Cool surface waters of the subtropical North Pacific Ocean during the lastglacial

One of the most controversial results of the CLIMAP(1,2) project's reconstr uction of past sea surface temperature (SST) is that large areas of the sub tropical Pacific Ocean were warmer during the last glacial period than they are today. This finding has important implications because SST patterns at low to subtropical latitudes strongly influence climate, and SST changes a re closely linked with climate fluctuations(3-5). Until now, a lack of well -preserved, high-resolution marine sediment cores from the region has hinde red efforts to confirm these unexpectedly high ice-age SST estimates. Here we use both the oxygen-isotope compositions and species assemblages of plan ktonic foraminifera in a shallow-water core with high deposition rates near Hawaii to estimate glacial SST of the subtropical North Pacific Ocean, Con trary to the CLIMAP results(2), our data indicate that the annual average S ST in this region was similar to 2 degrees C cooler during the last glaciat ion than it is today, These results help to reconcile the marine SST record with inferences drawn from snowline depressions on Hawaii during the last glacial(3,6), and should ultimately yield improved estimates of global clim ate sensitivity by providing important new constraints on climate model sim ulations of ice-age cycles.