Holocene climate and atmospheric circulation changes in northern Fennoscandia: Interpretations from lacustrine oxygen isotope records

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Jonsson, Christina E.,1965-Stockholms universitet,Institutionen för naturgeografi och kvartärgeologi (INK) (författare)

Holocene climate and atmospheric circulation changes in northern Fennoscandia : Interpretations from lacustrine oxygen isotope records

BokEngelska2009

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Stockholm :Department of Physical Geography and Quaternary Geology, Stockholm University,2009
30 s.
electronicrdacarrier

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LIBRIS-ID:oai:DiVA.org:su-29343
ISBN:9789171559043
https://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-29343URI

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Språk:engelska
Sammanfattning på:engelska

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Ämneskategori:dok swepub-publicationtype

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Dissertations from the Department of Physical Geography and Quaternary Geology,1653-7211 ;18

Anmärkningar

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: In press. Paper 2: Submitted. Paper 5: In progress.
This thesis investigates how variations in the oxygen isotopic composition of lake waters in northern Fennoscandia are recorded in lake sediment archives, especially diatoms, and how these variations can be used to infer past changes in climate and atmospheric circulation. Results from analyses of the oxygen isotopic composition of lake water samples (δ18Olakew) collected between 2001 and 2006 show that δ18O of northern Fennoscandian lakes is mainly controlled by the isotopic composition of the precipitation (δ18Op). Changes in local δ18Op depend on variations in ambient air temperature and changes in atmospheric circulation that lead to changes in moisture source, vapour transport efficiency, or winter to summer precipitation distribution. This study demonstrates that the amount of isotopic variation in lake water δ18O is determined by a combination of the original δ18Olakew, the amount and timing of the snowmelt, the amount of seasonally specific precipitation and groundwater, any evaporation effects, and lake water residence time. The fact that the same isotope shifts have been detected in various δ18Olakew proxies, derived from hydrologically different lakes, suggests that these records reflect regional atmospheric circulation changes. The results indicate that diatom biogenic silica isotope (δ18Odiatom) records can provide important information about changes in atmospheric circulation that can help explain temperature and precipitation changes during the Holocene. The reconstructed long-term Holocene decreasing δ18Op trend was likely forced by a shift from strong zonal westerly airflow (relatively high δ18Op) in the early Holocene to a more meridional flow pattern (relatively low δ18Op). The large δ18Olakew depletion recorded in the δ18O records around ca. 500 cal yr BP (AD 1450) may be due to a shift to more intense meridional airflow over northern Fennoscandia resulting in an increasing proportion of winter precipitation from the north or southeast. This climate shift probably marks the onset of the so-called Little Ice Age in this region.

Ämnesord och genrebeteckningar

NATURVETENSKAP Geovetenskap och miljövetenskap Naturgeografi hsv//swe
NATURAL SCIENCES Earth and Related Environmental Sciences Physical Geography hsv//eng
oxygen isotope
diatom silica
lake sediment
atmospheric circulation
North Atlantic Oscillation
northern Fennoscandia
The Holocene
Little Ice Age
Physical geography
Naturgeografi
Physical Geography
naturgeografi

Biuppslag (personer, institutioner, konferenser, titlar ...)

Rosqvist, Gunhild,DocentStockholms universitet,Institutionen för naturgeografi och kvartärgeologi (INK)(Swepub:su)ninis (preses)
Seibert, Jan,ProfessorStockholms universitet,Institutionen för naturgeografi och kvartärgeologi (INK)(Swepub:su)jseib (preses)
Barker, Philip,DrLancaster University, The Lancaster Environment Centre (opponent)
Stockholms universitetInstitutionen för naturgeografi och kvartärgeologi (INK) (creator_code:org_t)

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NATURVETENSKAP: NATURVETENSKAP; och Geovetenskap och ...; och Naturgeografi

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