High resolution records of atmospheric CO 2 concentration during the Holocene are obtained from the Dome Concordia and Dronning Maud Land (Antarctica) ice cores. These records confirm that the CO 2 concentration varied between 260 and 280 ppmv in the Holocene as measured in the Taylor Dome ice core. However, there are differences in the CO 2 records most likely caused by mismatches in timescales. Matching the Taylor Dome timescale to the Dome C timescale by synchronization of CO 2 indicates that the accumulation rate at Taylor Dome increased through the Holocene by a factor two and bears little resemblance to the stable isotope record used as a proxy for temperature. This result shows that different locations experienced substantially different accumulation changes, and casts doubt on the often-used assumption that accumulation rate scales with the saturation vapor pressure as a function of temperature, at least for coastal locations. D

[1] Subglacial lakes in East Antarctica can be separated into four categories specified by radar reflection properties. Definite lakes are brighter than their surroundings by at least 2 dB (relatively bright) and both are consistently reflective (specular) and have a reflection coefficient greater than À10 dB (absolutely bright). Dim lakes are relatively bright and specular but not absolutely bright, indicating nonsteady ice dynamics. Fuzzy lakes are both relatively and absolutely bright, but not specular, and may indicate saturated sediments or ''swamps.'' Indistinct lakes are absolutely bright and specular but no brighter than their surroundings. Lakes themselves and the different classes of lakes are not arranged randomly throughout Antarctica but are clustered around ice divides, ice stream onsets, and prominent bedrock troughs, with each cluster demonstrating a different characteristic lake classification distribution. The lake classification algorithm expands on previous studies and demonstrates a novel way to characterize icewater interactions in East Antarctica.

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Predictions about future changes in the Amundsen Sea sector of the West Antarctic ice sheet (WAIS) have been hampered by poorly known subglacial topography. Extensive airborne survey has allowed us to derive improved subglacial topography for the Pine Island Glacier basin. The trunk of this glacier lies in a narrow, 250‐km long, 500‐m deep sub‐glacial trough, suggesting a long‐lived and constrained ice stream. Two tributaries lie in similar troughs, others lie in less defined, shallower troughs. The lower basin of the glacier is surrounded by bedrock, which, after deglaciation and isostatic rebound, could rise above sea level. This feature would impede ice‐sheet collapse initiated near the grounding line of this glacier, and prevent its progress into the deepest portions of WAIS. The inland‐slope of the bed beneath the trunk of the glacier, however, confirms potential instability of the lower basin, containing sufficient ice to raise global sea by ∼24 cm.

Central Greenland ice cores provide evidence of abrupt changes in climate over the past 100,000 years. Many of these changes have also been identified in sedimentary and geochemical signatures in deep-sea sediment cores from the North Atlantic, confirming the link between millennial-scale climate variability and ocean thermohaline circulation. It is shown here that two of the most prominent North Atlantic events-the rapid warming that marks the end of the last glacial period and the Bolling/Allerod-Younger Dryas oscillation-are also recorded in an ice core from Taylor Dome, in the western Ross Sea sector of Antarctica. This result contrasts with evidence from ice cores in other regions of Antarctica, which show an asynchronous response between the Northern and Southern Hemispheres.