High-resolution alkenone sea surface temperature variability on the North Icelandic Shelf: implications for Nordic Seas palaeoclimatic development during the Holocene

Abstract

The palaeoceanography of the northern Icelandic Shelf for the Holocene period was reconstructed from alkenone indices measured in core JR51-GC35. This contains a continuous record of Holocene sedimentation spanning 0 10.2 cal. kyr BP with a resolution of ~ 20 yr/cm. We have identified a general Holocene cooling trend that has superimposed millennial-scale oscillations of >2°C. Their timing is in close agreement with the timing of glacier advances in northern Iceland. For the later half of the Holocene, the alkenone-sea surface temperature (SST) record from JR51-GC35 correlates with proxy data for the strength of NADW formation recorded in cores south of Iceland. This is interpreted as evidence of a close connection existing between north Icelandic sea surface temperatures and the North Atlantic meridonal overturning circulation. The timing of the millennial-scale SST variability in our core off North Iceland is found to be out of phase, or anti-phased, with the SST variability of a record in the eastern Nordic Seas (MD952011). This suggests that the evolution of Holocene climate in the Nordic Seas was more complex than previously proposed; and it is likely to be caused by differential responses of the Irminger and Norwegian Currents and modulated by changes in atmospheric circulation analogous to the North Atlantic Oscillation.