Hydrospheric transports, the oxygen isotope record, and tropical sea surface temperatures during the Last Glacial Maximum

Abstract

A model is developed to consider explicitly the effect of glacial-to-Holocene changes in transports of fresh and salt water on the distribution of oxygen isotopes in seawater and therefore on the calibration of the foraminiferal 18O paleothermometer. The published foraminiferal isotopic record is shown to be consistent with glacial surface temperatures at low latitudes cooler than today by about 4°C in the Atlantic and Indian Oceans and about 2°C in the Pacific, given glacial transport patterns supported by the geologic record. If, in addition, net vapor transport from the Indian and Atlantic Oceans to the Pacific was enhanced significantly during glacial times relative to today, the isotopic record would be consistent with a sea surface cooler by up to 5°C throughout the tropics at the last glacial maximum, as expected based on proxies for continental surface temperatures.