Arctic Archipelago Research Articles

Processes in the Kitikmeot Sea estuary constraining marine life

The Kitikmeot Sea, in the south-central Canadian Arctic Archipelago, is an estuarine system comprised of Coronation Gulf, Bathurst Inlet, Dease Strait, and Queen Maud Gulf. It is unique in the pan-Arctic system due to three defining features: (1) shallow bounding straits to the west (Dolphin and Union Strait) and northeast (Victoria Strait) that are less than 30 m deep; (2) Arctic Ocean inflow carrying nutrient and salt supplies over the bounding sills that are primarily delivered from the Canada Basin; and (3) massive freshwater input from the mainland watershed that drains an area almost 5 times larger than the Kitikmeot Sea. Here we present physical and geochemical observations obtained from 1999–2020 to show that these conditions maintain an estuarine circulation year-round, wherein the excess low-salinity water, formed from inflowing rivers and seasonal ice melt, exits over both bounding sills and is replenished by inflowing oceanic waters from Amundsen Gulf and Larsen Sound. The shallow sills both restrict the depth of inflow, dictating the salinity and nutrient concentrations of inflowing waters, and increase tidal speeds over the sills, which leads to mixing between the outflowing and inflowing water that further lowers inflowing salinity and nutrient concentrations. Together, all these processes establish a strongly stratified and overall low-productivity ecosystem within the Kitikmeot Sea. We propose a conceptual model of marine ecosystem function that favors an abundance of Arctic char and seals as top predators instead of the larger polar bears and whales as found adjacent to the Kitikmeot Sea in the Canadian Arctic Archipelago.

Snow depth estimation on leadless landfast ice using Cryo2Ice satellite observations

Abstract. Observations of snow on Arctic Sea ice are vitally important for sea ice thickness estimation, bio-physical processes, and human activities. While previous studies have combined CryoSat-2- and ICESat-2-derived freeboards to estimate snow depth over Arctic sea ice, these approaches require leads within the ice pack to estimate the freeboard heights above the sea surface. In regions such as the Canadian Arctic Archipelago (CAA), leads are scarce in winter, posing a significant challenge to estimate snow depth from altimeters. This study is the first assessment of the potential for near-coincident ICESat-2 and Cryosat-2 (Cryo2Ice) snow depth retrievals in a leadless region of the CAA including validation with in situ data. In lieu of sea surface height estimates from leads, snow depths are retrieved using the absolute difference in surface heights (ellipsoidal heights) from ICESat-2 and Cryosat-2 after applying an ocean tide correction based on tidal gauges between satellite passes on 29 April 2022. Both the absolute mean snow depths and distributions retrieved from Cryo2Ice were slightly underestimated (2 to 4 cm) when compared to in situ measurements. All four in situ sites had snow with saline basal layers and different levels of roughness and ridging, which significantly impact the accuracy of the Cryo2Ice snow depth retrievals. Differences between Cryo2Ice and in situ snow depth distributions reflect the varying sampling resolutions of the sensors and the in situ measurements. Cryo2Ice tends to miss snow depths greater than 30 cm, especially around ridges. The results suggest that it might be possible to estimate snow depth over landfast sea ice without leads. However, the observed biases of 2–4 cm likely stem from several factors: (1) discrepancies in sampling resolution between ICESat-2 and CryoSat-2; (2) the CryoSat-2 scattering horizon not aligning with the snow–ice interface due to snow salinity, density, and surface roughness; (3) the choice of retracker; and (4) potential errors in the altimeter's tidal corrections. Further investigation is needed to address these issues. Moreover, the proposed methodology for getting snow depth over leadless landfast sea ice needs to be validated using in situ datasets in other landfast sea ice regions in the Arctic.

