Changes in meridional temperature and salinity gradients in the North Atlantic Ocean (30°-72°N) during the last interglacial period

Eight deep-sea sediment cores from the North Atlantic Ocean ranging from 31 degrees to 72 degrees N are studied to reconstruct the meridional gradients in surface hydrographic conditions during the interval of minimum ice volume within the last interglacial period. Using benthic foraminiferal delta(18)O measurements and estimates of Sea Surface Temperature (SST) and Sea Surface Salinity (SSS), we show that summer SSTs and SSSs decreased gradually during the interval of minimum ice volume at high-latitude sites (52 degrees-72 degrees N) whereas they were stable or increased during the same time period at low-latitude sites (31 degrees-41 degrees N). This increase in meridional gradients of SSTs and SSSs may have been due to changes in the latitudinal distribution of summer and annual-average insolation and associated oceanic and atmospheric feedbacks. These trends documented for the Eemian ice volume minimum period are similar to corresponding changes observed during the Holocene and may have had a similar origin.