Japan Geoscience Union Meeting 2024

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[J] Poster

M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS12] Paleoclimatology and paleoceanography

Wed. May 29, 2024 5:15 PM - 6:45 PM Poster Hall (Exhibition Hall 6, Makuhari Messe)

convener:Atsuko Yamazaki(Graduate School of Environmental Studies, Nagoya University), Yusuke Okazaki(Department of Earth and Planetary Sciences, Graduate School of Science, Kyushu University), Hitoshi Hasegawa(Faculty of Science and Technology, Kochi University), Takashi Obase(Atmosphere and Ocean Research Institute, The University of Tokyo)

5:15 PM - 6:45 PM

[MIS12-P30] Effects of GIA and dynamic topography on sea level during the Mid-Miocene Climatic Optimum

*Yoshiya Irie1, Jun'ichi Okuno2,3,4 (1.Institute for Geothermal Sciences, Kyoto University, 2.Research Organization of Information and Systems, 3.National Institute of Polar Research, 4.The Graduate University for Advanced Studies, SOKENDAI)

Keywords:Glacial isostatic adjustment, Dynamic topography, Mid-Miocene Climatic Optimum, Sea-level

Estimating ice sheet volume change from observations of sea-level change during past warm periods provides an essential constraint on future projections of ice sheet melting and sea-level rise, which are currently accelerating due to global warming. However, relative sea-level change data reconstructed from geomorphological and geological observations include information on ice sheet volume change and crustal deformation components such as glacial isostatic adjustment (GIA). In addition, dynamic topography (DT) effects due to mantle convection cannot be ignored on time scales longer than 1 million years, and these solid earth changes complicate the interpretation of sea-level change. Recently, Richards et al. (2023, Sci. Adv.) estimated an equivalent sea level of ∼+16.0 m based on sea-level data from Australia during the Mid-Pliocene Warm Period (MPWP: ∼3 Ma), using a numerical model to correct for the effects of GIA and DT. Thus, by constructing a numerical model that combines GIA and DT, detailed estimates of ice sheet volume changes have been made from sea-level change data on time scales longer than 1 million years. Therefore, we attempt to estimate ice sheet volume change from sea-level change data during the Mid-Miocene Climatic Optimum (MMCO: ∼15 Ma). The MMCO is considered a period when the Northern Hemisphere ice sheet did not exist, which may lead to understanding the mechanism of Antarctic ice sheet fluctuations. This presentation will present the results of our numerical modelling of GIA and DT during the MMCO and our quantitative evaluation of the spatio-temporal variability of sea-level change.