Fifty Years of Tidewater Glacier Surface Elevation and Retreat Dynamics along the South-East Coast of Spitsbergen (Svalbard Archipelago)

Tidewater glaciers on the east coast of Svalbard were examined for surface elevation changes and retreat rate. An archival digital elevation model (DEM) from 1970 (generated from aerial images by the Norwegian Polar Institute) in combination with recent ArcticDEM were used to compare the surface elevation changes of eleven glaciers. This approach was complemented by a retreat rate estimation based on the analysis of Landsat and Sentinel-2 images. In total, four of the 11 tidewater glaciers became land-based due to the retreat of their termini. The remaining tidewater glaciers retreated at an average annual retreat rate of 48 m year−1, and with range between 10–150 m year−1. All the glaciers studied experienced thinning in their frontal zones with maximum surface elevation loss exceeding 100 m in the ablation areas of three glaciers. In contrast to the massive retreat and thinning of the frontal zones, a minor increase in ice thickness was recorded in some accumulation areas of the glaciers, exceeding 10 m on three glaciers. The change in glacier geometry suggests an important shift in glacier dynamics over the last 50 years, which very likely reflects the overall trend of increasing air temperatures. Such changes in glacier geometry are common at surging glaciers in their quiescent phase. Surging was detected on two glaciers studied, and was documented by the glacier front readvance and massive surface thinning in high elevated areas.

Impact of Timanian thrust systems on the late Neoproterozoic–Phanerozoic tectonic evolution of the Barents Sea and Svalbard

The Svalbard Archipelago consists of three basement terranes that record a complex Neoproterozoic–Phanerozoic tectonic history, including four contractional events (Grenvillian, Caledonian, Ellesmerian, and Eurekan) and two episodes of collapse- to rift-related extension (Devonian–Carboniferous and late Cenozoic). Previous studies suggest that these three terranes likely accreted during the early to mid-Paleozoic Caledonian and Ellesmerian orogenies. Yet recent geochronological analyses show that the northwestern and southwestern terranes of Svalbard both record an episode of amphibolite (–eclogite) facies metamorphism in the latest Neoproterozoic, which may relate to the 650–550 Ma Timanian Orogeny identified in northwestern Russia, northern Norway, and the Russian Barents Sea. However, discrete Timanian structures have yet to be identified in Svalbard and the Norwegian Barents Sea. Through analysis of seismic reflection, as well as regional gravimetric and magnetic data, this study demonstrates the presence of continuous thrust systems that are several kilometers thick, NNE-dipping, deeply buried, and extend thousands of kilometers from northwestern Russia to northeastern Norway, the northern Norwegian Barents Sea, and the Svalbard Archipelago. The consistency in orientation and geometry, as well as apparent linkage between these thrust systems and those recognized as part of the Timanian Orogeny in northwestern Russia and Novaya Zemlya, suggests that the mapped structures are likely Timanian. If correct, these findings would imply that Svalbard's three basement terranes and the Barents Sea were accreted onto northern Norway during the Timanian Orogeny and should hence be attached to Baltica and northwestern Russia in future Neoproterozoic–early Paleozoic plate tectonics reconstructions. In the Phanerozoic, the study suggests that the interpreted Timanian thrust systems represent major preexisting zones of weakness that were reactivated, folded, and overprinted by (i.e., controlled the formation of new) brittle faults during later tectonic events. These faults are still active at present and can be linked to folding and offset of the seafloor.