Revisiting the Last Ice Area projections from a high-resolution Global Earth System Model

The Last Ice Area—located to the north of Greenland and the northern Canadian Arctic Archipelago—is expected to persist as the central Arctic Ocean becomes seasonally ice-free within a few decades. Projections of the Last Ice Area, however, have come from relatively low resolution Global Climate Models that do not resolve sea ice export through the waterways of the Canadian Arctic Archipelago and Nares Strait. Here we revisit Last Ice Area projections using high-resolution numerical simulations from the Community Earth System Model, which resolves these narrow waterways. Under a high-end forcing scenario, the sea ice of the Last Ice Area thins and becomes more mobile, resulting in a large export southward. Under this potentially worst-case scenario, sea ice of the Last Ice Area could disappear a little more than one decade after the central Arctic Ocean has reached seasonally ice-free conditions. This loss would have profound impacts on ice-obligate species.

Pathogenic potential of ornithogenic <i>Escherichia coli</i> strains detected in the Earth's polar regions

Introduction. Pathogenic strains of Escherichia coli are an important object of surveillance within the One Health concept in the wild, agriculture and human society. Migratory bird colonies and high latitude avian colonies may be points of active intraspecies and interspecies contact between different animal species, accompanied by the spread of pathogens. At the same time, the phylogeography of E. coli in relation to the presence of natural foci of colibacillosis in polar regions remains virtually unstudied. The aim of this study was to assess the pathogenic potential of E. coli strains from the polar regions of the Earth, based on the analysis of the genomes of these bacteria from typical ornithogenic ecosystems of the Arctic and Antarctic. Materials and methods. The study used collections of E. coli isolated from ornithogenic biological material during expeditions to high latitude areas of the Arctic (archipelagos of Novaya Zemlya, Franz Josef Land, Svalbard) and Antarctic (Haswell Archipelago). 16 cultures associated with avian E. coli (12 polar and 4 temperate strains) were selected for genome-wide sequencing using BGI technology. The annotation of the genomes focused on the identification of genes for pathogenicity factors and antimicrobial resistance, as well as the identification of strains belonging to individual genetic lineages using the cgMLST method. Results. The annotation of the genomes allowed their assignment to different sequence types in the multilocus sequencing typing and genome-wide sequencing typing schemes. The analysis of the geographical distribution of the sequence types of polar E. coli strains determined by the cgMLST method showed their global representation in geographically distant regions of the planet. For example, cgST 133718 was observed in Antarctica (strain 17_1myr) and in the UK, and sequence 11903, to which strain 32-1 from the northernmost point of Novaya Zemlya belonged, was previously identified in the USA. All strains studied were characterized by the presence of extensive virulence. Among the pathogenicity factors identified were haemolysins A, E, F, siderophores, including the yersiniabactin gene cluster, a number of adhesion, colonization and invasion factors, as well as the thermostable enterotoxin EAST-1 and genes that characterize enteroaggregative strains of E. coli (the virulence regulator gene eilA and enteroaggregative protein (air)). One of the Arctic strains (33-1) had determinants of antibiotic resistance, in particular the extended-spectrum beta-lactamase gene TEM-1b and the Tn1721 transposon, including tetracycline resistance genes (tetA-TetR), were detected in its genome. Conclusion. The results of the study indicate the circulation of E. coli strains with strong pathogenic potential in high-latitude Arctic and Antarctic ornithogenic ecosystems. The analysis of genomic data indicates the presence of geographically widespread genetic lineages in these regions, which justifies the importance of monitoring epidemic clones of E. coli, along with monitoring for other pathogens, in bird colonies in high-latitude areas.

Updated Arctic melt pond fraction dataset and trends 2002–2023 using ENVISAT and Sentinel-3 remote sensing data

