Abrupt shift toward cooler condition in the earliest 20th century detected in a 165 year coral record from Ishigaki Island, SouthWestern Japan

摘要

We analyzed a 165 year δ~(18)O coral record from Ishigaki Island, southwestern Japan, and compared our results with observed sea surface temperatures, as well as with the East Asian winter monsoon and El Nio Southern Oscillation. Coral skeletal δ~(18)O fluctuations were consistent with other available SST information since the 1890s. The coral δ~(18)O data indicated abrupt shift toward cooler condition during 1900-1905, consistent with the extremely cold winter air temperatures observed in Japan in 1902. The cold event was also supported by coral Sr/Ca data. Development of the Siberian High may have intensified the EAWM at this time, in association with active heat convection in the tropics and weak westerlies. This cooling may also have been related to surface ocean freshening in the Ogasawara Islands in the early 20th century. Thus, several phenomena were uniquely coupled during the first few years of the 20th century in the northwestern subtropical Pacific.