Boron isotope evidence for oceanic carbon dioxide leakage during the last deglaciation

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dc.contributor.authorMartínez-Botí, M. A.
dc.contributor.authorMarino, G.
dc.contributor.authorFoster, G. L.
dc.contributor.authorZiveri, P.
dc.contributor.authorHenehan, M. J.
dc.contributor.authorRae, J. W. B.
dc.contributor.authorMortyn, P. G.
dc.contributor.authorVance, D.
dc.date.accessioned2015-03-19T23:11:52Z
dc.date.available2015-03-19T23:11:52Z
dc.date.issued2015-02-12
dc.date.updated2016-02-24T08:06:59Z
dc.description.abstractAtmospheric CO2 fluctuations over glacial-interglacial cycles remain a major challenge to our understanding of the carbon cycle and the climate system. Leading hypotheses put forward to explain glacial-interglacial atmospheric CO2 variations invoke changes in deep-ocean carbon storage, probably modulated by processes in the Southern Ocean, where much of the deep ocean is ventilated. A central aspect of such models is that, during deglaciations, an isolated glacial deep-ocean carbon reservoir is reconnected with the atmosphere, driving the atmospheric CO2 rise observed in ice-core records. However, direct documentation of changes in surface ocean carbon content and the associated transfer of carbon to the atmosphere during deglaciations has been hindered by the lack of proxy reconstructions that unambiguously reflect the oceanic carbonate system. Radiocarbon activity tracks changes in ocean ventilation, but not in ocean carbon content, whereas proxies that record increased deglacial upwelling do not constrain the proportion of upwelled carbon that is degassed relative to that which is taken up by the biological pump. Here we apply the boron isotope pH proxy in planktic foraminifera to two sediment cores from the sub-Antarctic Atlantic and the eastern equatorial Pacific as a more direct tracer of oceanic CO2 outgassing. We show that surface waters at both locations, which partly derive from deep water upwelled in the Southern Ocean, became a significant source of carbon to the atmosphere during the last deglaciation, when the concentration of atmospheric CO2 was increasing. This oceanic CO2 outgassing supports the view that the ventilation of a deep-ocean carbon reservoir in the Southern Ocean had a key role in the deglacial CO2 rise, although our results allow for the possibility that processes operating in other regions may also have been important for the glacial-interglacial ocean-atmosphere exchange of carbon.
dc.description.sponsorshipFinancial support was provided by the European Community through a Marie Curie Intra-European Fellowship for Career Development to M.A.M.-B., the Universitat Auto`noma de Barcelona through a Postdoctoral Research Grant to G.M., the Spanish Ministry of Science and Innovation (PROCARSO project CGL2009-10806) to G.M., P.Z. and P.G.M., a NERC PhD studentship awarded to M.J.H., a NOAA/UCAR Climate and Global Change Postdoctoral Fellowship to J.W.B.R., and NERC grant NE/D00876/X2 to G.L.F. G.M. was also supported by the Australian Laureate Fellowship project FL120100050 (E. J. Rohling).en_AU
dc.identifier.issn0028-0836
dc.identifier.urihttp://hdl.handle.net/1885/12994
dc.publisherNature Publishing Group
dc.rights© 2015 Macmillan Publishers Limited
dc.sourceNature
dc.subjectAtmosphere
dc.subjectBoron
dc.subjectCarbon Dioxide
dc.subjectClimate
dc.subjectForaminifera
dc.subjectFreezing
dc.subjectHistory, Ancient
dc.subjectHydrogen-Ion Concentration
dc.subjectIce Cover
dc.subjectIsotopes
dc.subjectOceans and Seas
dc.subjectSeawater
dc.titleBoron isotope evidence for oceanic carbon dioxide leakage during the last deglaciation
dc.typeJournal article
local.bibliographicCitation.issue7538en_AU
local.bibliographicCitation.lastpage222en_AU
local.bibliographicCitation.startpage219en_AU
local.contributor.affiliationMarino, G., Research School of Earth Sciences, The Australian National Universityen_AU
local.contributor.authoremailgianluca.marino@anu.edu.auen_AU
local.contributor.authoruidu5383967en_AU
local.identifier.absfor040203 - Isotope Geochemistry
local.identifier.absfor040303 - Geochronology
local.identifier.absfor040304 - Igneous and Metamorphic Petrology
local.identifier.ariespublicationa383154xPUB2930
local.identifier.citationvolume518en_AU
local.identifier.doi10.1038/nature14155en_AU
local.identifier.essn1476-4687en_AU
local.identifier.scopusID2-s2.0-84923083961
local.identifier.uidSubmittedByu1005913en_AU
local.publisher.urlhttp://www.nature.com/en_AU
local.type.statusPublished versionen_AU

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