Abstract. Melt ponds on Arctic sea ice affect the radiative balance of the region as they introduce darkening of the sea ice during the Arctic summer. The temporal extent and spatial extent of the ponding, as well as its amplitude, reflect the state of Arctic sea ice and are important for our understanding of Arctic sea ice change. Remote sensing retrievals of melt pond fraction (MPF) provide information on both the present state of the melt pond development and its change throughout the years, which is valuable information in the context of climate change and Arctic amplification. In this work, we transfer the earlier published Melt Pond Detector (MPD) remote sensing retrieval to the Ocean and Land Colour Instrument (OLCI) data on board the Sentinel-3 satellite and so complement the existing Medium Resolution Imaging Spectrometer (MERIS) MPF dataset (2002–2011) from Environmental Satellite (ENVISAT) with recent data (2017–present). To evaluate the bias of the MPF product, comparisons to Sentinel-2 MultiSpectral Instrument (MSI) high-resolution satellite imagery are presented, in addition to earlier published validation studies. Both MERIS and OLCI MPD tend to overestimate the small MPFs (ranging from 0 to 0.2), which can be attributed to the presence of water-saturated snow and sea ice before onset of ponding. Good agreement for the middle-range MPF (0.2–0.8) is observed, and the areas of exceptionally high MPF = 100 % are recognized as well. The earlier published MERIS MPFs (2002–2011) were reprocessed using an improved cloud clearing routine and together with recent Sentinel-3 data provide an internally consistent dataset, which allows the MPF development in the past 20 years to be analyzed. Although the total summer hemispheric MPF trend is moderate, at +0.75 % per decade, the regional weekly MPF trends display a pronounced dynamic and range from −10 % to as high as +20 % per decade, depending on the region. We conclude the following effects: The global Arctic melt onset shifted towards spring by at least 2 weeks, with the melt onset happening in late May in recent years as compared to early June to mid-June in the beginning of the dataset. There has been a change in the pond onset regime in recent years, with the East Siberian and Laptev Sea dominating the melt onset and not the Beaufort Gyre region as before. The central Arctic, north Greenland and the Canadian Arctic Archipelago (CAA) have shown signs of increasing first-year ice (FYI) fraction in recent years. The daily gridded MPF averages are available on the web page of the Institute of Environmental Physics, University of Bremen, as a historic dataset for the ENVISAT data and as ongoing operational processing for the Sentinel-3 data.

Crustal Heterogeneity Onshore Central Spitsbergen: Insights From New Gravity and Vintage Geophysical Data

AbstractGravity data provide constraints on lateral subsurface density variations and thus provide crucial insights into the geological evolution of the region. Previously, gravity data from the Norwegian Arctic archipelago of Svalbard comprised an onshore regional gravity database with coarse station spacing of 2–20 km, offshore gravity profiles acquired in some fjords, airborne gravity, and satellite altimetry. The sparse regional point‐based onshore coverage hampered the direct integration of gravity data with seismic profiles acquired onshore Svalbard in the late 1980s and early 1990s. In April 2022, we acquired gravity data at 260 new stations along seven profiles from western to eastern Spitsbergen, with a cumulative length of 329 km. The profiles were acquired directly along selected seismic profiles and provide much closer station spacing (0.5–2 km) compared to the regional inland grid (2–20 km) acquired in the late 1980s (total number of onshore stations: 1,037). Having processed the data, we compared the first‐order density trends of our new data with the legacy regional grid. The new gravity data are consistent with the regional data, imaging a gravity low in the western part of the area underlying a foreland basin and a gravity high in the northwestern part of the area likely associated with a basement high or denser basement. We compare the new and vintage gravity using maps and profiles, linked to the known major tectonic features such as major basinal axes and fault zones, as well as other geophysical data sets including seismics and magnetics.

Inter-comparisons of Arctic snow depth products

ABSTRACT Applying ICESat-2 and CryoSat-2 freeboards, the Arctic snow depth (ISCS) was obtained from October 2018 to April 2022. The results were assessed using Operation Ice Bridge (OIB) and Multidisciplinary Drifting Observatory for the Study of Arctic Climate (MOSAiC) in situ observations and compared with frequently used remote sensing (AMSR-E/AMSR2), climatology (modified W99 snow climatology data; MW99), and modelled (Pan-Arctic Ice Ocean Modelling and Assimilation Systems; PIOMAS) snow products. The ISCS snow depth exhibited high correlations (r = 0.67) and small mean bias (0.01 ± 0.06 m) against OIB results. We found good correlations (statistically significant) between MOSAiC and all snow depth products, except for MW99. Mean and absolute biases between ISCS and MOSAiC in situ observations were 0.01 ± 0.06 and 0.04 ± 0.04 m, respectively. The ISCS revealed clear spatial distribution from the Canadian Arctic Archipelago to open sea areas. In contrast, the PIOMAS snow depth revealed weak autumn variation, whereas the MW99 snow depth yielded distinct seasonal variability but a weak interannual change. Snow depth in October showed large differences among the various products, from which the AMSR topped the snow depth in the first-year ice region, while MW99 had the highest values for the multiyear ice zone.

