{"NOAAStudyId":"24850","contactInfo":{"address":"325 Broadway, E/NE31","city":"Boulder","constraints":"Please cite original publication, online resource, dataset and publication DOIs (where available), and date accessed when using downloaded data. If there is no publication information, please cite investigator, title, online resource, and date accessed. The appearance of external links associated with a dataset does not constitute endorsement by the Department of Commerce/National Oceanic and Atmospheric Administration of external Web sites or the information, products or services contained therein. For other than authorized activities, the Department of Commerce/NOAA does not exercise any editorial control over the information you may find at these locations. These links are provided consistent with the stated purpose of this Department of Commerce/NOAA Web site.","country":"USA","dataCenterUrl":"https://www.ncdc.noaa.gov/data-access/paleoclimatology-data","email":"paleo@noaa.gov","fax":"303-497-6513","longName":"National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce ","phone":"303-497-6280","postalCode":"80305-3328","shortName":"DOC/NOAA/NESDIS/NCEI","state":"CO","type":"CONTACT INFORMATION"},"contributionDate":"2018-08-11","dataPublisher":"NOAA","dataType":"CLIMATE FORCING","dataTypeInformation":"https://www.ncdc.noaa.gov/data-access/paleoclimatology-data/datasets/climate-forcing","difMetadataLink":"http://www1.ncdc.noaa.gov/pub/data/metadata/published/paleo/dif/xml/noaa-forcing-24850.xml","doi":null,"earliestYearBP":38490000,"earliestYearCE":-38488050,"entryId":"noaa-forcing-24850","funding":[{"fundingAgency":"US National Science Foundation","fundingGrant":"1203163"}],"investigators":"Zhang, Y.G.; Pagani, M.; Liu, Z.; Bohaty, S.M.; DeConto, R.M.","mostRecentYearBP":20000,"mostRecentYearCE":-18050,"onlineResourceLink":"https://www.ncdc.noaa.gov/paleo/study/24850","originalSource":null,"publication":[{"abstract":"The alkenone-pCO2 methodology has been used to reconstruct the partial pressure of ancient atmospheric carbon dioxide (pCO2) for the past 45 million years of Earth's history (Middle Eocene to Pleistocene epochs). The present long-term CO2 record is a composite of data from multiple ocean localities that express a wide range of oceanographic and algal growth conditions that potentially bias CO2 results. In this study, we present a pCO2 record spanning the past 40 million years from a single marine locality, Ocean Drilling Program Site 925 located in the western equatorial Atlantic Ocean. The trends and absolute values of our new CO2 record site are broadly consistent with previously published multi-site alkenone-CO2 results. However, new pCO2 estimates for the Middle Miocene are notably higher than published records, with average pCO2 concentrations in the range of 400-500 ppm. Our results are generally consistent with recent pCO2 estimates based on boron isotope-pH data and stomatal index records, and suggest that CO2 levels were highest during a period of global warmth associated with the Middle Miocene Climatic Optimum (17-14 million years ago, Ma), followed by a decline in CO2 during the Middle Miocene Climate Transition (approx. 14 Ma). Several relationships remain contrary to expectations. For example, benthic foraminiferal d18O records suggest a period of deglaciation and/or high-latitude warming during the latest Oligocene (27-23 Ma) that, based on our results, occurred concurrently with a long-term decrease in CO2 levels. Additionally, a large positive d18O excursion near the Oligocene-Miocene boundary (the Mi-1 event, approx. 23 Ma), assumed to represent a period of glacial advance and retreat on Antarctica, is difficult to explain by our CO2 record alone given what is known of Antarctic ice sheet history and the strong hysteresis of the East Antarctic Ice Sheet once it has grown to continental dimensions. We also demonstrate that in the Neogene with low CO2 levels, algal carbon concentrating mechanisms and spontaneous biocarbonate-CO2 conversions are likely to play a more important role in algal carbon fixation, which provides a potential bias to the alkenone-pCO2 method.","author":{"name":"Yi Ge Zhang, Mark Pagani, Zhonghui Liu, Steven M. Bohaty, Robert DeConto"},"citation":"Yi Ge Zhang, Mark Pagani, Zhonghui Liu, Steven M. Bohaty, Robert DeConto. 