Atlantic and Pacific Regional 450 KYr Benthic d13C Stacks Lisiecki, L.E.; Raymo, M.E.; Curry, W.B. Lisiecki, L.E. Raymo, M.E. Curry, W.B. Meridional Overturning Circulation (MOC) earth science/paleoclimate/paleoceanography (age,null,null,calendar kiloyear before present,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (delta 13C,Cibicidoides wuellerstorfi,null,per mil VPDB,null,paleoceanography,composited,null,N,deep Atlantic sites) earth science/paleoclimate/paleoceanography (delta 13C,Cibicidoides wuellerstorfi,null,per mil VPDB,null,paleoceanography,composited,null,N,shallow Atlantic sites) earth science/paleoclimate/paleoceanography (delta 13C,Cibicidoides wuellerstorfi,null,per mil VPDB,null,paleoceanography,composited,null,N,deep Pacific sites) earth science/paleoclimate/paleoceanography (delta 13C,Cibicidoides wuellerstorfi,null,per mil VPDB,null,paleoceanography,composited,null,N,mid-depth Atlantic sites) earth science/paleoclimate/paleoceanography (delta 13C,Cibicidoides wuellerstorfi,null,per mil VPDB,null,paleoceanography,composited,null,N,mid-depth Atlantic stack minus deep Pacific stack) earth science/paleoclimate/paleocean (ODP 925>LATITUDE 4.20415>LONGITUDE -43.4889) The factors driving glacial changes in ocean overturning circulation are not well understood. On the basis of a comparison of 20 climate variables over the past four glacial cycles, the SPECMAP project proposed that summer insolation at high northern latitudes (that is, Milankovitch forcing) drives the same sequence of ocean circulation and other climate responses over 100-kyr eccentricity cycles, 41-kyr obliquity cycles and 23-kyr precession cycles. SPECMAP analysed the circulation response at only a few sites in the Atlantic Ocean, however, and the phase of circulation response has been shown to vary by site and orbital band. Here we test the SPECMAP hypothesis by measuring the phase of orbital responses in benthic d13C (a proxy indicator of ocean nutrient content) at 24 sites throughout the Atlantic over the past 425 kyr. On the basis of d13C responses at 3,000-4,010m water depth, we find that maxima in Milankovitch forcing are associated with greater mid-depth overturning in the obliquity band but less overturning in the precession band. This suggests that Atlantic overturning is strongly sensitive to factors beyond ice volume and summer insolation at high northern latitudes. A better understanding of these processes could lead to improvements in model estimates of overturning rates, which range from a 40 per cent increase to a 40 per cent decrease at the Last Glacial Maximum and a 10-50 per cent decrease over the next 140 yr in response to projected increases in atmospheric CO2. STUDY NOTES: The d13C records used in this study are collected from previous studies and primarily measured from the epibenthic taxon Cibicidoides wuellerstorfi. All records are placed on a common age model by aligning their benthic d18O records to the LR04 benthic d18O stack (Lisiecki and Raymo, 2005). The posted data include regional stacks (averages) of benthic d13C (%VPDB) from shallow North Atlantic sites (DSDP552, ODP980, ODP982, ODP983), mid-depth Atlantic sites (ODP925, ODP927, ODP928, GeoB1214), deep Atlantic sites (DP929, ODP1089, GeoB1041, GeoB1211), and deep Pacific sites (ODP677, ODP846, ODP849, RC13-110, V21-146). A proxy for mid-depth NADW (Dd13C_mid) is found by subtracting the deep Pacific d13c stack from the mid-depth Atlantic d13c stack. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Lisiecki, L.E. Investigator : Raymo, M.E. Investigator : Curry, W.B. 2010-07-23 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/10251 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/lisiecki2008/lisiecki2008.xls https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/lisiecki2008/lisiecki2008.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/lisiecki2008/lisiecki2008.xls https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/lisiecki2008/lisiecki2008.txt English https://www.ncdc.noaa.gov/paleo/study/10251 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/lisiecki2008/lisiecki2008.xls https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/lisiecki2008/lisiecki2008.txt Lisiecki, L.E., M.E. Raymo, and W.B. Curry. 2008. Atlantic overturning responses to Late Pleistocene climate forcings. Nature, Vol. 456, pp. 85-88, 6 November 2008. doi:10.1038/nature07425 START YEAR: 450000 cal yr BP * END YEAR: 0 cal yr BP -43.4889 4.20415 -43.4889 4.20415