Climate impact of late quaternary equatorial Pacific sea surface temperature variations

Magnesium/calcium data from planktonic foraminifera in equatorial Pacific s ediment cores demonstrate that tropical Pacific sea surface temperatures (S STs) were 2.8 degrees +/- 0.7 degrees C colder than the present at the Last glacial maximum. Glacial-interglacial temperature differences as great as 5 degrees C are observed over the Last 450 thousand years. Changes in SST c oincide with changes in Antarctic air temperature and precede changes in co ntinental ice volume by about 3 thousand years, suggesting that tropical co oling played a major role in driving ice-age climate. Comparison of SST est imates from eastern and western sites indicates that the equatorial Pacific zonal SST gradient was similar or somewhat Larger during glacial episodes. Extraction of a salinity proxy from the magnesium/calcium and oxygen isoto pe data indicates that transport of water vapor into the western Pacific wa s enhanced during glacial episodes.