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The increasing anthropogenic CO 2 forcing of the climate system calls for a better understanding of how polar ice sheets may respond to accelerating global warming. The sensitivity of the Greenland ice sheet to polar amplification, changes in ocean heat transport, and deteriorating perennial sea ice conditions makes the Northeast Greenland margin a pertinent location with respect to understanding the impact of climate change on ice sheet instability and associated sea level rise. Throughout the Cenozoic, ocean heat fluxes toward and along Northeast Greenland have been controlled by water mass exchanges between the Arctic and Atlantic oceans. A key element here is the current flow through oceanic gateways, notably the Fram Strait and the Greenland–Scotland Ridge. To gain a long-term (million-year) perspective of ice sheet variability in this region, it is essential to understand the broader context of ice–ocean–tectonic interactions. Coupling between the ice sheet, the subsurface, the ocean, and sea ice are readily observable today in Northeast Greenland, but geological records to illuminate long-term trends and their interplay with other parts of the global climate system are lacking. Consequently, the NorthGreen workshop was organized by the Geological Survey of Denmark and Greenland in collaboration with Aarhus (Denmark) and Stockholm (Sweden) universities in November 2022 to develop mission-specific platform (MSP) proposals for drilling the Northeast Greenland margin under the umbrella of the MagellanPlus Workshop Series Programme of the European Consortium for Ocean Research Drilling (ECORD). Seventy-one participants representing a broad scientific community discussed key scientific questions and primary targets that could be addressed through scientific drilling in Northeast Greenland. Three pre-proposals were initiated during the workshop targeting Morris Jesup Rise, the Northeast Greenland continental shelf, and Denmark Strait. [ABSTRACT FROM AUTHOR]

The size of the last glacial ice sheet on the Northeast (NE) Greenland shelf and its interaction with ocean circulation have been the subject of debate. Here we provide insights into the extent of the ice sheet around the Last Glacial Maximum (LGM) and investigate timing and strength of changes in the flow of Atlantic Water. The study is based on a multiproxy investigation of a marine sediment core, gravity core DA17‐NG‐ST01‐019G, from 323‐m water depth at the NE Greenland shelf edge at 79.4°N. We present benthic and planktic foraminiferal distribution data, AMS‐14C dates, sedimentological (ice‐rafted debris (IRD) and grain sizes), and geochemical (XRF) data in combination with geophysical (sub‐bottom profiler) data. The oldest sediments at the study site are dated to 25.5–17.5 ka, encompassing the time frame from the beginning of the LGM to the early deglaciation. This part is overlain by sediments from the late deglaciation and Holocene. The deposits dating from the LGM are very rich in both planktic and benthic foraminifera and macrofossils of excellent preservation. The faunas show that the site generally was affected by a strong flow of relatively warm subsurface Atlantic Water during the LGM and Early Holocene. Conditions turned more polar with cold bottom water flow in the Middle–Late Holocene (c. 7.5 ka to Recent) with presence of mainly agglutinated benthic foraminiferal species. Our data from the LGM also indicate that the deposits were mixed by iceberg scouring, confirmed by the geophysical data showing extensive ploughing of the sediments on the outer shelf area. The results further indicate that the Greenland Ice Sheet did not reach to the edge of the NE Greenland shelf at 79.4°N during the LGM 24–18 ka. [ABSTRACT FROM AUTHOR]

Climate warming and the resulting acceleration of freshwater discharge from the Greenland Ice Sheet are impacting Arctic marine coastal ecosystems, with implications for their biological productivity. To accurately project the future of coastal ecosystems and place recent trends into perspective, palaeo-records are essential. Here, we show runoff estimates from the late 19th century to the present day for a large sub-Arctic fjord system (Nuup Kangerlua, southwest Greenland) influenced by both marine- and land-terminating glaciers. We followed a multiproxy approach to reconstruct spatial and temporal trends in primary production from four sediment core records, including diatom fluxes and assemblage composition changes and biogeochemical and sedimentological proxies (total organic carbon, nitrogen, C/N ratio, biogenic silica, δ13 C, δ15 N, and grain-size distribution). We show that an abrupt increase in freshwater runoff in the mid-1990s was reflected by a 3-fold increase in biogenic silica fluxes in the glacier-proximal area of the fjord. In addition to increased productivity, freshwater runoff modulates the diatom assemblages and drives the dynamics and magnitude of the diatom spring bloom. Our records indicate that marine productivity is higher today than it has been at any point since the late 19th century and suggest that increased mass loss of the Greenland Ice Sheet may continue promoting high productivity levels at sites proximal to marine-terminating glaciers. We highlight the importance of palaeo-records in offering a unique temporal perspective on ice–ocean–ecosystem responses to climate forcing beyond existing remote sensing or monitoring time series. [ABSTRACT FROM AUTHOR]

Sediment core ER11-16 from Køge Bugt in Southeast Greenland is used to assess early Holocene palaeoceanographic changes and sediment rafting from icebergs calved from the large outlet glaciers in the area. Diatom analysis reconstructs variability in surface water temperature, salinity and sea-ice concentrations, and benthic foraminiferal assemblages is used to reconstruct subsurface ocean conditions. We report Holocene Thermal Maximum in Southeast Greenland during the early Holocene (at least since onset of the record 9100 cal yr BP) until around 4500 cal yr BP, which contrasts with a delay until the mid-Holocene of the Holocene Thermal Maximum in South and Southwest Greenland. The early Holocene warming in Southeast Greenland was caused by a combination of high solar insolation and a weakened subpolar gyre, both of which served to warm the Irminger Current waters subducting onto the shelf. At the same time, the surface temperature was relatively high and sea-ice cover in the polar surface waters of the East Greenland Current was relatively low. High levels of iceberg rafting occurred in Køge Bugt during the early Holocene, synchronously with these warm oceanic temperatures. This is attributed to an increase in iceberg production from the extensive, but retreating, Greenland Ice Sheet. The warm surface conditions were interrupted by a marked and short-lived increase in sea ice around 8200 years ago, providing the first evidence of this global cold episode in Southeast Greenland. After 4500 cal. yr BP, sea-ice cover increased with an expansion of the East Greenland Current, suppressing the inflow of warmer subsurface Irminger Current water to the Southeast Greenland shelf. We relate this oceanic shift to the decreased Northern Hemisphere summer solar insolation. Multi-centennial variability is observed in the grain size spectrum of iceberg rafted debris; a finding we interpret in the context of palaeoceanographic changes. [ABSTRACT FROM AUTHOR]

