Western Equatorial Pacific ODP806B Late Pliocene Mg/Ca, d18O, and SST Medina-Elizalde, M.; Lea, D.W. Medina-Elizalde, M. Lea, D.W. Sea Surface Temperature Reconstruction Warm Pool earth science/paleoclimate/climate reconstructions|paleoceanography (sea surface temperature,magnesium/calcium,null,degree Celsius,null,climate reconstructions|paleoceanography,null,null,N,G. ruber) earth science/paleoclimate/climate reconstructions|paleoceanography (delta 18O,delta 18O|magnesium/calcium|sea water,null,per mil,null,climate reconstructions|paleoceanography,null,null,N,G. ruber) earth science/paleoclimate/paleoceanography (depth,null,null,meter,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (age,null,null,calendar kiloyear before present,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (magnesium/calcium,Globigerinoides ruber,null,dimensionless,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (depth,null,null,meter,null,paleoceanography,corrected,null,N,null) earth science/paleoclimate/paleoceanography (delta 18O,Globigerinoides ruber,null,per mil,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleocean earth science/paleoclimate/paleocean earth science/paleoclimate/paleocean (ODP 806B>LATITUDE .32>LONGITUDE 159.35) Late Pliocene foraminiferal Mg/Ca and d18O records from Ocean Drilling Program Hole 806B in the western equatorial Pacific (WEP) reveal warm pool climate evolution during the onset of Northern Hemisphere glaciation, 3.1-2.3 Myr B.P. Mg/Ca data indicate an average late Pliocene sea surface temperature (SST) of 27.8°C, a small long-term cooling of 0.3°C between 3.1 and 2.3 Ma, and a glacial-interglacial (G-I) SST range of 2°C throughout this time interval. For comparison, Pleistocene SSTs at this site over the last 0.9 Myr average 27.7°C with a G-I range of 3°C. Orbital-scale variability in Hole 806B SSTs during the late Pliocene occurs predominantly at ~100 ka, in contrast to foraminiferal d18O records, which show a dominant 41 kyr period. Variability at a 41 kyr period, out of phase with local annual insolation changes driven by obliquity, is also observed in the new WEP SST record. The WEP SST record suggests that an ~3°C equatorial Pacific SST zonal gradient prevailed during the late Pliocene, compatible with a weaker Walker circulation. Adjustment of Hole 806B SSTs for past changes in seawater Mg/Ca suggests that SSTs higher than 30°C prevailed at 3 Myr B.P., followed by a progressive cooling of the warm pool through the late Pliocene. The characteristics of late Pliocene tropical climate evolution suggest that atmospheric greenhouse gas forcing played a major role in driving the observed G-I SST changes. STUDY NOTES: Planktonic foraminiferal (G. ruber) Mg/Ca and d18O, plus Sea Surface Temperature (SST) and d18Oseawater estimates, for the Late Pliocene from Western Equatorial Pacific sediment core ODP806B. SST estimated from G. ruber Mg/Ca by the method of Lea et al. [2000]. d18O seawater record was calculated by removing the temperature component in planktonic d18O using the Mg/Ca derived SSTs and the paleotemperature equation of Bemis et al., [1998]. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Medina-Elizalde, M. Investigator : Lea, D.W. 2011-03-18 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/10551 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/medina-elizalde2010/medina-elizalde2010.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/medina-elizalde2010/medina-elizalde2010.xls https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/medina-elizalde2010/medina-elizalde2010.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/medina-elizalde2010/medina-elizalde2010.xls English https://www.ncdc.noaa.gov/paleo/study/10551 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/medina-elizalde2010/medina-elizalde2010.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/medina-elizalde2010/medina-elizalde2010.xls Medina-Elizalde, M. and D.W. Lea. 2010. Late Pliocene equatorial Pacific. Paleoceanography, 25, PA2208, doi:10.1029/2009PA001780 START YEAR: 3087400 cal yr BP * END YEAR: 2336900 cal yr BP 159.35 .32 159.35 .32