Reconstruction of East Asian climate during Holocene by using high-resolution isotope analyses

2020 Fiscal Year Final Research Report

• Project/Area Number: 17KK0012
• Research Category: Fund for the Promotion of Joint International Research (Fostering Joint International Research)
• Allocation Type: Multi-year Fund
• Research Field: Environmental dynamic analysis
• Research Institution: Nagoya University (2019-2020); University of the Ryukyus (2017-2018)
• Principal Investigator: Uemura Ryu 名古屋大学, 環境学研究科, 准教授 (00580143)
• Project Period (FY): 2018 – 2020
• Keywords: 鍾乳石 / 古気候 / 安定同位体

Outline of Final Research Achievements

To obtain a high-time resolution climate record in Okinawa region during the Holocene, we analyzed stalagmite samples. Sample measurements were conducted as an international joint research at each research institutions. We screened multiple samples and analyzed the samples collected in Minamidaito Island, Okinawa, Japan. An age model was established with precise U-Th ages (Error of 10-38 years) from present to 1.2 thousand years ago. Before the settlement started in 1900 CE, this island had been uninhabited. After 1900 CE, the land-use change due to sugar-cane plantation is clearly recorded as an abrupt shift of the carbon isotope record. The oxygen isotope record shows broad links with Indian and Asian climate records on centennial time scale. Although the travel plan was changed because of the COVID-19 pandemic, this project laid the foundation for international research.

Free Research Field

同位体気候学

Academic Significance and Societal Importance of the Research Achievements

長期間の気候データは、自然要因の気候変動のメカニズムを理解するために必要である。しかし、精確な年代をもつ長期間の気候変動データは日本周辺には少ない。本研究では、国際共同研究を通して鍾乳石の正確な年代決定を行い、気候変動の復元を行った。成果の一つとして、過去1200年間の絶対年代が求まった連続的な酸素・炭素安定同位体データを得ることができた。これらの研究活動を通して国際共同研究の基盤を強化することができた。