SEA-SURFACE TEMPERATURE FROM CORAL SKELETAL STRONTIUM CALCIUM RATIOS

Seasonal records of tropical sea-surface temperature (SST) over the past 10(5) years can be recovered from high-precision measurements of coral strontium/calcium ratios with the use of thermal ionization mass spectrometry. The temperature dependence of these ratios was calibrated with corals collected at SST recording stations and by O-18/O-16 thermometry. The results suggest that mean monthly SST may be determined with an apparent accuracy of better than 0.5-degrees-C. Measurements on a fossil coral indicate that 10,200 years ago mean annual SSTs near Vanuatu in the southwestern Pacific Ocean were about 5-degrees-C colder than today and that seasonal variations in SST were larger. These data suggest that tropical climate zones were compressed toward the equator during deglaciation.