Climatic trends and interdecadal variability from South-Central Pacific coral records

We study climate variability over interdecadal time scales from delta(13)C and delta(18)O records, measured in a Porites lutea coral core drilled in t he Moorea lagoon. Previously, we demonstrated that the annual delta(18)O va riations reflect those in sea-surface temperature (SST), while the annual d elta(13)C variations record primarily cloud-cover changes. We apply two dis tinct spectral analysis methods to the delta(13)C and delta(18)O time serie s from 1853 to 1989. Our analysis of the delta(18)O record shows a secular warming trend and a 35-year oscillation in temperatures over the last 137 y ears. A trend and a 34-year cycle are also found in the delta(13)C record. The latter trend may be caused by either anthropogenic effects or a cloud-c over increase in this region of the Pacific Ocean, while the interdecadal o scillation appears to be related to changes in cloud cover, as well as in p recipitation.