Greenland Ice Sheet on a quasi-uniform grid, proving ISCAL to be a potential valuable tool for the ice sheet modeling community.

  • 4.
    Alavaisha, Edmond
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Agricultural expansion impacts on wetland ecosystem services from Kilombero Valley, Tanzania2020Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Land use change has major impact on the world’s wetland ecosystems and biodiversity. The motivation behind this change has been to increase agricultural production, often resulting in negative effects on water quality and soil fertility. Tanzania has carried out a large expansion and intensification of agriculture under the Kilimo kwanza (First agriculture) initiative which has triggered the need for better knowledge on land use change effects and associated ecosystem functioning. This thesis considers small-scale irrigation schemes to understand the effects of agriculture expansion and farming practices on nutrients, water quality and ecosystem services (ES) in Kilombero Valley, Tanzania. The study approach is multidisciplinary involving interviews, remote sensing, geographical information system techniques, and in-field soil and water ecological sampling. The major land use change in the valley during the last three decades was transformation from forest, bushland and grassland into cultivated land. The rate of change was faster adjacent to irrigation schemes and most changes occurred downstream irrigation canals, close to the floodplain. Irrigation and fertilization contributed to soil carbon and nitrogen accumulation in crop fields, which both declined in concentration with depth into the soil. However, such management practices and agricultural land expansion had impacts on several ES – especially water quality in streams. Streams surrounded mainly by cultivated land, as well as downstream areas, had lower water quality compared to streams with less settlement, more natural vegetation and upstream areas. Furthermore, when evaluated, macroinvertebrates indices were found to be a good indicator of water quality and a complement to chemical and physical water analysis. Irrigation farming produced more food compared to rainfed farming, and also other ES such as flood regulation, erosion control and several cultural services, depending on the river discharge. The thesis shows the importance to use irrigation/fertilization management to enhance soil fertility and preserve soil structure, but also the need for proper irrigation management to prevent flooding and erosion, conserve natural vegetation, and protect water quality. To enhance nature conservation, preserve biodiversity and secure future supply of ES in the valley, investment in irrigation infrastructures should be done at small-scale to mitigate the large-scale exploitation of Kilombero wetland.

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    Agricultural expansion impacts on wetland ecosystem services from Kilombero Valley, Tanzania
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  • 5.
    Alavaisha, Edmond
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography. University of Dar es Salaam, Tanzania.
    Lindborg, Regina
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Smallholder perceptions on ecosystem services generation in irrigated and rainfed farming- Kilombero, TanzaniaManuscript (preprint) (Other academic)
  • 6.
    Alavaisha, Edmond
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography. University of Dar es Salaam, Tanzania.
    Mbande, Victor
    Stockholm University, Faculty of Social Sciences, Department of Human Geography.
    Börjeson, Lowe
    Stockholm University, Faculty of Social Sciences, Department of Human Geography.
    Lindborg, Regina
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Effects of land use change related to small-scale irrigation schemes in Kilombero wetland, TanzaniaManuscript (preprint) (Other academic)
  • 7.
    Alavimoghaddam, Mohammadreza
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Assessing the ability of HEC-HMS rainfall-runoff model to simulate stream flow across Sweden2017Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    Computer modeling is the powerful tool for simulating nature’s behavior; however, still more efforts are need for reaching perfect simulation with computer models (especially in the hydrological field of study). In this Master’s thesis, the accuracy of the HEC-HMS computer model for long term rainfall-runoff simulation was evaluated across Sweden. Five different catchments from north to south of Sweden were selected and then simulation have done for 34 years of available data. Simulation was conducted using daily, monthly and yearly time scale resolutions. Results from the north to the south of Sweden were completely different. Simulated runoff and observed runoff in northern catchments followed the same pattern over different time scales but in the southern part of Sweden the results had different patterns in space and time. The best results with HEC-HMS were found in the northern catchments with steep main river slopes. In the southern catchments the model could not predict runoff in any realistic manner at any time and space scale. In total the HEC-HMS model cannot simulate the rainfall runoff for long periods of simulation across Sweden. This is especially true in southern parts of the country dominate with low elevation catchments. However, with regards to its ability for event-based simulation HEC-HMS could be a suitable tool to simulate flood event discharges that are needed for road or other hydraulic structures designs. But, this would require significant amounts of calibration and model development.

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  • 8. Alekseeva, I.
    et al.
    Jarsjö, Jerker
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Schrum, C.
    Destouni, Georgia
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Reconstruction of historic changes of the Aral Sea water budget and sea-groundwater interactions by a coupled 3D sea-ice-groundwater model2007In: Geophysical Research Abstracts, Vol. 9, 10629, 2007, 2007Conference paper (Other academic)
    Abstract [en]

    A 3D coupled sea-ice-groundwater model has been developed and applied for an estimation of the water balance and groundwater-seawater interactions in the shrinking Aral Sea. The model developed combines the complete 3D sea-ice hydrodynamics model ECOSMO, including a mass and energy conserving wetting and drying scheme, and a simple groundwater model based on changes in hydraulic gradient in response to the sea surface variability. During the simulation period 1979-1993, the model successfully reproduced the rapid Aral Sea level drop, surface area decrease, coastline position changes and salinization. Model predictions of evaporation and groundwater inflow were also consistent with independent estimations. Model results indicated that within the 15 years period of simulations the net groundwater inflow to the Aral Sea might have increased by 10% or more as a direct effect of the sea level lowering.

    Furthermore, model scenario tests were carried out to examine effects of salinity on sea hydrodynamics and to estimate non-linear feedbacks of the sea thermo- and hydrodynamics, air-sea turbulent fluxes and the sea water balance. It was shown that a neglect of salinity in the sea hydro- and thermo dynamics resulted in considerable differences in the Aral Sea winter thermal conditions, which in turn influenced the air-sea exchange in the following spring and summer. As a result, the zero salinity scenario predicted higher evaporation rates and an considerably accelerated sea level lowering by up to 2 cm/yr, in comparison with the basic model run. An indirect influence of the fresh groundwater inflow in terms of water balance has been identified as less significant, however it was shown that the fresh groundwater input could influence the Aral Sea salinity distribution considerably since 1990’s.

  • 9.
    Alm, Klara
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Inventering av skred genom jämförelse av två generationer LiDAR-genererad höjddata2023Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Landslides are a natural hazard that is expected to increase in the future, due to climate change. In order to keep risk management plans up to date, an efficient inventory method is needed. In previous studies, multi-temporal high-resolution digital elevation models (DEM) produced with LiDAR technology have been used successfully for landslide inventory and monitoring in different parts of the world. The aim of this study has been to discover an inventory method for landslides in Sweden, using two generations of elevation data produced with LiDAR. The analysis was performed in GIS with the creation of a DEM of difference (DoD) and visual comparison as key components. The sites were also verified using Google Earth satellite imagery and aerial photos. The result of the study shows that a functional, efficient method was developed and several potential landslides were found in the three different study areas. The soil characteristics, slope gradient and distance to areas affected by forestry were recorded for all potential landslide sites. Using multi-temporal DEM for landslide inventory is time- and cost efficient, and the results are more accurate compared to traditional inventory techniques. Hopefully the method developed in this study can be used on a larger scale and lead to updated risk management and prevention plans throughout all risk areas for landslides in Sweden. In future studies field work is recommended to verify the potential landslide sites.

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  • 10.
    AL-Rubaye, Safa
    Stockholm University, Faculty of Humanities, Department of Teaching and Learning.
    Frihet eller tvång?: Hur upplevs dagens digitala lärande av lärare och elever i två årskurser i en högstadieskola?2022Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
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    fulltext
  • 11.
    Ampel, Linda
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Kylander, Malin E.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Steinthorsdottir, Margret
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Wohlfarth, Barbara
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Abrupt climate change and early lake development - the Lateglacial diatom flora at Hasseldala Port, southeastern Sweden2015In: Boreas, ISSN 0300-9483, E-ISSN 1502-3885, Vol. 44, no 1, p. 94-102Article in journal (Refereed)
    Abstract [en]

    The fossil diatom record from the Hasseldala Port palaeolake, southeastern Sweden, offers an excellent opportunity to investigate how past climatic shifts influenced catchment conditions and early lake development. The record, dating to between 13900 and 11200 cal. a BP, covers a climatically dynamic period, starting with deglaciation followed by oscillations between warmer and colder climate states. The stratigraphical changes in the fossil diatom assemblages show a trend of less open-water taxa and a successively more complex periphytic community as the lake shallows and the aquatic habitat structure develops. A diatom-based reconstruction of lake water pH indicates a natural acidification trend early in the record from 13900 to 12500 cal. a BP. From 12500 cal. a BP, coincident with the start of climate cooling, to 11300 cal. a BP this trend is disrupted and lake waters become more alkaline. A cooler and drier climate most likely resulted in reduced soil organic matter build-up as well as more frozen ground that impeded hydrological flow and decreased the input of dissolved organic matter and organic acids into the lake system. This study demonstrates the importance of the hydrological system as a link between terrestrial and aquatic ecosystems during early lake ontogeny.

