[MIS15-P23] Antarctic ice sheet dynamics during the Last Interglacial
Keywords:Antarctic Ice Sheet, Last interglacial, Nd isotope
potentially caused by the global warming is a sea level rise due to the melting of ice sheet. Antarctic
ice sheet, which hold a massive amount of fresh water, was considered to be stable even if global
warming progresses in a future. However, recent studies have shown that Antarctic ice sheet is more
sensitive to global warming than previously thought. Therefore, it is an important to better understand
extent to which Antarctic ice sheet sensitive to global warming.
Study of past warm period provides a useful insight into the prediction of sea level rise in a future.
In particular, the last interglacial (MIS 5e), which was ~1°C warmer than that of the preindustrial, is
receiving increased attention, since sea level in the period is estimated to be several meters higher than
that of the present. This suggests substantial loss of Antarctic ice sheet during MIS 5e. However,
variability of Antarctic ice sheet during MIS 5e has been poorly understood. In this study, we generate
high resolution records of mineral composition, Nd isotope and iceberg rafted debris (IBRD) in
GC1407 collected from near the Wilkes Basin, East Antarctica (130.518°E, 63.74°S) in order to better
understand Antarctic ice sheet dynamics during the warmer than the present climate condition.
The two episodic IBRD increase events are found to be recognized during MIS 5e in GC1407,
suggesting that increases in icebergs transport occurred during MIS 5e. Nd isotope and mineral
composition records in GC1407 suggest that icebergs originated from area with relatively higher eNd,
possibly either Wilkes Land Basin or West Antarctica ice sheets. The iceberg discharge events
happened when Antarctic air temperature was warmer than that of preindustrial era, suggesting a link
between Antarctic warming and increase in iceberg discharge. Furthermore, the timings of iceberg
discharge events are simultaneous with the onsets of sea level rises estimated from geological record
in Western Australia. The correspondence between the sea level and Antarctic ice sheet records
suggests substantial contribution of Antarctic ice mass loss to the sea level rises during MIS 5e.