Late Quaternary Sea-Ice Variability at the North Icelandic Shelf (Sub-Arctic): Reconstruction from Biomarkers

Abstract:

Sea ice, prevailing in the polar region and characterized by distinct seasonal and interannual variability, plays a pivotal role in Earth’s climate system (Thomas and Dieckmann, 2010). In order to understand processes controlling the recent dramatic reduction in Arctic sea-ice cover, it is essential to determine temporal changes in sea-ice occurrence and its natural variability in the past. The North Icelandic shelf, bordering a marginal area of the Arctic Ocean, is located at the present-day boundary between the cold polar currents and warm Atlantic water masses, very sensitive to the changes in sea-ice cover, ice sheet and oceanic circulation patterns (Knudsen and Eiriksson, 2002). All these processes have been recorded in the marine shelf-sediment cores. We determined the concentrations of sea-ice diatom-derived biomarker “IP25” (monoene highly-branched isoprenoid with 25 carbon atom; Belt et al., 2007), phytoplankton-derived biomarkers (brassicasterol and dinosterol) and terrigenous biomarkers (campesterol and ß-sitosterol) in a sediment core from the North Icelandic shelf to reconstruct the Late Quaternary sea-ice conditions and related surface-water processes. The sea-ice cover reached its maximum during the cold period (i.e., Last Glacial Maximum and Younger dryas), while an open ocean environment existed during less severe periods (e.g. Bølling-Allerød and 8.2 ka event) in the study area. The biomarker records from this sediment core give insights into the variability in sea ice and circulation patterns as well as primary productivity in the Arctic marginal area during the Late Quaternary.

References

Belt, S.T., Massé, G., Rowland, S.J., Poulin, M., Michel, C., LeBlanc, B., 2007. A novel chemical fossil of palaeo sea ice: IP25. Org. Geochem. 38, 16-27.

Knudsen, K.L. and Eiriksson, J., 2002. Application of tephrochronology to the timing and correlation of palaeoceanographic events recorded in Holocene and Late Glacial shelf sediments off North Iceland. Marine Geology 191, 165-188.

Thomas, D. N. and Dieckmann, G. S., 2010. Sea Ice, Blackwell Publ., Oxford, U. K.