CHANGES IN DEEP-OCEAN WATER delta O-18 AND TEMPERATURE FROM THE LAST GLACIAL MAXIMUM TO THE PRESENT

Estimates are made of changes of the oxygen isotope anomaly of deep-ocean water and of deep-ocean temperature for the Atlantic, Indian, and Pacific oceans from the time of the last glacial maximum to the present. Several independent sources of data, including oxygen isotope records of planktic and benthic foraminifera at selected core sites (primarily in the equatorial oceans) Climate: Long-Range Investigation, Mapping, and Prediction sea surface temperatures estimates, and GEOSECS delta O-18 data for the present ocean water, are utilized together with the paleo-temperature equation of Epstein et al. (1953). Glacial to interglacial change in oxygen isotope composition of the global deep-ocean water is found to be-1.41 per mil compared with a global average change of -1.75 per mil for benthic foraminifera. The former value implies a sea level change between 128 and 141 m, depending on the choice of the isotope sea level conversion constant. A global deep ocean warming of 1.4 degrees C from glacial maximum to the present is found from the above isotopic difference of 0.34 per mil. The consistency of the results in this paper with those of Chappell and Shackleton (1986) suggest that there is no significant contribution from isotopically light floating ice shelves surrounding Antarctica as proposed by Johnson and Andrews(1986), at least for the change from glacial maximum to the present. The ocean transition from glacial to interglacial episodes was accompanied by an estimated warming of 2.0 degrees C in the Atlantic, 1.4 degrees C in the Indian, and 1.1 degrees C in the Pacific oceans. The glacial Pacific was colder than the Atlantic Ocean, but the difference between the two oceans was smaller than today.