Marine climate variability from Arnarfjörður, NW Iceland, during the Medieval Warm period and early/middle Little Ice Age

Abstract

A high-resolution sedimentary record from the subarctic fjord Arnarfjörður in northwestern Iceland provides information on local changes in sea ice cover and a regional oceanographic climatic signal reflecting changes in the position of the Polar Front that separates the North Atlantic Current and the East Greenland Current. The 520 cm long sediment core spans approximately 2000 years and thus offers a multi-decadal time resolution during the Medieval Warm Period (MWP) and the early to middle part of the Little Ice Age (LIA). Approximately 150 years from the top of the core were lost during coring. The marine climate reconstruction is based on multi-proxy study with focus on benthic foraminiferal fauna allowing down-core bottom water temperature (BWT_{TF}) estimations based on the statistical transfer function approach. This first of the kind study from Arnarfjörður demonstrates significant variability in the benthic foraminiferal fauna dominated by Cibicides lobatulus, Cassidulina reniforme and Elphidium excavatum, BWT_{TF} variations of ∼3°C, fluctuating from ca. 1.5±1.1 °C to 4.5±0.6 °C. The data 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.