History of the grounded ice sheet in the Ross Sea sector of Antarctica during the Last Glacial Maximum and the last termination

Abstract

AbstractKnowledge of variations in the extent and thickness of the Antarctic Ice Sheet is key for understanding the behaviour of Southern Hemisphere glaciers during the last ice age and for addressing issues involving global sea level, ocean circulation and climate change. Insight into past ice-sheet behaviour also will aid predictions of future ice-sheet stability. Here, we review terrestrial evidence for changes in ice geometry that occurred in the Ross Sea sector of Antarctica at the Last Glacial Maximum (LGM) and during subsequent deglaciation. During the LGM, a thick grounded ice sheet extended close to the continental shelf edge in the Ross Embayment. This ice reached surface elevations of more than 1000 m along the coast of the central and southern Transantarctic Mountains and Marie Byrd Land. The local LGM occurred by 18 ka on the coast, but as late as 7–10 ka inland. The first significant thinning took place at roughly 13 ka, with most ice loss happening in the Holocene. This history makes it unlikely that the Ross Sea sector was a major contributor to meltwater pulse 1A (MWP 1A). Resolution of a possible Antarctic origin for MWP 1A awaits detailed reconstructions from all sectors of the ice sheet.