Discussion Pattern and Timing of Ice Retreat

The geological record provides convincing evidence that the Antarctic Ice Sheet was more extensive at the LGM and has subsequently reduced in area and thinned near the margins. The magnitude of ice retreat varies around the continent, ranging from relatively little marginal change at some terrestrial sites such as the Larsemann Hills, to retreat of the grounding line by hundreds of km in the large embayments currently occupied by the Ross, Filchner-Ronne and Amery ice shelves. At most of the marine sites studied, the evidence implies that the LGM maximum ice extent was relatively shortlived, while some of the terrestrial sites (e.g., Bunger Hills, Lutzow-Holm Bay) suggest that the LGM was not necessarily the period of greatest ice extent during the last glacial cycle, and that ice-sheet margins were more advanced prior to 35 ka BP.

Similarly, evidence for the timing of ice retreat following the LGM supports different retreat timings at different sites (Anderson, 1999). Some areas, such as the Antarctic Peninsula and the Bellingshausen Sea appear to have responded relatively rapidly to global climate and sea level changes following the LGM. At other locations, including the Ross Sea and the East Antarctic margin at Framnes Mountains, ice retreat appears to have begun relatively late and, in some places such as Marie Byrd Land, appears to have continued to the present day. While the evidence for this differential retreat timing cannot yet be considered definitive, the pattern may point to the differing sensitivities of each region to external forcing.

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