Japan Geoscience Union Meeting 2018

Presentation information

[EJ] Oral

M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS06] Global climate change driven by the Southern Ocean and the Antarctic Ice Sheet

Mon. May 21, 2018 9:00 AM - 10:30 AM 302 (3F International Conference Hall, Makuhari Messe)

convener:Osamu Seki(Institute of Low Temperature Science, Hokkaido University), Akira Oka(Atmosphere and Ocean Research Institute, The University of Tokyo), Ryosuke Makabe(国立極地研究所, 共同), Ryu Uemura(University of the Ryukyus), Chairperson:Nogi Yoshifumi(National Institute of Polar Research), Seki Osamu(Institute of Low Temperature Science, Hokkaido University), Matsui Hiroki(Kochi University)

9:00 AM - 9:15 AM

[MIS06-01] Do submarine volcanism in mid-ocean ridges impact global climate change? –Heading toward detection of topographic variation in precisely aged seafloor

*Masakazu Fujii1,2, Arata Kioka3, Toshitsugu Yamazaki4, Kyoko Okino4, Chiori Tamura4, Osamu Seki5, Yoshifumi Nogi1,2, Jun'ichi Okuno1,2, Takeshige Ishiwa1, Ikumi Oyabu1 (1.National Institute of Polar Research / SOKENDAI, 2.The Graduate University for Advanced Studies (SOKENDAI), 3.Leopold-Franzens-Universität Innsbruck, 4.Atmosphere and Ocean Research Institute, The University of Tokyo, 5.Institute of Low Temperature Science, Hokkaido University)

Keywords:Submarine volcanism, Mid-ocean ridge, Seafloor bathymetry, Near-seafloor magnetic anomaly, Global climate change

Submarine volcanism in mid-ocean ridge (MOR) systems transports heat and material from solid-Earth to ocean and potentially impacts global climate change. The CO2 production rate linked to seafloor spreading in MORs is known as 2×1012 mol/yr (~0.041 ppmv) in steady state (Resing et al., 2004). However, if episodic magma eruption controlled by sea-level change occurs over thousands years (Tolstoy, 2015, Crowley et al., 2015), the MORs system would theoretically result in ~100 ppmv rise in CO2. Observational evidence is essentially needed for estimating of the effect of seafloor spreading in the MORs on the climate reconstruction and prediction.

In order to evaluate the impact of the MORs on global climate, our team has submitted a proposal to coming 3-years projects of the R/V Hakuhomaru. The aim of this cruise is to estimate magma and CO2 production rate over 4.3 Myrs based on observed seafloor topography, high-resolution magnetic field, and newly developing model of magma eruption in spreading system. Short-wavelength variation of seafloor topography is detected by shipboard multibeam sonar, and detailed seafloor age is estimated by near-seafloor magnetic field data comparing with global paleo-intensity of the geomagnetic field. The study area is circum-Antarctic ridges, especially the fast-spreading East Pacific Rise and Pacific-Antarctic Ridge, and slow- to intermediate-spreading ridges in the Indian Ocean. In order to investigate “sea-level driven eruption hypothesis”, we aim to catch the signal from the seafloor created 3.4 Myrs ago when amplitude of sea-level change is considered to be small.

Here, we present overview of our geophysical survey plan in the southern ocean and previously obtained knowledge about solid-Earth response to climate. Finally, we discuss a role of the MOR study for understanding global climate change.