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Bedforms of Thwaites Glacier, West Antarctica both record and affect ice flow, as shown by geophysical data and simple models. Thwaites Glacier flows across the tectonic fabric of the West Antarctic rift system with its bedrock highs and sedimentary basins. Swath radar and seismic surveys of the glacier bed have revealed soft‐sediment flutes 100 m or more high extending 15 km or more across basins downglacier from bedrock highs. Flutes end at prominent hard‐bedded moats on stoss sides of the next topographic highs. We use simple models to show that ice flow against topography increases pressure between ice and till upglacier along the bed over a distance that scales with the topography. In this basal zone of high pressure, ice‐contact water would be excluded, thus increasing basal drag by increasing ice‐till coupling and till flux, removing till to allow bedrock erosion that creates moats. Till carried across highlands would then be deposited in lee‐side positions forming bedforms that prograde downglacier over time, and that remain soft on top through feedbacks that match till‐deformational fluxes from well upglacier of the topography. The bedforms of the part of Thwaites surveyed here are prominent because ice flow has persisted over a long time on this geological setting, not because ice flow is anomalous. Bedform development likely has caused evolution of ice flow over time as till and lubricating water were redistributed, moats were eroded and bedforms grew. Plain Language Summary: Thwaites Glacier, West Antarctica, is of great interest because ongoing retreat could lead to faster future changes that could notably increase sea‐level rise. Wide‐ranging studies are thus focused on gaining broad understanding of the glacier. Geophysical surveys discussed here show that the bed of the glacier has been sculpted by the flowing ice, eroding large "moats" upglacier and to the sides of bedrock obstacles, and depositing long tails of soft sediment downglacier of those obstacles. We use simple models to show that these features formed over time because of the interactions among ice, bedrock, and subglacial water and sediment, and that the behavior of the glacier must have changed as these features developed. This knowledge does not directly affect estimates of the potential for future sea‐level rise, but does guide further studies to improve those estimates. This knowledge also may help understand the formation of glacially sculpted landscapes left in widespread regions by former ice sheets. Key Points: Extensive, well‐developed bedforms occur beneath upglacier regions of Thwaites Glacier, West Antarctica where ice flow is unremarkablePressure variations from ice flow over bedrock topography caused erosion and deposition, producing stoss‐side moats and lee‐side flutesBedforms both record and influence ice flow [ABSTRACT FROM AUTHOR]

The article focuses on a study on the climate evolution at the West Antarctic ice sheet (WAIS) Divide site in West Antarctica during the late-Holocene period. It is said that instrumental data regarding climate change can be provided by ice cores as they concern constraints on the history of certain variables of climate. Under the study, bubble number-density estimates from the study area have been used in order to create a paleoclimate reconstruction for the late-Holocene period. Findings indicate a linear cooling of about ~1.7° Celsius (C) during the study period.

Determining the mass balance of the Greenland and Antarctic ice sheets (GIS and AIS) has long been a major challenge for polar science. But until recent advances in measurement technology, the uncertainty in ice sheet mass balance estimates was greater than any net contribution to sea level change. The Fourth Assessment Report of the Intergovernmental Panel on Climate Change (AR4) was able, for the first time, to conclude that, taken together, the GIS and AIS have probably been contributing to sea level rise over the period 1993-2003 at an average rate estimated at 0.4mmyr-1. Since the cut-off date for work included in AR4, a number of further studies of the mass balance of GIS and AIS have been made using satellite altimetry, satellite gravity measurements and estimates of mass influx and discharge using a variety of techniques. Overall, these studies reinforce the conclusion that the ice sheets are contributing to present sea level rise, and suggest that the rate of loss from GIS has recently increased. The largest unknown in the projections of sea level rise over the next century is the potential for rapid dynamic collapse of ice sheets. [ABSTRACT FROM AUTHOR]

Presents research which studied ice streams on the West Antarctic Ice Sheet. Drainage of the sheet through ice streams; Role of the Ross Ice Shelf; Conclusion that a margin of the upglacier part of an ice stream is directly above the boundary of a basin with sedimentary fill; Use of seismic observations; Frictional resistance in the basin fill; Ice stream position dependent upon subglacial geology.

Ice sheets reshape Earth's surface. Maps of the landscape formed by past ice sheets are our best tool for reconstructing historic ice sheet behavior. But models of glacier erosion and deposition that explain mapped features are relatively untested, and without observations of landforms developing in situ, postglacial landscapes can provide only qualitative insight into past ice sheet conditions. Here we present the first swath radar data collected in Antarctica, demonstrating the ability of swath radar technology to map the subglacial environment of Thwaites Glacier (West Antarctica) at comparable resolutions to digital elevation models of deglaciated terrain. Incompatibility between measured bedform orientation and predicted subglacial water pathways indicates that ice, not water, is the primary actor in initiating bedform development at Thwaites Glacier. These data show no clear relationship between morphology and glacier speed, a weak relationship between morphology and basal shear stress, and highlight a likely role for preexisting geology in glacial bedform shape. [ABSTRACT FROM AUTHOR]

Ice thickness in West Antarctica at the Last Glacial Maximum (LGM) is poorly known, yet is key information for understanding ice streams and interpreting ice cores. Although trim lines, moraine limits, and exposure-age dating provide geologic constraints on ice thickness near the Transantarctic Mountains and in Marie Byrd Land, lack of exposed bedrock hampers traditional geologic methods in a central, ∼2 × 106 km² region. Here we infer ice-sheet thickness changes in the central Ross Sea Embayment by using a transient ice-flow model to find combinations of accumulation-rate and ice-sheet thickness histories that match the depth-age relationship and the measured layer-thickness pattern in the Siple Dome ice core. After we reject unreasonable accumulation-rate histories, the remaining history pales indicate thinning of 200–400 m since the LGM. Our estimate is lower than previous reconstructions that were constrained by geologic evidence from the Transantarctic Mountains and by marine data from the Ross Sea floor, which indicate that a grounded ice sheet extended to the continental shelf margin during the last glacial period. Low surface elevations in the central Ross Sea Embayment during the LGM do not preclude thicker ice along its boundaries. However, if this grounded ice sheet came over 1000 km from interior West Antarctica, as is usually assumed, then it had very low surface slope, requiring a very slippery bed. Alternatively, the grounded Ross Sea ice might have flowed from the Transantarctic Mountains and western Marie Byrd Land. [ABSTRACT FROM AUTHOR]