Southern Svalbard Research Articles

Compilation of Apatite Fission-Track Data from the Northeast Atlantic Realm: A Jigsaw Puzzle with Missing Pieces

Abstract The northeast (NE) Atlantic is one of the best-studied geological regions in the world, incorporating a wide array of geological phenomena including extensional tectonism, passive margin development, orogenesis, and breakup-related volcanism. Apatite fission-track (AFT) thermochronology has been an important tool in studying the onshore evolution of the NE Atlantic for several decades. Unfortunately, large regional-scale studies are rare, making it difficult to study geological processes across the whole region. In this work, a compilation of published AFT data is presented from across Fennoscandia, the British Isles, East Greenland, and Svalbard, with the goal of providing an accessible overview of the data and how this vast body of work has improved our understanding of the region’s evolution. Alongside a review of previous literature, interpolated maps of fission track age and mean track length (MTL) highlight regional trends in the data that may result from major first-order processes and areas of low sample density that should be targeted for future study. Additionally, in the absence of metadata required for thermal history modeling, apparent exhumation rate estimates are calculated from available elevation profiles and the timing of major exhumation events inferred from “boomerang plots” of fission track ages against MTL values. Across Fennoscandia, data suggests that the opening of the NE Atlantic and exhumation of the margin have clearly played a major role in the thermal history of the upper crust. The remaining areas of Britain, Ireland, East Greenland, and Svalbard all present more complex trends consistent with a combination of the NE Atlantic’s opening and the interplay between specific bedrock geology of sampling sites and localized geological processes. Areas of low sample density include southern Britain, NE Britain, southeast Greenland, southern Svalbard, and Eastern Fennoscandia, each of which provides the natural laboratory required to answer many unresolved questions.

Compilation of Apatite Fission-Track Data from the Northeast Atlantic Realm: A Jigsaw Puzzle with Missing Pieces

Abstract The northeast (NE) Atlantic is one of the best-studied geological regions in the world, incorporating a wide array of geological phenomena including extensional tectonism, passive margin development, orogenesis, and breakup-related volcanism. Apatite fission-track (AFT) thermochronology has been an important tool in studying the onshore evolution of the NE Atlantic for several decades. Unfortunately, large regional-scale studies are rare, making it difficult to study geological processes across the whole region. In this work, a compilation of published AFT data is presented from across Fennoscandia, the British Isles, East Greenland, and Svalbard, with the goal of providing an accessible overview of the data and how this vast body of work has improved our understanding of the region’s evolution. Alongside a review of previous literature, interpolated maps of fission track age and mean track length (MTL) highlight regional trends in the data that may result from major first-order processes and areas of low sample density that should be targeted for future study. Additionally, in the absence of metadata required for thermal history modeling, apparent exhumation rate estimates are calculated from available elevation profiles and the timing of major exhumation events inferred from “boomerang plots” of fission track ages against MTL values. Across Fennoscandia, data suggests that the opening of the NE Atlantic and exhumation of the margin have clearly played a major role in the thermal history of the upper crust. The remaining areas of Britain, Ireland, East Greenland, and Svalbard all present more complex trends consistent with a combination of the NE Atlantic’s opening and the interplay between specific bedrock geology of sampling sites and localized geological processes. Areas of low sample density include southern Britain, NE Britain, southeast Greenland, southern Svalbard, and Eastern Fennoscandia, each of which provides the natural laboratory required to answer many unresolved questions.

High temporal resolution records of the velocity of Hansbreen, a tidewater glacier in Svalbard

Abstract. Monitoring changes in glacial dynamics is essential for understanding the environmental response to accelerated climate warming in the Arctic. However, geodetic surveys in polar regions continue to present considerable challenges because of the harsh environmental conditions and the polar night. This study records a 14-year-long time series (2006–2019) of global navigation satellite system (GNSS) surveys of the positions of 16 ablation stakes distributed across Hansbreen, a tidewater glacier in southern Svalbard. The measurements were conducted with an exceptionally high temporal resolution, from about 1 week to about 1 month, and covering altitudes ranging from 20 to 490 m a.s.l. The position of one stake was surveyed every day. The primary data products consist of the stake coordinates and velocities. Time series of annual and seasonal velocities are also provided. This dataset may be a subject of further studies of glacier dynamics in relation to the long-term and seasonal impact of climate change on ice flow in the region. It also offers unique material for tuning numerical models of glacier dynamics and for validating satellite-derived products such as velocity and digital elevation models. The dataset described here has been made publicly available through the Zenodo repository: https://doi.org/10.5281/zenodo.8289380 (Błaszczyk et al., 2023).

