NOAA/WDS Paleoclimatology - Kiritimati Island 2015/16 El Nino Coral and Seawater Oxygen Isotope Data

Coral oxygen isotopes (d18O) from the central equatorial Pacific provide monthly-resolved records of El Nino-Southern Oscillation (ENSO) activity over past centuries to millennia. However, calibration studies using in situ data to assess the relative contributions of warming and freshening to coral d18O records are exceedingly rare. Furthermore, the fidelity of coral d18O records under the most severe thermal stress events is difficult to assess. Here, we present six coral d18O records and in situ temperature, salinity, and seawater d18O data from Kiritimati Island (2N, 157W) spanning the very strong 2015/16 El Nino event. Local sea surface temperature (SST) anomalies of +2.4+/-0.4C and seawater d18O anomalies of -0.19+/-0.02 per mil contribute to the observed coral d18O anomalies of -0.58+/-0.05 per mil, consistent with a ~70% contribution from SST and ~30% from seawater d18O. Our results demonstrate that Kiritimati coral d18O records can provide reliable reconstructions even during the largest class of El Nino events.