We address here the specific timing and amplitude of sea‐surface conditions and productivity changes off SW Greenland, northern Labrador Sea, in response to the high deglacial meltwater rates, the Early Holocene maximum insolation and Neoglacial cooling. Dinocyst assemblages from sediment cores collected off Nuuk were used to set up quantitative records of sea ice cover, seasonal sea‐surface temperature (SST), salinity (SSS), and primary productivity, with a centennial to millennial scale resolution. Until ~10 ka BP, ice‐proximal conditions are suggested by the quasi‐exclusive dominance of heterotrophic taxa and low dinocyst concentrations. At about 10 ka BP, an increase in species diversity and abundance of phototrophic taxa marks the onset of interglacial conditions at a regional scale, with summer SST reaching up to 10 °C between 8 and 5 ka BP, thus in phase with the Holocene Thermal Maximum as recorded in the southern Greenlandic areas/northern Labrador Sea. During this interval, low SSS but high productivity prevailed in response to high meltwater discharge and nutrient inputs from the Greenland Ice Sheet. After ~5 ka BP, a decrease in phototrophic taxa marks a two‐step cooling of surface waters. The first started at ~5 ka BP, and the second at ~3 ka BP, with a shift toward colder conditions and higher SSS suggesting reduced meltwater discharge during the Neoglacial. This second step coincides with the disappearance of the Saqqaq culture. The gap in human occupation in west Greenland, between the Dorset and the Norse settlements from 2000 to 1000 years BP, might be linked to high amplitude and high frequency variability of ocean and climate conditions. [ABSTRACT FROM AUTHOR]

Climate warming is rapidly reshaping the Arctic cryosphere and ocean conditions, with consequences for sea ice and pelagic productivity patterns affecting the entire marine food web. To predict how ongoing changes will impact Arctic marine ecosystems, concerted effort from various disciplines is required. Here, we contribute multi‐decadal reconstructions of changes in diatom production and sea‐ice conditions in relation to Holocene climate and ocean conditions off northwest Greenland. Our multiproxy study includes diatoms, sea‐ice biomarkers (IP25 and HBI III) and geochemical tracers (TOC [total organic carbon], TOC:TN [total nitrogen], δ13C, δ15N) from a sediment core record spanning the last c. 9,000 years. Our results suggest that the balance between the outflow of polar water from the Arctic, and input of Atlantic water from the Irminger Current into the West Greenland Current is a key factor in controlling sea‐ice conditions, and both diatom phenology and production in northeastern Baffin Bay. Our proxy record notably shows that changes in sea‐surface conditions initially forced by Neoglacial cooling were dynamically amplified by the shift in the dominant phase of the Arctic Oscillation (AO) mode that occurred at c. 3,000 yr BP, and caused drastic changes in community composition and a decline in diatom production at the study site. In the future, with projected dominant‐positive AO conditions favored by Arctic warming, increased water column stratification may counteract the positive effect of a longer open‐water growth season and negatively impact diatom production. [ABSTRACT FROM AUTHOR]

Baffin Bay is a semi-enclosed basin connecting the Arctic Ocean and the western North Atlantic, thus making out a significant pathway for heat exchange. Here we reconstruct the alternating advection of relatively warmer and saline Atlantic waters versus the incursion of colder Arctic water masses entering Baffin Bay through the multiple gateways in the Canadian Arctic Archipelago and the Nares Strait during the Holocene. We carried out benthic foraminiferal assemblage analyses, X-ray fluorescence scanning, and radiocarbon dating of a 738 cm long marine sediment core retrieved from eastern Baffin Bay near Upernavik, Greenland (Core AMD14-204C; 987 m water depth). Results reveal that eastern Baffin Bay was subjected to several oceanographic changes during the last 9.2 kyr. Waning deglacial conditions with enhanced meltwater influxes and an extensive sea-ice cover prevailed in eastern Baffin Bay from 9.2 to 7.9 ka. A transition towards bottom water amelioration is recorded at 7.9 ka by increased advection of Atlantic water masses, encompassing the Holocene Thermal Maximum. A cold period with growing sea-ice cover at 6.7 ka interrupts the overall warm subsurface water conditions, promoted by a weaker northward flow of Atlantic waters. The onset of the neoglaciation at ca. 2.9 ka is marked by an abrupt transition towards a benthic fauna dominated by agglutinated species, likely in part explained by a reduction of the influx of Atlantic Water, allowing an increased influx of the cold, corrosive Baffin Bay Deep Water originating from the Arctic Ocean to enter Baffin Bay through the Nares Strait. These cold subsurface water conditions persisted throughout the Late Holocene, only interrupted by short-lived warmings superimposed on this cooling trend. [ABSTRACT FROM AUTHOR]

