[M-IS02] Evolution and variability of the Asian Monsoon and Indo-Pacific climate during the Cenozoic Era

[MIS02-P03] Western Pacific Warm Pool Sea Surface Temperature Variability during the Mid-Piacenzian Warm Period

*佐川 拓也¹、久保田 礼実³、久保田 好美²、ローゼンタール ヤイール⁴ (1.金沢大学理工研究域、2.国立科学博物館、3.金沢大学理工学域、4.ラトガース大学)

キーワード：海洋表層水温、西部太平洋暖水塊、鮮新世

The Late Pliocene is known as the period of warmer climate with atmospheric carbon dioxide concentrations comparable to those of the present and can serve as an analog for present and future climate change. Although recent studies have provided long-term sea surface temperature (SST) records through the Plio-Pleistocene, their orbital-scale variability is still poorly understood. In particular, the SST variability in the western Pacific warm pool region has not been well characterized, despite its importance in understanding past zonal and meridional temperature gradients. Here, we analyzed Mg/Ca of planktonic foraminifer, Globigerinoides ruber (sensu stricto), at IODP Site U1488 and reconstructed the orbital-scale SST variability during the mid-Piacenzian warm period, including MIS M2 glacial (~3.3 Ma) and KM5 interglacial (~3.2 Ma). The reconstructed SST shows a gradual decrease from 3.7 to 3.3 Ma and no distinct SST drop at MIS M2, which contrasts with the distinct positive peak of δ¹⁸O. The KM5 is ~1 degree warmer than Holocene but not as high as MIS 11. These results suggest the importance of some feedback mechanism other than the carbon dioxide radiative forcing.