Last Interglacial 120 ka BP

Data from a number of sources, including dated coral terraces and the oceanic 81SO record, have fixed the timing of the Eemian interglacial at 128116 ka BP (Stirling et al., 1998; Shackleton et al., 2003). During this period there was less ice in the world than at present and global sea level was between 3 and 6 m higher than today (Stirling et al., 1998; Overpeck et al., 2006). Some believe that this was caused by a smaller West Antarctic Ice Sheet (e.g., Mercer, 1978; Scherer et al., 1998), while others suggest the decay of the Greenland Ice Sheet was responsible (e.g., Cuffey and Marshall, 2000; Tarasov and Peltier, 2003). Evidence to support the reduction in volume of at least part of the West Antarctic Ice Sheet at the last interglacial comes from observations of marine diatoms of Quaternary age and the measurement of high concentrations of 10Be in sediments recovered from beneath the

West Antarctic Ice Sheet (Scherer et al., 1998). 10Be and diatoms are thought to accumulate only under open marine conditions; when the sea is ice covered there is very little deposition of these materials. Moreover, if ice is grounded, any small amounts of 10Be and diatoms will be eroded. Sediments retrieved from beneath Ice Stream B, on the Siple Coast of the Ross Sea embayment, were probably emplaced during the last interglacial when marine conditions prevailed. The current dynamics of the ice-sheet may be affected by the location of these low shear strength, now subglacial, sediments (Anandakrishnan et al., 1998; Studinger et al., 2001). Similarly the Institute and Moller ice streams may have been free of grounded ice at the LGM, which according to Bingham and Siegert (2007) could account for ~2m of sea-level rise during the Eemian interglacial.

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