The lost generation of Pemphigus populiglobuli (Hemiptera, Aphididae): exploring the taxonomy of the Svalbard aphids of genus Pemphigus

Species identification within the aphid genus Pemphigus Hartig, 1839 poses challenges due to morphological similarities and host-plant associations. Aphids of this genus generally exhibit complex life cycles involving primary hosts (poplars) and secondary (mostly unrelated herbaceous) host-plants, with some species relying solely on root-feeding generation. An example is a representative of the genus Pemphigus, trophically associated with grass roots, found in the High Arctic Svalbard archipelago. Historical records tentatively identify it as Pemphigus groenlandicus (Rübsaamen, 1898), although its formal classification remains elusive, due to limited material of freshly collected samples. Recent collections from 2007 to 2024 across various Svalbard sites, revealed its presence under stones in sheltered microhabitats, providing valuable specimens for comparative studies. Our molecular analyses indicate that the Svalbard specimens are not a separate species commonly identified as P. groenlandicus, nor an anholocyclic generation of Pemphigus bursarius (Linnaeus, 1758) or P. borealis Tullgren, 1909, but represent a secondary generation of Pemphigus populiglobuli Fitch, 1859, the Nearctic poplar bullet gall aphid. This suggests that they may have lost their primary host associations and adapted to living on grass roots year-round. Our specimens did not host any known facultative symbionts; however, we detected a strain of Pseudomonas Migula, 1894, closely related to a cold-tolerant bacterium abundant in polar regions. The present study also investigates the taxonomic relationships and morphometric characteristics of grass-feeding Pemphigus populations across the Arctic and an isolated locations on the European continent. Specimens from Svalbard were compared with samples from Greenland and Iceland, but identified no substantial morphometric differences among these geographically separated populations. Similarly, analyses of samples of Pemphigus groenlandicus crassicornis Hille Ris Lambers, 1952 from Sweden and Spain reveals a high morphometric similarity to the Arctic population, indicating a strong link between these traits and geographical variability. Despite the limitations in fresh material availability across locations, minor morphometric variations and shared ecological niches (all populations studied inhabiting grass roots, a unique trait within the Pemphigus genus) suggest treating both P. groenlandicus and its subspecies crassicornis as a junior synonym to P. populiglobuli. The study also demonstrates that the secondary generation of P. populiglobuli is a terrestrial microarthropod that overwinters in a postembryonic life-stage in situ in soil and vegetation under harsh Arctic conditions, and its cryptic life complicates its distribution mapping.

Dissolved Nitrogen Cycling in the Eastern Canadian Arctic Archipelago and Baffin Bay From Stable Isotopic Data.

Climate change is expected to alter the input of nitrogen (N) sources in the Eastern Canadian Arctic Archipelago and Baffin Bay due to increased discharge from glacial meltwater and permafrost thaw. Since dissolved inorganic N is generally depleted in surface waters, dissolved organic N (DON) could represent a significant N source fueling phytoplankton activity in Arctic ecosystems. Yet, few DON data for this region exist. We measured concentrations and stable isotope ratios of DON (δ15N) and nitrate (NO3 -; δ15N and δ18O) to investigate the sources and cycling of dissolved nitrogen in regional rivers and marine samples collected in the Eastern Canadian Arctic Archipelago and Baffin Bay during the summer of 2019. The isotopic signatures of NO3 - in rivers could be reproduced in a steady state isotopic model by invoking mixing between atmospheric NO3 - and nitrified ammonium as well as NO3 - assimilation by phytoplankton. DON concentrations were low in most rivers (≤4.9μmolNL-1), whereas the concentrations (0.54-12μmolNL-1) and δ15N of DON (-0.71-9.6‰) at the sea surface were variable among stations, suggesting dynamic cycling and/or distinctive sources. In two regions with high chlorophyll-a, DON concentrations were inversely correlated with chlorophyll-a and the δ15N of DON, suggesting net DON consumption in localized phytoplankton blooms. We derived an isotope effect of 6.9‰ for DON consumption. Our data helps establish a baseline to assess future changes in the nutrient regime for this climate-sensitive region.

