ALBERT

Description: We present new surface water proxy records of meltwater production (alkenone derived), relative sea surface temperature (diatom, alkenones) and sea ice (diatoms) changes from the Disko Bugt area off central West Greenland. We combine these new surface water reconstructions with published proxy records (benthic foraminifera - bottom water proxy; dinocyst assemblages – surface water proxy), along with atmospheric temperature from Greenland ice core and Greenland lake records. This multi-proxy approach allows us to reconstruct centennial scale middle to late Holocene palaeoenvironmental evolution of Disko Bugt and the Western Greenland coastal region with more detail than previously available. Combining surface and bottom water proxies identifies the coupling between ocean circulation (West Greenland Current conditions), the atmosphere and the Greenland Ice Sheet. Centennial to millennial scale changes in the wider North Atlantic region were accompanied by variations in the West Greenland Current (WGC). During periods of relatively warm WGC, increased surface air temperature over western Greenland led to ice sheet retreat and significant meltwater flux. In contrast, during periods of cold WGC, atmospheric cooling resulted in glacier advances. We also identify potential linkages between the palaeoceanography of the Disko Bugt region and key changes in the history of human occupation. Cooler oceanographic conditions at 3.5 ka BP support the view that the Saqqaq culture left Disko Bugt due to deteriorating climatic conditions. The cause of the disappearance of the Dorset culture is unclear, but the new data presented here indicate that it may be linked to a significant increase in meltwater flux, which caused cold and unstable coastal conditions at ca. 2 ka BP. The subsequent settlement of the Norse occurred at the same time as climatic amelioration during the Medieval Climate Anomaly and their disappearance may be related to harsher conditions at the beginning of the Little Ice Age. Highlights • Ocean temperature has a strong influence on ice sheet behaviour in West Greenland. • Similar trends in Holocene ocean and Camp Century ice core temperature proxies. • Oceanic conditions influenced the history of human occupation in West Greenland. • Results from surface and sub-surface proxies agree when meltwater influence is low. • Interpretation of surface water proxies complicated when meltwater influence is high

Description: The dataset contains multibeam-derived data and physical and imagery ground-truth data collected with RV Sanna during a 10-day survey in September 2018 in the Disko Bay pilot study area, Western Greenland. The area covers c. 600 km2 in a c. 30x20 km box and the survey combined continuous multibeam data acquisition with intermittent stops for collection of ground-truth data. The aim of the study was to generate the first high-resolution benthic habitat map from Greenland and develop 'best practice' protocol for seafloor mapping in the Arctic. The mapping was carried out using integrated analyses of multibeam bathymetry and backscatter data, and ground-truth data including video sled (14 transects), drop camera (17 deployments) and day grab (17 samples). Table S1 presents all ground-truth data along with corresponding measurements and analyses used in the Disko Bay pilot study, whereas Figures S2-S3 show the gridded multibeam data, bathymetric and backscatter grids (ASCII ESRI; 10x10 m resolution).

Description: The dataset contains multibeam-derived data and physical and imagery ground-truth data collected with RV Sanna during a 10-day survey in September 2018 in the Disko Bay pilot study area, Western Greenland. The area covers c. 600 km2 in a c. 30x20 km box and the survey combined continuous multibeam data acquisition with intermittent stops for collection of ground-truth data. The aim of the study was to generate the first high-resolution benthic habitat map from Greenland and develop 'best practice' protocol for seafloor mapping in the Arctic. The mapping was carried out using integrated analyses of multibeam bathymetry and backscatter data, and ground-truth data including video sled (14 transects), drop camera (17 deployments) and day grab (17 samples). Table S1 presents all ground-truth data along with corresponding measurements and analyses used in the Disko Bay pilot study, whereas Figures S2-S3 show the gridded multibeam data, bathymetric and backscatter grids (ASCII ESRI; 10x10 m resolution).

Description: Holocene oceanographic conditions in Disko Bay, West Greenland were reconstructed from high-resolution diatom records derived from two marine sediment cores. A modern dataset composed of 35 dated surface sediment samples collected along the entire West Greenland coast accompanied by remote sensing data were used to develop a diatom transfer function to reconstruct April Sea Ice Concentration (SIC) supported by July Sea Surface Temperature (SST) in the area. Our quantitative reconstruction shows that oceanographic changes recorded throughout the last c. 11000 years reflect seasonal interplay between spring (April SIC) and summer (July SST) conditions. Our records show clear correlation with climate patterns identified from ice core data from GISP2 and Agassiz-Renland for the early to mid Holocene. The early Holocene deglaciation of western Greenland Ice Sheet was characterised in Disko Bay by initial strong centennial-scale fluctuations in April SIC with amplitude of over 40%, followed by high April SIC and July SST. These conditions correspond to a general warming of the climate in the Northern Hemisphere. A decrease in April SIC and July SST was recorded during the Holocene Thermal Optimum reflecting more stable spring-summer conditions in Disko Bay. During the late Holocene, high April SIC characterised the Medieval Climate Anomaly, while high July SST prevailed during the Little Ice Age, supporting previously identified anti-phase relationship between surface waters in West Greenland and climate in NW Europe. This anti-phase pattern might reflect seasonal variations in regional oceanographic conditions and large-scale fluctuations within the North Atlantic Oscillation and Atlantic Meridional Overturning Circulation.