EEMIAN COOLING IN THE NORWEGIAN SEA AND NORTH-ATLANTIC OCEAN PRECEDING CONTINENTAL ICE-SHEET GROWTH

CHANGING conditions in the North Atlantic region may drive global climate changes(1,2). According to previous reconstructions of the last interglacial (the Eemian), North Atlantic sea surface temperatures (SSTs) were similar to present-day values(3). In the Norwegian Sea, even warmer conditions appeared as a single pulse of short duration(4,5), whereas the Greenland ice record suggests that the warm interglacial air temperatures were interrupted by several cold periods(6). Here we use faunal and stable-isotope analyses of foraminifera in two sediment cores from the North Atlantic ocean and Norwegian Sea to reconstruct high-resolution records of SST and sea surface salinity (SSS) during the Eemian interglacial. Our results, which differ significantly from the Greenland record(6), show a sharp decrease in SST and SSS of the Norwegian Sea, associated with a more moderate cooling and freshening of the North Atlantic at the middle of isotope substage 5e, several millennia before the beginning of continental ice-sheet growth. Changes in the Norwegian Sea surface conditions appear to have represented an important climate change affecting global atmospheric and thermohaline circulations.