09:00 〜 09:23
[MIS15-21] 東南極での陸-海シームレス調査から探る大規模氷床融解メカニズム
★招待講演
キーワード：南大洋・南極氷床、大規模氷床融解、湖底・海底堆積物、表面露出年代測定
The East Antarctic Ice Sheet (EAIS) is the largest continental ice mass on Earth. With freshwater storage equivalent to ~52.2 m of global sea level, even minor changes in ice sheet volume can strongly influence global sea level and climate dynamics. Thus, it is critical to understand its sensitivity to various forcing agents. Recent advances in satellite gravimetry and ice-sheet modeling have yielded refined estimates of EAIS mass balance and allowed for a re-examination of its response to global climatic changes. However, space-geodetic observations of ice-sheet change only extend over the last few decades. Modelling studies of ice-sheet sensitivity to atmospheric and oceanic warming and circulation and sea-level rise require well-constrained records of past ice-sheet changes for model validation and refinement. Together, these factors highlight the need for long-term (millennial-scale) glacio-geological records obtained from field-based studies. This is especially pertinent for understanding the large-scale retreat processes of the EAIS. For the last decade, our group has carried out a series of field surveys along the Dronning Maud Land, East Antarctica, to provide a better-constrained ice-sheet thinning history for the period since the Last Glacial Maximum. The ice-thinning chronology of the coastal Dronning Maud Land of the EAIS has been obtained by geomorphological survey and surface exposure dating of glacially transported rocks on inland nunataks. The detailed process of the ice sheet and ice shelf retreat along the EAIS margin has also been reconstructed by the marine-lake sedimentary records obtained by a newly developed sediment coring system and gravity coring from the ice breaker SHIRASE. In this talk, I will introduce an overview of these activities done by our group and their outcomes.