Age, annual coral growth rates and stable isotopes of coral sample Ningaloo

116-year record of coral skeletal delta18O is presented from a colony of Porites lutea from Ningaloo Reef, western Australia. Interannual variability of sea-surface temperatures (SST) inferred from skeletal delta18O is dominated by a 9.5-year period, and may constitute a characteristic signal of the Leeuwin Current. On long-terms coral skeletal delta18O indicates a near-continuous increase of SST at Ningaloo Reef over one century. The skeletal delta18O time series was checked for the presence of seasonal cooling events resulting from major volcanic eruptions. An ~1 °C cooling is evident following the eruption of Pinatubo in 1991, which reproduces the results of previous investigations. However, only weak or no signals can be related to the eruptions of Krakatau (1883) and Agung (1963).

Stable isotope record of a Bermuda coral

Records of skeletal delta18O in monthly and Sr/Ca ratios in half-yearly resolution were obtained from a Bermuda coral (Diploria labyrinthiformis) for the time period 1520-1603 (+/-15 yr) AD within the Little Ice Age. Annual and decadal averages of both sea-surface temperature proxies indicate temperature variabilities of 0.5°C (standard deviation) and 0.3°C, respectively. Both numbers are close to recent instrumental observations. Approximately 30% of the interannual time series variance of delta18O is concentrated in broad bands centered at periods of ~30, 16, and 7.8 yr, the last two reflecting the influence of the North Atlantic Oscillation. Although this large-scale climate signal is present in the record, there is no correlation with other contemporaneous northern hemisphere proxy data, resulting from spatial differences in climate variability.