A 2000 year record of marine climate variability from Arnarfjörður, NW Iceland

• Main Author: Ingibjörg Rósa Jónsdóttir 1985-
• Other Authors: Háskóli Íslands
• Format: Thesis
• Language: English
• Published: 2015
• Subjects: Jarðfræði; Hafstraumar; Setlög; Umhverfisbreytingar; Arnarfjörður; Greenland; East Greenland; east greenland current; Iceland; north atlantic current; North Atlantic; Sea ice; Subarctic
• Online Access: http://hdl.handle.net/1946/23143

A high-resolution sedimentary record from the subarctic Arnarfjörður in northwestern Iceland is being studied, with the ultimate goal to reconstruct the marine climate and the environmental history of Arnarfjörður for the past 2000 years. The fjord provides a regional oceanographic climatic signal reflecting changes in the Irminger Current, a branch of the warm and saline North Atlantic Current and the fresher East Greenland Current from the north, and changes in sea ice cover in the region. The sediment core spans approximately 2000 years and thus offers a high resolution record for that time interval, which includes both the Medieval Warm Period (MWP) and the early to middle part of the Little Ice Age (LIA). We estimate approximately 150 years missing from the top of the section. The marine climate reconstruction is based on multi-proxy study including; x-radiographs which are used to identify ice rafted debris (IRD), magnetic susceptibility, density, total carbon, x-ray diffraction (XRD) and foraminiferal research. The main emphasis was though on utilizing the benthic foraminifera to describe the oceanographic and environmental changes in the Arnarfjörður region. This first of the kind study from Arnarfjörður has multidecadal time resolution and demonstrates significant variability in the benthic foraminiferal fauna dominated by Cibicides lobatulus, Cassidulina reniforme and Elphidium excavatum. By applying statistical transfer function methods on the down-core faunal composition estimates on the bottom water temperatures (BWTTF) and salinities (BWSTF) was obtained. For the past 2000 years the estimated BWT’s in Arnarfjörður fluctuates from ca. 1.5 ± 1.09°C to 4.53 ± 0.646°C, a variability of ~3° C. The data from Arnarfjörður is in harmony with previously reported LIA characteristics from the region, which has been described as a period of high amplitude fluctuations, with non-stable conditions and cold bottom waters. Arnarfjörður er annar stærsti fjörður Vestfjarða. Setkjarni, sem var tekinn í firðinum ...