Impact of topographic change on the East Asian monsoon in Japan and Eastern Asia during the Last Glacial Maximum

Gowan, Evan James ORCID: https://orcid.org/0000-0002-0119-9440; Tomita, Tomohiko; Nishioka, Daiki; Zhang, Xu ORCID: https://orcid.org/0000-0003-1833-9689; Sun, Yong; Shi, Xiaoxu; Knorr, Gregor; Krebs-Kanzow, Uta; Gierz, Paul; Lohmann, Gerrit; Obase, Takashi; Kuniyoshi, Yuta; Abe-Ouchi, Ayako. 2025 Impact of topographic change on the East Asian monsoon in Japan and Eastern Asia during the Last Glacial Maximum. Progress in Earth and Planetary Science, 12 (8). 19, pp. 10.1186/s40645-024-00681-4

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Text (Open Access) © The Author(s) 2025. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. s40645-024-00681-4.pdf - Published Version Available under License Creative Commons Attribution 4.0. Download (10MB) | Preview

Abstract/Summary

The rainfall patterns in Eastern Asia are largely a consequence of the Asian winter and summer monsoons. On timescales 10 4 –10 6 of years, the position and strength of the monsoons change as a result of variations in Northern Hemisphere summer insolation. However, locally, it is possible there is a superimposed signal due to sea level change. Due to the growth of ice sheets, primarily in northern North America and Europe, global average sea level fell about 120 m during the Last Glacial Maximum (27,000–19,500 years ago). This caused the broad shallow continental shelf regions in coastal Eastern Asia to be exposed, and also greatly limited the flow of warm Pacific water into the Sea of Japan. In this study, we perform climate modelling experiments to isolate the impact of the lower sea level on the rainfall patterns in Eastern Asia. We find that the lowered sea level locally increases the summer precipitation, impacting the southern parts of Japan as well as Eastern China. The lower sea level also causes a decrease in winter precipitation in Japan. Our oxygen isotope modelling results show that the lower sea level alone is sufficient to explain the extremely depleted δ 18 O values measured from proxies in Last Glacial Maximum sediments in the Sea of Japan. These results show that the rainfall proxy records in the coastal Eastern Asia region, especially near the East China Sea, should not be interpreted as purely due to insolation driven changes to the monsoon front, as they also contain a local signal due to sea level changes. Further impacts of sea level changes on continental proxy records are likely limited, and they are measuring a purely global climate change signal.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1186/s40645-024-00681-4
ISSN:	2197-4284
Additional Keywords:	Last Glacial Maximum, East Asian monsoon, Sea level change, δ18O
Date made live:	03 Mar 2025 10:14 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/538994

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