  • 12.
    Andersson, Ingela
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Implementing the European Water Framework Directive at local to regional level -Case Study Northern Baltic Sea River Basin District, Sweden2011Licentiate thesis, comprehensive summary (Other academic)
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    sammanfattning
  • 13.
    Andersson, Ingela
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Petersson, Mona
    Jarsjö, Jerker
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Impact of the European Water Framework Directive on local-level water management: Case study Oxunda Catchment, Sweden2012In: Land use policy, ISSN 0264-8377, E-ISSN 1873-5754, Vol. 29, no 1, p. 73-82Article in journal (Refereed)
    Abstract [en]

    The Water Framework Directive (WFD) of the European Union provides a common framework for waterpolicy that focuses on holistic and integrated water management in river basins. In many member states,implementation of the WFD has shifted the main responsibility for local water issues from the municipallevel to the regional or supra-regional levels. In this study, we investigated how the implementation of theWFD has influenced local-level water management including the interpretation of the new environmentalquality standards. Specifically, we considered Sweden, which has traditionally had relatively stronggovernance at the municipal level. Because a sufficient amount of time has now passed for evaluationof WFD-related effects on operational water handling, we interviewed individuals directly involved inwater planning and land use planning at the municipal level in one sub catchment in the Northern BalticSea River Basin District of Sweden, as well as representatives for superior levels and associations. Despitedivergent views regarding the priority of water issues in physical planning among the local-level plannersinterviewed, they had all participated in successful inter-municipal pre-WFD collaboration projects.Although such collaborations could help increase the understanding and acceptance of WFD-related goalsand costs, as well as facilitate conflict solving, as shown in the Oxunda Catchment, they have not gainedmuch attention in the WFD implementation process. Additionally, physical planners have generally beenreluctant to accept new environmental quality standards resulting from WFD implementation, in partbecause they lack precise definitions, but also because they could challenge the municipal routine ofweighing various objectives against each other. Furthermore, despite WFD-related increases in ambitionlevels, lack of resource improvements at the municipal level were identified as potential problems by local environmental planners.

  • 14.
    Andréen, Sigrid
    Stockholm University, Faculty of Science, Department of Physical Geography.
    The development of landscape structures affecting biodiversity in the Hanveden and Tyresta green wedges2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The green wedges of Stockholm are meant to support a high level of biodiversity as well as cultural and recreational services but evaluating the spatial development of the wedges is difficult because their delineation has changed since they were first used in a regional development plan. This study examines a part of the Hanveden and Tyresta wedges in southern Stockholm, with the goal to use robust ecological theory to evaluate the development of the wedges from 1992 until today with focus on conserving a high level of biodiversity. Using an already existing GIS-based method of identifying connectivity weaknesses in the wedges, more weaknesses were found in 2010 than in 1992 although the total area of the wedges had only declined 3.3%. The shape of the wedges had also changed, with more narrow parts in 2010 than in 1992. To more effectively compare the development of factors in the landscape that are relevant for biodiversity, this study proposes a new method using the common shrew and hazel grouse as surrogate species. The total area loss for the common shrew was 2.96% from 1991 to 2013 and 2.23% for the hazel grouse. Fragmentation increased for both species. A large part of the greenspaces relevant to the surrogate species are covered by the green wedges, meaning that important cultural and recreational values identified by the county council are also present in areas relevant to the surrogate species. Using surrogate species to delineate and monitor the green wedges could enhance the cultural and recreational qualities of the wedges, emphasize the need for connectivity planning, identify ecologically important parts of the greenspaces as well as provide a tool for following up the development of the urban greenspaces of Stockholm. However, formulating goals relevant to biodiversity is important to fully evaluate development and municipal cooperation is needed.

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  • 15.
    Andwinge, Maria
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Reading Pollen Records at Peloponnese, Greece2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The eastern Mediterranean area is a region of high archaeological importance, it is also a region where climate has been a force interacting with humans in shaping the landscape and vegetation history. Variations in pollen content and composition in various climate archives (e.g. lake sediments and peat sections) are widely used to reconstruct vegetation changes and human impact in the Quaternary environments. Pollen sampling has been conducted throughout the Peloponnese peninsula but there is a lack of regional synthesis of these locally based studies. The aims of the thesis are partly to show how pollen data may be used in a regional analysis on Late Pleistocene and Holocene vegetation changes, partly to assemble all published pollen data from Peloponnese peninsula in a database. The question formulations are; i) how may a database with pollen dataserve as a basis for interpretations of regional vegetation changes on Peloponnese?, ii) what are the possibilities of using classification of pollen and distinguish between driving factors behind the historic vegetation changes? The constructed database facilitates further research regarding pollen records at Peloponnese. Pollen recordsmay show important patterns in landscape changes during Late Pleistocene and Holocene but using pollen records at a regional scale need comparisons between coring sites which may be troublesome due to different approaches, different species investigated and varied calculation of pollen sum. In order to distinguish between driving forces and actors affecting the vegetation, pollen data may be used both in detail but also in using groups and classifications of the pollen included.

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  • 16.
    Antikainen, Catarina
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Formation and Retention of Soil Organic Matter (SOM) in the Taygetos Mountains (Greece): Influence of Soil Properties and Wildfire2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Deforestation and soil degradation is a worldwide problem, and especially so in the Greek Taygetos mountains. With wildfires affecting thousands of square kilometers of land, soil quality assessments are important in order to choose the right land management measures in the process of landscape restoration. Soil organic matter (SOM) is a good indicator of soil quality, but its response to wildfires and dependence on other soil properties is not well known in the Taygetos area. This study attempts to investigate the influence of topographic aspect and slope inclination on SOM formation and retention in fire damaged forests. Results are put into context with other soil properties such as pH and water content as well as the influence of wildfires. The study found unexpectedly high amounts of SOM in all sampled slopes, which was attributed to the incorporation of charcoal from burnt litter produced during low intense fires. No correlation was detected between SOM and aspect, and only a weak negative correlation between SOM and slope inclination. However, the study found a strong correlation between SOM amounts and water content, which suggests that water is one of the main limiting factors of SOM in the Taygetos mountains.

  • 17.
    Applegate, Patrick J.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Kirchner, Nina
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Stone, E. J.
    Keller, K.
    Greve, R.
    An assessment of key model parametric uncertainties in projections of Greenland ice sheet behavior2012In: The Cryosphere, ISSN 1994-0416, E-ISSN 1994-0424, Vol. 6, no 3, p. 589-606Article in journal (Refereed)
    Abstract [en]

    Lack of knowledge about the values of ice sheet model input parameters introduces substantial uncertainty into projections of Greenland Ice Sheet contributions to future sea level rise. Computer models of ice sheet behavior provide one of several means of estimating future sea level rise due to mass loss from ice sheets. Such models have many input parameters whose values are not well known. Recent studies have investigated the effects of these parameters on model output, but the range of potential future sea level increases due to model parametric uncertainty has not been characterized. Here, we demonstrate that this range is large, using a 100-member perturbed-physics ensemble with the SICOPOLIS ice sheet model. Each model run is spun up over 125 000 yr using geological forcings and subsequently driven into the future using an asymptotically increasing air temperature anomaly curve. All modeled ice sheets lose mass after 2005 AD. Parameters controlling surface melt dominate the model response to temperature change. After culling the ensemble to include only members that give reasonable ice volumes in 2005 AD, the range of projected sea level rise values in 2100 AD is similar to 40 % or more of the median. Data on past ice sheet behavior can help reduce this uncertainty, but none of our ensemble members produces a reasonable ice volume change during the mid-Holocene, relative to the present. This problem suggests that the model's exponential relation between temperature and precipitation does not hold during the Holocene, or that the central-Greenland temperature forcing curve used to drive the model is not representative of conditions around the ice margin at this time (among other possibilities). Our simulations also lack certain observed physical processes that may tend to enhance the real ice sheet's response. Regardless, this work has implications for other studies that use ice sheet models to project or hindcast the behavior of the Greenland Ice Sheet.

  • 18.
    Aringo, Deborah
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Climate-resilient cities: A comparative study of climate adaptationstrategies in Botkyrka and Ekerö municipalities2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis research investigates and contributes to increased knowledge on municipalities’ approaches to climate adaptation and associated challenges that slow down or hinder climate adaptation approaches in cities. The Stockholm region has experienced climate change and impacts of severe floods, heat waves, storms, sea level rise, forest-fire outbreaks, erosion and landslides. To control the frequency and magnitude of these impacts, local authorities and administrations need to integrate mitigation and adaptation management strategies into physical plans of towns and cities.

