Search

We present Bedmap2, a new suite of gridded products describing surface elevation, ice-thickness and the seafloor and subglacial bed elevation of the Antarctic south of 60° S. We derived these products using data from a variety of sources, including many substantial surveys completed since the original Bedmap compilation (Bedmap1) in 2001. In particular, the Bedmap2 ice thickness grid is made from 25 million measurements, over two orders of magnitude more than were used in Bedmap1. In most parts of Antarctica the subglacial landscape is visible in much greater detail than was previously available and the improved data-coverage has in many areas revealed the full scale of mountain ranges, valleys, basins and troughs, only fragments of which were previously indicated in local surveys. The derived statistics for Bedmap2 show that the volume of ice contained in the Antarctic ice sheet (27 million km3) and its potential contribution to sea-level rise (58 m) are similar to those of Bedmap1, but the mean thickness of the ice sheet is 4.6% greater, the mean depth of the bed beneath the grounded ice sheet is 72m lower and the area of ice sheet grounded on bed below sea level is increased by 10 %. The Bedmap2 compilation highlights several areas beneath the ice sheet where the bed elevation is substantially lower than the deepest bed indicated by Bedmap1. These products, along with grids of data coverage and uncertainty, provide new opportunities for detailed modelling of the past and future evolution of the Antarctic ice sheets. [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]

Presents measurements of the gas content and isotopic composition of debris-rich basal layers of a polar glacier, Meserve Glacier, Antarctica. Indication of debris entrainment occurrence without alteration of the glacial ice; Direct evidence that active entrainment occurs at the beds of cold glaciers, without bulk freezing of water.

Focuses on a study which probed into the history of deglaciation of the West Antarctic Ice Sheet in the Ross Sea Embayment. Methodology; Results; Discussion and conclusion.

Presents evidence from surface measurements and remote sensing that demonstrates the highly dynamic nature of the Ross ice drainage system in Antarctica. Switch in flow direction resulting from continued thinning of the Whillans ice stream and recent thickening of ice stream C; Fluctuations in the activity of fast-flowing ice streams as controlling the mass balance of the ice sheet.

Describes the broadscale geometry of the surface, bed, and internal layering of Simple Dome, Antarctica with focus on the near summit area, which is a potential site for deep coring. Global positioning system location of the surface at the summit; Results from radar profiling across the crest; Implication of the stratigraphy on the existence of Simple Dome.