Japan Geoscience Union Meeting 2015

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Oral

Symbol M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS26] Biogeochemistry

Thu. May 28, 2015 9:00 AM - 10:45 AM 104 (1F)

Convener:*Muneoki Yoh(Tokyo University of Agriculture and Technology), Shibata, Hideaki(Field Science Center fot Northern Biosphere, Hokkaido University), Naohiko Ohkouchi(Japan Agency for Marine-Earth Science and Technology), Youhei Yamashita(Faculty of Environmental Earth Science, Hokkaido University), Chair:Chisato Yoshikawa(Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology), Takuro Nunoura(Research and Development Center for Marine Biosciences, Japan Agency for Marine-Earth Science & Technology (JAMSTEC))

9:00 AM - 9:15 AM

[MIS26-01] Ocean oxygen depletion due to decomposition of submarine methane hydrate

*Akitomo YAMAMOTO1, Yasuhiro YAMANAKA2, Akira OKA1, Ayako ABE-OUCHI1 (1.Atmosphere and Ocean Research Institute, the University of Tokyo, 2.Faculty of Environmental Earth Science, Hokkaido University)

Keywords:methane hydrate, global warming, ocean oxygen depletion

Global warming could decompose submarine methane hydrate and cause methane release into the ocean. The released methane causes oxygen depletion via oxidation; however, its global impact is yet to be quantitatively investigated. We have projected the potential impact of oxygen depletion due tomethane hydrate decomposition via numerical modeling. We find that the global methane hydrate inventory decreases by approximately 70% (35%) under four times (twice) the atmospheric CO2 concentration and is accompanied by significant global oxygen depletion on a timescale of thousands of years. In particular, we demonstrate the great expansion of suboxic and hypoxic regions, having adverse impact onmarine organisms and ocean biogeochemical cycles. This is because hydrate decomposition primarily occurs in the Pacific Ocean, where present-day seawater has low oxygen concentration. Besides the decrease in oxygen solubility and reduced ventilation associated with global warming, the process described in this study is also important in oxygen depletion.