Marine fjords with active glacier outlets are hot spots for organic matter burial in the sediments and subsequent microbial mineralization. Here, we investigated controls on microbial community assembly in sub-arctic glacier-influenced (GI) and non-glacier-influenced (NGI) marine sediments in the Godthåbsfjord region, south-western Greenland. We used a correlative approach integrating 16S rRNA gene and dissimilatory sulfite reductase (dsrB) amplicon sequence data over six meters of depth with biogeochemistry, sulfur-cycling activities, and sediment ages. GI sediments were characterized by comparably high sedimentation rates and had "young" sediment ages of <500 years even at 6 m sediment depth. In contrast, NGI stations reached ages of approximately 10,000 years at these depths. Sediment age-depth relationships, sulfate reduction rates (SRR), and C/N ratios were strongly correlated with differences in microbial community composition between GI and NGI sediments, indicating that age and diagenetic state were key drivers of microbial community assembly in subsurface sediments. Similar bacterial and archaeal communities were present in the surface sediments of all stations, whereas only in GI sediments were many surface taxa also abundant through the whole sediment core. The relative abundance of these taxa, including diverse Desulfobacteraceae members, correlated positively with SRRs, indicating their active contributions to sulfur-cycling processes. In contrast, other surface community members, such as Desulfatiglans , Atribacteria , and Chloroflexi , survived the slow sediment burial at NGI stations and dominated in the deepest sediment layers. These taxa are typical for the energy-limited marine deep biosphere and their relative abundances correlated positively with sediment age. In conclusion, our data suggests that high rates of sediment accumulation caused by glacier runoff and associated changes in biogeochemistry, promote persistence of sulfur-cycling activity and burial of a larger fraction of the surface microbial community into the deep subsurface. [ABSTRACT FROM AUTHOR]

The mass loss from the Greenland Ice Sheet has increased over the past 2 decades. Marine-terminating glaciers contribute significantly to this mass loss due to increased melting and ice discharge. Periods of rapid retreat of these tidewater glaciers have been linked to the concurrent inflow of warm Atlantic-sourced waters. However, little is known about the variability of these Atlantic-derived waters within the 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 the 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 conclude that the foraminiferal assemblage is predominantly controlled by changes in bottom water composition and provide a reconstruction of Atlantic water inflow to Upernavik Fjord, spanning the period 1925–2012. This reconstruction reveals peak Atlantic water influx during the 1930s and again after 2000, a pattern that is comparable to the Atlantic Multidecadal Oscillation (AMO). The comparison of these results to historical observations of front positions of Upernavik Isstrøm reveals that inflow of warm Atlantic-derived waters likely contributed to high retreat rates in the 1930s and after 2000. However, moderate retreat rates of Upernavik Isstrøm also prevailed in the 1960s and 1970s, showing that glacier retreat continued despite a 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 coming decade, potentially minimizing or stabilizing the retreat of Upernavik Isstrøm during this time interval. [ABSTRACT FROM AUTHOR]

Polar bear (Ursus maritimus) is the apex predator of the Arctic, largely dependent on sea-ice. The expected disappearance of the ice cover of the Arctic seas by the mid 21st century is predicted to cause a dramatic decrease in the global range and population size of the species. To place this scenario against the backdrop of past distribution changes and their causes, we use a fossil dataset to investigate the polar bear's past distribution dynamics during the Late Glacial and the Holocene. Fossil results indicate that during the last deglaciation, polar bears were present at the southwestern margin of the Scandinavian Ice Sheet, surviving until the earliest Holocene. There are no Arctic polar bear findings from 8000–6000 years ago (8–6 ka), the Holocene's warmest period. However, fossils that date from 8-9 ka and 5–6 ka suggest that the species likely survived this period in cold refugia located near the East Siberian Sea, northern Greenland and the Canadian Archipelago. Polar bear range expansion is documented by an increase in fossils during the last 4000 years in tandem with cooling climate and expanding Arctic sea ice. The results document changes in polar bear's distribution in response to Late Glacial and Holocene Arctic temperature and sea ice trends. • At the end of the last glacial period, from 15 to 11 ka, polar bears were present in the western coast of Scandinavia (Denmark, Sweden, Norway, Iceland), until this Scandinavian subpopulation went regionally extinct in the early Holocene, about 11.5 ka • No polar bear remains have been discovered from the period 8 to 6 ka anywhere in the Arctic, but the findings from Svalbard and eastern arctic Siberia 8–9 thousand years ago and from NW Greenland after 6 ka suggest that the likely refugia of the polar bear during the Holocene thermal maximum were in the High Arctic fringes of the Arctic Basin. • During the last four millennia there has been a significant expansion of the polar bear's range, driven by a cooling trend and associated expansion of the arctic sea ice, until the onset of the current, human-induced warming. • Our results highlight the dynamism of the polar bear's distribution range in response to changes in high-latitude climate and Arctic sea ice conditions. [ABSTRACT FROM AUTHOR]

In order to establish a baseline for proxy-based reconstructions for the Young Sound-Tyrolerfjord system (Northeast Greenland), we analysed the spatial distribution of primary production and sea ice proxies in surface sediments from the fjord, against monitoring data from the Greenland Ecosystem Monitoring Programme. Clear spatial gradients in organic carbon and biogenic silica contents reflected marine influence, nutrient availability and river-induced turbidity, in good agreement with in situ measurements. The sea ice proxy IP was detected at all sites but at low concentrations, indicating that IP records from fjords need to be carefully considered and not directly compared to marine settings. The sea ice-associated biomarker HBI III revealed an open-water signature, with highest concentrations near the mid-July ice edge. This proxy evaluation is an important step towards reliable palaeoenvironmental reconstructions that will, ultimately, contribute to better predictions for this High Arctic ecosystem in a warming climate. [ABSTRACT FROM AUTHOR]

The article presents preliminary results of the sediment coring work and information on the bathymetry in the fjord area in Greenland. Topics covered include the decrease in sea ice experienced in the northern hemisphere, the use of synthetic aperture radar (SAR) and visible band images to characterise the ice dynamics of the fjord system and the assessment of the lead and cesium content of the sediment cores.