    Surveys carried out in 2016 and 2017 consecutively, evaluate municipalities’ efforts in climate adaptation in different counties in Sweden. The survey report in 2017 reveals that not all municipalities are equally implementing climate adaptation in Stockholm county; and yet the impacts of climate change are to affect all municipalities regardless of size and geographical location.

    Therefore, to understand the state of climate change adaptation in the municipalities, the author interviewed municipal planners, engineers, environmental investigators, and climate group in Botkyrka, to collect qualitative data for analysis. Data was also gathered through qualitative document analysis to compare drivers of municipality approaches to climate adaptation in Botkyrka and Ekerö municipality. The study results show that there is a gap between Botkyrka and Ekerö municipalities’ climate adaptation work. However, much as these two municipalities are sustainably eveloping, they face a number of challenges that hamper their ability to integrate climate adaptation measure in urban physical plans in order to reduce urban vulnerabilities, and thus build sustainable and climate-resilient cities.

  • 19.
    Arleskär, Staffan
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Bostadsrätt, gräsmark eller skog?: Hur har exploatering för bostadsbyggande år 2000-2015 påverkat Järvakilens funktion som spridningsväg?2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Urbanization is a key driver of habitat loss, ecosystem degradation and has a great impact on biodiversity. Exploitation of buffer zones surrounding conservation areas and green structures in urban environment can affect biodiversity through reduced total area of habitat, increased edge effects and lost connectivity on a landscape level. The previous regional development plans for the Stockholm region, had the purpose of leaving large green structures undeveloped to secure core areas of great biological value by focusing on a dense city core. However, the latest regional development strategy puts stress on the green wedges by shifting the focal areas of the development into suburban regional city centers, in many cases close to the green wedges. The purpose of this study was to map habitat loss and changes in the total area of the Järva green wedge, west of Stockholm, caused by development of housing areas in previously sparsley exploited buffer zones, during the period 2000 – 2015. The study uses theories of landscape ecology, remote sensing and GIS to map and quantify habitat loss between 2000 and 2015. Two different birds were used as surrogate species, one grassland habitat specialist – Corncrake (Crex crex) and one forest habitat generalist – Eurasian jay (Garrulus glandarius). The two different surrogate species were used to identify how loss of two nature types could influence biodiversity and connectivity for a group of species. Documents and development plans on regional and local scale were also used to map and predict further habitat loss and exploitation of the green wedge until 2030. The result of the study shows that grassland habitat lost nearly twice the area than forest habitat due to development of housing areas during the period 2000 to 2015. A total of 1.3 km² of grassland and 0.7 km² forest habitat were replaced by housing areas during the fifteen years covered in the study, and the Järva green wedge will have lost a total of 3.84 km² buffer zones by the year 2030. The Corncrake and other grassland specialist species is likely to get most affected when grassland suffered the greatest habitat loss in the area. Even though the Eurasian jay has a key ecological function for the Oak forest in the Järva green wedge and relies on forest habitat for successful breeding, the loss of forest habitat will probably not affect the habitat generalist species in the same way. On a regional scale, the study suggests that habitat loss and fragmentation may affect grassland specialist species more than forest generalist species. The overall connectivity in the Järva green wedge is likely to get affected by a shrinking total area caused by narrowing of the green wedge until 2030. The function of the Järva green wedge as a dispersal corridor for biodiversity in the Stockholm region will most certainly get affected by further loss of buffer zones caused by exploitation of land for housing areas.

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  • 20.
    Arra, Venni
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Storm Frequency in the Northern Baltic Sea Region and its Association to the North Atlantic Oscillation2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Storms can be both destructive and valuable at the same time. They expose coastal areas to various risks but can also enhance the supply of wind energy and provide marine ecosystems with oxygen rich water. As the North Atlantic Oscillation (NAO) is known to have a significant impact on the wind climate in Europe, investigating its interconnection to storm frequency and intensity under global warming circumstances in the Northern Baltic Sea region was of interest in this study. Wind speed data series of annual storm counts were obtained from five meteorological stations along with PC-based NAO values over the period 1960-2017. The data series were analysed in Microsoft Excel and modelled using a Poisson regression or negative binomial regression model in SPSS Statistics. The results display an unsystematic spatial pattern both in the association to the NAO as well as in the overall storm frequency. However, storm (≥ 21 m s-1) frequency has generally been decreasing, whereas the proportion of severe storms (≥ 24 m s-1) has slightly been increasing, suggesting a tendency toward stronger but fewer storms. Even though only certain data series display statistically significant findings (p ≤ .05), a majority of the winter storms and severe winter storms display a positive association, indicating that a higher NAOI is related to a greater number of winter storms. The spatial and temporal variability in the obtained results can partially be explained by storm tracks and prevalent wind directions. Nevertheless, inhomogeneities do presumably affect the wind speed observations through internal and external influences and changes related to the meteorological stations. Future research should, therefore, also consider integrating other storm related parameters, such as direct air pressure measurements, wave heights and storm surges, as well as implement different data homogenization methods and techniques.

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  • 21.
    Asokan, Shilpa M.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Destouni, Georgia
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Appendix to Paper V: Climate model performance versus basin-scalehydro-climatic dataManuscript (preprint) (Other academic)
  • 22.
    Asokan, Shilpa M.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Destouni, Georgia
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Irrigation effects on hydro-climatic change: Basin-wise water balance-constrained quantification and cross-regional comparison2014In: Surveys in geophysics, ISSN 0169-3298, E-ISSN 1573-0956, Vol. 35, no 3, p. 879-895Article, review/survey (Refereed)
    Abstract [en]

    Hydro-climatic changes driven by human land and water use, including water use for irrigation, may be difficult to distinguish fromthe effects of global, natural and anthropogenic climate change. This paper quantifies and compares the hydro-climatic change effects ofirrigation using a data-driven, basin-wise quantification approach in two different irrigated world regions: the Aral Sea drainage basinin Central Asia, and the Indian Mahanadi River Basin draining into the Bay of Bengal. Results show that irrigation-driven changesin evapotranspiration and latent heat fluxes and associated temperature changes at the land surface may be greater in regions withsmall relative irrigation impacts on water availability in the landscape (here represented by the MRB) than in regions with severe suchimpacts (here represented by the Aral region). Different perspectives on the continental part of Earth’s hydrological cycle may thus implydifferent importance assessment of various drivers and impacts of hydro-climatic change. Regardless of perspective, however, actualbasin-wise water balance constraints should be accounted to realistically understand and accurately quantify continental water change.

  • 23.
    Asokan, Shilpa M.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Dutta, Dushmanta
    Analysis of water resources in the Mahanadi River Basin, India under projected climate conditions2008In: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 22, no 18, p. 3589-3603Article in journal (Refereed)
    Abstract [en]

    The paper presents the outcomes of a study conducted to analyse water resources availability and demand in the Mahanadi River Basin in India under climate change conditions. Climate change impact analysis was carried out for the years 2000, 2025, 2050, 2075 and 2100, for the months of September and April (representing wet and dry months), at a sub-catchment level. A physically based distributed hydrologic model (DHM) was used for estimation of the present water availability. For future scenarios under climate change conditions, precipitation output of Canadian Centre for Climate Modelling and Analysis General Circulation Model (CGCM2) was used as the input data for the DHM. The model results show that the highest increase in peak runoff (38%) in the Mahanadi River outlet will occur during September, for the period 2075-2100 and the maximum decrease in average runoff (32·5%) will be in April, for the period 2050-2075. The outcomes indicate that the Mahanadi River Basin is expected to experience progressively increasing intensities of flood in September and drought in April over the considered years. The sectors of domestic, irrigation and industry were considered for water demand estimation. The outcomes of the analysis on present water use indicated a high water abstraction by the irrigation sector. Future water demand shows an increasing trend until 2050, beyond which the demand will decrease owing to the assumed regulation of population explosion. From the simulated future water availability and projected water demand, water stress was computed. Among the six sub-catchments, the sub-catchment six shows the peak water demand. This study hence emphasizes on the need for re-defining water management policies, by incorporating hydrological response of the basin to the long-term climate change, which will help in developing appropriate flood and drought mitigation measures at the basin level.