Features of the Hydrocarbon Distribution in the Bottom Sediments of the Norwegian and Barents Seas

The results of the study of hydrocarbons (HCs): aliphatic (AHCs) and polycyclic aromatic hydrocarbons (PAHs) in bottom sediments (2019 and 2020, cruises 75 and 80 of the R/V Akademik Mstislav Keldysh) in the Norwegian-Barents Sea basin: Mohns Ridge, shelf Svalbard archipelago, Sturfiord, Medvezhinsky trench, central part of the Barents Sea, Novaya Zemlya shelf, Franz Victoria trough are presented. It has been established that the organo-geochemical background of the Holocene sediments was formed due to the flow of sedimentary material in the coastal regions of the Barents Sea on shipping routes. The anthropogenic input of HCs into bottom sediments leads to an increase in their content in the composition of Corg (in the sandy sediments of the Kaninsky Bank at an AHC concentration up to 64 μg/g, when its proportion in the composition of Corg reaches 11.7%). The endogenous influence on the of the Svalbard archipelago shelf in Sturfiord and in the Medvezhinsky Trench determines the specificity of local anomalies in the content and composition of HCs. This is reflected in the absence of a correlation between HCs and the grain size composition of sediments and Corg content, as well as a change in hydrocarbon molecular markers. At the same time, the sedimentary section is enriched in light alkanes and naphthalene’s that may be due to emission during point discharge of gas fluid from sedimentary rocks of the lower stratigraphic horizons and/or sipping migration.

SEISMICITY of the ARCTIC in 2015

The article provides an overview and analysis of seismicity within the boundaries of the Arctic region for 2015, a description of seismic station networks, and processing methods. The catalog of earthquakes in the Arctic region was compiled on the basis of catalogs of several organizations and seismological centers. In total, 334 earthquakes are included in the earthquake catalog. Most of the earthquakes that occurred in 2015, including all the strongest earthquakes, were located within the mid-ocean ridges of Mon, Knipovich and Gakkel. In the offshore territories, most of the earthquakes were confined to the Svalbard archipelago, in particular, to the seismically active zone in the Sturfjord strait. The renewal of instrumental seismological observations in 2011 (station ZFI) on Alexandra Land Island in the Franz Josef Land archipelago made it possible to record weak earthquakes in the north of the shelf of the Barents and Kara Seas. For twelve earthquakes, the focal mechanism parameters are presented according to the Global CMT catalog.

Insights into bear evolution from a Pleistocene polar bear genome

The polar bear (Ursus maritimus) has become a symbol of the threat to biodiversity from climate change. Understanding polar bear evolutionary history may provide insights into apex carnivore responses and prospects during periods of extreme environmental perturbations. In recent years, genomic studies have examined bear speciation and population history, including evidence for ancient admixture between polar bears and brown bears (Ursus arctos). Here, we extend our earlier studies of a 130,000-115,000-year-old polar bear from the Svalbard Archipelago using 10X coverage genome sequence and ten new genomes of polar and brown bears from contemporary zones of overlap in northern Alaska. We demonstrate a dramatic decline in effective population size for this ancient polar bear's lineage, followed by a modest increase just before its demise. A slightly higher genetic diversity in the ancient polar bear suggests a severe genetic erosion over a prolonged bottleneck in modern polar bears. Statistical fitting of data to alternative admixture graph scenarios favors at least one ancient introgression event from brown bears into the ancestor of polar bears, possibly dating back over 150,000 years. Gene flow was likely bidirectional, but allelic transfer from brown into polar bear is the strongest detected signal, which contrasts with other published works. These findings have implications for our understanding of climate change impacts: polar bears, a specialist Arctic lineage, may not only have undergone severe genetic bottlenecks, but also been the recipient of generalist, boreal genetic variants from brown bear during critical phases of Northern Hemisphere glacial oscillations.

Metabarcoding Reveals High Diversity of Benthic Foraminifera Driven by Atlantification of Coastal Svalbard

