East Asian monsoon to El Niño/Southern Oscillation: A shift in the winter climate of Ishigaki Island accompanying the 1988/1989 regime shift, based on instrumental and coral records
The relationship between the coral skeletal oxygen isotope ratio (δ 18Ocoral) of a coral core (Porites sp.), which was collected from the inshore area of Ishigaki Island, Japan (24°N, 124°E) and represents 180 years of continuous growth, and sea surface temperature (SST) was examined for the last 30 years. A significant linear correlation was found between winter δ 18Ocoral and SST measured at Ishigaki Port (SSTI), which suggests that the winter data from this coral sample is a good proxy for reconstructing past climate change. Furthermore, the winter instrumental SSTI shifted from being related to the East Asian Winter Monsoon to being dependent on the El Niño/Southern Oscillation in response to the 1988/1989 climate regime shift. Since this shift is also captured by the winter δ 18Ocoral values, this 180-year coral core record may provide insight into past climate regime shifts that occurred before instrumental records.