Rapid coupling between solid earth and ice volume during the Quaternary

• Published in: Scientific Reports
• Main Authors: Kuwahara, Yusuke, Yasukawa, Kazutaka, Fujinaga, Koichiro, Nozaki, Tatsuo, Ohta, Junichiro, Sato, Honami, Kimura, Jun-Ichi, Nakamura, Kentaro, Yokoyama, Yusuke, Kato, Yasuhiro
• Other Authors: Japan Society for the Promotion of Science
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer Science and Business Media LLC 2021
• Subjects: Multidisciplinary; Ice Sheet
• Online Access: http://dx.doi.org/10.1038/s41598-021-84448-7; http://www.nature.com/articles/s41598-021-84448-7.pdf; http://www.nature.com/articles/s41598-021-84448-7

Abstract The solid earth plays a major role in controlling Earth’s surface climate. Volcanic degassing of carbon dioxide (CO 2 ) and silicate chemical weathering are known to regulate the evolution of climate on a geologic timescale (> 10 6 yr), but the relationship between the solid earth and the shorter (< 10 5 yr) fluctuations of Quaternary glacial–interglacial cycles is still under debate. Here we show that the seawater osmium isotope composition ( 187 Os/ 188 Os), a proxy for the solid earth’s response to climate change, has varied during the past 300,000 years in association with glacial–interglacial cycles. Our marine Os isotope mass-balance simulation reveals that the observed 187 Os/ 188 Os fluctuation cannot be explained solely by global chemical weathering rate changes corresponding to glacial–interglacial climate changes, but the fluctuation can be reproduced by taking account of short-term inputs of (1) radiogenic Os derived from intense weathering of glacial till during deglacial periods and (2) unradiogenic Os derived from enhanced seafloor hydrothermalism triggered by sea-level falls associated with increases of ice sheet volume. Our results constitute the first evidence that ice sheet recession and expansion during the Quaternary systematically and repetitively caused short-term (< 10 5 yr) solid earth responses via chemical weathering of glacial till and seafloor magmatism. This finding implies that climatic changes on < 10 5 yr timescales can provoke rapid feedbacks from the solid earth, a causal relationship that is the reverse of the longer-term (> 10 6 yr) causality that has been conventionally considered.