Estimates of sea surface temperatures in the Coral Sea

The CLIMAP [1981] reconstruction of the Coral Sea found relatively little cooling (2°C) in the low latitudes (10°S) but a warming off Australia at about 25°S. The small low-latitude changes are of interest because terrestrial pollen and snowline data from the New Guinea highlands imply that surface temperatures may have been 6° to 9°C colder at the last glacial maximum (LGM). The purpose of this paper is to evaluate these conclusions on the basis of additional core sites, new oxygen isotope stratigraphy, and new sea surface temperature (SST) estimates using the modern analog technique (MAT). In the northern Coral Sea, planktonic foraminifer assemblages consist of tropical-subtropical species that show little change over the past 20 kyr. Quantitative estimates of SST using the modern analog technique (MAT) confirm the CLIMAP [1981] conclusion that little or no temperature change occurred in this tropical region at the LGM, thus reinforcing the conflict with terrestrial evidence. In the southern region (25°S), two cores indicate that foraminifer faunas became more subtropical at the LGM. The MAT estimates for the LGM are 3° to 4°C colder than modern, producing a steeper thermal gradient in the southern Coral Sea. These data remove the warm SST anomaly along the eastern coast of Australia and indicate that during the LGM, cool high- latitude waters were displaced northward along the coast of Australia into the southern Coral Sea.