The relationship between changes in surface water temperature and δ 18Oseawater in the tropics and subtropics following the Last Glacial Maximum

Comparison of published proxy sea surface temperature (SST) and oxygen isotope (δ ¹⁸O) profiles for glacial/interglacial sequences from fourteen tropical and subtropical oceanic settings enables assessment of the spatial differences in the timing and progression of ocean warming following the last glacial maximum (LGM: 18,000 - 21,000 calendar years). These stratigraphic records indicate that on average SST increased ~ 2.5-3 ° C since the LGM in the tropical and subtropical regions. At 5 sites the δ ¹⁸O termination was synchronous with SST changes inferred from foraminiferal Mg/Ca and alkenones, while at 9 sites it lagged SST by approximately 3,000 years. A comparison of SST and residual δ ¹⁸O (ice volume component removed) across the glacial-interglacial transition indicate a linear increase in SST with younger age. At sites where the δ ¹⁸O and SST transitions are synchronous, δ ¹⁸O_residual continuously decreased into the Holocene reaching a plateau at ~ 7 kyr. This indicates that δ ¹⁸O_residual at these sites was mainly influenced by changes in SST. At sites where SST was leading the δ ¹⁸O record, foraminiferal δ ¹⁸O_residual increased for approximately 3,000 years up to 17 kyr, and then continuously decreased to the mid-Holocene, indicating large regional changes in precipitation-evaporation balance. These sites where SST was leading the δ ¹⁸O record are all located in areas that today have anomalously higher precipitation rates under La Niña-like conditions possibly indicating that the ENSO system was dramatically influenced by changing climatic conditions across the glacial-interglacial transition.