Alfred Wegener Institute for Polar and Marine Research
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Ice Shelf Water‐Influenced Fast Ice and Sub‐Ice Platelet Layer Near the Campbell Ice Tongue, Terra Nova Bay
Full text linkHere, we present the first dedicated in situ measurements of the thickness distributions of fast ice and the sub‐ice platelet layer, formed by supercooled Ice Shelf Water in north Terra Nova Bay, Antarctica. With the objective of inferring source regions and circulation of Ice Shelf Water, we measured fast ice and sub‐ice platelet layer thickness distributions near the Campbell Ice Tongue in late spring of 2021, using drill hole surveys and high‐resolution ground‐based electromagnetic induction soundings. We observed thicker fast ice and sub‐ice platelet layer near the ice tongue with very thick and narrow sub‐ice platelet layer maxima indicating highly channeled outflow of supercooled Ice Shelf Water from beneath the ice tongue directed by ice mélange, subglacial formations, and grounded regions. We conclude that a significant volume of supercooled Ice Shelf Water is locally sourced from the Campbell Ice Tongue through basal melting and affirm that the icescape in north Terra Nova Bay results from a complex interplay of glacial morphology, polynya forcing, and ocean circulation.
Plain Language Summary Fresh meltwater from glacial ice on the Antarctic continent can influence coastal sea ice formation. If the meltwater forms deep in the ocean, it can be supercooled and freeze into platelet ice crystals, which contribute to sea ice formation and form thick layers beneath sea ice called sub‐ice platelet layers (SIPL). Platelet ice, a crystallographic signature of supercooled glacial meltwater provides important information on difficult to observe interacting processes occurring between the atmosphere, glacial ice, the ocean, and sea ice along the Antarctic coast. In late spring of 2021, we carried out detailed surveys of glacially influenced coastal sea ice and SIPL beside the Campbell Ice Tongue in north Terra Nova Bay, Ross Sea, Antarctica, with high‐resolution geophysical surveying. Our objective was to use sea ice and SIPL distributions to infer where the glacial meltwater was coming from and where it circulates. Our surveys revealed thicker sea ice and SIPL near the ice tongue with thick bands of SIPL indicating highly channeled outflow of supercooled glacial meltwater from beneath the Campbell Ice Tongue through glacial formations. We conclude that a significant volume of supercooled glacial meltwater in north Terra Nova Bay is locally sourced from the Campbell Ice Tongue through basal melting.
Key Points Basal melt of the Campbell Ice Tongue is a significant source of Ice Shelf Water in north Terra Nova Bay Thickness distributions of fast ice and the sub‐ice platelet layer were used to infer Ice Shelf Water outflow from the Campbell Ice Tongue Fast ice in north Terra Nova Bay is stabilized by the Campbell Ice Tongue and broken up by the Terra Nova Bay Polyny
IceBird CAN25 Campaign Report
Full text linkBetween March 13 and April 21, 2025, the IceBird CAN25 airborne campaign of AWI’s Polar 6 research airplane took place in Canada, Greenland, and Svalbard to survey characteristic sites of snow on land and sea ice, to observe long-term sea ice variability and change, and to develop new snow remote sensing techniques. During 21 survey flights snow and sea ice in the vicinity of Whitehorse (YT), Inuvik (NWT), Cambridge Bay, Resolute Bay, Pond Inlet (all NU), Station Nord (Greenland), and Longyearbyen (Svalbard) took place. These included overflights of seven sites in Trial Valley Creek, Tuktoyaktuk, Cambridge Bay, Pond Inlet, Resolute Bay and Longyearbyen where collaborators from the SmartIce/Sikunnguak, MOACC, Str3TART, and IceView projects had collected extensive in-situ validation data
Hidden cascades of seismic ice stream deformation
No full textIce streams are major regulators of sea level change. However, standard viscous flow simulations of their evolution have limited predictive power due to incomplete understanding of involved processes. On the Greenland ice sheet, borehole fiber-optic observations reveal a brittle deformation mode that is incompatible with viscous flow over length scales similar to the resolution of modern ice sheet models: englacial ice quake cascades that are unobservable at the surface. Nucleating near volcanism-related impurities that promote grain boundary cracking, they appear as a macroscopic form of crystal-scale wild plasticity. A conservative estimate indicates that seismic cascades are likely to produce strain rates that are comparable in amplitude to those measured geodetically, thereby providing a plausible missing link between current ice sheet models and observations
FESOM2.1-REcoM3-MEDUSA2: an ocean–sea ice–biogeochemistry model coupled to a sediment model
Full text linkThis study describes the coupling of the process-based Model of Early Diagenesis in the Upper Sediment with Adaptable complexity (MEDUSA version 2) to an existing ocean biogeochemistry model consisting of the Finite-volumE Sea ice–Ocean Model (FESOM version 2.1) and the Regulated Ecosystem Model (REcoM version 3). Atmospheric CO2 in the model is a prognostic variable which is determined by the carbonate chemistry in the surface ocean. The model setup and its application to a pre-industrial control climate state is described in detail. In the coupled model, 1390 PgC is stored in the top 10 cm of the bioturbated sediment, mainly as calcite, but also as organic matter (10 %). In the coupled simulation, atmospheric CO2 stabilizes at ∼295 ppm after 2000 years, in line with the CO2 level expected from the climate forcing conditions. Sediment burial of carbon, alkalinity, and nutrients in the coupled simulation is set to be compensated by riverine input. The spatial distribution of biological production is altered depending on the location of riverine input and reduction in sedimentary input, as well as the strength of local nutrient limitation, while the global productivity is not affected substantially. With this coupled ocean–sediment system the model is able to simulate the carbonate compensation feedback under moderate perturbation of CO2 in the atmosphere
