Central Equatorial Pacific Warming and Freshening in the Twentieth Century: Insights From a Coral Ensemble Approach

The tropical Pacific influences climate patterns across the globe, yet robust constraints on decadal to centennial-scale climate variations are difficult to extract from sparse instrumental observations in this region. Oxygen isotope (δ¹⁸O) records from long-lived corals enable the quantitative reconstruction of tropical Pacific climate variability and trends over the twentieth century and beyond, but such corals are exceedingly rare. Here, we use multiple short coral δ¹⁸O records to create a coral ‘ensemble’ reconstruction of twentieth century climate in the central tropical Pacific. Ten U/Th-dated fossil coral δ¹⁸O records from Kiritimati Island (2°N, 157°W) span 1891 CE to 2006 CE, with the younger samples enabling quantitative comparison to a large ensemble of modern coral records and instrumental sea surface temperature. A composite record constructed of modern and fossil Kiritimati coral δ¹⁸O records shows a shift toward warmer and fresher conditions from 1970 CE onward, consistent with previously published records in this region.