  • 24.
    Asokan, Shilpa M.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Jarsjö, Jerker
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Destouni, Georgia
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Vapor flux by evapotranspiration: effects of changes in climate, land-use and water-use2010In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 115, no D24Article in journal (Refereed)
    Abstract [en]

    Enhanced evapotranspiration (ET) over irrigated land and associated latent heat flux change can modify the climate. Model studies of such climate change effects of irrigation are commonly based on land use parameterizations, in terms of irrigated land area, or land area equipped for irrigation. Actual ET change, however, may also be driven by water use change in addition to land use change. This study quantifies and compares ET changes due to changes in climate, land use, and water use from the preirrigation period 1901–1955 to the recent period 1990–2000 (with irrigation) for the example case of Mahanadi River Basin (MRB) in India. The results show that actual water use per unit area of irrigated land may vary greatly over a hydrological drainage basin. In MRB, much higher water use per irrigated land unit in the downstream humid basin parts leads to higher vapor flux by ET, and irrigation‐induced ET flux change, than in the upstream, water‐stressed basin parts. This is consistent with water supply limitations in water‐stressed basins. In contrast, the assumption in land use−based models that irrigation maintains high soil moisture contents can imply higher modeled water use and therefore also higher modeled ET fluxes under dry conditions than under humid conditions. The present results indicate water use as an important driver of regional climate change, in addition to land use and greenhouse gas‐driven changes.

  • 25.
    Auffret, Alistair G.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Seed mobility and connectivity in changing rural landscapes2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The success or failure of many organisms to respond to the challenges of habitat destruction and a warming climate lies in the ability of plant species to disperse between isolated habitats or to migrate to new ranges. European semi-natural grasslands represent one of the world's most species-rich habitats at small scales, but agricultural intensification during the 20th century has meant that many plant species are left only on small fragments of former habitat. It is important that these plants can disperse, both for the maintenance of existing populations, and for the colonisation of target species to restored grasslands. This thesis investigates the ecological, geographical and historical influences on seed dispersal and connectivity in semi-natural grasslands, and the mobility of plants through time and space. Seed dispersal by human activity has played a large role in the build-up of plant communities in rural landscapes, but patterns have shifted. Livestock are the most traditional, and probably the most capable seed dispersal vector in the landscape, but other dispersal methods may also be effective. Motor vehicles disperse seeds with similar traits to those dispersed by livestock, while 39% of valuable grasslands in southern Sweden are connected by the road network. Humans are found to disperse around one-third of available grassland species, including several protected and red-listed species, indicating that humans may have been valuable seed dispersers in the past when rural populations were larger. Past activities can also affect seed mobility in time through the seed bank, as seeds of grassland plant species are shown to remain in the soil even after the grassland had been abandoned. Today however, low seed rain in intensively grazed semi-natural grasslands indicates that seed production may be a limiting factor in allowing seeds to be dispersed in space through the landscape.

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  • 26.
    Baheram, Elina
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Nollalternativ i en miljökonsekvensbeskrivning2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This study of the zero alternatives in an Environmental Impact Assessment (EIA) constitutes a thesis in the Master's program in Environmental Management and Physical Planning at the Department of Physical Geography and Quaternary Geology at Stockholm University. The work has also been produced in collaboration with WSP Civils.

    In the current situation, it seems to lack a clear consensus over how the zero alternatives in an EIA should be formulated and managed. The purpose of this study was to explore the attitudes towards the zero alternatives (or the no-action alternative) in an EIA and try to give a better understanding of how the alternative should be managed. Therefore, this study describes what the purpose and function of the zero alternatives have in an EIA, together with the aspects that should be considered when dealing with zero alternatives in an EIA.

    The study was conducted using four different methods that together should be able to answer the study's purpose and issues. To provide a better understanding the empirical data was connected to theories of prediction, uncertainties and scenarios in an EIA.

    The results of the study indicate that the purpose of the zero alternatives in an EIA is to put a plan or a project into context, and therefore fulfill an important function. It is important in an EIA to illustrate the uncertainty that exists in the predictions made about the future, which are the basis for the assessments that are made. This is also important for the zero alternatives. Regarding the uncertainty, it is also necessary to consider whether it in all circumstances is appropriate to use the zero alternatives as a reference alternative in relation to the other alternatives in the EIA. The Swedish Environmental Code also has two definitions that describe the zero alternatives, depending on whether it is a plan or a project the EIA should describe. This distinction is unfortunately not always visible in practice.

    During the study, it emerged that there is a demand for advice and recommendations for dealing with zero alternatives in an EIA. One hope is that this study will generate a greater knowledge of the handling of zero alternatives in an EIA.

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  • 27. Baresel, Christian
    et al.
    Destouni, Georgia
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Uncertainty-Accounting Environmental Policy and Management of Water Systems2007In: Environmental Science & Technology, Vol. 41, no 10, p. 3653–3659-Article in journal (Refereed)
    Abstract [en]

    Environmental policies for water quality and ecosystem

    management do not commonly require explicit stochastic

    accounts of uncertainty and risk associated with the

    quantification and prediction of waterborne pollutant loads

    and abatement effects. In this study, we formulate and

    investigate a possible environmental policy that does require

    an explicit stochastic uncertainty account. We compare

    both the environmental and economic resource allocation

    performance of such an uncertainty-accounting environmental

    policy with that of deterministic, risk-prone and riskaverse

    environmental policies under a range of different

    hypothetical, yet still possible, scenarios. The comparison

    indicates that a stochastic uncertainty-accounting

    policy may perform better than deterministic policies over

    a range of different scenarios. Even in the absence of

    reliable site-specific data, reported literature values appear

    to be useful for such a stochastic account of uncertainty.

  • 28.
    Barnett, Jamie
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Modelling the effects of climate change on ice dynamics at Kangerlussuaq Glacier, Greenland2021Independent thesis Advanced level (degree of Master (Two Years)), 40 credits / 60 HE creditsStudent thesis
    Abstract [en]

    A consequence of climate change is rising global sea levels, predicted to bring increased socio-economic and environmental impacts to coastal communities. The Greenland Ice Sheet has become a prominent contributor to rising sea levels, a consequence of the Arctic warming at twice the rate of the global average. Mass loss from the ice sheet is separated between changes in surface mass balance and ice discharge at marine terminating outlet glaciers, with the later dominating mass loss over the past fifty years. While advances in ice sheet modelling have provided greater clarity on Greenland’s future mass loss, there remains inefficiencies in modelling the response of outlet glaciers in Greenland’s fjords. This thesis aims to provide greater insight into behaviour of Kangerlussuaq Glacier, SE Greenland, by employing a 2D flowline model to understand the processes governing ice dynamics and to explore how the glacier may respond to a warming climate. Results indicate that the presence of a winter ice mélange is the principle dictator of Kangerlussuaq Glacier’s behaviour and likely protects against further retreat towards a reverse sloped section of bedrock. However, if such a retreat does materialise, then large overdeepenings in Kangerlussuaq Fjord raise the spectre of uncontrollable retreat and excessive mass loss.

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  • 29. Beer, C.
    et al.
    Runge, A.
    Grosse, G.
    Hugelius, Gustaf
    Stockholm University, Faculty of Science, Department of Physical Geography. Stockholm University, Faculty of Science, The Bolin Centre for Climate Research (together with KTH & SMHI).
    Knoblauch, C.
    Carbon dioxide release from retrogressive thaw slumps in Siberia2023In: Environmental Research Letters, E-ISSN 1748-9326, Vol. 18, no 10, article id 104053Article in journal (Refereed)
    Abstract [en]

    Thawing of ice-rich permafrost soils in sloped terrain can lead to activation of retrogressive thaw slumps (RTSs) which make organic matter available for decomposition that has been frozen for centuries to millennia. Recent studies show that the area affected by RTSs increased in the last two decades across the pan-Arctic. Combining a model of soil carbon dynamics with remotely sensed spatial details of thaw slump area and a soil carbon database, we show that RTSs in Siberia turned a previous quasi-neutral ecosystem into a strong source of carbon dioxide of 367 ± 213 gC m-1 a-1. On a global scale, recent CO2 emissions from Siberian thaw slumps of 0.42 ± 0.22 Tg carbon per year are negligible so far. However, depending on the future evolution of permafrost thaw and hence thaw slump-affected area, such hillslope processes can transition permafrost landscapes to become a major source of additional CO2 release into the atmosphere.

  • 30. Bendt, Pim
    et al.
    Barthel, Stephan
    Stockholm University, Faculty of Humanities, Department of History. Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Colding, Johan
    Stockholm University, Faculty of Science, Stockholm Resilience Centre. Royal Swedish Academy of Science, Beijer Institute of Ecological Economics, Sweden.
    Civic greening and environmental learning in public-access community gardens in Berlin2013In: Landscape and Urban Planning, ISSN 0169-2046, E-ISSN 1872-6062, Vol. 109, no 1, p. 18-30Article in journal (Refereed)
    Abstract [en]

    We analyse environmental learning in public-access community gardens (‘PAC-gardens’) in Berlin, representing public green spaces that are collectively managed by civil society groups. Through extensive fieldwork, and drawing upon social theories of learning, we describe learning communities in four PAC-gardens and analyse factors that influence participation and boundary interaction, that is when experiences brought in from the outside encounter socially defined competences. Results show that these PAC-gardens have self-generated social and physical structures, which to different degrees inhibit or facilitate boundary interactions, whereas skills of individuals to put those to work, in combination with the quality of the surrounding neighbourhoods, can be ascribed for creating broader participation and greater diversity in the content of learning about local sustainability. Identified learning streams included learning about gardening and local ecological conditions; about urban politics, and about social entrepreneurship. We discuss results in relation to environmental learning that combats the generational amnesia in cities about our dependence on nature, where PAC-gardens clearly distinguish themselves from more closed forms of urban gardening such as allotment gardens and gated community gardens. We conclude that PAC-gardens that intertwine gardening with social, political and economic practices can create broader and more heterogeneous learning about social–ecological conditions, and help develop sense-of-place in degraded neighbourhoods.

