2026-10-16 琉球大学
図. 約4万年前から1万8千年前にかけての全球平均海面水位の変動史（単位：メートル）。濃い青色の線は全球平均海面水位を示す。青色の網掛けは95%信頼区間を示す。破線は、全球平均海面水位の変動史における5つの期間の境界を示す。LD：最終退氷期、LGM：最終氷期最盛期（最新研究に基づきLGM-aとLGM-bに区分）、MIS 3：海洋酸素同位体ステージ3。
＜関連情報＞
- https://www.u-ryukyu.ac.jp/news/97997/
- https://www.sciencedirect.com/science/article/abs/pii/S0012821X26005595
グレートバリアリーフの大型底生有孔虫群集から推定された海洋酸素同位体ステージ3から最終氷期最盛期にかけての全球平均海面水位の低下 Global mean sea-level fall from late Marine Isotope Stage 3 into the Last Glacial Maximum inferred from Great Barrier Reef large benthic foraminiferal assemblages
Kazuhiko Fujita, Choko Nakada, Noriko Yagioka, Yosuke Miyairi, Marc Humblet, Hironobu Kan, Yasufumi Iryu, Jody M. Webster, Yusuke Yokoyama
Earth and Planetary Science Letters Available online: 3 October 2026
DOI:https://doi.org/10.1016/j.epsl.2026.120379
Highlights
- A new global mean sea level (GMSL) record covering late MIS 3 and the LGM.
- Foraminifera-based GMSL record likely reflects long-term mean trends.
- The GMSL shows incrementally lowering sea levels divided into five periods.
- Late MIS 3 GMSL was between –101 and –119 m.
- Sea-level reconstruction shows a ∼17 m sea-level fall from ca. 35 ka to the LGM.
Abstract
Marine Isotope Stage (MIS) 3, the period from 57 to 30 thousand years ago (ka), is critical to understand how glaciers and ice sheets advanced into the Last Glacial Maximum (LGM; 30–17 ka). Previous estimates of ice-volume changes and their equivalent global mean sea level (GMSL) during MIS 3 remain uncertain, particularly regarding the extent of Northern Hemisphere ice-sheet reduction and exact GMSL values during this period. Here we present a new GMSL record from late MIS 3 to the LGM (ca. 39–18 ka) inferred from paleo-water depth estimates of photosymbiotic large benthic foraminiferal assemblages in upper slope sediment cores from the Great Barrier Reef. The relative sea-level-based GMSL record reconstructed using a Bayesian statistical model, revealed long-term mean trends characterized by incrementally lowering sea levels divided into five periods. Late MIS 3 GMSL decreased from –101 m (average with a 95% confidence interval (CI) of –89 to –113 m) at ca. 39 ka to –119 m (average with a 95% CI of –114 to –124 m) at ca. 30 ka, then finally reached down to –137 m (average with a 95% CI of –131 to –142 m) during the LGM. A relatively steep sea-level fall into the LGM—approximately 17 m in magnitude—began at ca. 35 ka and took ca. 7000 years, implying an acceleration of large-scale ice sheet advance into the LGM.
