SST and SSS from corals

Modified from Gagan et al. (1998) Science 279: 1014-1018.

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Caption: Comparison between sea surface temperatures calculated from coral Sr/Ca ratio (blue curves) and 18O (upper red curve) for modern (left) and 5,350 yrs BP (right) Porites corals from Orpheus Island, central Great Barrier Reef, Australia. Differences in seawater 18O (lower red curves), relative to the modern mean, are obtained by removal of the temperature component of the 18O signal. The horizontal lines show the mean 18O of seawater, as defined by the seven 18O values (squares) falling in the austral winters (vertical lines). Relative to the mid-Holocene, the modern coral indicates cooler average water temperatures (by 1.2°C and the characteristic interannual variability in salinity (~18O seawater) that accompanies the ENSO cycle (from Gagan et al. 1998).

M. Gagan, et al. (1998) Temperature and surface-ocean water balance of the mid-Holocene tropical western Pacific, Science,  279, 1014-1018.