On the terrestrial and freshwater invertebrate diversity of the High Arctic archipelago of Svalbard: a revised species inventory and synopsis of the community composition

On the terrestrial and freshwater invertebrate diversity of the High Arctic archipelago of Svalbard: a revised species inventory and synopsis of the community composition

Vertical stratification of arctic microbial communities near potential hydrocarbon seepage off Cape Dyer, Nunavut

Climate change disproportionately affects the Arctic, where warming is up to four times greater than the global annual average experienced in southern regions. Baffin Bay in the Canadian Arctic Archipelago is an ecologically and biologically significant area that will likely experience an increase in marine vessel traffic as a result of consistent declines in annual sea ice coverage. Along the western coast of Baffin Bay is known to be a region of active, natural hydrocarbon seeps where elevated levels of methane have been detected in previous surveys. Petroleum hydrocarbons released from the seafloor can fuel microbial production and shape the baseline microbiome. Establishing a microbial baseline is highly valuable as it contributes to a fundamental understanding of the existing microbial diversity that may be impacted in the future by anthropogenic stressors. In this study, 16S and 18S rRNA gene amplicon sequencing surveys revealed that the vertical stratification of the water column is largely driven by differences in depth, temperature, salinity, and inorganic nutrient concentrations. Chemical analysis provides further support that active petrogenic methane seepage occurs around Cape Dyer but not in areas targeted in this study. Presence of n-alkanes and toluene in association with hydrocarbon-synthesizing phytoplankton suggests biogenic production of these compounds. These findings provide a baseline for future environmental monitoring assessments to evaluate how the prokaryotic and eukaryotic microbiome may be impacted by ongoing climate change and anthropogenic stressors in western Baffin Bay.

A moderator of tropical impacts on climate in Canadian Arctic Archipelago during boreal summer

The Canadian Arctic Archipelago consists of important international trade routes, and local surface air temperatures (SAT) greatly control sea ice melting in situ during boreal summer (June-July-August-September). However, the drivers of the Arctic Archipelago summer SAT variability have not yet been fully elucidated. Here, we find that the impact of tropical Indo-Pacific convection on the Arctic Archipelago SAT through induced poleward-propagating Rossby wave train is strongly modulated by Russian Arctic sea surface temperature anomalies (SSTA). Negative Russian Arctic SSTA lead to a weakened East Asia westerly jet via equatorward Rossby wave activity. The weakened westerly jet enhances the meridional gradient of the potential vorticity over the North Pacific, guiding the poleward-propagating Rossby wave to the Arctic Archipelago and therefore affecting the local SAT. Conversely, positive Russian Arctic SSTA impede the northward-propagating Rossby wave via enhancing the East Asia westerly jet, resulting in a weakened relationship between the tropical Indo-Pacific convection and Arctic Archipelago SAT. The present study proposes a mechanism whereby changes in the Tropical-Arctic connection stem from thermal conditions elsewhere in the Arctic, through shaping poleward-propagating Rossby waves by changing the background mean flow.