Projected sea-level contributions from tidewater glaciers are highly sensitive to chosen bedrock topography: a case study at Hansbreen, Svalbard

AbstractCalculation of the calving loss of tidewater glaciers depends on accurate bedrock information. In regional to global-scale projections of future tidewater glacier evolution this dependence is problematic. Bedrock topographies are often unknown and can only be modelled from surface properties. Existing approaches, however, mostly underestimate the ice thickness towards the calving fronts of marine-terminating glaciers. This implies a compromised performance of global-scale projection models which often employ functions of water depth at the calving fronts of tidewater glaciers. Here, we present a sensitivity study that analyses the impact of five different bedrock datasets on projected mass losses from the tidewater glacier Hansbreen in southern Svalbard. Our modelling study calculates the glacier's response to artificial mass-balance forcing. We show that bedrock inaccuracies may lead to a substantially deviating retreat behaviour. The common underestimation of frontal ice thickness/water depth in the modelled bedrock datasets induces an underestimation of sea level-relevant mass losses over the first several decades of modelling. The duration of this period is reduced when assuming warmer climates. Our results thus underline the importance of accurate bedrock topography data for the reliability of glacier evolution projections and for the accuracy of the temporal trajectories of related sea level-relevant mass losses.

Accelerating future mass loss of Svalbard glaciers from a multi-model ensemble

AbstractProjected climate warming and wettening will have a major impact on the state of glaciers and seasonal snow in High Arctic regions. Following up on a historical simulation (1957–2018) for Svalbard, we make future projections of glacier climatic mass balance (CMB), snow conditions on glaciers and land, and runoff, under Representative Concentration Pathways (RCP) 4.5 and 8.5 emission scenarios for 2019–60. We find that the average CMB for Svalbard glaciers, which was weakly positive during 1957–2018, becomes negative at an accelerating rate during 2019–60 for both RCP scenarios. Modelled mass loss is most pronounced in southern Svalbard, where the equilibrium line altitude is predicted to rise well above the hypsometry peak, leading to the first occurrences of zero accumulation-area ratio already by the 2030s. In parallel with firn line retreat, the total pore volume in snow and firn drops by as much as 70–80% in 2060, compared to 2018. Total refreezing remains largely unchanged, despite a marked change in the seasonal pattern towards increased refreezing in winter. Finally, we find pronounced shortening of the snow season, while combined runoff from glaciers and land more than doubles from 1957–2018 to 2019–60, for both scenarios.

Seasonal and Spatial Differences in Metal and Metalloid Concentrations in the Snow Cover of Hansbreen, Svalbard

Metals and metalloids in snow on glaciers, depending on the season of deposition, may come from various sources: local rock dust (erosion of the geological substratum), marine aerosol, local human activity (e.g., impurities in combusted fuel and waste incineration), and long-range atmospheric transport. Hansbreen, a glacier located close to the Polish Polar Station in southern Svalbard, is a perfect site to study metals and metalloids: it has a complex geological substratum, has a year-round presence of a small group of people, and is near the coast. We analyzed a snapshot of metal and metalloid concentrations in snow samples from shallow cores corresponding to autumn, winter, and spring deposition on Hansbreen. Eighteen cores of snow were collected across the glacier, revealing the influence of potential local sources of metals and metalloids. In these samples, we predominantly found Na, Mg, and K, followed by Zn, Ca, Al, and Fe. Heavy metals, such as Bi or Hg, were also detected. Cluster analysis of the determined elemental concentrations divided them into three distinct groups: Group 1: Ag, As, Bi, Cd, Hg, Mo, Sb, Se, and Zn—the most diverse cluster, representing mostly long-range transported volatile elements, with possible extra local geological sources; Group 2: Al, Fe, Cu, and Mn—elements with crustal sources; and Group 3: Na, Ca, Mg, K, and Sr—with the main source in sea spray aerosol. The latter interpretation was confirmed by the calculation of sea salt contribution based on the composition of mean seawater and the positive significant correlation between their concentrations and the electrical conductivity of snow samples. In the study site, snow was up to six times more efficient in bringing metal pollution into terrestrial environment, when compared to rain.

