Abstract
AbstractEast Antarctica hosts large subglacial basins into which the East Antarctic Ice Sheet (EAIS) likely retreated during past warmer climates. However, the extent of retreat remains poorly constrained, making quantifying past and predicted future contributions to global sea level rise from these marine basins challenging. Geomorphological analysis and flexural modeling within the Wilkes Subglacial Basin are used to reconstruct the ice margin during warm intervals of the Oligocene‐Miocene. Flat‐lying bedrock plateaus are indicative of an ice sheet margin positioned >400–500 km inland of the modern grounding zone for extended periods of the Oligocene‐Miocene, equivalent to a 2‐m rise in global sea level. Our findings imply that if major EAIS retreat occurs in the future, isostatic rebound will enable the plateau surfaces to act as seeding points for extensive ice rises, thus limiting extensive ice margin retreat of the scale seen during the early EAIS.
Highlights
Ice thickness measurements from ice-penetrating radar surveys show that ∼40% of the Antarctic Ice Sheet (AIS) is marine-based (Fretwell et al, 2013)
Our findings imply that if major East Antarctic Ice Sheet (EAIS) retreat occurs in the future, isostatic rebound will enable the plateau surfaces to act as seeding points for extensive ice rises, limiting extensive ice margin retreat of the scale seen during the early EAIS
We conclude that the newly mapped bedrock plateau surfaces within the WSB provide (a) a constraint on the extent of the EAIS during Oligocene-Miocene warm intervals and (b) an improved understanding of the processes that likely operated at the ice sheet margin during subsequent retreat phases and may operate in the future
Summary
Ice thickness measurements from ice-penetrating radar surveys show that ∼40% of the Antarctic Ice Sheet (AIS) is marine-based (Fretwell et al, 2013) This includes much of the West Antarctic Ice Sheet (WAIS) and large subglacial basins around the margin of the East Antarctic Ice Sheet (EAIS). These low-lying subglacial basins are thought to be vulnerable to rapid ice sheet retreat in response to ocean and climate warming (DeConto & Pollard, 2016; Li et al, 2015; Mercer, 1978; Pollard et al, 2015; Schoof, 2007). Significant variation remains between numerical ice sheet model predictions of EAIS retreat within the WSB during past warmer periods such as the mid-Pliocene (ca. 3 Ma) and mid-Miocene
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