SST and salinity patterns in the northern North Atlantic and the Arctic during interglacial MIS 11c: Implications for oceanic circulation reconstruction


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ekandiano [ at ] ifm-geomar.de

Abstract

Sea surface temperature (SST) patterns in the northern North Atlantic, the Nordic seas, and the western Arctic Ocean (AO) were reconstructed across MIS 11c, a potential future climate analogue, using planktic foraminiferal abundances, alkenone-based Uk’37 and glycerol dialkyl glycerol tetraether (GDGT)-based TEX86 analyses, where possible. SSTforam reconstructions were supported by foraminiferal counts of small-sized fractions and rare foraminiferal species, stable oxygen isotope measurements on benthic and planktic foraminiferal species, and ice rafted debris (IRD) records. Additionally, the hydrogen isotopic (δD) compositions of long chain alkenones were determined to assess variations in paleo sea surface salinity in the North Atlantic. The preliminary alkenone δD data show that during MIS 11c salinity values in the North Atlantic were similar to Holocene values. In the North Atlantic our newly produced TEX86 –based SSTs range between 14 and 19 °C in agreement with summer SSTforam (13 and 18 °C) and alkenone SSTs (13 and 16 °C). However, the former showed higher fluctuations than SSTs based on foraminiferal abundances. In concordance with δ18O records TEX86 SSTs demonstrate notable variability in the middle of MIS 11c, between 400 and 410 ka, which we tentatively correlate with an intra-MIS 11c cold event occurring in the Arctic as we previously detected. This implies that MIC 11c climate was probably not as stable as it was believed before. SSTforam records imply that during MIS 11c parts of the AO experienced unusually warm, ice free conditions, whereas the Nordic seas remained rather cold, especially during the early phase of this period, as it is inferred from foraminiferal and alkenone SSTs. At the same time all our SST records show that the North Atlantic was 1-2°C warmer than present during MIS 11c. This pattern suggests that during MIS 11c the North Atlantic Current was deflected to the west, which intensified the subpolar gyre and that, therefore, less warm water was transported to the Nordic seas. Consequently, warm water transport from the Nordic seas to the Arctic was also reduced relative to the modern situation and proportionally more water entered the Arctic from the Pacific Ocean.



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Conference (Poster)
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Primary Division
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Not peer-reviewed
Publication Status
Published
Event Details
AGU Fall Metting, 09 Dec 2013 - 13 Dec 2013, San Francisco.
Eprint ID
33884
Cite as
Kandiano, E. S. , Van der Meer, M. , Schouten, S. , Fahl, K. , Polyak, L. , Cronin, T. , Bauch, H. A. and Sinninghe Damste, J. S. (2013): SST and salinity patterns in the northern North Atlantic and the Arctic during interglacial MIS 11c: Implications for oceanic circulation reconstruction , AGU Fall Metting, San Francisco, 9 December 2013 - 13 December 2013 .


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