Greenland cockles (Serripes groenlandicus Mohr 1786) from Bjørnøya (Bear Island), Svalbard record environmental change: Local and regional drivers of growth

Long time series are necessary to separate natural variability from that due to climate change and make it possible to interpret the impact of environmental change on ecosystems. Sclerochronological analysis of environmental records in the shells of mollusks make it possible to reconstruct environmental-ecological linkages over sufficiently long time scales to detect ecosystem change. Annually resolved archives can be key indicators of how climate change manifests in the marine ecosystem and are especially important in areas with limited instrumental records. We developed a master growth chronology of the Greenland Cockle (Serripes groenlandicus) from Bear Island (Bjørnøya), Svalbard, Norway (74°41′N, 18°56′E) from analysis of annual shell growth increments. The chronology was developed from 13 individuals collected from 80 m deep and ranging in age from 40 to 48 years old (the oldest known individuals of this species to date). The master chronology, expressed as a growth index (GI), extended from 1968 to 2012 and exhibited a cyclical pattern with decadal periods of high growth alternating with slower growth intervals. We identified significant relationships between variations in large-scale climate regimes (e.g. Atlantic Multidecadal Oscillation), local environmental conditions (e.g., sea temperature, sea ice), and shell growth. A model using sea temperature and sea ice explained 34–49% of the annual variations in shell growth patterns. The growth chronology and environmental linkages for cockles at this site in southern Svalbard near the southern extent of Arctic water in the Barents Sea were substantially different than at other locations in Svalbard. We conclude that the Greenland Cockle is quite sensitive to environmental changes over annual to decadal scales and therefore can serve as a proxy of climate change effects on ecosystem processes in the Arctic, but that local environmental processes that regulate food availability to the seabed are key determinants of environmental regulation on shell growth.

Does foraminiferal test size reflect changes in palaeoenvironmental conditions?—a case study from the southern Svalbard shelf

Although the environmental factors influencing the growth rate and reproduction of benthic foraminifera are known, the relationship between foraminifera test size and environmental variables remains unclear, especially on geological timescales. In this article, we present two records of benthic foraminiferal test size over the last 14 000 years from the southern Svalbard shelf. We use statistical correlation to relate test size changes with environmental conditions recorded by other proxies, including benthic δ18O and δ13C, foraminiferal flux and abundance, and relative abundances of different ecologically indicative foraminiferal groups. The general trends in test size were relatively consistent between the two cores. Still, we found that none of the analysed proxies was statistically correlated with the test size in both records. This leads to a conclusion that foraminifera size is primarily impacted by local oceanographic conditions. These local conditions are partly influenced by global oceanographic transitions. Therefore, large-scale changes can have a secondary impact on foraminiferal test size. The analysis of test size correlation between species similarly revealed that not all species react consistently to environmental changes. Our results indicate that foraminiferal test size cannot be used as a universal and straightforward proxy, but in combination with other methods it can yield valuable palaeoenvironmental information.

New fjords, new coasts, new landscapes: The geomorphology of paraglacial coasts formed after recent glacier retreat in Brepollen (Hornsund, southern Svalbard)

AbstractChanges in the properties and dynamics of tidewater glacier systems are key indicators of the state of Arctic climate and environment. Calving of tidewater glacier fronts is currently the dominant form of ice mass loss and a major contributor to global sea‐level rise. An important yet under‐studied aspect of this process is transformation of Arctic landscapes, where new lands and coastal systems are revealed due to the recession of marine‐terminating ice masses. The evolution of those freshly exposed paraglacial coastal environments is controlled by nearshore marine, coastal and terrestrial geomorphic processes, which rework glacial‐derived sediments to create new coastal paraglacial landforms and landscapes. Here, we present the first study of the paraglacial coasts of Brepollen, one of the youngest bays of Svalbard revealed by ice retreat. We describe and classify coastal systems and the variety of landforms (deltas, cliffs, tidal flats, beaches) developed along the shores of Brepollen during the last 100 years. We further discuss the main modes of sediment supply to the coast in different parts of the new bay, highlighting the fast rate of coastal transformation as a paraglacial response to rapid deglaciation in the Arctic. This study provides an exemplar of likely coastal responses to be anticipated in similar tidewater settings under future climate change. © 2020 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd

