NOAA/WDS Paleoclimatology - Amedee Lighthouse - Paleothermometry Assessment

We perform replication tests using monthly variations in Sr/Ca and δ18O in four cores from three Porites lutea coral heads from New Caledonia to assess the reproducibility of coral-based climate records. Coral Sr/Ca (δ18O) records are well correlated to each other and to the instrumental SST record (1967–1992), especially in terms of differences in the mean values of 25-year SST records (∼0.2°C, Sr/Ca-SST; 0.6°C, δ18O-SST). The average error associated with the coral Sr/Ca-SST (δ18O-SST) of any particular month, season or year is ~0.8°C (1.1°C), 0.6°C (0.8°C) and 0.5°C (0.6°C), respectively. “Stacking” or averaging the individual proxy records reduces the error between observed and predicted SST, although the reduction is small for coral Sr/Ca. Excellent reproducibility among the coral proxies implies that reliable climate records can be generated from a single coral core and that coral Sr/Ca-SST records are not compromised, beyond the errors stated herein, by non-temperature-related biological effects.