Plant interactions associated with a directional shift in the richness range size relationship during the Glacial-Holocene transition in the Arctic
Full text linkA nearly ubiquitous negative relationship between taxonomic richness and mean range-size (average area of taxa) is observed across space. However, the complexity of the mechanism limits its applicability for conservation or range prediction. We explore whether the relationship holds over time, and whether plant speciation, environmental heterogeneity, or plant interactions are major factors of the relationship within northeast Siberia and Alaska. By analysing sedimentary ancient DNA from seven lakes, we reconstruct plant richness, biotic environmental heterogeneity, and mean range-size over the last 30,000 years. We find positive richness to range-size relationships during the glacial period, shifting to negative during the interglacial period. Our results indicate neither speciation nor environmental heterogeneity is the principal driver. Network analyses show more positive interactions during the glacial period, which may contribute to positive richness to range-size relationships. Conversely, in the interglacial environment, negative interactions may result in negative relationships. Our findings suggest potential susceptibility to invasion but conservation advantages in far northern tundra given their positive interactions
Biological Processes Underlying Genetic Adaptation of Larches to Cold and Dry Winter Conditions in Eastern Siberia
Full text linkABSTRACTThe boreal forests of central and eastern Siberia, dominated by larches, are challenged by increasingly harsher continental conditions and more frequent droughts. Despite the crucial ecosystem services provided by these Siberian boreal forests, the major stressors driving the selective factors as well as the genetic adaptation mechanisms of larches are still unknown. Here we present a landscape genomics study on 243 individuals of the dominant larch tree species, Larix gmelinii and L. cajanderi. We assessed genotype‐environment associations (GEAs) between genetic variation of individual markers based on genotyping‐by‐sequencing (GBS) data and bioclimatic variables recorded at the sampling locations. We find that the cold and dry winter conditions of eastern Siberia are likely the main selective factor driving the genetic adaptation of larches. Gene ontology (GO) enrichment analysis identified metabolic, transmembrane transport, and homeostatic, as well as developmental processes among the main biological processes underlying genetic adaptation driven by cold and dry winter conditions.</jats:p
Dynamic land-plant carbon sources in marine sediments inferred from ancient DNA
Full text linkAbstract
Terrigenous organic matter in marine sediments is considered a significant long-term carbon sink, yet our knowledge regarding its source taxa is severely limited. Here, we leverage land-plant ancient DNA from six globally distributed marine sediment cores covering the Last Glacial–Holocene transition as a proxy for the share, burial rate, preservation, and composition of terrigenous organic matter. We show that the spatial and temporal plant composition as revealed by sedimentary ancient DNA records reflects mainly the vegetation dynamics of nearby continents as revealed by comparison with pollen from land archives. However, we also find indications of a global north-to-south translocation of sedimentary ancient DNA. We also find that plant sedimentary ancient DNA has a higher burial rate in samples from the Late Glacial, which is characterized by high runoff and mineral load. This study provides an approach to understanding the global linkages between the terrestrial and marine carbon cycle, highlighting the need for further research to quantify the processes of DNA preservation and dispersal in marine sediments.</jats:p
Greening of Svalbard in the twentieth century driven by sea ice loss and glaciers retreat
Full text linkClimate change and terrigenous inputs decrease the efficiency of the future Arctic Ocean’s biological carbon pump
Full text linkThe Arctic experiences climate changes that are among the fastest in the world and affect all
Earth system components. Despite expected increase in terrigenous inputs to the Arctic Ocean,
their impacts on biogeochemical cycles are currently largely neglected in IPCC-like models. We
used a state-of-the-art high-resolution ocean biogeochemistry model, that includes carbon and
nutrient inputs from rivers and coastal erosion, to produce twenty-first-century pan-Arctic
projections. Surprisingly, even with an anticipated rise in primary production across a wide range
of emission scenarios, our findings indicate that climate change leads to a counterintuitive 40%
reduction in the efficiency of the Arctic's biological carbon pump by 2100, to which terrigenous
inputs contribute 10%. Terrigenous inputs will also drive intense coastal CO2 outgassing,
reducing the Arctic Ocean's carbon sink by at least 10% (33 TgC yr-1). These unexpected positive
feedbacks, mostly due to accelerated remineralization rates, lower the Arctic Ocean’s capacity
for sequestering carbon