Arctic rock coast responses under a changing climate

It has been widely reported that Arctic sea ice has decreased in both extent and thickness, coupled with steadily rising mean annual temperatures. These trends have been particularly severe along the rock coast of southern Svalbard. Concerns have been raised over the potential for higher energy storms and longer ice-free open water seasons to increase the exposure of Arctic coasts, and consequently the concentration of infrastructure critical to Arctic community survival, to enhanced rates of erosion. Here we present and apply innovative remote sensing, monitoring and process analyses to assess the impact of recent coastal climatic changes. High resolution analyses demonstrate that the small scale (<0.001 m3) changes that are rarely considered quantitatively exhibit geomorphic responses distinct from those of larger, more readily detected cliff failures. We monitor temperature depth profiles in both the shore platform and the cliff face to show rock sensitivity over time to both global and local influences. The results demonstrate the efficacy of thermal processes on Arctic rock cliffs relative to platforms, and may hold implications for understanding strandflat development rates. New three-dimensional thermography (thermal mapping) and process zone characterisation has been used to spatially assess the sensitivity of Arctic rock coast responses to contemporary processes on deglaciating coasts. Through the spatial and temporal analyses of key geomorphic behaviour zones and comparison over a range of sites, the complex and changing interplay between subaerial weathering and cryogenic and intertidal processes has been highlighted. These data challenge long standing assumptions over the future of Arctic rock coasts and identify new, focused lines of enquiry on the decline in cryogenic processes and understanding the sensitivity of Arctic rock coasts to climatic changes.

Contribution of the atmospheric channel to lead contamination of soils in the Arctic territories

Although the Arctic territories have long been considered “the gold standard of purity”, global climate change and environmental pollution are having a significant impact on the state of Arctic ecosystems. In particular, industrial complexes combined with transboundary transport are having a negative impact. The aim of this work is to determine the contribution of atmospheric Pb to the contamination of soils of the Arctic territories using the trajectory statistics method which combines correlation and factor statistical processing approaches while taking the actual lead content in the upper soil horizon into account. In order to assess the transfer of pollutants, an analysis of multiannual air mass tracts and impurity transfer trajectories to certain points was carried out. The objects of study are the soil of the Khorey-Ver settlement, the basin of the Shapkin and Sula rivers, northeastern and southern Svalbard and the islands of the Southern Archipelago of Novaya Zemlya. It was established that the primary contribution to airborne pollution of the Nenets Autonomous District (NAO) during the summer period comes from sources located within a radius of about 400 km. Aerogenic influence of the mainland on the territory of Svalbard is practically absent, with the main atmospheric transport of substances coming from nearby marine areas. The transfer of impurities from the mainland to the Novaya Zemlya District is also insignificant. During the summer months, there is practically no airborne lead contamination of the island territories. Some influences on the territory of Novaya Zemlya and the NEO can be traced to sources on the Kola Peninsula, the coasts of the Barents and Kara seas, as well as long-distance transport from the southern regions. On the territory of the NAO, the number of heavy metal (HM) precipitations increases from west to east, possibly indicating a stronger impact of emissions from the Norilsk industrial hub than from the enterprises of the Kola Peninsula on this territory. In terms of seasonal dynamics, the island points are characterised by an increase in HM fluxes during the winter period; conversely, for the NAO territory, such an increase takes place during the summer. This discrepancy is primarily due to the changing nature of the atmospheric circulation.

Seabirds modify trophic groups, while altitude promotes xeric-tolerant species of Tardigrada in the high Arctic tundra (Svalbard archipelago)

In the Arctic, especially in the coastal mountainous areas, gradual changes in elevation above sea level and allochthonous nutrients delivered by seabirds modify environmental conditions. Increasing elevation affects temperature whereas allochthonous nutrients delivered by seabirds to the terrestrial ecosystem remarkably influence primary production and diversity of organisms. Knowing the abundance of ubiquitous tardigrades (a microinvertebrate phylum), their multitrophic level function and their trophic composition might be essential for understanding ecosystem functioning and matter flow in fragile polar ecosystems. In this study, we tested the effects of altitude and seabird guano on modifying trophic diversity of tardigrades. We found that the tardigrades in Hornsund were herbivorous and microbivorous species dominated. Microbivores were significantly more abundant in guano-supplied than in control areas, which may be explained by the presence of higher nutrient and organic matter content in comparison with areas not fertilised by birds. We observed no significant relationship between the abundance of tardigrade trophic groups and altitude. However, the abundance of xeric-tolerant herbivorous terrestrial tardigrades representing the class Heterotardigrada increased with altitude. Strongly hygrophilic conditions (ponds, swamps, streams) at lower elevations as well as acidic conditions formed by seabird guano may reduce the abundance of heterotardigrades. Our study shows that seabirds rather than the effect of altitude or the generally predicted increasing temperatures in the Arctic, are affecting high Arctic tundra limno-terrestrial invertebrate trophic groups proportion. Our results provide baseline data for future studies of the Hornsund region, since climate change scenarios predict decreased guano delivery by seabirds on mountain slopes, shifts in plant species dominance and more intense fertilisation of lakes by geese, all of which may alter invertebrate trophic composition in southern Svalbard.

