Preindustrial 14CH4 indicates greater anthropogenic fossil CH4 emissions

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dc.contributor.authorHmiel, Ben_AU
dc.contributor.authorPetrenko, VVen_AU
dc.contributor.authorDyonisius, MNen_AU
dc.contributor.authorBuizert, Cen_AU
dc.contributor.authorSmith, AMen_AU
dc.contributor.authorPlace, PFen_AU
dc.contributor.authorHarth, CMen_AU
dc.contributor.authorBeaudette, Ren_AU
dc.contributor.authorHua, Qen_AU
dc.contributor.authorYang, Ben_AU
dc.contributor.authorVimont, Ien_AU
dc.contributor.authorMichel, SEen_AU
dc.contributor.authorSeveringhaus, JPen_AU
dc.contributor.authorEtheridge, DMen_AU
dc.contributor.authorBromley, Ten_AU
dc.contributor.authorSchmitt, Jen_AU
dc.contributor.authorFaïn, Xen_AU
dc.contributor.authorWeiss, RFen_AU
dc.contributor.authorDlugokencky, Een_AU
dc.date.accessioned2022-07-21T23:14:25Zen_AU
dc.date.available2022-07-21T23:14:25Zen_AU
dc.date.issued2020-02-19en_AU
dc.date.statistics2022-05-10en_AU
dc.description.abstractAtmospheric methane (CH4) is a potent greenhouse gas, and its mole fraction has more than doubled since the preindustrial era1. Fossil fuel extraction and use are among the largest anthropogenic sources of CH4 emissions, but the precise magnitude of these contributions is a subject of debate2,3. Carbon-14 in CH4 (14CH4) can be used to distinguish between fossil (14C-free) CH4 emissions and contemporaneous biogenic sources; however, poorly constrained direct 14CH4 emissions from nuclear reactors have complicated this approach since the middle of the 20th century4,5. Moreover, the partitioning of total fossil CH4 emissions (presently 172 to 195 teragrams CH4 per year)2,3 between anthropogenic and natural geological sources (such as seeps and mud volcanoes) is under debate; emission inventories suggest that the latter account for about 40 to 60 teragrams CH4 per year6,7. Geological emissions were less than 15.4 teragrams CH4 per year at the end of the Pleistocene, about 11,600 years ago8, but that period is an imperfect analogue for present-day emissions owing to the large terrestrial ice sheet cover, lower sea level and extensive permafrost. Here we use preindustrial-era ice core 14CH4 measurements to show that natural geological CH4 emissions to the atmosphere were about 1.6 teragrams CH4 per year, with a maximum of 5.4 teragrams CH4 per year (95 per cent confidence limit)—an order of magnitude lower than the currently used estimates. This result indicates that anthropogenic fossil CH4 emissions are underestimated by about 38 to 58 teragrams CH4 per year, or about 25 to 40 per cent of recent estimates. Our record highlights the human impact on the atmosphere and climate, provides a firm target for inventories of the global CH4 budget, and will help to inform strategies for targeted emission reductions 9,10. © The Author(s), under exclusive licence to Springer Nature Limited 2020.en_AU
dc.description.sponsorshipThis work was supported by US NSF awards OPP-1203779 (V.V.P.) OPP-1203686, OPP-0230452, ANT-0839031 (J.P.S.) ARC-1204084, ARC-1702920 (C.B.), a Packard Fellowship for Science and Engineering (V.V.P.), the National Institute of Water and Atmospheric Research through the Greenhouse Gases, Emissions and Carbon Cycle Science Programme (T.B.) and the Australian Government for the Centre for Accelerator Science at ANSTO through the National Collaborative Research Infrastructure Strategy (A.M.S.).en_AU
dc.identifier.citationHmiel, B., Petrenko, V. V., Dyonisius, M. N., Buizert, C., Smith, A. M., Place, P. F., Harth, C., Beaudette, R., Hua, Q., Yang, B., Vimont, I., Michel, S. E., Severinghaus, J. P., Etheridge, D., Bromley, T., Schmitt, J., Faïn, X., Weiss, R. F. & Dlugokencky, E. (2020). Preindustrial 14CH4 indicates greater anthropogenic fossil CH4 emissions. Nature, 578(7795), 409-412. doi:10.1038/s41586-020-1991-8en_AU
dc.identifier.issn1476-4687en_AU
dc.identifier.issue7795en_AU
dc.identifier.journaltitleNatureen_AU
dc.identifier.pagination409-412en_AU
dc.identifier.urihttps://doi.org/10.1038/s41586-020-1991-8en_AU
dc.identifier.urihttps://apo.ansto.gov.au/dspace/handle/10238/13414en_AU
dc.identifier.volume578en_AU
dc.language.isoenen_AU
dc.publisherSpringer Natureen_AU
dc.subjectAtmospheric chemistryen_AU
dc.subjectCarbon cycleen_AU
dc.subjectMethaneen_AU
dc.subjectGreenhouse gasesen_AU
dc.subjectDrill coresen_AU
dc.subjectIceen_AU
dc.titlePreindustrial 14CH4 indicates greater anthropogenic fossil CH4 emissionsen_AU
dc.typeJournal Articleen_AU
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