From Reconstructing the Antarctic Ice Sheet History to Understanding Large-scale Ice Mass Loss Mechanisms

The East Antarctic Ice Sheet (EAIS) is the largest continental ice mass on Earth, hold a freshwater storage equivalent to approximately 52.2 m of global sea level. Consequently, even minor volume alterations in the ice sheet can have significant ramifications for global sea level and climate dynamics. The imperative to understand the EAIS's sensitivity to different forcing agents is heightened by this potential impact. Although recent advancements in satellite gravimetry and ice-sheet modeling have resulted in refined EAIS mass balance estimates and evaluation of its response to global climatic shifts, space-geodetic data on ice-sheet changes span only recent decades. To validate and refine models studying the ice-sheet's sensitivity to atmospheric and oceanic warming, circulation changes, and sea-level rise, well-constrained records of past ice-sheet changes are essential. These emphasize the need for long-term (millennial-scale) glacio-geological records from field-based studies. Historical efforts by Japanese researchers have employed glacial geomorphology and geology to reconstruct past changes in EAIS at Dronning Maud Land, East Antarctica. Building on these foundational efforts, recent research has delved into the mechanisms behind EAIS mass loss over longer time scales, integrating space geodetic measurements, oceanographic observations, and numerical modelings. Recently, key findings highlighted rapid thinning of EAIS during the Early to Middle Holocene, as evidenced by the deglacial chronology derived from in situ cosmogenic nuclide surface exposure dates and simulations encompassing ice sheet, oceanographic, and glacial isostatic adjustments. Additionally, innovative techniques, such as marine sediment coring aboard the icebreaker Shirase and the use of a newly developed portable percussion piston coring system, are poised to provide further insights into the transition from ice shelf breakup to potential EAIS collapse. It is emphasized that glacial geomorphological and geological studies hold great potential to provide essential insights into the mechanisms of large-scale ice mass loss in EAIS, insights that cannot be obtained from modern observations alone.