  • 31.
    Bennich, Therese
    Stockholm University, Faculty of Science, Department of Physical Geography.
    The transition to a bio-based economy: Toward an integrated understanding2020Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The bio-based economy has gained increasing attention in societal and academic debates over the past two decades, and is argued to hold solutions to several pressing sustainability challenges. However, it is not yet clear if the high-reaching aspirations of the bio-based economy can be realized. The bio-based economy discourse has been criticized for being promissory, vague, and single-sector focused, thereby overlooking larger systemic impacts, trade-offs, and unintended consequences that may result from pursuing the goals of the bio-based economy. Against this background, this thesis aims to advance an integrated and systemic understanding of the transition to a bio-based economy and what it implies for sustainability. Sweden is used as an empirical case, where specific bio-based economy goals, as well as their interactions and sustainability outcomes, are examined. The focus is primarily on developments in the forestry, agriculture, and energy sectors. The analysis also seeks to identify how goals related to the bio-based economy are interconnected with goals promoted by parallel sustainability initiatives, specifically the 2030 Agenda and the associated Sustainable Development Goals (SDGs). Integration is achieved by using systems analysis tools and methods. Further, the weak and strong sustainability paradigms, and the opposing definitions of sustainability they provide, are used to assess the contribution of the bio-based economy to sustainability. 

    The integrated analysis provides a detailed and operational conceptualization of transition pathways to a Swedish bio-based economy. The goals of the Swedish bio-based economy are divergent and broad-reaching, emphasizing that there is no general agreement on what the transition to a bio-based economy entails. The results point to multiple barriers that need to be addressed to realize the goals of the Swedish bio-based economy. Goal conflicts constitute one such barrier. These are found internal to as well as across the bio-based economy and the parallel 2030 Agenda. Additional hindrances include policy resistance, negative cross-sectoral spillovers, and patterns of path dependency. However, the results also highlight several opportunities for supporting the transition process in a Swedish context. These opportunities include the identification of goals and interventions with synergetic potential, which offer a basis for developing efficient implementation strategies with high systemic impact. There is also large potential to support cross-sectoral collaboration and learning, based on shared interests and challenges. Finally, the results emphasize the importance of better understanding and addressing perceptions about risk, conflict, legitimacy, and trust in the transition process.

    In terms of the overarching question of what the bio-based economy implies for sustainability, the results find that the bio-based economy has been contributing to developments that align primarily with weak sustainability. From the perspective of the strong sustainability paradigm, the prospects of the bio-based economy are less promising, potentially leading to outcomes that could worsen ongoing environmental and social issues. For the future, fundamental changes to the way the bio-based economy is conceptualized and implemented are needed for it to contribute to sustainability according to the notion of strong sustainability.

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  • 32. Benson, Vitus
    et al.
    Donges, Jonathan F.
    Stockholm University, Faculty of Science, Stockholm Resilience Centre. Potsdam Institute for Climate Impact Research (PIK), Germany; Princeton University, United States of America.
    Boers, Niklas
    Hirota, Marina
    Morr, Andreas
    Staal, Arie
    Stockholm University, Faculty of Science, Stockholm Resilience Centre. Utrecht University, The Netherlands.
    Vollmer, Jürgen
    Wunderling, Nico
    Stockholm University, Faculty of Science, Stockholm Resilience Centre. Potsdam Institute for Climate Impact Research (PIK), Germany; Princeton University, United States of America.
    Measuring tropical rainforest resilience under non-Gaussian disturbances2024In: Environmental Research Letters, E-ISSN 1748-9326, Vol. 19, no 2, article id 024029Article in journal (Refereed)
    Abstract [en]

    The Amazon rainforest is considered one of the Earth's tipping elements and may lose stability under ongoing climate change. Recently a decrease in tropical rainforest resilience has been identified globally from remotely sensed vegetation data. However, the underlying theory assumes a Gaussian distribution of forest disturbances, which is different from most observed forest stressors such as fires, deforestation, or windthrow. Those stressors often occur in power-law-like distributions and can be approximated by α-stable Lévy noise. Here, we show that classical critical slowing down (CSD) indicators to measure changes in forest resilience are robust under such power-law disturbances. To assess the robustness of CSD indicators, we simulate pulse-like perturbations in an adapted and conceptual model of a tropical rainforest. We find few missed early warnings and few false alarms are achievable simultaneously if the following steps are carried out carefully: first, the model must be known to resolve the timescales of the perturbation. Second, perturbations need to be filtered according to their absolute temporal autocorrelation. Third, CSD has to be assessed using the non-parametric Kendall-τ slope. These prerequisites allow for an increase in the sensitivity of early warning signals. Hence, our findings imply improved reliability of the interpretation of empirically estimated rainforest resilience through CSD indicators.

  • 33.
    Berencreutz, Magnus
    Stockholm University, Faculty of Social Sciences, Department of Human Geography.
    Ett paradigmskifte (?) i svensk geografi2014In: Geografiska Notiser, ISSN 0016-724X, Vol. 62, no 3, p. 127-136Article in journal (Other academic)
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    Ett paradigmskifte (?) i svensk geografi
  • 34.
    Berggren, Anna
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Inledande försökt till mätning med Europas navigeringssystem Galileo2016Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    Europe is presently building up a satellite navigation system of their own, Galileo. Unlike the American system, GPS, and the Russian system, Glonass, Galileo will be a civilian system. It will be independent from, but interoperable with both GPS and Glonass. After many delays have enough satellites been launched and placed in orbit to make it possible to start up Galileo’s initial services during December 2016.

    This study gives an account of the construction and development of the Galileo system. During two weeks in the spring 2016 experimental RTK measurements were made with Galileo combined with GPS where the satellite corrections were distributed from Lantmäteriet’s (the Swedish mapping, cadastral and land registration authority’s) supportsystem for satellite positioning, SWEPOS. The measurements were carried out with singlestation RTK towards a SWEPOS reference station at Mosebacke on Södermalm in Stockholm. The rover was placed over a fixed point about 1.2 km from the reference station.The purpose of the study was to determine if it was possible in the spring 2016 to make any measurements with Galileo and to see what Galileo can add to RTK measurements combined with GPS in SWEPOS.

    During the spring 2016 it was not possible to make any measurements with only Galileo satellites due to the fact that there were too few satellites in orbit. The results from the measurements indicate that combining Galileo and GPS could be positive for network RTK in SWEPOS. The part of achieved fixed solutions increases, the average time until fixed solution is achieved shortens and the space vehicle geometry (PDOP) gets a better value when combining GPS and Galileo. It is however too soon to say anything certain about the influence of Galileo on the position uncertainty.

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  • 35.
    Bergsten, Arvid
    et al.
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Zetterberg, Andreas
    To model the landscape as a network: A practitioner's perspective2013In: Landscape and Urban Planning, ISSN 0169-2046, E-ISSN 1872-6062, Vol. 119, p. 35-43Article in journal (Refereed)
    Abstract [en]

    Recent years have shown a rapid increase in the number of published studies that advocate network analysis (graph theory) to ecologically manage landscapes that suffer from fragmentation and loss of connectivity. This paper studies the reasons, benefits and difficulties of using network analysis to manage landscape fragmentation in the practice of land-use planning. The results are based on interviews with thirteen municipal ecologists and environmental planners in Stockholm, Sweden, who had been introduced to a GIS-tool for network-based connectivity analysis. Our results indicate that fragmentation is not considered enough in municipal planning and demonstrate that none of the interviewed practitioners used systematic methods to assess landscape connectivity. The practitioners anticipate that network-level and patch-level connectivity measures and maps would help them to communicate the meaning and implications of connectivity to other actors in the planning process, and to better assess the importance of certain habitats affected by detailed plans. The main difficulties of implementing network-based connectivity analyses reported by the respondents related to the choice of focal species and the lack of model input in terms of landscape data and dispersal distances. The main strengths were expressed by the practitioners as graphical, quantitative and credible results; the ability to compare planning alternatives and to find critical sites in a more objective manner than today; and to relate local planning and ecology to the regional structure of the landscape. Many respondents stressed the role of fragmentation assessments in the endeavor to overcome current spatial mismatches of ecological and administrative scales.

