noaa-forcing-24850 Paleo-pCO2 Database Atlantic ODP925 40 Million Year Alkenone and CO2 Data Zhang, Y.G.; Pagani, M.; Liu, Z.; Bohaty, S.M.; DeConto, R.M. Paleo-pCO2 Database Atlantic ODP925 40 Million Year Alkenone and CO2 Data 2018-08-11 NCDC-Paleoclimatology ONLINE Files Pending https://www.ncdc.noaa.gov/paleo/study/24850 Investigator Y.G. Zhang Investigator M. Pagani Investigator Z. Liu Investigator S.M. Bohaty Investigator R.M. DeConto earth science paleoclimate paleoceanography delta 13C,dissolved inorganic carbon,null,per mil,null,paleoceanography,null,null,N,null earth science paleoclimate climate reconstructions|paleoceanography sea surface temperature,glycerol dialkyl glycerol tetraether index,null,degree Celsius,null,climate reconstructions|paleoceanography,null,null,N,based on TEX86 earth science paleoclimate climate reconstructions|paleoceanography depth,null,null,meter,null,climate reconstructions|paleoceanography,null,null,N,meter below sea floor earth science paleoclimate climate forcing|paleoceanography carbon dioxide,bulk atmosphere,null,parts per million,null,climate forcing|paleoceanography,null,null,N,null earth science paleoclimate paleoceanography alkenone unsaturation index Uk37 prime,null,null,dimensionless,null,paleoceanography,null,null,N,null earth science paleoclimate climate reconstructions|paleoceanography sea surface temperature,alkenone unsaturation index,null,degree Celsius,null,climate reconstructions|paleoceanography,null,null,N,null earth science paleoclimate climate reconstructions|paleoceanography age,null,null,million years ago,null,climate reconstructions|paleoceanography,null,null,N,null earth science paleoclimate paleoceanography delta 13C,alkenone,null,per mil,null,paleoceanography,null,null,N,null earth science paleoclimate climate forcing carbon dioxide geoscientificInformation 38490000 cal yr BP 20000 cal yr BP Complete 4.204133 4.204133 -43.48915 -43.48915 -3041 -3041 Ocean Atlantic Ocean North Atlantic Ocean ODP 925B>LATITUDE 4.204133>LONGITUDE -43.48915 None 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. English DOC/NOAA/NESDIS/NCEI National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce https://www.ncdc.noaa.gov/data-access/paleoclimatology-data DATA Center Contact Bruce Bauer bruce.a.bauer@noaa.gov paleo@noaa.gov 303-497-6280 303-497-6513

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Boulder CO 80305-3328 USA online ASCII Yi Ge Zhang, Mark Pagani, Zhonghui Liu, Steven M. Bohaty, Robert DeConto 2013 Philosophical Transactions of The Royal Society A 371 2001 10.1098/rsta.2013.0096 http://rsta.royalsocietypublishing.org/content/371/2001/20130096

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. STUDY NOTES: Alkenone data and estimated atmospheric pCO2 data from core ODP925, Western Equatorial Atlantic, for the past 40 milion years

GET DATA https://www1.ncdc.noaa.gov/pub/data/paleo/climate_forcing/trace_gases/Paleo-pCO2/zhang2013alkenone.txt NOAA Template File; ODP925 Alkenone and CO2 Data GET DATA https://www1.ncdc.noaa.gov/pub/data/paleo/climate_forcing/trace_gases/Paleo-pCO2/zhang2013alkenone.xlsx Excel File; ODP925 Alkenone and CO2 Data USA/NOAA DIF Version 9.8.4 2019-05-06 2019-05-06