Volatile fatty acids (VFAs) are key intermediates in the anaerobic mineralization of organic matter in marine sediments. We studied the role of VFAs in the carbon and energy turnover in the sulfate reduction zone of sediments from the sub-arctic Godthåbsfjord (SW Greenland) and the adjacent continental shelf in the NE Labrador Sea. VFA porewater concentrations were measured by a new two-dimensional ion chromatography-mass spectrometry method that enabled the direct analysis of VFAs without sample pretreatment. VFA concentrations were low and surprisingly constant (4-6 µmol L-1 for formate and acetate, and 0.5 µmol L-1 for propionate) throughout the sulfate reduction zone. Hence, VFAs are turned over while maintaining a stable concentration that is suggested to be under a strong microbial control. Estimated mean diffusion times of acetate between neighboring cells were <1 s, whereas VFA turnover times increased from several hours at the sediment surface to several years at the bottom of the sulfate reduction zone. Thus, diffusion was not limiting the VFA turnover. Despite constant VFA concentrations, the Gibbs energies (Gr) of VFA-dependent sulfate reduction decreased downcore, from -28 to -16 kJ (mol formate)-1, -68 to -31 kJ (mol acetate)-1, and -124 to -65 kJ (mol propionate)-1. Thus, Gr is apparently not determining the in-situ VFA concentrations directly. However, at the bottom of the sulfate zone of the shelf station, acetoclastic sulfate reduction might operate at its energetic limit at ~ -30 kJ (mol acetate)-1. It is not clear what controls VFA concentrations in the porewater but cell physiological constraints such as energetic costs of VFA activation or uptake could be important. We suggest that such constraints control the substrate turnover and result in a minimum Gr that depends on cell physiology and is different for individual substrates. [ABSTRACT FROM AUTHOR]

The freshwater runoff from the glaciated and snow-covered Sermilik Fjord catchment, SE Greenland, was estimated at annual resolution for the period 1900–2008 and at decadal resolution for the past four millennia. Our simulations were forced with available meteorological station data (1900–2008) and Greenland ice core estimated temperature data (1899 bc–ad 1980) from Dye3 and GISP2. Time series of estimated ice discharge (2000–2009) for the three major outlet glaciers Helheim, Fenris, and Midgård indicate that 53–74% of the ice discharge variations could be explained by variations in areally averaged glacier terminus surface (supraglacial) runoff. Based on these data and together with calculated subglacial geothermal and frictional melting as well as net precipitation for the fjord area, the Sermilik Fjord freshwater flux was deduced for the period 1900–2008. Our simulations indicated that during the last century surface freshwater runoff has equaled 13% of the Sermilik Fjord average freshwater flux of 33.0±5.7×109 m3/yr, covering a periodic runoff variation of 20 years. Ice discharge has accounted for 81%, with 63% of the freshwater flux originated from the Helheim glacier. This indicates that the Helheim outlet glacier plays a dominant role as a freshwater source to both Sermilik Fjord and ultimately the Irminger Sea. For the palaeorecords of the last 4000 years, simulated surface runoff has averaged 4.4±0.2×109 m3/yr. A very weak decreasing trend in runoff over the last 4 k years (1899 bc–ad 1980) is presumably associated with the general insolation-generated Northern Hemisphere cooling since the Holocene Thermal Maximum. Our simulations furthermore indicated centennial- to submillennial-scale variations in surface runoff concurrent with the well-known climate episodes such as the ‘Roman Warm Period’, the ‘Dark Ages Cold Period’, the ‘Medieval Climate Anomaly’, and the ‘Little Ice Age’. During the ‘Little Ice Age’, e.g., the average surface runoff was about 0.7×109 m3/yr lower than today, while the increase in runoff for the Modern Warming, since the late 1800s, was the second strongest and fastest for the last 4 k years. [ABSTRACT FROM PUBLISHER]

A marine sediment core from Vaigat in Disko Bugt, West Greenland, has been analysed in terms of lithology, dinoflagellate cysts and foraminifera in order to evaluate the influence of oceanographic variability on West Greenland glacier stability. The data show that during the past 5200 years the Atlantic foraminiferal abundance in the subsurface waters of the West Greenland Current (WGC) episodically increased, indicating periods of increases in the inflow of subsurface warm Atlantic water at 2000—1500 cal. yr BP and 1300 cal. yr BP as well as periods of less pronounced increased bottom-water temperatures around 4700—4000 cal. yr BP, 3100—2800, 2600, 1000—800, 500—400, and at 200 cal. yr. The sedimentological and dinoflagellate cyst data indicate that these episodes with enhanced advection of Irminger Sea-derived waters are accompanied by increased iceberg rafting, which we link to increased iceberg calving in relation to destabilization of the Jakobshavn Isbrae. The long-term trend in the data documents the end of a late-Holocene Thermal Maximum between 5200 and 4300 cal. yr BP and a final onset of the Neoglaciation at 3500 cal. yr BP. Increased responses of the iceberg rafting after 3500 cal. yr BP, reflects a westward/seaward advance of the glacier margin in relation to onset of Neoglaciation and a development of the glacier into a floating tongue after 2000 cal. yr BP. A comparison of our record with a record from the eastern North Atlantic indicates that a NAO-like anomaly pattern between subsurface waters in West Greenland and atmospheric temperature in the Eastern North Atlantic may have been operating during most of the late Holocene. However, during the past 1000 years the NAO signal may have weakened as some other mode of climate variability overprints the anti-phase climate signal in this region. [ABSTRACT FROM AUTHOR]