  • 36.
    Bergström, Erik
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Den prerecenta lokalglaciationens utbredningshistoria inom Skanderna: The history of the pre-recent local glaciation in the Scandinavian mountains1973Doctoral thesis, monograph (Other academic)
  • 37.
    Berntell, Ellen
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Understanding West African Monsoon Variability: Insights from Paleoclimate Modelling of Past Warm Climates2023Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The Sahel, a water-vulnerable region in West Africa, relies heavily on rainfed agriculture. The region experienced pronounced droughts during the 20th Century, emphasising the socio-economic importance of understanding the drivers of the rainfall variability. However, future rainfall projections remain uncertain due to the complex nature of the West African Monsoon (WAM), which is influenced by internal climate variability, external forcing, and feedback processes. Limited observational records in West Africa and the need for longer time series further complicate the understanding of these drivers.

     This thesis uses paleoclimate modelling to investigate internal and external drivers of monsoon variability in West Africa across four distinct periods. Our study confirms that atmosphere-only model simulations can capture the observed multidecadal rainfall variability in the 20th Century, even though reanalyses struggle to reproduce the correct timing. Analysis of a last millennium simulation using the Earth System Model EC-Earth3 identified two drivers of multidecadal rainfall variability, accounting for 90% of the total co-variability between the West African rainfall and Atlantic sea surface temperatures (SSTs). This finding strengthens our understanding of SST-WAM relationships observed during the 20th Century. An ensemble of climate model simulations (PlioMIP2) shows that high CO2 levels and a different paleogeography during the mid-Pliocene Warm Period led to increased rainfall and a strengthened WAM. Our study emphasised vegetation's crucial role in enhancing the monsoon in past climates.

     However, simulations forced with prescribed vegetation only capture a one-directional forcing. A mid-Holocene simulation using an Earth System Model with dynamic vegetation revealed that vegetation feedbacks strengthen the WAM response to external orbital forcing but are insufficient to shift the monsoon northward or increase vegetation cover over the Sahara. These results reveal a dry bias and under-representation of simulated vegetation compared to proxy records, highlighting the importance of model development and the need for additional feedback processes in driving an enhanced, northward WAM and extending vegetation to the Sahara.

     Overall, this thesis advances our understanding of the drivers of West African monsoon variability and provides valuable insights for improving future rainfall projections in this vulnerable region.

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  • 38.
    Berntsson, Annika
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Rosqvist, Gunhild C.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Velle, Gaute
    Late-Holocene temperature and precipitation changes in Vindelfjallen, mid-western Swedish Lapland, inferred from chironomid and geochemical data2014In: The Holocene, ISSN 0959-6836, E-ISSN 1477-0911, Vol. 24, no 1, p. 78-92Article in journal (Refereed)
    Abstract [en]

    In this article, we present results from a palaeolimnological study from Lake Vuoksjavratje in the mountain tundra region in the Vindelfjallen Mountains, northwest Sweden. We suggest that the influence of precipitation may be one of the factors causing discrepancies between chironomid-based late-Holocene July temperature (JulyT) reconstructions from Fennoscandia. We combine quantitative temperature reconstruction using chironomids for the last 5100 years with qualitative analysis of chironomid composition and geochemical analyses, such as x-ray fluorescence (XRF), total organic carbon (TOC) and C/N analysis. The studied sequence is dated by Pb-210, Cs-137 and 11 C-14 datings from terrestrial macrofossils. The aim of the study was to use chironomids to reconstruct late-Holocene summer temperature variation on a multi-centennial to centennial timescale and to use geochemical data to identify periods during which the changes in chironomid composition might have been forced by environmental variables other than temperature, such as within lake processes or precipitation. Based on ordination techniques, and a comparison between chironomid-inferred JulyTs and changes in minerogenic sedimentation with regional temperature and wetness records, it is concluded that the JulyT signal was modulated by precipitation. The proxies indicate that both JulyT and annual precipitation have influenced the chironomid communities in Lake Vuoksjavratje, and that catchment-related processes caused by enhanced precipitation have overridden the summer temperature signal between 3000 and 2200 cal. yr BP, and between 1050 and 100 cal. yr BP.

  • 39.
    Bienzle Arruda, Katrin
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Vad är geografi?: Gestaltning av geografiämnet i gymnasiets läromedel 1994-20112020Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    While the school subject geography is defined as a unified subject, academic geography is divided into two scientific disciplines; human geography and physical geography, which makes the relationship between the academic disciplines and the school subject geography somewhat complicated. Research shows that the textbook is often equal to the course. The textbook has a central role in the teacher's planning of the course and is thus crucial for the student's learning. The purpose of this study is to investigate and discuss how the school subject geography is presented in textbooks. I examine how the interdisciplinary, unified subject geography, which illustrates the connections and the mutual influence between societal development, natural environments and human activity, is exemplified, and what challenges teachers face depending on the design of the textbooks.

    In addition to a quantitative analysis, I make a more qualitative one in order to concretize and nuance the image that emerges. The study shows that the school subject geography is mainly presented according to the identified common and specialized areas of interest, concepts and theories for the respective discipline of human and physical geography. Overall, relatively few examples in the textbooks are identified, only about 35 percent of all analyzed pages, where human-nature interaction is clear and which portrays the coherent, unified subject of geography according to the curriculum.

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  • 40. Bigg, G. R.
    et al.
    Clark, C. D.
    Greenwood, Sarah L.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Haflidason, H.
    Hughes, A. L. C.
    Levine, R. C.
    Nygard, A.
    Sejrup, H. P.
    Sensitivity of the North Atlantic circulation to break-up of the marine sectors of the NW European ice sheets during the last Glacial: A synthesis of modelling and palaeoceanography2012In: Global and Planetary Change, ISSN 0921-8181, E-ISSN 1872-6364, Vol. 98-99, p. 153-165Article in journal (Refereed)
    Abstract [en]

    The marine-based Atlantic periphery of the last NW European Ice Sheet experienced significant advances and retreats of its marine sector during its existence. It therefore had considerable potential to intermittently inject freshwater or ice pulses to the North Atlantic. These European inputs had poorly known consequences for ocean circulation and climate. Here we examine the history of the western margin of the European Ice Sheet, from 34 to 15 cal ka BP, and use a combination of modelling and proxy evidence to explore the impact on the North Atlantic of the fresh water and iceberg injections that accompanied phases of retreat of the marine sector of the NW European Ice Sheet. We find that the lack of geographical synchronicity in the responses of the different components of the 3000 km long sector meant that the scale of the climate consequences of ice discharge most likely remained regional, except during the final deglaciation phase, around 17-15 cal ka BP. At this time, as the later component of the recently introduced concept of an extended Heinrich event H1, both proxy and modelling evidence suggest rapid sector collapse led to partial shut-down of the Atlantic overturning and a basin-wide cooling.

  • 41. Bishop, Paul
    et al.
    Jansen, John
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Castillo, Miguel
    Reinhardt, Liam
    Whitbread, Katie
    Kim, Jong-Yong
    Fabel, Derek
    Hoey, Trevor
    ‘Bottom-up’ bedrock river response to rock uplift: Unravelling the controls of landscape responses to transience.2010In: British Society for Geomorphology Programme & Abstracts. London, England, Aug 2010., 2010Conference paper (Other academic)
    Abstract [en]

    Bedrock rivers set the boundary conditions for landscape evolution. Most recent bedrock river research has been in steady-state settings in which rock uplift is matched by landscape lowering driven by bedrock river incision and slope lowering, but more attention is now being paid to bedrock rivers is transient settings (where transience in the fluvial system is triggered by changes in the rate of rock uplift and/or by climatic oscillations).  Transient responses in bedrock rivers close to base-level are dominated by ‘bottom-up’ processes.  Those processes remain less well understood than the ‘top-down’ processes that are thought to be characteristic of steady state landscapes and are driven by discharges of water and sediment. Key issues in understanding rates of landscape-wide response to transience are (i) rates of knickpoint retreat to transmit a base-level fall signal through the drainage net, and (ii) rates of hillslope response once that base-level fall has passed the foot of a hillslope.  Terrestrial cosmogenic nuclide (TCN) data from a transient landscape in southern Spain point to the latter being the rate-limiting control (“fast rivers, slow hillslopes”).  In terms of the former, morphometric and TCN data from coastal rivers in Scotland confirm knickpoint retreat in response to glacio-isostatic rebound, whereas TCN data from higher up these rivers, above the reach affected by glacio-isostatic base-level fall, point to more diffusive bedrock channel incision, without knickpoint retreat.  Determining why diffusive incision is initiated at a particular locality in those settings is difficult but in at least one case the incision is probably ‘pinned’ on resistant lithologies.  A wider and more taxing issue is the relationship between ‘bottom-up’ and ‘top-down’ incisional processes and whether the former must precede, and can evolve into, the latter.

