| Summary: | The ongoing climate warming has a profound impact on the sensitive Arctic region and the recent changes in Arctic environment have an alarming rate and magnitude. To better understand the changes taking place in the Arctic region, and to project the future impacts of the ongoing climate change, we need to have records of past climate conditions and past interactions between climate system components, which can be obtained using marine proxy records. This work examines ocean surface conditions from high northern latitudes after the Last Glacial Maximum using marine fossil diatom assemblages. Long-term paleoclimatic and -oceanographic records are obtained from northern Svalbard and central-eastern Baffin Bay using quantitative and qualitative diatom analyses, and sediment grain size distribution analysis. An additional focus of this work was to study the ecology of common northern North Atlantic diatom species and define their relationship to environmental variables (aSSTs and sea ice) in order to identify the best indicator species for these environmental variables and to improve their reliability as paleoceanographic indicators. The Baffin Bay study site was investigated for the deglacial period (10−14 kyr BP), and the results suggest a warmer ocean surface in central-eastern Baffin Bay during the cold Younger Dryas period (11.7−12.9 kyr BP) indicating that the ocean was out of phase with atmospheric conditions over Greenland. The warmer conditions were caused by enhanced inflow of Atlantic-sourced waters and increased solar insolation on the Northern Hemisphere, which amplified seasonality over Baffin Bay and had a significant role triggering the ice margin in West Greenland. The paleoceanographic record from northern Svalbard represents the late Holocene (last ca. 4 200 years), and the results show a clear climate shift at 2.5 kyr BP, as the study location changed from stable, glacier-proximal conditions into fluctuating glacier-distal conditions, emphasizing the sensitivity of the Arctic environment to ...
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