ALBERT

Description: Atlantic Water (AW) advection plays an important role for climatic, oceanographic and environmental conditions in the eastern Arctic. Situated along the only deep connection between the Atlantic and the Arctic Ocean, the Svalbard Archipelago is an ideal location to reconstruct the past AW advection history and document its linkage with local glacier dynamics, as illustrated in the present study of a 275 cm long sedimentary record from Woodfjorden (northern Spitsbergen; water depth: 171 m) spanning the last ~15,500 years. Sedimentological, micropalaeontological and geochemical analyses were used to reconstruct changes in marine environmental conditions, sea-ice cover and glacier activity. Data illustrate a partial breakup of the Svalbard-Barents Sea Ice Sheet from Heinrich Stadial 1 onwards (until ~14.6 ka). During the Bølling-Allerød (~14.6-12.7 ka), AW penetrated as a bottom water mass into the fjord system and contributed significantly to the destabilisation of local glaciers. During the Younger Dryas (~12.7-11.7 ka), it intruded into intermediate waters while evidence for a glacier advance is lacking. A short-term deepening of the halocline occurred at the very end of this interval. During the early Holocene (~11.7-7.8 ka), mild conditions led to glacier retreat, a reduced sea-ice cover and increasing sea surface temperatures, with a brief interruption during the Preboreal Oscillation (~11.1-10.8 ka). Due to a ~6,000-years gap, the mid-Holocene is not recorded in this sediment core. During the late Holocene (~1.8-0.4 ka), a slightly reduced AW inflow and lower sea surface temperatures compared to the early Holocene are reconstructed. Glaciers, which previously retreated to the shallower inner parts of the Woodfjorden system, likely advanced during the late Holocene. In particular, as topographic control in concert with the reduced summer insolation partly decoupled glacier dynamics from AW advection during this recent interval.

Description: Sedimentological and geochemical (XRF) data together with information from diatom and benthic foraminiferal records of a 3.5 m long gravity core from Ameralik Fjord, southern West Greenland, is used for reconstructing late-Holocene environmental changes in this area. The changes are linked to large-scale North Atlantic ocean and climate variability. AMS 14C-dating of benthic foraminifera indicates that the sediment core records the last 4400 years and covers the termination of the Holocene Thermal Maximum (HTM). The late HTM (4.4 3.2 ka BP) is characterized by high accumulation rates of fine (silty) sediments related to strong meltwater discharge from the Inland Ice. The HTM benthic foraminiferal fauna demonstrates the presence of well-ventilated, saline bottom water originating from inflow of subsurface West Greenland Current water of Atlantic (Irminger Sea) origin. The hydrographic conditions were further characterized by limited sea ice probably related to a mild and relatively windy winter climate. After 3.2 ka BP lower fine-grained sedimentation rates, but a larger input from sea-ice rafted or aeolian coarse material prevailed. This can be related to colder atmospheric conditions with a decreased meltwater discharge and more widespread sea-ice cover in the fjord.

Description: A multiproxy study of palaeoceanographic and climatic changes in northernmost Baffin Bay shows that major environmental changes have occurred since the deglaciation of the area at about 12 500 cal. yr BP. The interpretation is based on sedimentology, benthic and planktonic foraminifera and their isotopic composition, as well as diatom assemblages in the sedimentary records at two core sites, one located in the deeper central part of northernmost Baffin Bay and one in a separate trough closer to the Greenland coast. A revised chronology for the two records is established on the basis of 15 previously published AMS 14C age determinations. A basal diamicton is overlain by laminated, fossil-free sediments. Our data from the early part of the fossiliferous record (12 300 - 11 300 cal. yr BP), which is also initially laminated, indicate extensive seasonal sea-ice cover and brine release. There is indication of a cooling event between 11 300 and 10 900 cal. yr BP, and maximum Atlantic Water influence occurred between 10 900 and 8200 cal. yr BP (no sediment recovery between 8200 and 7300 cal. yr BP). A gradual, but fluctuating, increase in sea-ice cover is seen after 7300 cal. yr BP. Sea-ice diatoms were particularly abundant in the central part of northernmost Baffin Bay, presumably due to the inflow of Polar waters from the Arctic Ocean, and less sea ice occurred at the near-coastal site, which was under continuous influence of the West Greenland Current. Our data from the deep, central part show a fluctuating degree of upwelling after c. 7300 cal. yr BP, culminating between 4000 and 3050 cal. yr BP. There was a gradual increase in the influence of cold bottom waters from the Arctic Ocean after about 3050 cal. yr BP, when agglutinated foraminifera became abundant. A superimposed short-term change in the sea-surface proxies is correlated with the Little Ice Age cooling.

Description: Dinoflagellate cysts and XRF core scanning data from two marine sediment cores from embayments north (Bonavista Bay) and south ((Placentia Bay) of Newfoundland show significant changes in ocean and atmospheric conditions of the SW Labrador Sea region during the last 5700 years. Fresh and cold conditions, probably accompanied by seasonal sea ice, prevailed both north and south of Newfoundland from c. 5.7 to 4.0 cal. kyr BP. This may be linked to intensified Labrador Current export of cold meltwater and/or sea ice from the Arctic, presumably related to warmer conditions in the northernmost latitudes and the prevalence of strong (north)westerly winds. After c. 4.0 cal. kyr BP, sea-surface conditions warmed up and sea ice decreased northeast of Newfoundland, but conditions were still cold south of Newfoundland. This suggests a decrease in Arctic meltwater export and westerly wind strength. After 2.9 - 2.5 cal. kyr BP, only minor changes in sea-surface conditions affected the study sites. Sea-surface temperatures increased and sea ice decreased at both sites, which may be related to a more meridional atmospheric circulation pattern associated with the general Northern Hemisphere neoglacial cooling. In Placentia Bay the warmest part of the record corresponds to the Roman Warm Period, while the warmest part of the records in Bonavista Bay notably corresponds to the Dark Ages.

Description: The mass loss from the Greenland Ice Sheet has increased over the past two decades. Marine-terminating glaciers contribute significantly to this mass loss due to increased melting and ice discharge. Rapid retreat periods of these tidewater glaciers have been linked to the concurrent inflow of warm, Atlantic derived waters. However, little is known about the 15 variability of Atlantic-derived waters within these fjords, due to a lack of multi-annual, in situ measurements. Thus, to better understand the potential role of ocean warming on glacier retreat, reconstructions that characterize the variability of Atlantic water inflow to these fjords are required. Here, we investigate foraminiferal assemblages in a sediment core from Upernavik Fjord, West Greenland, in which the major ice stream Upernavik Isstrøm terminates. We investigate the environmental characteristics that control species diversity and derive that it is predominantly controlled by changes in bottom water 20 variability. Hence, we provide a reconstruction of Atlantic water inflow to Upernavik Fjord, spanning the period 1925-2012. This reconstruction reveals peak Atlantic water inflow during the 1930s and again after 2000, a pattern that is similar to the Atlantic Multidecadal Oscillation (AMO). We compare these results to historical observations of front positions of Upernavik Isstrøm. This reveals that inflow of warm, Atlantic-derived waters indeed likely contributed to high retreat rates in the 1930s and after 2000. However, moderate retreat rates of Upernavik Isstrøm also prevailed in the 1960s/1970s, showing that retreat 25 continued despite reduced Atlantic water inflow, albeit at a lower rate. Considering the link between bottom water variability and the AMO in Upernavik Fjord and the fact that a persistent negative phase of the AMO is expected for the next decade, Atlantic water inflow into the fjord may decrease in the next ~10 years.