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Subglacial lakes are bodies of water that form at the base of ice sheets and glaciers. Ice‐surface elevation above these lakes responds to water volume changes, providing one of few ways to monitor subglacial hydrological systems. Here, we use numerical models to compare surface elevation‐derived estimates of subglacial‐lake length, water‐volume change, and highstand or lowstand timing with their true values. Because ice flow influences the surface expression of lake‐volume change, the correspondence between these estimates and their true values depends strongly on ice thickness, volume‐change rate, and basal drag coefficient. For many realistic combinations of these factors, viscous relaxation of the ice‐sheet surface can render lake volume‐changes unobservable with altimetry. Our results highlight the need for new estimation methods that account for the effects of ice flow, as well as improvements to current resolution limitations that render some events unobservable with altimetry.

Antarctic subglacial lakes can play an important role in ice sheet dynamics, biology, geology, and oceanography, but it is difficult to definitively constrain their character and locations. Subglacial lake locations are related to factors including heat flux, ice surface slope, ice thickness, and bed topography, though these relationships are not fully quantified. Bed topography is particularly important for determining where water flows and accumulates, but digital elevation models of the ice sheet bed rely on interpolation and are unrealistically smooth, biasing estimates of subglacial lake location and surface area. To address this issue, we use geostatistical methods to simulate realistically rough bed topography. We use our simulated topography to predict subglacial lake distribution across the continent using a binomial logistic regression, which uses physical parameters and known lake locations to calculate the probabilities of lake occurrences. Our results suggest that topography models interpolated without appropriate geostatistics overestimate subglacial lake surface area and that total lake surface area is lower than previously predicted. We find that radar‐detected lakes are more likely to occur in the interior of East Antarctica, while altimetry‐detected (active) lakes are expected to be found in West Antarctica and near the grounding line. We observe that radar‐detected lakes have a high correlation with heat flux and ice thickness, while active lakes are associated with higher ice velocity.

Understanding ice sheet evolution through the geologic past can help constrain ice sheet models that predict future ice dynamics. Existing geological records of grounding line retreat in the Ross Sea, Antarctica, have been confined to ice‐free and terrestrial archives, which reflect dynamics from periods of more extensive ice cover. Therefore, our perspective of grounding line retreat since the Last Glacial Maximum remains incomplete. Sediments beneath Ross Ice Shelf and grounded ice offer complementary insight into the southernmost extent of grounding line retreat, yielding a more complete view of ice dynamics during deglaciation. Here we thermochemically separate the youngest organic carbon to estimate ages from sediments extracted near the Whillans Ice Stream grounding line to provide direct evidence for grounding line retreat in that region as recent as the mid‐Holocene (7.2 kyr B.P.). Our study demonstrates the utility of accurately dated, grounding‐line‐proximal sediment deposits for reconstructing past interactions between marine and subglacial environments.