Abstract: The reconstruction of past sea-surface conditions in the Labrador Sea is essential for understanding climate fluctuations in the North Atlantic region. We here study late Holocene sea-surface conditions off West Greenland in order to elucidate the possible relationship between a North Atlantic seesaw and centennial to millennial-scale climate fluctuations in the Labrador Sea region. For that purpose we have studied the particulate organic matter (especially dinoflagellate cysts and acritarchs) from two marine sediment cores from Disko Bugt, central West Greenland. Our data show significant variations in sea-surface temperature and sea-ice cover during the last ca. 3200 years. After a cooling at ca. 2.9 ka cal. BP, presumably related to the Neoglacial cooling seen in large parts of the Northern Hemisphere, the area was subjected to significant variability both in the entrainment of Atlantic Water (West Greenland Current water) and in atmospheric temperatures. From 2.0–1.5 ka cal. BP corresponding to the later part of the ‘Roman Warm Period’, the area experienced a return to a stronger influx of Atlantic water and an increased fresh-water influx from land probably related to increased precipitation or to melt-water outflow from the nearby inland ice. The ‘Dark Ages’ (1.5–1.3 ka cal. BP) were characterised by an only minor cooling of the surface waters. However, as seen in other records from the Labrador Sea region, the beginning of the ‘Medieval Warm Period’ (1.3–0.9 ka cal. BP) signified a severe cooling presumably due to a significant reduction in Atlantic water entrainment. The cold conditions continued through the ‘Little Ice Age’ (after 0.9 ka cal. BP) although the area seems to have experienced a minor decrease in sea-ice cover until 0.5 ka cal. B.P., after which sea-ice cover may again have increased. The period of ‘Modern Warming’ is not represented in our data. Our study shows that a North Atlantic Oscillation-type pattern played a significant role in the late Holocene centennial to millennial-scale climate fluctuations in the Labrador Sea region. However, this cannot explain the full complexity of the climate signal. The fact that a simple pattern of ‘cold’ versus ‘warm’ climate scenario does not exist demonstrates that it will hardly be feasible to select the correct ‘baseline’ data set when modelling future climate development. [Copyright &y& Elsevier]

Historical records of Arctic ice margin show a general retreat of seasonal ice since the late 19th century, and according to model simulations, the Arctic Ocean may become seasonally ice-free in about 20 years. However, despite the extreme societal and environmental relevance, natural sea-ice variability around Greenland and its linkages with ocean circulation, Greenland ice-sheet dynamics and external forcing is still not well understood. Because of the scarce knowledge about late-Holocene marine environments and corresponding natural sea-ice states around Greenland, it is crucial to develop high-resolution reconstructions extending back in time beyond the instrumental and satellite era. Therefore, a 410 cm long sediment core sampled on the North East Greenland shelf (79°06'N, 11°90'W) was analyzed in order to establish multidecadal to millennial-scale time series of general oceanic conditions and sea ice during the Holocene, with primary focus on the last few millennia. Here the first results are presented, based on a combination of sedimentological and benthic foraminiferal assemblage analyses of the selected core. [ABSTRACT FROM AUTHOR]

The subpolar gyre (SPG) is a major feature controlling climate and ocean circulation of North Atlantic region, with significant variability of cold and warm ocean currents feeding into the gyre. The western sector of the SPG, the Labrador Sea, is a major deep water formation site, thus also directly influencing the Atlantic Meridional Overturning Circulation (AMOC). Here we compare records of SPG circulation from selected sites off south Iceland, west and southeast Greenland and Newfoundland in order to establish a combined record of SPG circulation through the Holocene. Our records combine multi-proxy studies (foraminifera, diatoms, dinoflagellate cysts, sediment properties, biomarkers, elemental composition and environmental magnetics) from a range of marine sediment cores to test for large-scale changes in ocean circulation in the Holocene. The SPG region has experienced several major changes in ocean circulation, with a major reorganisation occurring during the deglaciation and again at approximately 7.5 kyr BP and 3-4 kyr BP. Especially during the late Holocene, climatic conditions were largely antiphase in the Labrador Sea to the general North Atlantic region climate due to influence of the Northern Annular Mode affecting the strength of the Atlantic component of the West Greenland Current as well as the flow of the Labrador Current. This again influenced the strength and expansion of the SPG and exemplifies that the SPG has undergone significant variability at multi-decadal to millennial time scales during the Holocene. [ABSTRACT FROM AUTHOR]

Climate archives available from deep sea and marine shelf sediments, glaciers, lakes, and ice cores in and around Greenland allow us to place the current trends in regional climate, ice sheet dynamics, and land surface changes in a broader perspective. We show that, during the last decade (2000s), atmospheric and sea surface temperatures are reaching levels last encountered millennia ago, when northern high latitude summer insolation was higher due to a different orbital configuration. Records from lake sediments in southern Greenland document major environmental and climatic conditions during the last 10,000 years, highlighting the role of soil dynamics in past vegetation changes, and stressing the growing anthropogenic impacts on soil erosion during the recent decades. Furthermore, past and present changes in atmospheric and oceanic heat advection appear to strongly influence both regional climate and ice sheet dynamics. Projections from climate models are investigated to quantify the magnitude and rates of future changes in Greenland temperature, which may be faster than past abrupt events occurring under interglacial conditions. Within one century, in response to increasing greenhouse gas emissions, Greenland may reach temperatures last time encountered during the last interglacial period, approximately 125,000 years ago. We review and discuss whether analogies between the last interglacial and future changes are reasonable, because of the different seasonal impacts of orbital and greenhouse gas forcings. Over several decades to centuries, future Greenland melt may act as a negative feedback, limiting regional warming albeit with global sea level and climatic impacts. WIREs Clim Change 2012 doi: 10.1002/wcc.186 For further resources related to this article, please visit the WIREs website. [ABSTRACT FROM AUTHOR]

