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Abstract A major subglacial lake, Lake Snow Eagle (LSE), was identified in East Antarctica by airborne geophysical surveys. LSE, contained within a subglacial canyon, likely hosts a valuable sediment record of the geological and glaciological changes of interior East Antarctica. Understanding past lake activity is crucial for interpreting this record. Here, we present the englacial radiostratigraphy in the LSE area mapped by airborne ice-penetrating radar, which reveals a localized high-amplitude variation in ice unit thickness that is estimated to be ∼12 ka old. Using an ice-flow model that simulates englacial stratigraphy, we investigate the origin of this feature and its relationship to changes in ice dynamical boundary conditions. Our results reveal that local snowfall redistribution initiated around the early Holocene is likely the primary cause, resulting from a short-wavelength (∼10 km) high-amplitude (∼20 m) ice surface slope variation caused by basal lubrication over a large subglacial lake. This finding indicates an increase in LSE water volume during the Holocene, illustrating the sensitivity in volume of a major topographically constrained subglacial lake across a single glacial cycle. This study demonstrates how englacial stratigraphy can provide valuable insight into subglacial hydrological changes before modern satellite observations, both for LSE and potentially at other locations. 

Abstract Geothermal heat plays a vital role in Antarctic ice sheet stability. The continental geothermal heat flow distribution depends on lithospheric composition and ongoing tectonism. Heat‐producing elements are unevenly enriched in the crust over deep time by various geological processes. The contribution of crustal heat production to geothermal heat flow is widely recognized; however, in Antarctica, crustal geology is largely hidden, and its complexity has frequently been excluded in thermal studies due to limited observations and oversimplified assumptions. Li and Aitken (2024),https://doi.org/10.1029/2023GL106201take a significant step forward, focusing on Antarctic crustal radiogenic heat. Utilizing gravity inversion and rock composition data, they show that the crustal heterogeneity introduces considerable variability to heat flow. However, modeling crustal heat production proves challenging because it lacks distinct associations with geophysical observables and has a narrow spatial association. Robust quantification of geothermal heat production and heat flow must incorporate explicit aspects of geology. 

Abstract An array of information about the Antarctic ice sheet can be extracted from ice-sheet internal architecture imaged by airborne ice-penetrating radar surveys. We identify, trace and date three key internal reflection horizons (IRHs) across multiple radar surveys from South Pole to Dome A, East Antarctica. Ages of ~38 ± 2.2, ~90 ± 3.6 and ~162 ± 6.7 ka are assigned to the three IRHs, with verification of the upper IRH age from the South Pole ice core. The resultant englacial stratigraphy is used to identify the locations of the oldest ice, specifically in the upper Byrd Glacier catchment and the Gamburtsev Subglacial Mountains. The distinct glaciological conditions of the Gamburtsev Mountains, including slower ice flow, low geothermal heat flux and frozen base, make it the more likely to host the oldest ice. We also observe a distinct drawdown of IRH geometry around South Pole, indicative of melting from enhanced geothermal heat flux or the removal of deeper, older ice under a previous faster ice flow regime. Our traced IRHs underpin the wider objective to develop a continental-scale database of IRHs which will constrain and validate future ice-sheet modelling and the history of the Antarctic ice sheet. 

Abstract Reconstructing the history of polar temperature from ice core water isotope (δ¹⁸O) calibration has remained a challenge in paleoclimate research, because of our incomplete understanding of various temperature–δ¹⁸O relationships. This paper resolves this classical problem in a new framework called the unified slope equations (USE), which illustrates the general relations among spatial and temporalδ¹⁸O–surface temperature slopes. The USE is applied to the Antarctica temperature change during the last deglaciation in model simulations and observations. It is shown that the comparable Antarctica-mean spatial slope with deglacial temporal slope inδ¹⁸O–surface temperature reconstruction is caused, accidentally, by the compensation responses between theδ¹⁸O–inversion layer temperature relation and the inversion layer temperature itself. Furthermore, in light of the USE, we propose that the present seasonal slope ofδ¹⁸O–inversion layer temperature is an optimal paleothermometer that is more accurate and robust than the spatial slope. This optimal slope suggests the possibility of reconstructing past Antarctic temperature changes using present and future instrumental observations. Significance StatementThis paper develops a new framework called the unified slope equations (USE) to provide, for the first time, a general relation among various spatial and temporal water isotope–temperature slopes. The application of the USE to Antarctic deglacial temperature change shows that the optimal paleothermometer is the seasonal slope of the inversion layer temperature. 

