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dc.contributor.authorSosdian, S. M.
dc.contributor.authorGreenop, R.
dc.contributor.authorHain, M. P.
dc.contributor.authorFoster, G. L.
dc.contributor.authorPearson, P. N.
dc.contributor.authorLear, C. H.
dc.identifier.citationSosdian , S M , Greenop , R , Hain , M P , Foster , G L , Pearson , P N & Lear , C H 2018 , ' Constraining the evolution of Neogene ocean carbonate chemistry using the boron isotope pH proxy ' , Earth and Planetary Science Letters , vol. 498 , pp. 362-376 .
dc.identifier.otherPURE: 255029597
dc.identifier.otherPURE UUID: 13a35cd5-48fc-4c75-9b48-9c6fb7339f22
dc.identifier.otherRIS: urn:6D1F83B506143F549CD7BA770E5304DB
dc.identifier.otherScopus: 85049972417
dc.identifier.otherWOS: 000442060600032
dc.descriptionThis work was funded by NERC Grant NE/I006427/1 (CHL and GLF). PNP and GLF were supported by NERC/DEFRA/DECC Grant NE/H017581/1 (U.K. Ocean Acidification Research Programme). MPH was supported by NERC fellowship (NE/K00901X/1). SMS acknowledges the financial support provided by the Welsh Government and Higher Education Funding Council for Wales through the Sêr Cymru National Research Network for Low Carbon, Energy and Environment Returning Fellowship.en
dc.description.abstractOver the course of the Neogene, the Earth underwent profound climatic shifts from the sustained warmth of the middle Miocene to the development of Plio-Pleistocene glacial–interglacial cycles. Major perturbations in the global carbon cycle have occurred alongside these shifts, however the lack of long-term carbonate system reconstructions currently limits our understanding of the link between changes in CO2, carbon cycling, and climate over this time interval. Here we reconstruct continuous surface ocean pH, CO2, and surface ocean aragonite saturation state using boron isotopes from the planktonic foraminifer Trilobatus trilobus and we perform a sensitivity analysis of the key variables in our calculations (e.g. δ11Bsw, [Ca]sw, CCD). We show that the choice of δ11Bsw influences both seawater pH and CO2 while [Ca]sw reconstructed dissolved inorganic carbon exerts a significant influence only on CO2. Over the last 22 Myr, the lowest pH levels occurred in the Middle Miocene Climate Optimum (MMCO; 17–14 Myr ago) reaching ∼7.6 ± 0.1 units in all our scenarios. The extended warmth of the MMCO corresponds to mean CO2 and aragonite saturation state levels of 470–630 ppm and 2.7–3.5, respectively. Despite a general correspondence between our CO2 record and climate, all CO2 scenarios show a peak at ∼9 Ma not matched by corresponding changes in climate reconstructions. This may suggest decoupling (i.e. significant CO2 change without a discernible climate response) for a limited interval in the Late Miocene (11.6–8.5 Ma), although further refinement of our understanding of the temporal evolution of the boron isotopic composition of seawater is necessary to fully evaluate the nature of the relationship between CO2 and climate. Nonetheless, from our long-term view it is clear that low-latitude open ocean marine ecosystems are unlikely to have experienced sustained surface pH and saturation levels below 7.7 and 1.7, respectively, during the past 14 million years (66% CI).
dc.relation.ispartofEarth and Planetary Science Lettersen
dc.rights© 2018 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (
dc.subjectBoron isotopesen
dc.subjectCarbonate systemen
dc.subjectGE Environmental Sciencesen
dc.subjectGC Oceanographyen
dc.subjectQD Chemistryen
dc.titleConstraining the evolution of Neogene ocean carbonate chemistry using the boron isotope pH proxyen
dc.typeJournal articleen
dc.description.versionPublisher PDFen
dc.contributor.institutionUniversity of St Andrews.School of Earth & Environmental Sciencesen
dc.contributor.institutionUniversity of St Andrews.St Andrews Isotope Geochemistryen
dc.description.statusPeer revieweden

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