Potential of the Arkhangelsk seismic network for European Arctic monitoring

The Arkhangelsk Seismic Network (ASN) of the N. Laverov Federal Center for Integrated Arctic Research of the Ural Branch of the Russian Academy of Sciences, founded in 2003, includes 10 permanent seismic stations located on the coasts of the White, Barents, and Kara Seas and on the Arctic archipelagos of Novaya Zemlya, Franz Josef Land, and Severnaya Zemlya. The network is registered with the International Federation of Digital Seismograph Networks and the International Seismological Center. We used not only ASN data to process earthquakes but also the waveforms of various international seismic stations. The 13,000 seismic events were registered using ASN data for 2012–2022, and for 5,500 of them, we determined the parameters of the earthquake epicenters from the European Arctic. The spatial distribution of epicenters shows that the ASN monitors not only the main seismically active zones but also weak seismicity on the shelf of the Barents and Kara Seas. The representative magnitude of ASN was ML, rep=3.5. The level of microseismic noise has seasonal variations that affect the registration capabilities of each station included in the ASN and the overall sensitivity of the network as a whole. In summer, the sensitivity of the ASN decreased owing to the increasing microseismic and ambient noises, whereas in winter, the sensitivity of the ASN increased significantly because of the decrease.

The marine methane cycle in the Canadian Arctic Archipelago during summer

In the Arctic Ocean, methane concentrations surpassing global averages are prevalent, especially along sub-Arctic and Arctic continental shelf margins. Despite elevated dissolved methane levels, the Arctic Ocean exhibits minimal methane fluxes to the atmosphere, indicating a potential role of water column oxidation in methane processing. During the Northwest Passage Project in the summer of 2019, we integrated thermohaline, chemical, and biological data with in-situ and in-vitro methane data in Canadian Arctic Archipelago (CAA) waters. Elevated in-situ dissolved methane was prominent in near-surface Pacific waters (between 2 and 7 m), particularly in meltwater regions, with av. concentrations of 5.8 ± 2.5 nM within the upper 30m. While methane oxidation constants were generally low (av. 0.006 ± 0.002 d−1), surface waters in Wellington Channel and Croker Bay exhibited higher rates (av. 0.01 ± 0.0004 d−1), associated with Pacific-origin microbial taxa like Oleispira and Aurantivirga. Deeper layers (>200 m) displayed lower methane concentrations (av. 3.1 ± 1.1 nM) and oxidation rates (av. 0.005 ± 0.001 d−1). Sea ice showed elevated dissolved methane concentrations (av. 9.2 ± 5 nM). Waters in the western CAA exhibited a 25% increase in methane concentrations compared to ice-free areas. The overall picture suggested supersaturation of in-situ methane in shallow waters (between 2 and 50 m), coupled with faster oxidation rates in meltwater and Pacific dominant layers, suggesting rapid seasonal cycling of methane and prevention of the methane migration into the atmosphere.

Passage and removal of the Amundsen Gulf Ice Stream, NW Laurentide Ice Sheet, recorded by the glacial and sea level history of southern Banks Island, Arctic Canada

Earlier reconstructions of the glacial history of the western Canadian Arctic Archipelago, commonly portrayed Banks Island as an ice-free biological refugium during the Last Glacial Maximum, ostensibly constituting the northeast extremity of Beringia. This has now been contradicted by widespread fieldwork across the northern and western coasts documenting their inundation by the northwest Laurentide Ice Sheet that extended onto the polar continental shelf. Here we report the surficial geology and deglacial sea levels across southern Banks Island completing the island-wide evidence for a pervasive ice cover during the Late Wisconsinan.Moraines and erratics confirm the passage of an ice stream at least 1.1 km thick through Amundsen Gulf that onlapped the south coast of the island. The inland margin of the ice stream is marked by a prominent 80 km long shear moraine (Sachs moraine) that contacted thin, cold-based Laurentide ice crossing the island's interior. Subsequent thinning and retreat of the Amundsen Gulf Ice Stream from the Sachs moraine occurred in concert with its separation from topographically-confined ice lobes in the interior recorded by prominent ice-marginal meltwater channels. As the ice stream retreated offshore, a prominent kettled outwash plain was deposited along the coast marking marine limit at 20 m asl. From an unknown position offshore, the ice stream readvanced deforming the south shore of the kettled lowland marked by the 40 km long ‘Sand Hills moraine’. Based on updated field mapping, the 'Sand Hills moraine' is now recognized as the westward extension of the more widespread Jesse moraine belt.Deglacial marine limit rises eastward across the island from 11 to 40 m asl, bordering Prince of Wales Strait. Marine limit and all lower shorelines across the island's south coast (for ∼ 200 km) are barren of marine shells. This is because sea level had regressed from marine limit to a lowstand offshore before Pacific molluscs recolonized the western Canadian Arctic at 13.7 cal ka BP, their entry occasioned by the resubmergence of Bering Strait. This requires that the breakup of the western Amundsen Gulf Ice Stream (including the M'Clure Strait Ice Stream along northern Banks Island) occurred before 14 cal ka BP, documenting that the NW Laurentide Ice Sheet must have contributed to Meltwater-Pulse-1A. Although the retreat from the outermost parts of the Jesse moraine belt also pre-date the arrival of shells, we show that the youngest (central) segment along eastern Amundsen Gulf dates to ∼12.9 cal ka BP, documenting that the Jesse moraine belt is highly time transgressive (spanning >13.7 to 12.9 cal ka BP). Radiocarbon dates on woody plants and bryophytes demonstrate that the island was biologically viable as early as 12.6 cal ka BP and that all coastlines were submergent soon afterwards and remain so today.

