Tropical Atlantic coral oxygen isotopes: glacial-interglacial sea surface temperatures and climate change

We have generated a detailed oxygen isotope time-series from the fossil coral reefs from offshore Barbados. The Barbados coral-based record is a unique paleoceanographic data set with an equivalent sedimentation rate in excess of 600 cm/kyr where not only is the annual signal uniquely preserved but seasonality as well. Oxygen isotope values during the late glacial and LGM (16-20 (14)C kyrs; 19-24 calendar kyrs) are similar to2.3 parts per thousand heavier than corresponding living specimens, and indicate a regional cooling on the order of 4.5 degreesC. There is also an isotopic expression of the Bolling-Pre-Boreal climate oscillation, with values reflecting a cooling during the Younger Dryas. Seasonality, a key diagnostic of the state of the climate system, remained the same or slightly less than present and indicates that the observed coolings were a change in the mean state of the western tropical Atlantic. Pan-tropic cooling during the last glaciation is best explained by a change in the radiative balance of the tropics. Variable tropical sea surface temperatures during climate oscillations such as the Younger Dryas challenge the paradigm that climate change only cascades from variations in North Atlantic deep water production. (C) 2001 Elsevier Science Ltd All rights reserved.