Sökning: "8.2 ka event"

Hittade 4 avhandlingar innehållade orden 8.2 ka event.

1. 1. The palaeolimnological record of regime shifts in lakes in response to climate change

   Författare :Linda Randsalu Wendrup; Kvartärgeologi; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; palaeolimnology; regime shifts; thresholds; alternative stable states; climate change; ecosystem dynamics; diatoms; hydrocarbons; monitoring; lake sediments; shallow lakes; 8.2 ka event;

   Sammanfattning : Regime shifts in lake ecosystems can occur in response to both abrupt and continuous climate change, and the imprints they leave in palaeolimnological records allow us to investigate and better understand patterns and processes governing ecological changes on geological time scales. This thesis aims at investigating palaeolimnological records of regime shifts in lakes during the Holocene to explore how lake ecosystems responded to climate changes and anthropogenic activities and to identify thresholds or tipping points that produced regime shifts. LÄS MER

3. 2. Speleothems from Warm Climates : Holocene Records from the Caribbean and Mediterranean Regions

   Författare :Meighan Boyd; Karin Holmgren; Ian J. Fairchild; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Stable isotopes; U-Th dating; trace elements; stalagmite; speleothem; Mid-Holocene; Caribbean; ITCZ; rapid climate change; climate; Eastern Mediterranean; Peloponnese; Santorini; Neolithic; Alepotrypa Cave; Physical Geography; naturgeografi;

   Sammanfattning : This thesis contributes to increased knowledge on Holocene climate and environmental variability from two complex and sparsely studied areas. Using a speleothem from Gasparee Cave, Trinidad, as a paleoclimate archive, the local expression of the 8. LÄS MER

4. 3. Holocene climate and environmental dynamics on the Tristan da Cunha island group, South Atlantic

   Författare :Karl Ljung; Kvartärgeologi; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; palynologi; Geology; climate change; pollen analysis; Palaeobotany; phylogeny; palynology; Paleobotanik; fylogeni; vegetation change; gyttja; peat; Holocene; Quaternary; South Atlantic; Tristan da Cunha; physical geography; Geologi; fysisk geografi;

   Sammanfattning : It has been shown that the present interglacial has been climatically dynamic with both rapid and severe climatic fluctuations. The spatial and temporal differences of these changes are however not fully resolved. The aim of this thesis is to present a detail high resolution record of past climate changes from the central South Atlantic. LÄS MER

5. 4. Setting the Holocene clock using varved lake sediments in Sweden

   Författare :Lovisa Zillén; Kvartärgeologi; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; climate change; Physical geography; tephrochronology; palaeomagnetic secular variations; radiocarbon time-scale; Holocene varved lake sediments; varve chronology; geomorphology; pedology; cartography; climatology; Fysisk geografi; geomorfologi; marklära; kartografi; klimatologi;

   Sammanfattning : The aim of this thesis was to study annually laminated (varved) Holocene lake sediment in Sweden, their formation and their potential as chronological and palaeoecological archives. Five lakes with continuous Holocene varved lake sediment sequences in northern (Västerbotten) and west central Sweden (Värmland) were investigated. LÄS MER