Sökning: "Holocene climate"

Visar resultat 21 - 25 av 91 avhandlingar innehållade orden Holocene climate.

  1. 21. The Ups and Downs of the Holocene: Exploring Relationships between Global CO2 and Climate Variability in the North Atlantic Region

    Författare :Catherine Jessen; Kvartärgeologi; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; marklära; geomorfologi; climatology; klimatologi; rapid climate change; Holocene climate; atmospheric CO2 concentrations; geochemical proxy indicators; Paleobotanik; palynology; Geology; palynologi; fylogeni; geomorphology; fysisk geografi; Geologi; physical geography; kartografi; pedology; cartography; phylogeny; Palaeobotany; stomatal frequency; lake sediments;

    Sammanfattning : This thesis aimed to examine the relationship between climate and atmospheric CO2 concentrations through rapid climate changes during the Holocene. Climate was reconstructed using high-resolution, radiocarbon dated, lake sediment geochemical proxies (magnetic susceptibility, loss-on-ignition, total carbon/nitrogen/sulphur determinations and biogenic silica), vegetational reconstruction (pollen analysis) and stomatal frequency based CO2 reconstructions. LÄS MER

  3. 22. Environmental and climatic aspects of the early to mid Holocene calcareous tufa and land mollusc fauna in southern Sweden

    Författare :Björn Gedda; Kvartärgeologi; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; southern Sweden; environment; climate; Early Holocene; Calcareous tufa; mollusc; Skåne.; Geology; physical geography; Geologi; fysisk geografi;

    Sammanfattning : Although deposition of freshwater calcium carbonates, tufa, has occurred in large areas with carbonate soil or bedrock in Sweden, no tufa formation has been observed in Sweden. To better understand the factors controlling tufa formation in southern Sweden, bio- and lithostratigraphical studies were carried out on (paludal) calcareous tufa deposits in the province of Skåne. LÄS MER

  4. 23. Understanding West African Monsoon Variability : Insights from Paleoclimate Modelling of Past Warm Climates

    Författare :Ellen Berntell; Qiong Zhang; Alessandra Giannini; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; West African Monsoon; Monsoon Variability; Paleoclimate; Climate modelling; naturgeografi; Physical Geography;

    Sammanfattning : 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. LÄS MER

  5. 24. Past environmental and climate changes in northern Tanzania : Vegetation and lake level variability in Empakaai Crater

    Författare :Maria Ryner; Karin Holmgren; Peter Kuhry; Lars-Ove Westerberg; Henry Lamb; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; palaeoecology; palaeolimnology; physical and societal factors; Holocene; Tanzania; Lake Emakat; Engaruka; Earth sciences; Geovetenskap; Physical Geography; geografi med naturgeografisk inriktning;

    Sammanfattning : This thesis presents palaeoenvironmental data from equatorial Africa covering two important time intervals; i) the warming period forming the Pleistocene/Holocene transition and ii) the last millennium. The Empakaai Crater, in northern Tanzania contains a lake from where sediment cores, spanning two time-slices 14.8-9. LÄS MER

  7. 25. Tree-limit ecotonal response to Holocene climate change in the Scandes Mountains of west-central Sweden

    Författare :Jonas Bergman; Kvartärgeologi; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; tree-limit ecotone; alpine vegetation; tephrochronology; peat humification; plant macrofossils; Palaeobotany; fylogeni; Paleobotanik; palynology; phylogeny; palynologi; Geologi; Geology; pedology; geomorphology; Physical geography; klimatologi; geomorfologi; climatology; Fysisk geografi; cartography; Holocene climate; palaeoecology; marklära; kartografi; pollen influx;

    Sammanfattning : The aim of this thesis was to reconstruct the Holocene vegetational and climatic development in the Sylarna-Storulvån area, western Jämtland, in the central Scandes Mountains. Temporal trends and fluctuations in the elevation and vegetational character of the tree-limit ecotone were studied mainly by means of pollen and plant macrofossil analysis of two lake sediment sequences (Lakes Stentjärn and Spåime), located above the present-day tree-limit. LÄS MER