Funding provided by: Natural Science Foundation of Jiangsu ProvinceCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100004608Award Number: BK20210991Funding provided by: State Key Laboratory of Palaeobiology and Stratigraphy (Nanjing Institute of Geology and Palaeontology Chinese Academy of Sciences)*Crossref Funder Registry ID: Award Number: 20202104Funding provided by: Research Grants Council of Hong Kong*Crossref Funder Registry ID: Award Number: 17300720Funding provided by: Small Equipment Grant of the University of Hong Kong*Crossref Funder Registry ID: Award Number: 202011159122Funding provided by: Germany-Hong Kong Joint Research Scheme*Crossref Funder Registry ID: Award Number: G-HKU709/21Funding provided by: Seed Collaborative Research Fund*Crossref Funder Registry ID: Award Number: SKLMP/SCRF/0031Funding provided by: HKU-TCL Joint Research Centre for Artificial Intelligence*Crossref Funder Registry ID: Award Number: Funding provided by: Ecology and Biodiversity Division Fund, the University of Hong Kong, and Peter Buck Postdoc Fellowship, Smithsonian Institution*Crossref Funder Registry ID: Award Number: Funding provided by: Nanjing Institute of Geology and Palaeontology*Crossref Funder Registry ID: Award Number: 203108Funding provided by: Post-doctoral Fellow Scheme of the University of Hong Kong*Crossref Funder Registry ID: Award Number: Funding provided by: China Geological SurveyCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100004613Award Number: DD20190818Funding provided by: China Geological SurveyCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100004613Award Number: DD20160152Funding provided by: The National Natural Science Foundation of ChinaCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100001809Award Number: 41702162Funding provided by: Research Grants Council of Hong Kong*Crossref Funder Registry ID: Award Number: 17300821Funding provided by: Small Equipment Grant of the University of Hong Kong*Crossref Funder Registry ID: Award Number: 202111159167

The East Asian winter monsoon (EAWM) is associated with northerly surface winds affecting crop and livestock productivity and social and economic activities across East Asia. However, the relationship between EAWM dynamics and marine biota remains poorly understood. In this study, we analyzed fossil ostracods from sediment cores collected in the northwestern Pacific Ocean to detect the appearance/disappearance of circumpolar species during the late Quaternary. We compared our ostracod records, including dating results, with ice-rafted debris records from the Sea of Japan, and identified two southward migration events of Arctic ostracods at 120–100 ka (Marine Isotope Stage [MIS] 5d stadial) and 30–15 ka (MIS 3 and 2, peak Last Glacial), which corresponded to a strengthened EAWM system. Our results indicate that an intensified EAWM influenced the Yellow Sea Bottom Cold Water formation, lowered the winter water temperatures, and allowed Arctic ostracods to migrate southward into the Yellow Sea.