Proxy-based 300-year High Arctic climate warming record from Svalbard

AbstractWe used fossil Chironomidae assemblages and the transfer function approach to reconstruct summer air temperatures over the past 300 years from a High Arctic lake in Hornsund, Svalbard. Our aims were to compare reconstructed summer temperatures with observed (last 100 years) seasonal temperatures, to determine a potential climate warming break point in the temperature series and to assess the significance and rate of the climate warming trend at the study site. The reconstructed temperatures were consistent with a previous proxy record from Svalbard and showed good correlation with the meteorological observations from Bjørnøya and Longyearbyen. From the current palaeoclimate record, we found a significant climate warming threshold in the 1930s, after which the temperatures rapidly increased. We also found that the climate warming trend was strong and statistically significant. Compared with the reconstructed Little Ice Age temperatures in late eighteenth century cooling culmination, the present day summer temperatures are &gt;4°C higher and the temperature increase since the 1930s has been 0.5°C per decade. These results highlight the exceptionally rapid recent warming of southern Svalbard and add invaluable information on the seasonality of High Arctic climate change and Arctic amplification.

Fluid flow and pore pressure development throughout the evolution of a trough mouth fan, western Barents Sea

AbstractUsing a combination of geophysical and geotechnical data from Storfjorden Trough Mouth Fan off southern Svalbard, we investigate the hydrogeology of the continental margin and how this is affected by Quaternary glacial advances and retreats over the continental shelf. The geotechnical results show that plumites, deposited during the deglaciation, have high porosities, permeabilities and compressibilities with respect to glacigenic debris flows and tills. These results together with margin stratigraphic models obtained from seismic reflection data were used as input for numerical finite element models to understand focusing of interstitial fluids on glaciated continental margins. The modelled evolution of the Storfjorden TMF shows that tills formed on the shelf following the onset of glacial sedimentation (ca. 1.5 Ma) acted as aquitards and therefore played a significant role in decreasing the vertical fluid flow towards the sea floor and diverting it towards the slope. The model shows that high overpressure ratios (up to λ ca. 0.6) developed below the shelf edge and on the middle slope. A more detailed model for the last 220 kyrs accounting for ice loading during glacial maxima shows that the formation of these aquitards on the shelf focused fluid flow towards the most permeable plumite sediments on the slope. The less permeable glacigenic debris flows that were deposited during glacial maxima on the slope hinder fluid evacuation from plumites allowing high overpressure ratios (up to λ ca. 0.7) to develop in the shallowest plumite layers. These high overpressures likely persist to the Present and are a critical precondition for submarine slope failure.

Reconstruction of ice sheet retreat after the Last Glacial maximum in Storfjorden, southern Svalbard

Storfjorden is a large north-south trending sound located in the southern part of Svalbard in the northwestern Barents Sea. Presently, several glaciers drain into the northern and western part of Storfjorden. Our study area covers the southern part of the sound, which is divided by a north-south striking basement ridge (the ‘Mid-ridge’) into a narrow western trough (‘Little-Storfjorden’) and a broader eastern trough (‘Storfjorden’). In the latter, three grounding-zone wedges (GZWs) were discovered in 2005 showing evidence of former grounded ice. Here we confirm the existence and map the extent of the GZWs and reconstruct the pattern and timing of ice retreat in Storfjorden during the deglaciation. The study is based on high-resolution seismic and shallow-acoustic profiles and swath bathymetry, combined with information of lithology and radiocarbon dates from sediment cores. The results show that the three GZWs stretch across the fjord, and that all three are located south of higher basement areas that were upstream of the GZWs and which acted as pinning points during ice retreat. The Mid-ridge imposed a lateral drag to the ice, resulting in an uneven ice retreat across the fjord. Outside of the GZWs only a thin cover of glacial deposits was found. The cores were taken in vicinity of the GZWs and all reached till deposits overlain by glacimarine or hemipelagic sediments, enabling dating of the GZWs. Altogether we find that the fjord and basement topography played an important role in the ice retreat. AMS-14C dates show that the formation of the three GZWs correlate with three well-known atmospheric warming phases (start of Bølling interstadial, Allerød interstadial and Holocene interglacial, respectively) associated with inflows of warm Atlantic water, indicating a strong ocean/climate control on the deglaciation of Storfjorden.

