日本地球惑星科学連合2019年大会

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[J] 口頭発表

セッション記号 M (領域外・複数領域) » M-IS ジョイント

[M-IS19] 古気候・古海洋変動

2019年5月29日(水) 13:45 〜 15:15 304 (3F)

コンビーナ:岡崎 裕典(九州大学大学院理学研究院地球惑星科学部門)、岡 顕(東京大学大気海洋研究所)、加 三千宣(愛媛大学沿岸環境科学研究センター)、長谷川 精(高知大学理工学部)、座長:加 三千宣(愛媛大学沿岸環境科学研究センター)

13:45 〜 14:00

[MIS19-07] 大気中二酸化炭素増大に伴う2つの気候変化への海洋石灰化生物の応答に関する将来展望

*川幡 穂高1 (1.東京大学 大気海洋研究所)

キーワード:地球温暖化、海洋酸性化、石灰化生物、炭酸塩、アルカリ度

This talk is developed from our comprehensive review paper of PEPS: Kawahata, H., Fujita, K., Iguchi, A, Inoue, M., Iwasaki, S., Kuroyanagi, A., Maeda, A., Manaka, T., Moriya, K., Takagi, H., Toyofuku, T., Yoshimura, T., Suzuki, A. (2019) Perspective on the response of marine calcifiers to global warming and ocean acidification – Behavior of corals and foraminifera in a high CO2 world “hot house”. Progress in Earth and Planetary Science 6: 5 (p.1-37).

Our planet will experience global warming and ocean acidification due to increased partial pressure of CO2 in the atmosphere. They are often referred to as the “evil twins” of climate change, potentially inducing severe threats in the near future.

Generally, majority of marine calcifying organisms show decreases in calcification rates in response to acidified seawater by increased pCO2. However, the response often differs depending on situations, species, and life-cycle stage. Calcification of Calcarina gaudichaudii, generally increased with increased pCO2. As one possible cause of these different sensitivities, Calcarina hosts diatoms as its symbiotic algae. High-CO2 seawater is favorable to diatom growth.

X-ray micro-computed tomography will provide valuable information regarding biomineralization including calcification of planktic and benthic foraminifera in response to ocean acidification as well as regarding carbonate dissolution.

Based upon the analysis of the biogeochemical cycle (today, at P/E boundary and in Cretaceous), “high speed” and “high level” pCO2 are the primary and secondary factors, respectively, leading to acidification in the Earth surface’s system. Over the long-term, it is well known that alkalinity has fluctuated largely in the Earth’s surface environment. Therefore, it is important to quantitatively reconstruct alkalinity, which is another key factor determining the saturation state of carbonate minerals.