Geophysics, Geology, Stratigraphy, Global and Planetary Change
135
Scopus Publications
Scopus Publications
Evolution of the East Antarctic Ice Sheet Since Glacial Inception From Seismic Stratigraphic Records in Vincennes Bay Timo Mühlberger‐Krause, Karsten Gohl, Katharina Hochmuth, German Leitchenkov, Chiara A. Tobisch, et al. Paleoceanography and Paleoclimatology, 2026 Seismic reflection data from Vincennes Bay, East Antarctica, provide the first insights into the Cenozoic evolution of the East Antarctic Ice Sheet (EAIS) in the Knox Coast. Long‐distance seismic horizon correlation allows age estimates for the seismic stratigraphic framework constructed for the continental shelf. Preglacial depositional patterns reveal extensive fluvial plains on the continental shelf from the Late Cretaceous until the latest Eocene (∼34 Ma). These transitioned to glaciofluvial outwash plains during the late Oligocene. The earliest clear indication of ice sheets present on the Vincennes Bay continental shelf are two generations of large buried tunnel valley systems that developed during the Oligocene‐Miocene Transition (∼24 Ma) and early Miocene during meltwater‐rich glaciations originating in the Knox Coastal Plain. Glacially transported sediment wedges deposited at the end of the early mid‐Miocene (>∼14 Ma) mark the beginning of steep glacial progradation of the continental shelf continuing through the Miocene and Pliocene. Ice sheet development from the late mid‐Miocene to the Quaternary is likely driven by the Aurora Subglacial Basin via the Vanderford Glacier. This suggests a major reorganization of ice flow from the early glaciations of the Oligocene and early Miocene to the later development of modern configurations, established in the late mid‐Miocene. Our results provide the first data of the Cenozoic development of the EAIS in Vincennes Bay and demonstrate the variability of ice flow conditions with past climatic changes.
Repeated major inland retreat of Thwaites and Pine Island glaciers (West Antarctica) during the Pliocene Keiji Horikawa, Masao Iwai, Claus-Dieter Hillenbrand, Christine S. Siddoway, Anna Ruth Halberstadt, et al. Proceedings of the National Academy of Sciences of the United States of America, 2026 The stability of the West Antarctic Ice Sheet (WAIS), crucial for predicting future sea-level rise, is threatened by ocean-forced melting in the Pacific sector of the Southern Ocean. While some geological records and ice-sheet models suggest WAIS retreat during past warm periods, reliable data constraining the extent of retreat are lacking. Detrital Nd, Sr, and Pb isotope data of sediments recently drilled at International Ocean Discovery Program (IODP) Site U1532 on the Amundsen Sea continental rise manifest repeated alternations in sediment provenance during glacial–interglacial cycles of the Pliocene (5.33 to 2.58 Mya), a time warmer than present. The variations reflect large fluctuations in WAIS extent on the Antarctic continent. A unique high Pb/low ε Nd signature of sediments found at the onset of glacial intervals (3.88, 3.6, and 3.33 Ma) is attributed to the supply of detritus sourced from plutonic rocks located in the West Antarctic interior. Its isotopic signature at Site U1532 indicates major inland retreat of the WAIS during the preceding interglacials. During peak interglacials, the ice margin had retreated inland, and icebergs rafted and deposited inland-sourced detritus over 500 km across the Amundsen Sea shelf. Subsequent readvance of grounded ice then “bulldozed” these inland-derived fine-grained sediments from the shelf down to the continental slope and rise, resulting in a high Pb/low ε Nd peak in the rise sediments. Our continuous Pliocene records provide conclusive evidence for at least five major inland retreat events of the WAIS, highlighting the significant vulnerability of the WAIS to ongoing warming.
West Antarctic ice retreat and paleoceanography in the Amundsen Sea in the warm early Pliocene Sandra Passchier, Claus-Dieter Hillenbrand, Sidney Hemming, Werner Ehrmann, Thomas Frederichs, et al. Nature Communications, 2025 Mass loss from polar ice sheets is poorly constrained in estimates of future global sea-level rise. Today, the marine-based West Antarctic Ice Sheet is losing mass at an accelerating rate, most notably in the Thwaites and Pine Island glacier drainage basins. Early Pliocene surface temperatures were about 4 °C warmer than preindustrial and maximum sea level stood ~20 m above present. Using data from a sediment archive on the Amundsen Sea continental rise, we investigate the impact of prolonged Pliocene ocean warmth on the ice-sheet−ocean system. We show that, in contrast to today, during peak ocean warming ~4.6 − 4.5 Ma, terrigenous muds accumulated rapidly under a weak bottom current regime after spill-over of dense shelf water with high suspended load down to the rise. From sediment provenance data we infer major retreat of the Thwaites Glacier system at ~4.4 Ma several hundreds of km inland from its present grounding line position, highlighting the potential for major Earth System changes under prolonged future warming.