Coast formation in an Arctic area due to glacier surge and retreat: The Hornbreen–Hambergbreen case from Spistbergen

AbstractGlacierised coasts undergo faster geomorphic processes than unglaciated ones. We have studied changes of the coastal area in southern Svalbard with the glacier bridge between Torell Land and Sørkapp Land since the beginning of the 20th century. The existence of a continuous subglacial depression beneath the Hornbreen–Hambergbreen glacier system has been debated since the 1960s, with inconclusive results. In this study we assess both the subglacial topography and the bathymetry of Hornsund Fjord and Hambergbukta bay. This included ~40 km of radar surveys over the glacial system and sea depth sounding. The extent of the glaciers from maps and satellite images together with digital terrain models and surface elevation data based on GPS profiling were used to analyse geometry changes of the glacier surfaces. The results confirm the existence of a continuous subglacial depression below sea level (c. 40 m deep) between Hornsund and the Barents Sea. The Hornbreen‐Hambergbreen system has changed in shape over the past century, reflecting its dynamic origin and activity, also exemplified by the sequential surges identified since 1899. There was a pre‐surge build‐up event of Flatbreen causing a surge and subsequent lowering of the Hornbreen‐Hambergbreen frontal parts by the 1960s. After, the entire surface lowered, albeit with a delay in the Hornbreen terminal zone. Since the year 2000, Hornbreen terminus has retreated at an average rate of 106 m a−1; ~50% faster than that of Hambergbreen. If the retreat continues at the 2000–2015 average rate, the ice bridge between Hornsund and Hambergbukta will be broken sometime between 2055 and 2065 and the Hornsund strait will separate Sørkapp Land from the Spitsbergen island. The processes and events described in this study, particularly the effects of the glacier surge, may provide a model for changes likely to occur in other coastal glaciated regions experiencing rapid change. Copyright © 2017 John Wiley &amp; Sons, Ltd.

Terrestrial Remote Sensing of Snowmelt in a Diverse High-Arctic Tundra Environment Using Time-Lapse Imagery

Snow cover is one of the crucial factors influencing the plant distribution in harsh Arctic regions. In tundra environments, wind redistribution of snow leads to a very heterogeneous spatial distribution which influences growth conditions for plants. Therefore, relationships between snow cover and vegetation should be analyzed spatially. In this study, we correlate spatial data sets on tundra vegetation types with snow cover information obtained from orthorectification and classification of images collected from a time-lapse camera installed on a mountain summit. The spatial analysis was performed over an area of 0.72 km2, representing a coastal tundra environment in southern Svalbard. The three-year monitoring is supplemented by manual measurements of snow depth, which show a statistically significant relationship between snow abundance and the occurrence of some of the analyzed land cover types. The longest snow cover duration was found on “rock debris” type and the shortest on “lichen-herb-heath tundra”, resulting in melt-out time-lag of almost two weeks between this two land cover types. The snow distribution proved to be consistent over the different years with a similar melt-out pattern occurring in every analyzed season, despite changing melt-out dates related to different weather conditions. The data set of 203 high resolution processed images used in this work is available for download in the supplementary materials.

Late Holocene glacier activity at inner Hornsund and Scottbreen, southern Svalbard

New 10Be dating on two late Holocene maximum moraines on the Treskelen Peninsula and at Scottbreen, Svalbard, improve constraints on the timing and character of Holocene glacial activity in this region. Average moraine ages of 1.9 ± 0.3 ka (n = 4) on the Treskelen Peninsula and 1.7 ± 0.1 ka (n = 5) on Scottbreen indicate the timing of a glacial culmination. The age of moraine abandonment at Treskelen and Scottbreen correlates with snowline lowering and glacier expansion between ∼2.0 and 1.5 ka observed elsewhere on Svalbard. Both Scottbreen and the glaciers near Treskelen have surged in the instrumental record, like many glaciers across Svalbard. Yet, the age relation between our possible surge-related moraines and other glacier records leads us to hypothesize that on centennial and longer timescales, climate forcing outweighs surge dynamics, which exerts a stronger control on glacier length on centennial timescales at our study sites.

