Japan Geoscience Union Meeting 2023

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[J] Oral

M (Multidisciplinary and Interdisciplinary) » M-IS Intersection

[M-IS08] Global climate change driven by the Southern Ocean and the Antarctic Ice Sheet

Fri. May 26, 2023 1:45 PM - 3:00 PM 103 (International Conference Hall, Makuhari Messe)

convener:Kazuya Kusahara(Japan Agency for Marine-Earth Science and Technology), Masahiro Minowa(Institute of Low Temperature Science, Hokkaido University), Yoshifumi Nogi(National Institute of Polar Research), Osamu Seki(Institute of Low Temperature Science, Hokkaido University), Chairperson:Kazuya Kusahara(Japan Agency for Marine-Earth Science and Technology)

2:45 PM - 3:00 PM

[MIS08-16] Rapid progress of ocean acidification over the Southern Ocean

*BOFENG LI1, XIANLIANG PAN1, YUTAKA WATANABE1 (1.Hokkaido University)

Keywords:Southern Ocean, Ocean acidification, Anthropogenic carbon dioxide

The Southern Ocean (SO, south of 30°S) covers 30% of the global ocean surface area and is presumed to account for 40% of the global ocean's anthropogenic CO2 (DICanth) absorption as shown by numerical modeling calculations. This may lead to intensive anthropogenic acidification in the SO. Clarifying the ocean dynamics of the anthropogenic component of the carbon system in the SO is crucial for gaining a deep understanding of the human impact on the ocean. However, natural processes also influence the change in ocean pH. Distinguishing anthropogenic and natural components from the observed dissolved inorganic carbon (DIC) and pH is essential for clarifying the acidification in the SO. Here we separated the anthropogenic and natural components by combining new parameterization techniques with high-resolution grid data constructed based on ship-based observations. The change of DICanth inventory during the 1990s-2010s, showed that anthropogenic effect on DIC accounted for 62% of the total change of DIC, which was comparable to 11% of the global emission amount of CO2 due to human activities. Ocean acidification derived from this DICanth covered most of the surface and intermediate depths by 3,500 m over the SO, and the maximum decreasing rate of anthropogenic pH was 0.004 pH year–1 as twice decreasing of the global average.