Evolution of the thermocline in the Indo Pacific Warm Pool during warmer climate phases of the late Neogene

2023 Fiscal Year Final Research Report

• Project/Area Number: 19KK0089
• Research Category: Fund for the Promotion of Joint International Research (Fostering Joint International Research (B))
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 17:Earth and planetary science and related fields
• Research Institution: The University of Tokyo
• Principal Investigator: Matsuzaki Kenji 東京大学, 大気海洋研究所, 助教 (50728582)
• Co-Investigator(Kenkyū-buntansha): 久保田 好美 独立行政法人国立科学博物館, 地学研究部, 研究主幹 (80710946)
• Project Period (FY): 2019-10-07 – 2024-03-31
• Keywords: モンスーン / 表層水温 / 放散虫 / 寒冷期

Outline of Final Research Achievements

During this project, we developed a new method based on extant radiolarian species to estimate past sea surface temperatures over the last 10 million years in the Northwest Pacific. Additionally, we developed a method on the Australian margin to estimate past sea surface temperatures for the last 2 million years based on radiolarian species. By utilizing these two methods, we have clarified how the East Asian Monsoon and the Australian Monsoon behaved during the Late Miocene Global Cooling and the Mid-Pleistocene Transition in the Japan Sea, the central Northwest Pacific, and off the northwestern Australian margin. As a result, we identified a strong intensification during the Late Miocene Global Cooling and the Mid-Pleistocene Transition, which reorganized the marine biosphere and marine productivity system.

Free Research Field

古海洋学

Academic Significance and Societal Importance of the Research Achievements

北半球の高緯度地域では、過去50年間で+2°Cの温暖化が起こり、これがさらに 2100年までに2°C増加する可能性があります。 この温暖化により、緯度温度勾配の低下や大気系統の乱れなどが引き起こされ、世界人口の3分の1に影響を及ぼすと予測されます。従って、高度に変動する緯度勾配下の地球気候システムの理解が非常に重要です。 この文脈では、当研究が明らかにした寒冷期を基にした冬季モンスーンの変化やそれが及ぼす海洋生産性の影響は、特に漁業などの日常生活を保護する上で貴重な知見となり得ます。