This dataset presents physical parameters (temperature, Stokes and anti-Stokes Raman scattering signals) measured during the emplacement of bare single-mode optical fiber within the Greenland Ice Sheet using the Ice Diver melt probe at Summit Station, Greenland (specifically, at 72.5817 N, 38.4578 W). In addition to Stokes and Anti-Stokes signals, the dataset includes englacial temperature profiles derived via Raman distributed temperature sensing (DTS) at 1 m resolution, from ice depths -50 – 355 m (with 0 m representing the top of the borehole). The Raman backscatter signals (Stokes and Anti-Stokes) were captured by the ULTIMA Single Mode Distributed Temperature System (Silixa Ultima Single Mode interrogator) operating at a source wavelength of 1550 nm. Temperature data represent the first 108 hours of cooling (from June 7 – June 12, 2024) following melt probe entrapment in the ice at a depth of ~350 m. Temperature data were calibrated using a section of 25 m of the unreinforced fiber placed in an insulated controlled temperature bath during deployment. Two external PT-100 temperature probes were placed within the bath above and below the spool of fiber optic cable to monitor calibration bath temperatures. External temperature probes were an average of 1.5±0.2 °C warmer than the fiber optic cable. Data records are contained in three Excel spreadsheets (ice_diver_temperatures, Stokes_ice_diver and Anti_Stokes_ice_diver). The first column represents depth below the ice surface, with time in both standard and Matlab datenum format across the top of the spreadsheet. For additional information contact: Scott Tyler styler@unr.edu; Dale Weinbrenner dpw@apl.washington.edu; Sophie Wensman Sophia.Wensman@dri.edu 

This dataset contains snapshots of carbon dioxide and methane concentrations, total air content, stable isotope measurements of carbon dioxide, as well as measurements of molecular oxygen and nitrogen and their stable isotopic signatures. Samples come from the ALHIC1901 ice core from the Allan Hills, Antarctica. Where possible, new ages have been assigned to previous measurements from the ALHIC1503 ice core. For samples containing excess CO2 from a secondary source, estimated atmospheric CO2 ranges are included. 

Between about 2.8-0.9 Ma, Earth’s climate was characterized by 40 kyr cycles, driven or paced by changes in the tilt of Earth’s spin axis. Much is known about the 40k world from studies of deep-sea sediments, but our understanding of climate change during this period and the transition between the 40kyr glacial cycles from 2.8-0.9 Ma and the 100kyr glacial cycles of the last 0.9 Myr is incomplete because we lack records of Antarctic climate and direct records of atmospheric greenhouse gas concentrations. We propose to address these issues by building on our recent studies of >1 Ma ice discovered in shallow ice cores in the Allan Hills Blue Ice Area (BIA), Antarctica. During the 2015-2016 field season we recovered ice from two nearby drill cores that dates to > 2 million years in age using the 40Ar/38Ar ratio of the trapped gases. Our discovery of ice of this antiquity in two cores demonstrates that there is gas-record quality ice from the 40k world in the Allan Hills BIA. To further characterize the composition of Earth’s atmosphere and Antarctic climate during the 40k world we request support for two field seasons to drill new large-volume (4” or 9” diameter) ice cores at sites where we have previously identified >1 Ma ice and nearby sites where ground penetrating radar has identified bedrock features conducive to the preservation of old ice. 

Between about 2.8-0.9 Ma, Earth’s climate was characterized by 40 kyr cycles, driven or paced by changes in the tilt of Earth’s spin axis. Much is known about the 40k world from studies of deep-sea sediments, but our understanding of climate change during this period and the transition between the 40kyr glacial cycles from 2.8-0.9 Ma and the 100kyr glacial cycles of the last 0.9 Myr is incomplete because we lack records of Antarctic climate and direct records of atmospheric greenhouse gas concentrations. We propose to address these issues by building on our recent studies of >1 Ma ice discovered in shallow ice cores in the Allan Hills Blue Ice Area (BIA), Antarctica. During the 2015-2016 field season we recovered ice from two nearby drill cores that dates to > 2 million years in age using the 40Ar/38Ar ratio of the trapped gases. Our discovery of ice of this antiquity in two cores demonstrates that there is gas-record quality ice from the 40k world in the Allan Hills BIA. To further characterize the composition of Earth’s atmosphere and Antarctic climate during the 40k world we request support for two field seasons to drill new large-volume (4” or 9” diameter) ice cores at sites where we have previously identified >1 Ma ice and nearby sites where ground penetrating radar has identified bedrock features conducive to the preservation of old ice. 

Between about 2.8-0.9 Ma, Earth’s climate was characterized by 40 kyr cycles, driven or paced by changes in the tilt of Earth’s spin axis. Much is known about the 40k world from studies of deep-sea sediments, but our understanding of climate change during this period and the transition between the 40kyr glacial cycles from 2.8-0.9 Ma and the 100kyr glacial cycles of the last 0.9 Myr is incomplete because we lack records of Antarctic climate and direct records of atmospheric greenhouse gas concentrations. We propose to address these issues by building on our recent studies of >1 Ma ice discovered in shallow ice cores in the Allan Hills Blue Ice Area (BIA), Antarctica. During the 2015-2016 field season we recovered ice from two nearby drill cores that dates to > 2 million years in age using the 40Ar/38Ar ratio of the trapped gases. Our discovery of ice of this antiquity in two cores demonstrates that there is gas-record quality ice from the 40k world in the Allan Hills BIA. To further characterize the composition of Earth’s atmosphere and Antarctic climate during the 40k world we request support for two field seasons to drill new large-volume (4” or 9” diameter) ice cores at sites where we have previously identified >1 Ma ice and nearby sites where ground penetrating radar has identified bedrock features conducive to the preservation of old ice.