Ocean circulation and climate variability in the northern South China Sea during the Greek Minimum derived from coral Δ14C and Sr/Ca records

• Published in: Palaeogeography, palaeoclimatology, palaeoecology palaeoclimatology, palaeoecology, 2022-12, Vol.607 (C), p.111276, Article 111276
• Main Authors: Wang, Ning, Shen, Chengde, Ding, Ping, Ding, Xingfang, Liu, Kexin, Sun, Weidong, Chen, Xuefei, Deng, Wenfeng, Wei, Gangjian
• Format: Article
• Language: English
• Subjects: Coral; East Asian Monsoon; ENVIRONMENTAL SCIENCES; Grand Solar Minimum; Ocean circulation; Radiocarbon; South China Sea; SST
• ISSN: 0031-0182; 1872-616X
• DOI: 10.1016/j.palaeo.2022.111276

Ocean circulation transports heat, salt and nutrients, and has profound impacts on the marine environment and climate change. However, the seasonal to centennial variations of the paleocirculation of the South China Sea (SCS) and their driving forces are still unclear due to limited records. Here we reconstructed a high-resolution Δ14C record of a coral from Sanya to investigate the seasonal variations of the SCS ocean circulation around 2300 cal yr BP during a grand solar minimum (GSM) period. The seasonal Δ14C variability shows the influence of coastal upwelling caused by the East Asian Summer Monsoon (EASM) in summer and the effect of water intrusion from the western Pacific Ocean driven by the Kuroshio Intrusion (KI) in winter. We compiled the marine radiocarbon reservoir correction (ΔR) records since 2500 cal yr BP, which indicate a gradual decrease of upwelling significantly correlated with the EASM. Comparisons with other climate records suggest that both the EASM and KI may regulate the ocean circulation variability on centennial time scales. As a good index of the sea surface temperature (SST), our Sr/Ca record and spectral analysis results show a low temperature and a low frequency of El Niño-Southern Oscillation (ENSO) events around 2300 cal yr BP. Moreover, the composite coral Sr/Ca-SST and ENSO index records since 2500 cal yr BP show relatively low SST and weak ENSO during GSMs, supporting the modulation of tropical SST and ENSO by solar activity. Our study has provided high-resolution proxy data and revealed the driving forces of ocean circulation and climate change in the SCS at multiple time scales, which should be considered in further modeling work. •Upwelling and the Kuroshio Intrusion affect the seasonal change of coral Δ14C.•Upwelling in the northern SCS is stronger during the Greek Minimum than at present.•A gradual decrease of upwelling since 2500 a BP is driven by the weakening EASM.•Low SST and weak ENSO during the Greek Minimum imply a solar activity forcing.•TraCE model should include the solar forcing for a better simulation of ENSO.