The Pacific Decadal Oscillation (PDO) is a dominant climate mode in the Pacific Ocean and thought to be related to seasonal to decadal changes in sea surface conditions. Colonies of long-living Porites coral, widely used to reconstruct monthly to century-scale tropical sea surface temperature and sea surface salinity records, were discovered near Koshiki Island, Japan (31°N, 129°E). A monthly resolved, 106 year δ18O record revealed that distinct decadal-scale variability was significantly correlated with the PDO index. Our comparison showed 1 to 3 years lead-lag correlation of summer coral δ18O with the winter PDO index, suggesting that the East Asian summer monsoon (EASM) may act as the driving force of winter PDO variability over the last 100 years. Cross-spectral analysis between the winter PDO index and summer coral δ18O suggested that recent and future global warming may lead to a more frequent and/or stronger teleconnection between EASM and PDO.
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