Isotopic constraints on marine and terrestrial N 2 O emissio

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TitleIsotopic constraints on marine and terrestrial N 2 O emissions during the last deglaciationAbstractNitrous oxide (N2O) is an important greenhouse gas and ozone-depleting substance that has anthropogenic as well as natural marine and terrestrial sources. The tropospheric N2O concentrations have varied substantially in the past in concert with changing climate on glacial-interglacial and millennial timescales. It is not well understood, however, how N2O emissions from marine and terrestrial sources change in response to varying environmental conditions. The distinct isotopic compositions of marine and terrestrial N2O sources can help disentangle the relative changes in marine and terrestrial N2O emissions during past climate variations. Here we present N2O concentration and isotopic data for the last deglaciation, from 16,000 to 10,000 years before present, retrieved from air bubbles trapped in polar ice at Taylor Glacier, Antarctica. With the help of our data and a box model of the N2O cycle, we find a 30 per cent increase in total N2O emissions from the late glacial to the interglacial, with terrestrial and marine emissions contributing equally to the overall increase and generally evolving in parallel over the last deglaciation, even though there is no a priori connection between the drivers of the two sources. However, we find that terrestrial emissions dominated on centennial timescales, consistent with a state-of-the-art dynamic global vegetation and land surface process model that suggests that during the last deglaciation emission changes were strongly influenced by temperature and precipitation patterns over land surfaces. The results improve our understanding of the drivers of natural N2O emissions and are consistent with the idea that natural N2O emissions will probably increase in response to anthropogenic warming. â"' 2014 Macmillan Publishers Limited.AcknowledgementsFinancial support was provided by the Swiss National Science Foundation (NSF) and the US NSF, including a Swiss NSF Fellowship for Prospective Researchers (139404) to A.S., US NSF Grant PLR08-38936 to E.J.B. and US NSF Grant PLR08-39031 to J.P.S. Further support came from the Marsden Fund Council from New Zealand Government funding, administered by the Royal Society of New Zealand. We thank C. Buizert, X. FaÂ¨Ä±n, J. Lee, L. Mitchell and P. Rose for fieldwork, R. Roth for providing the Bern3D Earth System Model run, J. Schwander for providing the NEEM firn air cylinder, S. Jaccard for comments and A. Ross for lab assistance. We thank B. Otto-Bliesner and Z. Liu for providing climate data from the TraCE-21ka model computation, which was carried out at the Oak Ridge Leadership Computational Facility, sponsored by the US Department of Energy, and the National Center for Atmospheric Research Supercomputing Facility, sponsored by the US NSF. The TraCE-21ka project was supported by the US NSF and the US Department of Energy.

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1st AuthorSchilt, A.AuthorSchilt, A.Brook, E.Bauska, T.Baggenstos, D.Fischer, H.Joos, F.Petrenko, V.Schaefer, H.Schmitt, J.Severinghaus, J.Spahni, R.Stocker, T.Year2014JournalNatureVolume516Number7530Pages234-237DOI10.1038/nature13971URLhttps://www.scopus.com/inward/recor.....e0da4f94492ebed2620be69d2Keywordsnitrous oxidenitrogennitrous oxideoxygenrain, anthropogenic effectclimate variationgreenhouse gasisotopic analysislast deglaciationmarine atmospherenitrous oxideozonepaleoclimatepolar fronttroposphere, Articleclimate changedeglaciationenvironmental changeglobal changeinterglacialmarine environmentnitrogen cyclenitrous oxide emissionnonhumanpriority journalstratospheresurface propertytropospherevegetationwarmingYounger DryasAntarcticaaquatic speciesatmospherechemistrygreenhouse effecthistoryice covermetabolismtemperaturetime, AntarcticaEast AntarcticaTaylor Glacier, Antarctic RegionsAquatic OrganismsAtmosphereGlobal WarmingHistory, AncientIce CoverNitrogen IsotopesNitrous OxideOxygen IsotopesRainTemperatureTime Factors, rank1

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TypeArticleCitationSchilt, A., Brook, E., Bauska, T., Baggenstos, D., Fischer, H., Joos, F., Petrenko, V., Schaefer, H., Schmitt, J., Severinghaus, J., Spahni, R. and Stocker, T. (2014) Isotopic constraints on marine and terrestrial N 2 O emissions during the last deglaciation. Nature, 516(7530): 234-237 doi:10.1038/nature13971 IdentifierSchilt2014Relevancerank1