Reliability of coral isotope records from the western Pacific warm pool: A comparison using age-optimized records

Stable isotope analysis of two separate corals from Nauru Island in the warm pool of the western tropical Pacific confirm that coral oxygen isotopes are a robust recorder of environmental variables. Coral delta(18)O faithfully records interannual variability even when strongly influenced by kinetic effects. Interannual to decadal variability of coral delta(13)C remains enigmatic; only one of the two corals exhibits the expected light-delta(13)C response in the interannual band. Coral delta(18)O from this region has a great similarity to global instrumental temperature records reflecting the impact of the Pacific warm pool and variations of the Indonesian Low in concert with El Nino-Southern Oscillation on global climate. Since 1896, coral delta(18)O has exhibited a cumulative decrease of 0.7 parts per thousand, which reflects a combination of warming and more frequent El Nino events (precipitation) affecting the surface waters of this region.