Here we present a 100 year long proxy record for the renewal rate of the subsurface ocean waters in Sermilik Fjord at the edge of Helheim Glacier, based on investigations of two sediment cores (ER11-24 and ER11-25) obtained from the head of the fjord. By calculating the mean sortable silt (SS¯) in current-sorted melt water plume sediments we find that episodes of increased water renewal rates lasting 3–5 years coincide with a positive North Atlantic Oscillation (NAO) index. This is not surprising as low pressure systems and northeasterly storms are observed more frequently along the east coast of Greenland during positive NAO years as a result of the northward shift in the North Atlantic storm track. Previous studies of sediment cores obtained from the mid-region of the fjord showed that Helheim Glacier destabilization coincides with a negative NAO index. Therefore we conclude that inter-annual variability in storm-induced flushing of Sermilik Fjord and thus the water renewal rate towards the glacier margin is not the controlling factor for inter-annual variability in Helheim Glacier destabilization. Such knowledge may have implications on predictive model studies of ice-ocean interactions and glacier behavior. [ABSTRACT FROM AUTHOR]

Abstract: A diatom-based reconstruction of surface-water paleoclimatic and paleoceanographic changes in Ameralik Fjord, southwest Greenland, is presented for the Holocene interval 8800 to 3600 cal yrs B.P. A minor episode of cold surface-water conditions is found at ca. 8000–7800 cal yrs B.P. This may be due to the local conditions in the fjord and linked to the culmination of a strong melt-water outflow rather than reflecting the widespread North Atlantic (8.2 ka) cooling event. Warming of surface-water condition from 7800 to 7100 cal yrs B.P., probably corresponding to the early and warmest part of the Holocene Thermal Maximum (HTM) in this region, is reflected in the diatom assemblages and supported by other proxies. The West Greenland Current (WGC) influences the fjord strongly during this interval, indicating enhanced advection of Atlantic water-masses derived from the Irminger Current (IC). A major sedimentary change with a hiatus between 6800 and 4400 cal yrs B.P. prevents a reconstruction of mid-Holocene paleoceanograpy. The final and less prominent part of the HTM is found after 4400 cal yrs B.P. Previous studies from the same site have shown this final stage of the HTM to end at 3200 cal yrs B.P. with the onset of the ‘Neoglaciation’. Our study provides further evidence that the marine sedimentary record from West Greenland fjords yields paleoenvironmental information reflecting a significant link between local and large scale North Atlantic oceanographic and climatic changes. [Copyright &y& Elsevier]

A better understanding of past extent and dynamics of the Greenland Ice Sheet (GrIS) is required to provide context for present-day observations, to constrain numerical climate models and to predict future scenarios of ice-sheet response to recent climatic change. The presence of a grounded GrIS on the NE Greenland shelf during the Last Glacial Maximum (LGM) is supported by high-resolution seismic data combined with multi-proxy analyses of sediment gravity cores from Norske Trough. Our results indicate that an ice stream advanced to the outer shelf during the LGM. Recessional moraines and grounding zone wedges on the seafloor of the outer to middle shelf show that initial retreat was episodic, punctuated by two major stillstands. Pinning points for grounding-zone stabilization were controlled by pre-LGM trough topography. In contrast, preserved large-scale glacial lineations on the seafloor of the inner shelf, formed during the advance, indicate that ice retreat from the inner trough to the coast-proximal position was rapid in order to maintain the former carved morphology. Initial ice retreat was underway before 16.6 cal Kyr BP, earlier than previously known for this sector of the NE Greenland shelf. The inner shelf was free from grounded ice at least by 12.5 cal Kyr BP, and likely before. Retreat occurred in a glaciomarine setting and the ice sheet was fringed by a floating ice shelf. There is no evidence of grounded-ice readvances during the Younger Dryas, although a floating ice shelf with vigorous sea-ice and iceberg rafting production occupied the inner shelf at 11.3 cal Kyr BP. 14C dates reveal initial stepwise ice retreat followed by a fast retreat that coincides with Heinrich Stadial 1 and the Bølling-Allerød interstadial, respectively. During both periods there was increased inflow of warm Atlantic Water, indicating a strong ocean/climate control on the late deglaciation of Norske Trough. Following the late deglaciation, postglacial (Holocene) sedimentation records a change from an ice-distal glaciomarine environment, to an open marine environment and complete ice shelf disintegration. On the innermost shelf of the Norske Trough, the ice shelf disintegrated and reformed once before the final break-up occurred at 9.6 cal Kyr BP. [ABSTRACT FROM AUTHOR]