Influence of Transient Bottom Water Temperature Variations on Geothermal Heat Flow Measurements From the Bellingshausen Sea, West Antarctica, and the Baltic Sea Caroline Brand, Norbert Kaul, Mareen Lösing, Karsten Gohl Journal of Geophysical Research Oceans, 2025 Geothermal heat flow (GHF) data provide important constraints for ice‐sheet flow dynamics as GHF affects sliding conditions at the ice‐bed contact and englacial temperatures. However, marine measurements of the geothermal gradients can get distorted down to ∼3–10 m below seafloor by annual bottom water temperature variations. First‐ever geothermal data from the Bellingshausen Sea shelf, West Antarctica, are presumably affected by temperature variations in the modified Circumpolar Deep Water (mCDW) over annual and multidecadal periods. As magnitude and resolution of temperature data are low in the Bellingshausen Sea, we test a 1D water‐sediment model on Baltic Sea data, which includes long‐term water temperature and semiannual GHF measurements. The model approximates the measured sub‐bottom temperatures satisfactorily, although sparse data in Antarctica lead to uncertainties in reconstructed bottom water temperatures. Distortions in the geothermal gradients of the Bellingshausen Sea can be modeled using annual water temperature variations of ±0.03–0.15°C. However, the spatial heterogeneity of mCDW temperatures, recorded by heat flow lance sensors, shows no connection to geothermal gradient distortions. Therefore, the mCDW temperature variations are likely not strongly seasonal but are local changes of similar magnitude. Higher‐resolution water temperature records are needed to quantify uncertainties through annual water temperature variations in the current measurement‐derived GHF of 47–84 mWm−2 in Ronne Entrance and 21–57 mWm−2 in Eltanin Bay. Multidecadal ocean warming reduces the geothermal gradient by 16%–55% in the Bellingshausen Sea and leads to a reversed geothermal gradient in the Baltic Sea. This highlights the need to correct marine GHF for environmental factors.
Circum-Antarctic Glacially Induced Fault Reactivation Since the Last Glacial Maximum Ingra Barbosa, Rebekka Steffen, Holger Steffen, Elisabeth Seidel, Karsten Gohl, et al. Tectonics, 2025 Glacial isostatic adjustment (GIA) has the potential to reactivate faults in the crust due to the generation of stresses caused by changes in the ice load. Research on the release of stress along pre‐existing faults, known as glacially induced faults, in Antarctica is limited due to the lack of detailed information about the region's ice sheet history, Earth's rheology, and fault parameters. Here, we analyse the reactivation potential of 62 faults since the Last Glacial Maximum (LGM) by calculating Coulomb failure stress changes (CFS) for a thrust faulting and a strike‐slip faulting stress regime in combination with various GIA models and stress parameters. In general, a higher fault instability was observed in a strike‐slip faulting stress regime compared to a thrust faulting stress regime. Furthermore, the ice sheet history models had a higher effect on fault instability than the Earth models. Faults located in the Ross Sea area show the highest potential of fault reactivation, while those in the Antarctic Peninsula show the lowest. Our results suggest that the potential for glacially triggered faulting has increased since the LGM in many inherited rift systems, and some faults remain unstable until today.
Antarctic ice-shelf meltwater outflows in satellite radar imagery: ground-truthing and basal channel observations Jakob Stanley Hamann, Thomas Arney, James David Kirkham, Paul Wachter, Karsten Gohl Journal of Glaciology, 2024 Ice shelves regulate the flow of the Antarctic ice sheet toward the ocean and its contribution to sea-level rise. Accurately monitoring the basal and surface melting of ice shelves is therefore essential for predicting the ice sheet's response to climatic warming. In this study, we utilize Sentinel-1A synthetic aperture radar satellite imagery combined with shipboard measurements of water temperature and salinity to investigate the presence of surficial meltwater plumes along the Antarctic coastline. Our approach reveals a strong correlation between areas of pronounced low radar backscatter extending from ice shelves and significant decreases in water temperature and salinity, suggesting meltwater-enriched ocean waters. We propose that the low radar backscatter signature of meltwater outflows is caused by stable stratification of the upper water column, driven by density contrasts from buoyant, low-salinity meltwater and surface current shear that reduce Bragg scattering waves. The resulting smooth water surfaces were observed adjacent to the surface expression of deep basal channels, documented in a helicopter survey along part of the Bellingshausen Sea ice edge. We present high-temporal resolution satellite radar as a tool for identifying meltwater release from beneath ice shelves, capable of all-weather, day-and-night imaging.
