Middle Eocene Climatic Optimum Stable Isotope Data Bohaty, S.M.; Zachos, J.C.; Florindo, F.; Delaney, M.L. Bohaty, S.M. Zachos, J.C. Florindo, F. Delaney, M.L. earth science/paleoclimate/paleoceanography (depth,null,null,meter,null,paleoceanography,composited,null,N,null) earth science/paleoclimate/paleoceanography (notes,null,null,null,null,paleoceanography,null,null,C,sample material (fine; bulk; etc)) earth science/paleoclimate/paleoceanography (delta 13C,Cibicidoides sp.,null,per mil VPDB,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (depth at sample start,null,null,centimeter,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (delta 13C,carbonate,null,per mil VPDB,null,paleoceanography,null,null,N,bulk carbonate or fine fraction (mostly calcareous nannofossils)) earth science/paleoclimate/paleoceanography (depth,null,null,meter,null,paleoceanography,averaged,null,N,null) earth science/paleoclimate/paleoceanography (age,null,null,million years ago,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (depth at sample end,null,null,centimeter,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (depth,null,null,meter,null,paleoceanography,null,null,N,mbsf) earth science/paleoclimate/paleoceanography (delta 18O,carbonate,null,per mil VPDB,null,paleoceanography,null,null,N,bulk carbonate or fine fraction (mostly calcareous nannofossils)) earth science/paleoclimate/paleoceanography (delta 18O,Cibicidoides sp.,null,per mil VPDB,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleocean earth science/paleoclimate/paleocean (ODP 738B>LATITUDE -62.709>LONGITUDE 82.7878) (ODP 689B>LATITUDE -64.517>LONGITUDE 3.0999) (ODP1263B>LATITUDE -28.5327>LONGITUDE 2.7794) (ODP523>LATITUDE -28.5522>LONGITUDE -2.2513) (ODP748>LATITUDE -58.441>LONGITUDE 78.9981) (ODP702B>LATITUDE -50.946>LONGITUDE -26.36865) (ODP 1051>LATITUDE 30.0529>LONGITUDE -76.357633) The Middle Eocene Climatic Optimum (MECO) is an enigmatic warming event that represents an abrupt reversal in long-term cooling through the Eocene. In order to further assess the timing and nature of this event, we have assembled stable isotope and calcium carbonate concentration records from multiple Deep Sea Drilling Project and Ocean Drilling Program sites for the time interval between ~43 and 38 Ma. Revised stratigraphy at several sites and compilation of d18O records place peak warming during the MECO event at 40.0 Ma (Chron C18n.2n). The identification of the d18O excursion at sites in different geographic regions indicates that the climatic effects of this event were globally extensive. The total duration of the MECO event is estimated at ~500 ka, with peak warming lasting <100 ka. Assuming minimal glaciation in the late middle Eocene, ~4°-6°C total warming of both surface and deep waters is estimated during the MECO at the study sites. The interval of peak warming at ~40.0 Ma also coincided with a worldwide decline in carbonate accumulation at sites below 3000 m depth, reflecting a temporary shoaling of the calcite compensation depth. The synchroneity of deepwater acidification and globally extensive warming makes a persuasive argument that the MECO event was linked to a transient increase in atmospheric pCO2. The results of this study confirm previous reports of significant climatic instability during the middle Eocene. Furthermore, the direct link between warming and changes in the carbonate chemistry of the deep ocean provides strong evidence that changes in greenhouse gas concentrations exerted a primary control on short-term climate variability during this critical period of Eocene climate evolution. STUDY NOTES: Stable isotope data from 7 marine sediment cores distributed around the global ocean for the Middle Eocene (~43 and 38 Ma). NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Bohaty, S.M. Investigator : Zachos, J.C. Investigator : Florindo, F. Investigator : Delaney, M.L. 2011-08-19 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/11924 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/bohaty2009/bohaty2009.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/bohaty2009/bohaty2009.xls https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/bohaty2009/bohaty2009.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/bohaty2009/bohaty2009.xls English https://www.ncdc.noaa.gov/paleo/study/11924 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/bohaty2009/bohaty2009.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/bohaty2009/bohaty2009.xls Bohaty, S.M., J.C. Zachos, F. Florindo, and M.L. Delaney. 2009. Coupled greenhouse warming and deep-sea acidification in the middle Eocene. Paleoceanography, 24, PA2207, doi:10.1029/2008PA001676. START YEAR: 43000000 cal yr BP * END YEAR: 38000000 cal yr BP -76.357633 -64.517 82.7878 30.0529