Marine sedimentary cores were collected off western Greenland margins to reconstructchanges in sea-surface conditions during the Holocene and to document the climate-ocean-icedynamics. In the south, close to Nuuk in eastern Labrador Sea, core SA13-ST3-20G providedrecords with a centennial resolution over the last 12,000 years. North of Davis Strait, in theeastern Baffin Bay, core MSM343300 from Disko Bugt permitted to document changesthrough the last 10,000 years in complement to other Baffin Bay records (cf. Gibb et al. theHolocene 2015). The dinocyst assemblages provided information on past sea-surfaceconditions, including temperature (SST), salinity and sea ice based on modern analoguetechnique. Both cores recorded significant changes throughout the Holocene. At regionalscale, during the early Holocene, a change from harsh conditions with dense sea-icecover to interglacial conditions occurred in two steps: at ca. 10 ka BP significantdecrease of heterotrophic taxa (Islandinium minutum and Brigantedinium spp.) andthe occurrence of phototrophic taxa (Pentapharsodinium dalei, Spiniferites spp.Operculodinium centrocarpum), corresponds to an increase of summer SST and adecrease of the sea ice cover; after 7.5 ka BP, the establishment of full interglacialconditions both south and north of Davis Strait is marked by maximum percentages ofphototrophic taxa and the occurrence of Nematosphaeropsis labyrinthus in dinocystassemblages, which corresponds to onset of minimum sea ice, optimum SST and salinity.Optimal conditions persisted until about 2.5 ka BP south of Davis Strait and 1.5 ka BPin the Disko Bugt. The change towards more unstable conditions during the LateHolocene is notably marked by decrease in the percentages of Pentapharsodiniumdalei and increase of Islandinium cezare. It corresponds to spreading of sea iceand successive cooling pulses. The changes towards harsher and more unstableconditions seem to coincide with the disappearance of the Saqqaq culture at about3 ka BP and to the gap of human occupation in western Greenland, which wasrecorded from about 2 to 1 ka BP between the Dorset and the Norse settlements. [ABSTRACT FROM AUTHOR]

Analysis of benthic foraminifera in surface samples from 23 sites on the Northeast Greenland continental shelf reveal key assemblage differences between sites. Cluster analysis creates two clear geographical faunal assemblage zones: the 1) inner shelf, and 2) mid and outer shelf sites. These assemblages differ significantly, with the inner shelf sites being characterised by a high percentage and concentration of calcareous species, whilst the mid and outer shelf sites are dominated by agglutinated taxa. At almost all sites, the calcareous assemblages are dominated by Cassidulina neoteretis and Cassidulina reniforme , suggesting that they thrive across the shelf. Stetsonia horvathi , Oridorsalis tener , as well as Glomulina oculus and other miliolid species are found to be key calcareous species at many sites in the inner shelf zone, but they are rare-to-absent on the mid and outer shelf. Canonical correspondence analysis shows that September sea-ice cover and bottom water oxygen content are positively correlated with benthic foraminiferal assemblages at inner shelf sites, whereas organic carbon content is correlated with those in the mid and outer shelf. The formation of seasonal sea-ice and the Northeast Water polynya rejects brine into surrounding waters and transports CO 2 to the seafloor, creating a highly corrosive environment for calcium carbonate. These environments are also highly productive, as indicated by the high organic carbon content and low bottom water oxygen content. The oxidation of this organic material creates CO 2. We propose that these processes are key drivers in the dissolution of calcareous tests. In contrast, extensive sea-ice, high bottom water oxygen content and low primary productivity in the glacier-proximal region facilitates carbonate preservation. • Benthic foraminiferal assemblages differ across the Northeast Greenland continental shelf. • Sea-ice, glacial proximity and primary productivity are key drivers of assemblages. • Specific indicator species are useful for regional paleo-reconstructions. [ABSTRACT FROM AUTHOR]

The western Fram Strait is the only deep-water gateway connecting the Arctic Ocean and North Atlantic. Consequently, today, the western Fram Strait and the Northeast Greenland shelf receive cold, low saline Polar and Arctic Atlantic waters from the Arctic Ocean incorporated in the East Greenland Current, together with warmer, saline recirculated Atlantic Water masses derived from the West Spitsbergen Current. We present a multiproxy study (grain size distribution, XRF core scans, and benthic foraminiferal assemblages) based on the lower part of the radiocarbon dated marine sediment core DA17-NG-ST03-039G, covering the period from 13.3 to 3.9 cal ka BP. We reconstruct the deglacial conditions of the Northeast Greenland shelf together with Early to Mid Holocene fluctuations in subsurface Atlantic Water and Polar Water advection. The results show that the outer Northeast Greenland shelf was deglaciated and marine conditions were established prior to c. 13.3 cal ka BP. At this time, our data show Atlantic Water masses flowing beneath an extensive sea-ice cover in a glaciomarine setting, potentially related to the Bølling-Allerød warm period. Around 12.9 cal ka BP, the onset of high surface and bottom water productivity may be associated with the Younger Dryas onset. This was followed by a transition towards warmer bottom and subsurface water conditions from c. 11.7 until 10.2 cal ka BP caused by enhanced advection of Atlantic-derived water masses. A cold period with marginal ice zone conditions and enhanced East Greenland Current incursion is evident from 10.2 to 9.4 cal ka BP, succeeded by harsher sea-ice conditions and Atlantic Water inflow, prevailing until c. 7.5 cal ka BP. Holocene Thermal Maximum conditions, characterized by high surface and subsurface water productivity, were promoted by enhanced Atlantic Water flow to the shelf from c. 7.5 to 6.7 cal ka BP. In contrast, the transition towards a cold period with increased drift-ice transport via a strong East Greenland Current is recorded from c. 6.2 cal ka BP and to the end of our record at 3.9 cal ka BP; it was associated with the onset of the Neoglaciation. • First study to investigate the glacial-Holocene transition in Westwind Trough. •The Westwind Trough was free from grounded ice as early as 13.3 cal ka BP. •Atlantic water was present in the Westwind Trough during the deglacial. •Strongest Atlantic Water inflow was recorded during the Holocene Thermal Maximum. [ABSTRACT FROM AUTHOR]