     

  • 42. Björk, Alexandra
    et al.
    Skånes, Helle
    Stockholm University, Faculty of Science, Department of Physical Geography.
    The Need for Awareness of Semantic Plasticity in International Harmonization of Geographical Information: Seen from a Nordic Forest Classification Perspective2015In: Land Use and Land Cover Semantics: Principles, Best Practices and Prospects / [ed] Ola Ahlqvist, Dalia Varanka, Steffen Fritz, Krzysztof Janowicz, Boka Raton: CRC Press, 2015, p. 41-58Chapter in book (Refereed)
    Abstract [en]

    The aim of this chapter is to address and clarify the important issues and challenges of semantic plasticity when it comes to forest classification and geographical information. Necessary improvements for international data harmonization and implementation are highlighted along with the need for increased awareness of the consequences for ecological modeling. We envisage a combination of thoroughly described metadata and controlled vocabularies as a means to ensure the future use of a wide range of regional and national classification systems in an ontological framework that enables crosswalks between classification systems and spatial comparisons between existing data sets. This would allow for a wide range of old, contemporary, and future data sets to be used together in landscape-related analyses.

  • 43. Björk, Alexandra
    et al.
    Skånes, Helle
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Ahlqvist, Ola
    Ser vi skogen för alla träd? Vikten av semantisk plasticitet vid harmonisering av geodata2015In: Sinus, no 4, p. 2Article in journal (Other (popular science, discussion, etc.))
  • 44.
    Björklund, Oskar
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Evaluating the Bluespot model with the August 2021 flood in Gävle, Sweden2023Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Floods are one of the most common types of natural disasters. They annually affect vast amounts of people and cause severe economic losses. While fluvial, coastal, and flash floods are well studied, pluvial floods (rain related) have received modest attention from researchers and decision-makers in comparison. There are several reasons for this, one is that it has been considered a fixed problem with infrastructure and other engineered solutions and another is that they are generally undramatic and small-scale. However, as cities expand, the environment’s ability to retain and dispose of excess water is inhibited and as the frequency of extreme weather events is expected to increase due to climate change, the risk associated with pluvial floods has become increasingly recognized. Commercial and open-source Urban pluvial flood models tend to require advanced modelling expertise, considerable computational power, large amounts of input data and are often expensive. Consequently, there is less knowledge of flood inundation caused by pluvial floods compared to other types. This thesis investigates the Bluespot model, which aims to provide an approachable tool to generate an overview of the effects of pluvial floods in urban areas. The model requires few input data and is relatively simple to perform. Results from the model are compared to the August 2021 flood event in Gävle, Sweden.The study finds that results ranged from accurate to over- and underestimated. Slope and incoming water were found to affect the outcome most. Blue spots without the influence of streams or other waterways, with a distinct slope were mapped with accuracy and showed consistency with coarser resolutions. Consequently, underpasses in the road network were mapped with especially good consistency. Further, blue spots within close distance to large flow accumulation were underestimated and the accuracy tended to decrease with a coarser resolution. The model cannot account for water outside blue spots, thus, when large volumes of water accumulate and spread beyond these boarders it generates poor results. These areas were found to be efficiently indicated by generating a heatmap from high-flow accumulation points. Thus, indicating low confidence and where a hydraulic flood model should be performed. Depending on the scope a 1-3m resolution is recommended for investigating effects on property etc and a 5-10m resolution is sufficient for investigating underpasses, however, a finer resolution will generate more accurate results.

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  • 45.
    Blomdin, Robin
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Deglaciationsförloppet och Isdämda sjöar i Vindelälvens källområde2009Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    A detailed landform mapping was carried out in the mountain region of the source area of River Vindelälven. The aim of this mapping study was to increase the current knowledge of the dynamics and character (the ice margin retreat, ice flow directions and the subglacial thermal organization) of the Fennoscandian Ice Sheet during the last deglaciation in this part of the Swedish mountain range.

    The study area has been proposed to be situated within the cold based core area that characterized the last Ice age maxima (LGM). However, despite the lack of subglacial melting, glacial meltwater still exists. Traces after ancient glacial lakes and the glaciofluvial landform system are therefore the only data that exist when reconstructing the recession pattern of cold based ice sheets or when there is a general lack of glacial landforms.

    The aerial photograph interpretation focused on glaciolacustrine, glaciofluvial and subglacial landforms. The reconstruction of the ice sheet recession pattern was thus based on the distribution of the glacial geomorphology, the dammed glacial lakes and the hypothetical damming ice sheet margin. A theoretical model for calculation of the ice surface slope profile was used to increase the detail level of the reconstruction and as a control of the landform based reconstruction. Mapped landforms formed the base for the glacial lake reconstruction that was carried out in a GIS. Lantmäteriets height database was used as a topographical base dataset.

    Ice sheet margins reconstructed by the theoretical model showed good conformity with the mapped landforms. Eight glacial lakes where identified, two of these, Glacial lake Vindelälven and Glacial lake Båssjuosjávrrie – Gávásjávrries, existed with large safety and where dominant features in the landscape during the deglaciation. They where dammed in the northwest and west respectively between revealed saddle points in the terrain and the retreating ice sheet.

    The damming of large glacial lakes shows that the ice sheet, in the study area, was active throughout the entire deglaciation. The ice sheet retreated generally towards the southeast. The presented deglaciation model indicated northwesterly and westerly ice flow directions in an early phase of the deglaciation, and westerly in a late phase. The last ice flow direction in the study area was towards west and it stemmed probably from the last ice divide situated above the low fell Kráhpiesvarrie. The subglacial thermal organization in the study area may be viewed as uncertain due to ambiguous evidence.

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  • 46.
    Blomdin, Robin
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Paleoglaciology of the Tian Shan and Altai Mountains, Central Asia2016Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The mountain-systems of Central Asia, act as barriers to atmospheric circulation patterns, which in turn impose striking climate gradients across the region. Glaciers are sensitive indicators of climate change and respond to changes in climate gradients over time by advancing during cold and wet periods and receding during warm and dry periods. The aim of this thesis is to investigate whether there are large-scale patterns in how past glaciers in the Tian Shan and the Altai Mountains of Central Asia responded to climate change. Multiple methods have been used, including: remote sensing, terrain analysis, field investigations, and cosmogenic nuclide (CN) dating. The glacial landform records indicate that the region experienced mainly alpine-style glaciations in the past. Large complexes of ice-marginal moraines in high elevation basins are evidence of outlet glaciers sourced from large valley glaciers, ice caps and ice-fields, and these moraine sequences, record the maximum extent of paleoglaciation. In the Ikh-Turgen Mountains, located in the continental, eastern Altai Mountains, deglaciation of these moraines occurred during marine oxygen isotope stage (MIS) 3 at ~45 ka. This is consistent with a colder and wetter climate during this time, inferred from ice core and lake level proxies. Another deglacial phase occurred during MIS 2 at ~23 ka, synchronous with the global Last Glacial Maximum. In the Russian Altai Mountains, lobate moraines in the Chuya Basin indicate deglaciation at ~19 ka, by a highly dynamic paleoglacier in the Chagan-Uzun catchment, which experienced surge-like behaviour. Furthermore, across the Tian Shan, an evaluation of new and existing CN glacial chronologies (25 dated moraines) indicates that only one regional glacial stage, between 15 and 28 ka (MIS 2), can be defined and spatially correlated across the region. These paleoglaciers were mainly restricted to valleys as a result of arid conditions during this time and variation in their extents is interpreted to reflect topographic modulation on regional climate. The ages of the oldest evidence for robust local glacial stages in the Tian Shan are not yet well constrained, however, moraines in the central Kyrgyz Tian Shan and the eastern Chinese Tian Shan have apparent minimum ages overlapping with MIS 5 and MIS 3 (with missing MIS 4 and 6 stages). However, different geological processes, such as inheritance and post-depositional shielding (e.g. deposition by surging glaciers or hummocky terrain deposition), have influenced the dating resolution, making several moraine ages inappropriate for regional comparison. Finally, to quantify regional patterns of paleoglaciation, the hypsometry (area-elevation distribution) of glacial landforms is used to estimate average paleo equilibrium line altitudes for the region. This analysis shows that while present-day ELAs mirror strong climate gradients, paleoglaciation patterns were characterised by more gentle ELA gradients. The paleo-ELA depressions across Central Asia were most prominent in the continental southern and eastern regions (500–700 m). Finally, the results from this thesis, show that Central Asia was repeatedly glaciated in the past, but underscore the importance of considering 1) catchment characteristics and styles of glaciation and 2) other non-climatic factors controlling glacier dynamics when interpreting CN chronologies to make paleoclimate inference.

