10:45 〜 11:05
[MIS05-01] Modelling the Stability of Antarctic ice sheet for investigating the link between the past and future
★Invited Papers
キーワード：climate, ice sheet, modelling, Antarctic ice sheet, deglaciation
Linking the paleo-ice sheet modelling studies and the future projection is challenging because of its millennial-scale long response time to external forcing which leads to its long commitment. Here in this study, in order to investigate the existence of threshold in the system which characterizes the irreversible behavior under climate changes, we use three-dimensional ice sheet model, SICOPOLIS, to investigate the Antarctic ice sheet response to atmospheric and oceanic warming, systematically. Ice sheet change is calculated for a given anomaly of surface temperature of 1 to 20 degree C as atmosphere forcing and basal melting beneath ice shelves of 1 to 400 m/a as ocean forcing. The response of ice sheet mass balance and volume for different time scales, 100, 1000, 10000 and 100, 000 years are analyzed for different initial conditions. We find that the collapse of West Antarctic ice sheet (WAIS) and the retreat of coastal areas of East Antarctic ice sheet (EAIS) such as Wilkes Subglacial Basin result in sea-level contributions of about 10m within 1kyr if an oceanic melt anomaly were around 5 to 10 m/a. The ice sheet change is little for the first 100 years, partly because of the compensation between the accumulation increase and the ice sheet retreat. Especially, continuous basal melting rate of 2-10m/a leads to Marine ice sheet instability (MISI) in a few hundred years before the major glacial rebound, while it takes much longer time for the recovery after eliminating the melting or warming. Implication for paleoclimate and ice sheet modelling as well as future projection will be further discussed.