The Fram Strait is one of the largest gateways through which meltwater and sea ice are exported to the subarctic North Atlantic, transiting the North-East Greenland shelf via the southward flowing East Greenland Current. Observations indicate a recent freshening of the East Greenland Current that may have implications for wider oceanic circulation regimes. The North-East Greenland shelf is an opportune region to assess these changes back through time. Paleoceanographic reconstructions from the North-East Greenland shelf are sparse and their temporal coverage is limited to the Holocene, limiting our ability to assess the impact of rapid climatic variations on marine conditions, such as during the Younger Dryas/Holocene transition. Here, we present data from a well-dated marine sediment core retrieved from the North-East Greenland shelf (74°N; east of Young Sound-Tyrolerfjord system) that captures the late Younger Dryas Stadial through to the Mid-Holocene at sub-centennial resolution. We apply a multi-proxy approach to reconstruct changes in productivity, surface and bottom ocean conditions. We show that at 74° N the presence of warm Atlantic waters on the inner North-East Greenland shelf was limited to the late Younger Dryas, as the Greenland Ice Sheet retreated landward and isostatic rebound caused the area to uplift. A unique dimension to this record is its location within one of the few biological hotspots on the East Greenland shelf today; the Sirius Water polynya. Archaeological studies indicate the polynya was forming as early as 4500 years ago, but nothing is known about its evolution from a marine perspective. Cooling of bottom waters, increasing sea-surface productivity and more frequent open water conditions indicate an Early Holocene onset of the Sirius Water (ca. 10–8.7 ka BP). • First paleoceanographic study from the Sirius Water polynya on the North-East Greenland shelf. • Multi-proxy approach to reconstruct productivity and bottom water conditions. • Sub-centennial resolution over the Younger Dryas/Holocene transition. • Extensive Atlantic Water influence during the late Younger Dryas. • Indications of recurrent Sirius Water Polynya formation since the Early Holocene (∼10–8.7 ka BP). [ABSTRACT FROM AUTHOR]

The melting of marine terminating glaciers in Northeast Greenland is a visible sign that our climate is changing. This melt has been partly attributed to changes in oceanic heat fluxes, particularly warming of Atlantic Water (AW). Yet our understanding of the interaction between glaciers and the ocean is limited by the length of instrumental records. Here, we present a multi-proxy study (benthic foraminifera assemblages, CT scans, grain size, XRF, and stable isotope data) on core DA17-NG-ST08-092G, located 90 km east of the Northeast Greenland Ice Stream (NEGIS). Whilst the exact timing of deglaciation is uncertain, it is certain to have occurred at least as early as 12.5 ka cal BP, and likely before 13.4 ka cal BP. The inflow of AW may have played a role in the seemingly early deglaciation on the Northeast Greenland continental shelf. Following deglaciation, the site was overlain by an ice shelf, with AW and Polar Water (PW) flowing beneath until 11.2 ka cal BP. The NEGIS briefly retreated westwards between 11.2 and 10.8 ka cal BP before our site returned to glacier-proximal conditions dominated by colder subsurface water and persistent AW flowing beneath (10.8–9.6 ka cal BP). Between 9.6 and 7.9 ka cal BP the NEGIS retreated westwards; there was a continued presence of AW and PW at the site. A drastic shift in ocean circulation occurred at 7.9 ka cal BP, with a decline in AW flow and dominance of PW flowing beneath perennial sea ice. During the Late Holocene, there was return of AW and likely breakup of perennial sea ice. • Multi-proxy reconstruction on the Northeast Greenland continental shelf. • Deglaciation occurred before 12.5 ka cal BP, possibly even before 13.4 ka cal BP. • Atlantic water inflow likely played a key role in deglaciation in this region. • Drastic decline in Atlantic water inflow occurred at 7.9 ka cal BP. [ABSTRACT FROM AUTHOR]

This study presents multi-proxy data from a high-resolution marine sediment core from the SW Greenland shelf. This climatically sensitive region is influenced by warm water inflows from the Atlantic Ocean and cold water inflows from the Arctic Ocean, as well as meltwater release and ice discharge from the Greenland Ice Sheet. Variations in the ocean surface temperatures and sea ice conditions in this region have a significant implications to the North Atlantic Deep Water Formation and Atlantic Meridional Overturning Circulation. The aim of this study is to reconstruct ocean surface conditions (sea surface temperatures; SST and sea ice conditions; SIC) and identify iceberg and meltwater discharge from the Greenland ice sheet during the last 2 000 years using microfossil assemblages (diatoms, dinocysts and benthic foraminiferas) and sedimentological proxies (XRF-scan, sediment grain size and IRD). The results of this study are compared with other temperature reconstructions from the Southeast Greenland, subpolar North Atlantic and the Norwegian Sea to identify possible temperature seesaw-pattern linked to the atmospheric forcing of the North Atlantic Oscillation (NAO) and to investigate variations in the strength of Atlantic-sourced warm water inflows.The results reveal fluctuations in sea surface temperatures on a centennial and decadal timescales. The temperature record shows that cooler oceanic conditions prevailed over the Medieval Climate Anomaly (from ca. 1000 CE to 1500 CE), whereas warmer conditions prevailed over the Little Ice Age (from ca. 1500 CE to 1800 CE). Similar temperature trend was discovered in the subpolar North Atlantic while the opposite temperature trend prevailed in the Norwegian Sea region. This seesaw pattern is likely to be linked to the atmospheric forcing of the NAO, which regulates the strength of the Irminger Current carrying warm Atlantic waters to northwest North Atlantic. The relative percentage of the coarse grain material in the sediment (>63 µm) indicates decreasing amount of iceberg rafting during the last 2000 years, whereas sea ice proxies imply increasing sea conditions towards the present day. [ABSTRACT FROM AUTHOR]