The Antarctic ice sheet has been losing mass over the past decades through the accelerated flow of its glaciers conditioned by ocean temperature and bed topography. Glaciers retreating along retrograde slopes (i.e., bed elevation drops in the inland direction) are potentially unstable, whereas subglacial ridges slow down the glacial retreat. Despite major advances in mapping subglacial bed topography, significant sectors of Antarctica remain poorly resolved and critical spatial details are missing. Here we present a novel, high-resolution, and physically-based description of Antarctic bed topography using mass conservation. Our results reveal previously unknown basal features with major implications for glacier response

Antarctica is the largest reservoir of ice on Earth. Understanding its ice sheet dynamics is crucial to unraveling past global climate change and making robust climatic and sea level predictions. Of the basic parameters that shape and control ice flow, the most poorly known is geothermal heat flux. Direct observations of heat flux are difficult to obtain in Antarctica, and until now continent‐wide heat flux maps have only been derived from low‐resolution satellite magnetic and seismological data. We present a high‐resolution heat flux map and associated uncertainty derived from spectral analysis of the most advanced continental compilation of airborne magnetic data. Small‐scale spatial variability and features consistent with known geology are better reproduced than in previous models, between 36% and 50%. Our high‐resolution heat flux map and its uncertainty distribution provide an important new boundary condition to be used in studies on future subglacial hydrology, ice sheet dynamics, and sea level change.

The timing of events leading to the earliest connection between the Pacific and Atlantic oceans at Drake Passage is controversial but important, because gateway opening probably had a profound effect on global circulation and climate. A rigorous new analysis of marine geophysical data demonstrates a major change in the motion of the South American and Antarctic plates at about 50 Ma, from N-S to WNW-ESE, accompanied by an eightfold increase in separation rate. This would have led to crustal extension and thinning, and perhaps the opening of small oceanic basins, with the probable formation of a shallow (b 1000 m) gateway during the Middle Eocene. No change in South American-Antarctic motion is observed near the Eocene-Oligocene boundary, but a deep-water connection developed between 34 and 30 Ma, when continued extension led to the initiation of seafloor spreading at the West Scotia Ridge. These timings correlate with events seen in the oxygen isotope record from benthic foraminera, and support the view that Drake Passage opening was the trigger for abrupt Eocene-Oligocene climate deterioration and the growth of extensive Antarctic ice sheets. D

[1] Drake Passage opening has often been viewed as a single, discrete event, possibly associated with abrupt changes in global circulation and climate at or near the Eocene-Oligocene boundary. A new plate tectonic model, based on recent reinterpretations of the opening history of basins in the Scotia Sea, suggests that an effective ocean gateway may have developed even earlier, during the middle Eocene. This is consistent with a growing body of evidence from sediment core proxy data for Eocene changes in Southern Ocean circulation and biological productivity. The period between earliest opening after 50 Ma and the latest Eocene was characterized by the evolution of various current pathways across the subsiding continental shelves and intervening deep basins. This shallow opening may have caused important changes in Southern Ocean circulation, contributing to Eocene cooling and the growth of Antarctic ice sheets.

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