Arctic marine biodiversity is undergoing rapid changes due to global warming and modifications of oceanic water masses circulation. These changes have been demonstrated in the case of mega- and macrofauna, but much less is known about their impact on the biodiversity of smaller size organisms, such as foraminifera that represents a main component of meiofauna in the Arctic. Several studies analysed the distribution and diversity of Arctic foraminifera. However, all these studies are based exclusively on the morphological identification of specimens sorted from sediment samples. Here, we present the first assessment of Arctic foraminifera diversity based on metabarcoding of sediment DNA samples collected in fjords and open sea areas in Svalbard Archipelago. We obtained a total of 5,968,786 reads that represented 1,384 ASVs. More than half of the ASVs (51.7%) could not be assigned to any group in the reference database suggesting a high genetic novelty of Svalbard foraminifera. The sieved and unsieved samples resolved comparable communities, sharing 1023 ASVs, comprising over 97% of reads. Our analyses show that the foraminiferal assemblage differs between the localities, with communities distinctly separated between fjord and open sea stations. Each locality was characterized by a specific assemblage, with only a small overlap in the case of open sea areas. Our study demonstrates a clear pattern of the influence of water masses on the structure of foraminiferal communities. The stations situated on the western coast of Svalbard that is strongly influenced by warm and salty Atlantic Water (AW) are characterized by much higher diversity than stations in the northern and eastern part, where the impact of AW is less pronounced. This high diversity and specificity of Svalbard foraminifera associated with water mass distribution indicate that the foraminiferal metabarcoding data can be a very useful tool for inferring present and past environmental conditions in the Arctic.

Chronology of sedimentation in Colesbukta, Spitsbergen (Svalbard Archipelago): the results of the 2018 expedition

This paper presents results of a study of sedimentation in Colesbukta (Isfjorden, Spitsbergen), a typical example of sedimentation in a shallow bay of the Svalbard Archipelago. We have examined sediment samples from several cores collected in Colesbukta in May 2018. To meet the goals of this study, geomorphological features of the Colesbukta catchment area have been identified and described. The lithological characteristics of bottom sediments from the study area have been described and their spatial and temporal changes analyzed. The chronology of sedimentation has been reconstructed by 210Pb and 137Cs. We have calculated sedimentation rates in Colesbukta and their temporal dynamics over the several latest decades. According to our estimations, the sedimentation rate has increased by 2–4 times compared to the middle of the 20th century and ranges from 0.2 to 0.46 mm/year depending on the individual conditions of sedimentation in each part of the bay. Climatic fluctuations are shown to have a direct impact on sedimentation processes in Colesbukta. We have revealed that on the periphery of the studied area the rate of sedimentation better depends on the temperature regime while in its central part it is rather a result of the amount of atmospheric precipitation.

8. Arctic futures

‘Arctic futures’ discusses the future of the Arctic that starts in the Norwegian territory of Svalbard wherein the Global Seed Vault functions as an Arctic sanctuary for the genetic diversity of crops. The Svalbard archipelago is a hotspot of Arctic amplification as rapid warming has been keenly felt by the small community. However, the environmental changes, no matter how stark and widespread, will not dampen interest in economic development and strategic posturing. Arctic states and northern peoples remain eager to improve their social and economic conditions as well as adapt to ongoing climate change. The Arctic is a haven of international peace and cooperation as the Arctic Council is cited as a governance model that others could emulate.

Effects of Arctic Warming on Microbes and Methane in Different Land Types in Svalbard

Climate change is having a profound impact on Arctic microbiomes and their living environments. However, we have only incomplete knowledge about the seasonal and inter-annual variations observed among these microbes and about their methane regulation mechanisms with respect to glaciers, glacial melting, snow lakes and coastal marine water. This gap in our knowledge limits our understanding of the linkages between climate and environmental change. In the Arctic, there are large reservoirs of methane which are sensitive to temperature changes. If global warming intensifies, larger quantities of methane stored in deep soil and sediments will be released into the atmosphere, causing irreversible effects on the global ecosystem. Methane production is mainly mediated by microorganisms. Although we have some knowledge of microbial community structure, we know less about the methane-correlated microbes in different land types in the Svalbard archipelago, and we do not have a comprehensive grasp of the relationship between them. That is the main reason we have written this paper, in which current knowledge of microorganisms and methane-correlated types in High Arctic Svalbard is described. The problems that need to be addressed in the future are also identified.