(English) Holocene Marine and Lacustrine Paleoclimate and Paleomagnetic Records from Iceland

Holocene Marine and Lacustrine Paleoclimate and Paleomagnetic Records from Iceland: Land – Sea Correlations

Sædís Ólafsdóttir´s PhD research (defended in Spring 2010) was to a part based on both the Warm Times/Cold Times project and the VAST project and was partially supported by RANNIS VAST grant, where she tackled the research question:

• What is the magnitude and timing of summer temperature based on climate proxies from marine sediment cores and correlation with terrestrial vegetation change through the Holocene?

Support from RANNÍS student grants to Sædís Ólafsdóttir, PhD student at the University of Iceland, Eimskipafélagsfund University of Iceland awarded to Sædís Ólafsdóttir. Warm Times/Cold Times grant & VAST grant from RANNIS awarded to Áslaug Geirsdóttir & Gifford H Miller.
Collaborators: Áslaug Geirsdóttir, Anne E. Jennings, Gifford H. Miller, Joseph Stoner, Sædís Ólafsdóttir

The implementation of this dissertation was a detailed reconstruction of IC variability on the western shelf of Iceland. The maximum heat transport in the IC occurred between 8 and 4 ka years based on quantitative bottom water temperature reconstruction. Demonstrating a delayed Holocene Thermal Maximum in the marine current system around Iceland compared to the Northern Hemisphere summer insolation receipts. A reconstruction of the ambient seawater δ18Osw based on paired samples of C2 transfer function temperature estimates and oxygen isotopic composition indicates repeated freshwater input to the N Atlantic inflow in the early Holocene impacting the current system before 8 ka. Moreover, a development of a precise chronostratigraphic tool, paleomagnetic secular variations, that operates on a detailed scale to synchronize sediment sequences from land and sea has been conducted. By applying the PSV-method to the marine and lacustrine cores a first hand evaluation on leads and lags in the development of the Holocene climate in Iceland and North Atlantic has been constructed. The combined information indicates that the first order trend in the Holocene climate is driven by solar insolation. The early Holocene is defined by strong influence of the surrounding water masses directly linked to the dynamics of the North Atlantic Ocean. In late Holocene the records diverge and Holocene high frequency variability in the records show anti-phase relationship. This may indicate that parameters other than secular solar insolation, such as volcanism, solar irradiance or changes in ocean atmosphere dynamics, start to play important role in the climate of the northern North Atlantic.