Paleo‐sea surface temperature calculations in the equatorial east Atlantic from Mg/Ca ratios in planktic foraminifera: A comparison to sea surface temperature estimates from U37K′, oxygen isotopes, and foraminiferal transfer function

We present two ∼270 kyr paleo‐sea surface temperature (SST) records from the Equatorial Divergence and the South Equatorial Current derived from Mg/Ca ratios in the planktic foraminifer Globigerinoides sacculifer . The present study suggests that the magnesium signature of G. sacculifer provides a seasonal SST estimate from the upper ∼50 m of the water column generated during upwelling in austral low‐latitude fall/winter. Common to both down‐core records is a glacial‐interglacial amplitude of ∼3°–3.5°C for the last climatic changes and lower Holocene and glacial oxygen isotope stage 2 temperatures compared with interglacial stage 5.5 and glacial stage 6 temperatures, respectively. The comparison to published SST estimates from alkenones, oxygen isotopes, and foraminiferal transfer function from the same core material pinpoints discrepancies and conformities between methods.