2013. A 40-million-year history of atmospheric CO2. Philosophical Transactions of The Royal Society A, 371(2001). doi: 10.1098/rsta.2013.0096 ","edition":null,"identifier":{"id":"10.1098/rsta.2013.0096 ","type":"doi","url":"http://dx.doi.org/10.1098/rsta.2013.0096 "},"issue":"2001","journal":"Philosophical Transactions of The Royal Society A","pages":null,"pubRank":"1","pubYear":2013,"reportNumber":null,"title":"A 40-million-year history of atmospheric CO2","type":"publication","volume":"371"}],"reconstruction":"Y","scienceKeywords":null,"site":[{"NOAASiteId":"19254","geo":{"geoType":"Feature","geometry":{"coordinates":["4.204133","-43.48915"],"type":"POINT"},"properties":{"easternmostLongitude":"-43.48915","maxElevationMeters":"-3041","minElevationMeters":"-3041","northernmostLatitude":"4.204133","southernmostLatitude":"4.204133","westernmostLongitude":"-43.48915"}},"locationName":"Ocean>Atlantic Ocean>North Atlantic Ocean","mappable":"Y","paleoData":[{"NOAADataTableId":"36613","coreLengthMeters":null,"dataFile":[{"NOAAKeywords":["earth science>paleoclimate>climate forcing>carbon dioxide"],"fileUrl":"https://www1.ncdc.noaa.gov/pub/data/paleo/climate_forcing/trace_gases/Paleo-pCO2/zhang2013alkenone.txt","linkText":"ODP925 Alkenone and CO2 Data","urlDescription":"NOAA Template File","variables":[{"cvAdditionalInfo":"meter below sea floor","cvDataType":"CLIMATE RECONSTRUCTIONS|PALEOCEANOGRAPHY","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":null,"cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"meter","cvWhat":"depth variable>depth"},{"cvAdditionalInfo":null,"cvDataType":"CLIMATE RECONSTRUCTIONS|PALEOCEANOGRAPHY","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":null,"cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"million years ago","cvWhat":"age variable>age"},{"cvAdditionalInfo":null,"cvDataType":"PALEOCEANOGRAPHY","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":"chemical composition>element or single-element molecule>dissolved inorganic carbon","cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"per mil","cvWhat":"chemical composition>isotope>isotope ratio>delta 13C"},{"cvAdditionalInfo":null,"cvDataType":"PALEOCEANOGRAPHY","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":"chemical composition>compound>organic compound>organooxygen compound>ketone>alkenone","cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"per mil","cvWhat":"chemical composition>isotope>isotope ratio>delta 13C"},{"cvAdditionalInfo":null,"cvDataType":"PALEOCEANOGRAPHY","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":null,"cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"dimensionless","cvWhat":"chemical composition>compound>organic compound>organic compound index>alkenone unsaturation index>alkenone unsaturation index Uk37 prime"},{"cvAdditionalInfo":null,"cvDataType":"CLIMATE RECONSTRUCTIONS|PALEOCEANOGRAPHY","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":"reconstruction material>organic compound index>alkenone unsaturation index","cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"degree Celsius","cvWhat":"earth system variable>temperature variable>temperature>sea water temperature>sea surface temperature"},{"cvAdditionalInfo":"based on TEX86","cvDataType":"CLIMATE RECONSTRUCTIONS|PALEOCEANOGRAPHY","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":"reconstruction material>organic compound index>glycerol dialkyl glycerol tetraether index","cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"degree Celsius","cvWhat":"earth system variable>temperature variable>temperature>sea water temperature>sea surface temperature"},{"cvAdditionalInfo":null,"cvDataType":"CLIMATE FORCING|PALEOCEANOGRAPHY","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":"atmospheric material>bulk atmosphere","cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"parts per million","cvWhat":"chemical composition>compound>inorganic compound>carbon dioxide"}]},{"NOAAKeywords":["earth science>paleoclimate>climate forcing>carbon dioxide"],"fileUrl":"https://www1.ncdc.noaa.gov/pub/data/paleo/climate_forcing/trace_gases/Paleo-pCO2/zhang2013alkenone.xlsx","linkText":"ODP925 Alkenone and CO2 Data","urlDescription":"Excel File","variables":[]}],"dataTableName":"Zhang2013alkenone","dataTableNotes":null,"earliestYear":38490000,"earliestYearBP":38490000,"earliestYearCE":-38488050,"mostRecentYear":20000,"mostRecentYearBP":20000,"mostRecentYearCE":-18050,"species":[],"timeUnit":"cal yr BP"}],"siteName":"ODP 925B"}],"studyCode":null,"studyName":"Paleo-pCO2 Database Atlantic ODP925 40 Million Year Alkenone and CO2 Data","studyNotes":"Alkenone data and estimated atmospheric pCO2 data from core ODP925, Western Equatorial Atlantic, for the past 40 milion years","version":"1.0","xmlId":"22995"}