Ice sheet–free West Antarctica during peak early Oligocene glaciation J. P. Klages, C.-D. Hillenbrand, S. M. Bohaty, U. Salzmann, T. Bickert, et al. Science, 2024 One of Earth’s most fundamental climate shifts, the greenhouse-icehouse transition 34 million years ago, initiated Antarctic ice sheet buildup, influencing global climate until today. However, the extent of the ice sheet during the Early Oligocene Glacial Maximum (~33.7 to 33.2 million years ago) that immediately followed this transition—a critical knowledge gap for assessing feedbacks between permanently glaciated areas and early Cenozoic global climate reorganization—is uncertain. In this work, we present shallow-marine drilling data constraining earliest Oligocene environmental conditions on West Antarctica’s Pacific margin—a key region for understanding Antarctic ice sheet evolution. These data indicate a cool-temperate environment with mild ocean and air temperatures that prevented West Antarctic Ice Sheet formation. Climate–ice sheet modeling corroborates a highly asymmetric Antarctic ice sheet, thereby revealing its differential regional response to past and future climatic change.
A large-scale transcontinental river system crossed West Antarctica during the Eocene Maximilian Zundel, Cornelia Spiegel, Chris Mark, Ian Millar, David Chew, et al. Science Advances, 2024 Extensive ice coverage largely prevents investigations of Antarctica’s unglaciated past. Knowledge about environmental and tectonic development before large-scale glaciation, however, is important for understanding the transition into the modern icehouse world. We report geochronological and sedimentological data from a drill core from the Amundsen Sea shelf, providing insights into tectonic and topographic conditions during the Eocene (~44 to 34 million years ago), shortly before major ice sheet buildup. Our findings reveal the Eocene as a transition period from >40 million years of relative tectonic quiescence toward reactivation of the West Antarctic Rift System, coinciding with incipient volcanism, rise of the Transantarctic Mountains, and renewed sedimentation under temperate climate conditions. The recovered sediments were deposited in a coastal-estuarine swamp environment at the outlet of a >1500-km-long transcontinental river system, draining from the rising Transantarctic Mountains into the Amundsen Sea. Much of West Antarctica hence lied above sea level, but low topographic relief combined with low elevation inhibited widespread ice sheet formation.
The Impact of Different Atmospheric CO2 Concentrations on Large Scale Miocene Temperature Signatures Akil Hossain, Gregor Knorr, Wilfried Jokat, Gerrit Lohmann, Katharina Hochmuth, et al. Paleoceanography and Paleoclimatology, 2023 Based on inferences from proxy records the Miocene (23.03–5.33 Ma) was a time of amplified polar warmth compared to today. However, it remains a challenge to simulate a warm Miocene climate and pronounced polar warmth at reconstructed Miocene CO2 concentrations. Using a state‐of‐the‐art Earth‐System‐Model, we implement a high‐resolution paleobathymetry and simulate Miocene climate at different atmospheric CO2 concentrations. We estimate global mean surface warming of +3.1°C relative to the preindustrial at a CO2 level of 450 ppm. An increase of atmospheric CO2 from 280 to 450 ppm provides an individual warming of ∼1.4°C, which is as strong as all other Miocene forcing contributions combined. Substantial changes in surface albedo are vital to explain Miocene surface warming. Simulated surface temperatures fit well with proxy reconstructions at low‐ to mid‐latitudes. The high latitude cooling bias becomes less pronounced for higher atmospheric CO2 concentrations. At such CO2 levels simulated Miocene climate shows a reduced polar amplification, linked to a breakdown of seasonality in the Arctic Ocean. A pronounced warming in boreal fall is detected for a CO2 increase from 280 to 450 ppm, in comparison to weaker warming for CO2 changes from 450 to 720 ppm. Moreover, a pronounced warming in winter is detected for a CO2 increase from 450 to 720 ppm, in contrast to a moderate summer temperature increase, which is accompanied by a strong sea‐ice concentration decline that promotes cloud formation in summer via enhanced moisture availability. As a consequence planetary albedo increases and dampens the temperature response to CO2 forcing at a warmer Miocene background climate.
Petrology, geochemistry and K-Ar age constraints of the eastern de Gerlache Seamount alkaline basalts (Bellingshausen Sea, southeast Pacific) Polarforschung, 2006
Tectonic evolution of the Pacific margin of Antarctica 2. Structure of Late Cretaceous - Early Tertiary plate boundaries in the Bellingshausen Sea from seismic reflection and gravity data Journal of Geophysical Research Solid Earth, 2002
Tectonic evolution of the Pacific margin of Antarctica 1. Late Cretaceous tectonic reconstructions Journal of Geophysical Research Solid Earth, 2002
Acoustic parameters and hydroacoustic equipment: Natural noise, industrial exploration and basic science Polarforschung, 2002
Peter I Island, Pacific Ocean, Western Antarctic Doklady Earth Sciences, 2002