Benthic foraminiferal biogeography in NW European fjords: A baseline for assessing future change

The seaboard extending from northern Svalbard to Scotland is the only region of the world where fjords have been comprehensively studied for their live (stained) benthic foraminiferal faunas. These modern faunas provide essential baseline data for the interpretation of the postglacial and continuing environmental changes in those fjords and this is the first biogeographic synthesis. The data come from the surface sediment assemblages (mainly sampled in the 1990's) from all the available literature. Due to limited information of shallow water assemblages in the north, only the species occurrences in deeper water from below the halocline are considered. Amongst these, only “common species” species occurring in more than one fjord are included. There is a clear pattern of distribution with five groups of taxa: 5 widespread species found throughout the region; 53 species reaching their northern limit; 13 species reaching their southern limit; 11 deep-sea species; 1 recently introduced species. Although there is an abrupt change in temperature from Tanafjorden in northern Norway to Hornsund in southern Svalbard, the faunal change from N to S is progressive throughout the investigated region. The area of overlap of the northern and southern species corresponds with the previously recognised boundary between the Barents Sea Province and the Norwegian Coast Province based on shelf and upper slope invertebrate macrofaunal benthos and plankton. Temperature is the main abiotic control on the distributions. For the fjords which have shallow sills separating them from the open shelf it is likely that most of the foraminiferal colonisers of the deeper fjord basins are sourced from the shelf or slope via propagules. One species has recently been introduced from further south into the southern region probably through the discharge of ballast water from ships. The biodiversity of the pristine Svalbard fjords extends below what is considered to reflect acceptable ecological status for mainland Norway, illustrating the need to introduce new methods to determine possible deviations from the reference conditions as defined in the EU's Water Framework Directive (WFD; 2000/60/EC). Altogether 347 species have so far been recorded in Norwegian waters: 214 in fjords (60 above and 180 below the halocline of which 26 occur both above and below the halocline) and 266 on the shelf and slope (133 of which also occur in fjords).

Brine formation recorded by stable isotopes of Recent benthic foraminifera in Storfjorden, Svalbard: palaeoceanographical implications

We discuss water oxygen isotopes (δ18Ow) and carbon isotopes of dissolved inorganic carbon (δ13CDIC) of brine‐enriched shelf water (BSW) from Storfjorden (southern Svalbard) in comparison to Recent benthic foraminiferal δ18Oc and δ13Cc calcified in the same water. We determined relatively high δ18Ow values of 0.15±0.03‰ VSMOW in BSW below sill depth at temperatures below −1.8 °C, and high δ18Oc values of 3.90±0.18‰ VPDB. Such high BSW δ18Ow cannot significantly deplete 18Ow contents of Arctic Ocean deep water; furthermore, such high δ18Oc cannot be distinguished from δ18Oc values of 3.82±0.12‰, calcified in warmer Arctic and Nordic seas intermediate and deeper waters. Today, in Storfjorden low benthic δ13Cc and high δ18Oc reflect the low δ13CDIC and relatively high δ18Ow of BSW. High benthic δ18Oc is in contrast to expected low δ18Oc as brine rejection is widely thought to predominantly take place in surface water diluted by meteoric water with very low δ18Ow. Low epibenthic δ13Cc values of 0.50±0.12‰ partly reflect low δ13CDIC caused by enhanced uptake of atmospheric low δ13CCO2 decreased by anthropogenic activities. An adjustment for preindustrial higher values would increase δ13Cc by about 0.6‰. Therefore, in Storfjorden brine formed before the industrial era would be characterized by both high δ13Cc as well as high δ18Oc values of benthic foraminiferal calcite. Our data may cast doubt on scenarios that explain negative excursions in benthic foraminiferal stable isotope records from the Atlantic Ocean during cold stadials in the last glacial period by enhanced brine formation in Nordic seas analogously to modern processes in Storfjorden.