Examinaiton of weathering feedbacks to climate change and glacial erosion

2023 Fiscal Year Final Research Report

• Project/Area Number: 21H01204
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 17050:Biogeosciences-related
• Research Institution: Japan Agency for Marine-Earth Science and Technology
• Principal Investigator: Yoshimura Toshihiro 国立研究開発法人海洋研究開発機構, 海洋機能利用部門(生物地球化学センター), 副主任研究員 (90710070)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 氷河作用 / 化学風化 / 削剥 / 気候 / 氷期・間氷期

Outline of Final Research Achievements

Atmospheric CO2 has received increasing public attention as a factor determining climate. Recently, it has been proposed that dissolution reactions of reactive fine-grained silicate minerals produced by glaciers contributed to CO2 consumption, which may have promoted colder temperatures. However, there is a lack of direct evidence for a link with geological events. In this study, we reconstruct changes in silicate weathering intensity in response to climate change and ice sheet formation from chemical indices (element ratios and lithium isotope ratios) of sediment samples from New Zealand and the Antarctic Ocean, where materials produced by glacial ablation were deposited. The results indicate that fresher material was supplied in the past million years and that chemical weathering was enhanced in ice sheet formation.

Free Research Field

地球化学

Academic Significance and Societal Importance of the Research Achievements

ケイ酸塩岩の化学風化によって生産された溶質が海洋に運搬されると，海洋生物の石灰化反応によって炭素が海底に固定されることで効率的な二酸化炭素の除去に寄与することが予想されるが，氷河により新鮮な物質の供給が促進されることで，より風化反応の強度が増加したことを確認した。地球上の気候レジームを左右する炭素動態の長期変動の理解に寄与する成果である。