The Antarctic Ice Sheet is a key component of the world's climatic system and has a major influence on global sea levels. To test models of its behavior, it is necessary to examine its fluctuations during episodes of climate change (Fig. 1). A precise date for the onset of Antarctic glaciation has yet to be determined, and there is little known of the preglacial biota (Abreu and Anderson, 1998). There is only a small amount of data pertaining to whether the current ice sheet will grow or diminish with global warming, and there is controversy over the stability of the East Antarctic Ice Sheet, particularly during the Pliocene (Webb et al., 1984; Sugden et al., 1993) and Pleistocene (Schere, 1998). Knowledge of its fluctuations during the Pleistocene is confined to areas such as the Ross Sea and Transantarctic Mountains. Establishing a detailed history of ice-sheet growth and decay will depend on drilling the sedimentary record of the Antarctic continental margin and an understanding of how the ice sheet behaves in response to changes in the adjoining ocean. Estimates of the volume of glacially eroded sediments delivered to the continental margin during different phases of the continent's history is a significant factor in modeling ice sheet behavior through time.

To address these problems, the Scientific Committee for Antarctic Research supports the ANTOSTRAT committee, which has fostered the development of a series of Antarctic drilling proposals. Each proposal has been designed to address different aspects of Antarctic glacial history. Leg 178 scientists examined the glaciation history of the Antarctic Peninsula, which is covered by small ice masses that developed during the Neogene and respond rapidly to climate changes. Leg 188 is designed mainly to address the history of the East Antarctic Ice Sheet, which is long lived and responds relatively slowly to major climate events. In particular, Leg 188 results, in conjunction with the results of Leg 119, can provide insights into the state of the interior of East Antarctica (Fig. 2).

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