The Antarctic Ice Sheet during the Last Glacial Maximum and its subsequent retreat history: a review
An emerging body of evidence from studies of the last glacial/interglacial cycle suggests that the East and West Antarctic ice sheets have not advanced and retreated in concert. The West Antarctic ice sheet advanced to the outer shelf in most regions during the Last Glacial Maximum (LGM). The retreat from the shelf commenced shortly after the LGM and continued into the late Holocene. The West Antarctic Ice Sheet in Ross and Amundsen seas slid across a deforming bed, at least during the final phases of extended glaciation. This implies that at this time the ice sheet had a low profile. Differences in the number and locations of grounding-zone wedges and smaller grounding zone features from trough to trough imply that individual West Antarctic Ice Sheet ice streams retreated episodically. Details concerning the expansion, retreat, and behavior of the East Antarctic Ice Sheet (EAIS) are more sparse. The picture emerging is that the EAIS did not expand to the continental shelf edge during the LGM; rather, it achieved a maximum extent of a mid-shelf position in some locations, while in other areas the ice terminus was situated near its present location. The timing of retreat along sectors within the EAIS appears diachronous, and in places occurred prior to the LGM. The Antarctic Peninsula shelf contained considerably more ice during the LGM than previously proposed. The results presented in this paper support more recent published ice-sheet models that call for greater contributions of melting ice from West Antarctica, including the Antarctic Peninsula, to the post-glacial rise in sea level.