noaa-forcing-25490 Paleo-pCO2 Database ODP668 Early Pleistocene Boron Isotope and CO2 Data Dyez, K.A.; Hönisch, B.; Schmidt, G.A. Paleo-pCO2 Database ODP668 Early Pleistocene Boron Isotope and CO2 Data 2018-10-31 NCDC-Paleoclimatology ONLINE Files Pending https://www.ncdc.noaa.gov/paleo/study/25490 Investigator K.A. Dyez Investigator B. Hönisch Investigator G.A. Schmidt earth science paleoclimate climate forcing|climate reconstructions|paleoceanography age,null,null,calendar year before present,null,climate forcing|climate reconstructions|paleoceanography,null,null,N,null earth science paleoclimate climate reconstructions|paleoceanography pH,delta 11B,null,dimensionless,null,climate reconstructions|paleoceanography,null,null,N,null earth science paleoclimate climate reconstructions|paleoceanography sea surface temperature,magnesium/calcium,null,degree Celsius,null,climate reconstructions|paleoceanography,null,null,N,null earth science paleoclimate paleoceanography delta 11B,Trilobatus sacculifer,two standard deviations,per mil,null,paleoceanography,null,thermal ionization mass spectrometry,N,N-TIMS earth science paleoclimate climate forcing|paleoceanography carbon dioxide,bulk atmosphere,null,parts per million,null,climate forcing|paleoceanography,null,null,N,based on planktic foram delta 11B earth science paleoclimate paleoceanography magnesium/calcium,Globigerinoides ruber,null,millimole per mole,null,paleoceanography,null,null,N,null earth science paleoclimate climate forcing|paleoceanography carbon dioxide,bulk atmosphere,two standard deviations lower bound,parts per million,null,climate forcing|paleoceanography,null,null,N,based on planktic foram delta 11B earth science paleoclimate climate forcing|paleoceanography carbon dioxide,bulk atmosphere,two standard deviations upper bound,parts per million,null,climate forcing|paleoceanography,null,null,N,based on planktic foram delta 11B earth science paleoclimate paleoceanography delta 11B,Trilobatus sacculifer,null,per mil,null,paleoceanography,averaged,thermal ionization mass spectrometry,N,N-TIMS earth science paleoclimate paleoceanography magnesium/calcium,Globigerinoides ruber,two standard deviations,millimole per mole,null,paleoceanography,null,null,N,null earth science paleoclimate climate forcing carbon dioxide geoscientificInformation 1535666 cal yr BP 1384000 cal yr BP Complete 4.77 4.77 -20.93 -20.93 -2693 -2693 Ocean Atlantic Ocean North Atlantic Ocean ODP668B>LATITUDE 4.77>LONGITUDE -20.93 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

325 Broadway, E/NE31

Boulder CO 80305-3328 USA online ASCII Dyez, Kelsey A.; Hönisch, Bärbel; Schmidt, Gavin A. 2018 Paleoceanography and Paleoclimatology

In the early Pleistocene, global temperature cycles predominantly varied with ~41-kyr (obliquity-scale) periodicity. Atmospheric greenhouse gas concentrations likely played a role in these climate cycles; marine sediments provide an indirect geochemical means to estimate early Pleistocene CO2. Here we present a boron isotope-based record of continuous high-resolution surface ocean pH and inferred atmospheric CO2 changes. Our results show that, within a window of time in the early Pleistocene (1.38-1.54 Ma), pCO2 varied with obliquity, confirming that, analogous to late Pleistocene conditions, the carbon cycle and climate co-varied at ~1.5 Ma. Pairing the reconstructed early Pleistocene pCO2 amplitude (92 ±13 matm) with a comparably smaller global surface temperature glacial/interglacial amplitude (3.0 ±0.5 K), yields a surface temperature change to CO2 radiative forcing ratio of S[CO2]~0.75 (±0.5) degC/Wm-2, as compared to the late Pleistocene S[CO2] value of ~1.75 (±0.6) degC/Wm-2. This direct comparison of pCO2 and temperature implicitly incorporates the large ice sheet forcing as an internal feedback and is not directly applicable to future warming. We evaluate this result with a simple climate model, and show that the presumably thinner, though extensive, northern hemisphere ice sheets would increase surface temperature sensitivity to radiative forcing. Thus, the mechanism to dampen actual temperature variability in the early Pleistocene more likely lies with Southern Ocean circulation dynamics or antiphase hemispheric forcing. We also compile this new carbon dioxide record with published Plio-Pleistocene d11B records using consistent boundary conditions and explore potential reasons for the discrepancy between Pliocene pCO2 based on different planktic foraminifera. STUDY NOTES: Paleo-CO2 derived from boron isotope measurements on marine sediment core ODP668 the early Pleistocene 1.53-1.38 ma), plus secondary Mg/Ca-based SST reconstructions, contributed to the Paleo-pCO2 Database

GET DATA https://www1.ncdc.noaa.gov/pub/data/paleo/climate_forcing/trace_gases/Paleo-pCO2/dyez2018odp668boron.xlsx Excel File; ODP668 Early Pleistocene Boron Isotope and CO2 Data GET DATA https://www1.ncdc.noaa.gov/pub/data/paleo/climate_forcing/trace_gases/Paleo-pCO2/dyez2018odp668boron.txt NOAA Template File; ODP668 Early Pleistocene Boron Isotope and CO2 Data USA/NOAA DIF Version 9.8.4 2018-12-11 2018-12-11