Chromosomal-level reference genome assembly of muskox (Ovibos moschatus) from Banks Island in the Canadian Arctic, a resource for conservation genomics

The muskox (Ovibos moschatus), an integral component and iconic symbol of arctic biocultural diversity, is under threat by rapid environmental disruptions from climate change. We report a chromosomal-level haploid genome assembly of a muskox from Banks Island in the Canadian Arctic Archipelago. The assembly has a contig N50 of 44.7 Mbp, a scaffold N50 of 112.3 Mbp, a complete representation (100%) of the BUSCO v5.2.2 set of 9225 mammalian marker genes and is anchored to the 24 chromosomes of the muskox. Tabulation of heterozygous single nucleotide variants in our specimen revealed a very low level of genetic diversity, which is consistent with recent reports of the muskox having the lowest genome-wide heterozygosity among the ungulates. While muskox populations are currently showing no overt signs of inbreeding depression, environmental disruptions are expected to strain the genomic resilience of the species. One notable impact of rapid climate change in the Arctic is the spread of emerging infectious and parasitic diseases in the muskox, as exemplified by the range expansion of muskox lungworms, and the recent fatal outbreaks of Erysipelothrix rhusiopathiae, a pathogen normally associated with domestic swine and poultry. As a genomics resource for conservation management of the muskox against existing and emerging disease modalities, we annotated the genes of the major histocompatibility complex on chromosome 2 and performed an initial assessment of the genetic diversity of this complex. This resource is further supported by the annotation of the principal genes of the innate immunity system, genes that are rapidly evolving and under positive selection in the muskox, genes associated with environmental adaptations, and the genes associated with socioeconomic benefits for Arctic communities such as wool (qiviut) attributes. These annotations will benefit muskox management and conservation.

Change of global land extreme temperature in the future

Understanding future temperature extremes is pivotal to preparing for and mitigating the impacts of climate change. This study proposed machine learning techniques to develop a multi-model ensemble model for high-resolution projection of global land temperature extremes under different emission scenarios, hence providing enhanced precision over previous climate model projections. By utilizing the NEX-GDDP-CMIP6 dataset with bias adjustment and the Gradient Booster algorithm, we reduced the biases that existed in Global Climate Models. The model significantly reduces the root mean square errors (RMSEs) for both the daily maximum and daily minimum temperature extremes. A future scenario analysis revealed that global temperature extremes would substantially increase under high-emission scenarios, highlighting the urgency for stringent emission reduction commitments. This study also identified regions like Greenland, the Tibetan Plateau, and the regional Arctic Archipelago as potential hotspots of temperature extremes under these scenarios. The multi-model ensemble approach, tuned with machine learning and driven by high-resolution data, contributes to climate science by providing refined insights into future temperature extremes, thereby offering direction to climate change mitigation and adaptation strategies.