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  • 47.
    Blomdin, Robin
    Stockholm University, Faculty of Science, Department of Physical Geography. Stockholm University.
    The Late Glacial History of the Magellan Strait in southern Patagonia, Chile: Testing the Applicability of KF-IRSL Dating2012Independent thesis Advanced level (degree of Master (Two Years)), 40 credits / 60 HE creditsStudent thesis
    Abstract [en]

    The timing of the ice margin retreat of the Late Glacial Patagonian ice sheet (PIS) in southern Patagonia has been the object of discussion for many years. In order to resolve questions about the complex response of the PIS to past climate change; geological interpretation and modelling data needs evaluation against absolute chronology. The aim of this project is to re-map the landforms and sediment of the Magellan Strait, to reconstruct the late glacial ice retreat during the deglaciation and to investigate the applicability of OSL dating to glaciofluvial sediment from this region. Unfortunately previous studies have shown that the quartz OSL luminescence characteristics, of this region, are unsuitable for dating. Therefore the potential of K-feldspar IRSL signals are reviewed and examined. Samples were collected from landforms interpreted as being deposited during the deglaciation of the Magellan ice lobe, with an expected age range between 17.5 and 23 ka, and from recently deposited sediments (<1 ka). Small aliquots and single grain distributions were studied by applying a IR50 SAR protocol with IRSL stimulation at 50°C for 100 s and a preheat of 250 °C (held at 60 s) are measured.  Appropriate uncertainties were assigned to the dose distribution data, by quantifying the laboratory over-dispersion (σOD) parameter (22.2% for small aliquots and 17.7 % for single grains) in laboratory bleached and γ-irradiated samples.  Thereafter the possible effects of incomplete bleaching and anomalous fading were examined. For the natural samples environmental over-dispersions between 30–130 % and mean interpreted residual doses between ~30 and 80 Gy were observed. Statistical models were further applied to identify the part of the dose population that was most likely to have been completely bleached. The models are consistent with each other which imply that they successfully identified the fully-bleached grains in the distributions; however observed discrepancies between the small aliquot and single grain data were also discussed. Large g2day values (on average 7.92±0.6%/decade for large aliquots) were observed but nevertheless, comparing our fading corrected ages to the expected age range result in 2 out of 3 ages consistent with geological interpretation and an established radiocarbon and cosmogenic nuclide chronology suggesting that this correction was done successfully. The results of these investigations suggest that small aliquot/single grain fading can be corrected for using an average value and that KF-IRSL dating is applicable in this part of Southern Patagonia. The third age is supported by an alternative geological interpretation while the two consistent ages imply that in the Magellan Strait the hills of the Brunswick peninsula (70-100 m.a.s.l) were deglaciated at around ~21 ka. Finally some recommendations for future research are considered.

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  • 48.
    Blomdin, Robin
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology. Purdue University, USA.
    Heyman, Jakob
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Stroeven, Arjen P.
    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.
    Harbor, Jonathan M.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology. Purdue University, USA.
    Gribenski, Natacha
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Jansson, Krister N.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Petrakov, Dmitry A.
    Ivanov, Mikhail N.
    Alexander, Orkhonselenge
    Rudoy, Alexei N.
    Walther, Michael
    Glacial geomorphology of the Altai and Western Sayan Mountains, Central Asia2016In: Journal of Maps, E-ISSN 1744-5647, Vol. 12, no 1, p. 123-136Article in journal (Refereed)
    Abstract [en]

    In this article, we present a map of the glacial geomorphology of the Altai andWestern Sayan Mountains, covering an area of almost 600,000 km2. Although numerous studies provide evidence for restricted Pleistocene glaciations in this area, others have hypothesized the past existence of an extensive ice sheet. To provide a framework for accurate glacial reconstructions of the Altai and Western Sayan Mountains, we present a map at a scale of 1:1,000,000 based on a mapping from 30 m resolution ASTER DEM and 15 m/30 mresolution Landsat ETM+ satellite imagery. Four landform classes have been mapped: marginal moraines, glacial lineations, hummocky terrain, and glacial valleys. Our mapping reveals an abundance of glacial erosional and depositional landforms. The distribution of these glacial landforms indicates that the Altai and Western Sayan Mountains have experienced predominantly alpine-style glaciations, with some small ice caps centred on the higher mountain peaks. Large marginal moraine complexes mark glacial advances in intermontane basins. By tracing the outer limits of present-day glaciers, glacial valleys, and moraines, we estimate that the past glacier coverage have totalled to 65,000 km2 (10.9% of the mapped area), whereas present-day glacier coverage totals only 1300 km2 (0.2% of the mapped area). This demonstrates the usefulness of remote sensing techniques for mapping the glacial geomorphology in remote mountain areas and for quantifying the past glacier dimensions. The glacial geomorphological map presented here will be used for further detailed reconstructions of the paleoglaciology and paleoclimate of the region.

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  • 49.
    Blomdin, Robin
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Stroeven, Arjen P.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Harbor, Jonathan M.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Gribenski, Natacha
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Caffee, Marc W.
    Heyman, Jakob
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Rogozhina, Irina
    Ivanov, Mikhail N.
    Petrakov, Dmitry A.
    Walther, Michael
    Rudoy, Alexei N.
    Zhang, Wei
    Orkhonselenge, Alexander
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Lifton, Nathaniel A.
    Jansson, Krister N.
    Paleoglaciation on opposite flanks of the Ikh-Turgen Mountains, Central Asia: Importance of style of moraine deposition for 10-Be surface exposure datingManuscript (preprint) (Other academic)
    Abstract [en]

    The ages of marginal moraines that record extensive glacier expansions across the Altai Mountains of Central Asia are poorly documented. We present 18 10Be exposure ages from moraines in valleys on opposite flanks of the Ikh-Turgen Mountains. On the eastern side, exposure ages from a latero-frontal moraine indicate deglaciation during MIS 3 (45.3±2.7 ka) and MIS 2 (22.8±3.5 ka). Corresponding exposure ages, from the western side, indicate a more complex story with large scatter (~14-53 ka). Owing to their close proximity, the paleoglaciers should have responded similarly to climate forcing, yet they exhibited a distinctly different behavior. We propose that differences in glacier dynamics caused differences in ice-marginal depositional environments, explaining the scatter in exposure ages on the western side. This study shows the importance of style of deposition in chronological studies of glacial landforms and demonstrates that certain moraine types can be difficult to use as paleoclimate proxies.

  • 50.
    Blomdin, Robin
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Stroeven, Arjen P.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Harbor, Jonathan M.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Hättestrand, Clas
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Heyman, Jakob
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Gribenski, Natacha
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Topographic and climatic controls on paleoglaciation patterns across the Tian Shan and Altai Mountains, Central AsiaManuscript (preprint) (Other academic)
    Abstract [en]

    Reconstructing spatial patterns of the extents and dynamics of paleoglaciers across Central Asia is key in understanding the mechanisms of global environmental change. The Tian Shan and Altai Mountains are located in the continental interior of Eurasia, at the confluence of several major climate systems. In order to test hypothesized patterns in paleoglacier extent, and to test the role of paleoclimate and mountain topography in modulating the evolution of these glacial systems, we perform a domain-wide terrain analysis. We first divide the Tian Shan and the Altai Mountains into six physiographic regions delineated by major drainage divides and outlining generalised climate zones. Thereafter we mine published datasets on the distribution of glaciers and glacial landforms, calculate their area-elevation distributions (hypsometry), and extract present-day regional equilibrium line altitudes (ELAs) and long-term average ELAs (paleo-ELAs). We show that the use of glacial landform hypsometry is an effective tool to quantify broad-scale paleoglaciation patterns and find that there is a regional variability in glacier extents across the Tian Shan and Altai Mountains. Reconstructed ELAs show pronounced spatial gradients; increasing ELAs from northern to southern Tian Shan, and increasing ELAs from the northern to both the southeastern and southwestern Altai Mountains. In contrast, maximum paleoglaciation patterns and paleo-ELAs were more uniform across the two mountain systems, with inter-regional topographic variability influencing moraine distributions and thus complicating regional paleo-ELA determinations. Because estimated paleo-ELAs were relatively uniform across the Tian Shan and Altai Mountains, the paleo-ELA lowering were most pronounced in the more continental southern and eastern regions. Our current data is insufficient to explain whether this observation is the result of a different regional paleoclimatic regime than today, or if paleoglaciers responded dynamically different to a paleoclimate forcing of the same magnitude. Our ELA reconstructions also lack temporal constraints, so we furthermore propose that future studies systematically compare hypsometry-derived ELA reconstructions with those stemming from surface energy mass balance models, other proxy records (i.e. lake- and ice core records), and from chronologically constrained ice-marginal moraines.  

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