East China Sea climate and Kuroshio variability since the Last Glacial Maximum

The Kuroshio is crucial in transporting heat and materials poleward. Its variability interacts with the global climate system and affects local and regional climates. However, long-term Kuroshio variability remains poorly understood, especially during the last glacial time. Here, we use a depth sediment cores recovered from the northern Okinawa Trough to investigate past Kuroshio variability. Radiocarbon results indicate that the recovered cores range in age from modern to ~50 ka. Bottom water temperature on the eastern edge of the trough at a relatively shallow site (~300 mbsl) was stable during the past 12 ka, with little increase during the Holocene. We estimate that this site experience ~60 m sea level rise. Based on World Ocean Atlas data for the site, an increase in depth of 60 m corresponds roughly to a 2˚C temperature decrease. Thus, Holocene warming was likely offset by rising sea level. The results further suggest that the vertical temperature gradient and thus the temperature structure was similar at 12 ka to the late Holocene, probably related to the existence of the Kuroshio main axis since that time.