Shelf-to-basin shuttle of highly fractionated chromium isotopes in the Arctic Ocean

The oceanic chromium (Cr) cycle is mainly governed by the interconversion and the distribution of Cr(VI) and Cr(III) species and their stable isotopic ratios (δ53Cr) in the water column. As a result, the Cr cycle generates a strong correlation between the natural logarithm of its dissolved concentration and δ53Cr regardless of the location of sampling. A few studies have reported the Cr composition of certain regions falling off the global Cr array, highlighting the local prevalence of underlying mechanisms participating in the Cr cycle in the oceans. In an effort to better constrain the global Cr array, this study presents an extensive dataset for total dissolved Cr concentration ([Cr]T) and δ53Cr in the Arctic Ocean in regions meeting the environmental conditions where Cr was observed to fall off the global Cr array (e.g. continental shelves, restricted water circulation, sea ice melting). We find that more than 70% of the Arctic seawater collected plot below the global Cr array due to a small addition of highly fractionated Cr (−2.8 ‰ to −1.1 ‰) and its transport across all the Arctic regions sampled. We identify the Chukchi Shelf as the region where highly fractionated Cr is produced, from where a Cr shuttle could work in tandem with the Arctic Fe and Mn shuttles to explain the production and widespread export of isotopically light Cr in the Arctic waters. We identify a second non-reductive release of highly fractionated Cr in the Canadian Arctic Archipelago, Baffin Bay and potentially the Labrador Sea via sediment resuspension, alongside addition of isotopically light Cr originating from crustal rocks. These findings demonstrate that the Arctic-modified outflow signature of Cr isotopes modify the Cr isotopic signature of the North Atlantic waters, and that the North Atlantic waters may deviate from the global Cr array depending on whether the isotopically light Cr added to the Arctic Ocean is Cr(III) that has not been scavenged or Cr(III) that has oxidized to Cr(VI).

Atmospheric-river-induced foehn events drain glaciers on Novaya Zemlya

Recently, climate extremes have been grabbing attention as important drivers of environmental change. Here, we assemble an observational inventory of energy and mass fluxes to quantify the ice loss from glaciers on the Russian High Arctic archipelago of Novaya Zemlya. Satellite altimetry reveals that 70 ± 19% of the 149 ± 29 Gt mass loss between 2011 and 2022 occurred in just four high-melt years. We find that 71 ± 3% of the melt, including the top melt cases, are driven by extreme energy imports from atmospheric rivers. The majority of ice loss occurs on leeward slopes due to foehn winds. 45 of the 54 high-melt days (>1 Gt d−1) in 1990 to 2022 show a combination of atmospheric rivers and foehn winds. Therefore, the frequency and intensity of atmospheric rivers demand accurate representation for reliable future glacier melt projections for the Russian High Arctic.

Rethinking the exercise of sovereignty in the Anthropocene: From extraction to environmental protection in Arctic Svalbard

This paper explores the implications of the Anthropocene and its associated planetary awareness on the concept and exercise of sovereignty, particularly through the lens of the Svalbard Treaty. The Arctic archipelago of Svalbard is not only a space undergoing rapid environmental change today, but its treaty-based governance arrangements are based on an early-twentieth century spatial imaginary of fishery, coal, and resource extraction. By examining Norway's governance shift from resource extraction to environmental stewardship on Svalbard, this paper reflects on transformations of the practice of sovereignty in response to global environmental challenges. Through interviews with local stakeholders, the research highlights the contentious nature of these shifts, revealing how increased environmental regulations, while necessary, may paradoxically entrench existing power structures and complicate the presence of non-Norwegian entities. This case study of the Svalbard Treaty serves as a normative microcosm for broader issues of sovereignty, treaty obligations, and international governance as they may evolve due to planetary change, pointing to the urgent need to rethink these evolving dynamics. The paper underscores the pressing and complex challenges facing the international system in the Anthropocene, suggesting that while Svalbard's geopolitical stability may be maintained and Norwegian sovereignty remains uncontested, the instability of global environmental realities is already leading to changes to the ways in which sovereignty is exercised in the present.