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Original Research Papers

Observations and modelling of the global distribution and long-term trend of atmospheric 14CO2

Authors:

Ingeborg Levin ,

Institut für Umweltphysik, University of Heidelberg, DE
About Ingeborg
Joint first authors.
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Tobias Naegler,

Institut für Umweltphysik, University of Heidelberg, DE
About Tobias
Joint first authors.
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Bernd Kromer,

Institut für Umweltphysik, University of Heidelberg; Heidelberger Akademie der Wissenschaften, DE
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Moritz Diehl,

Interdisziplinäres Zentrum für wissenschaftliches Rechnen (IWR), University of Heidelberg, DE
About Moritz
Now at: Electrical Engineering Department (ESAT) and OPTEC, K.U. Leuven, Kasteelpark Arenberg 10, 3001 Leuven, Belgium.
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Roger J. Francey,

Centre for Australian Weather and Climate Research CSIRO Marine and Atmospheric Research (CMAR), AU
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Angel J. Gomez-Pelaez,

Izãna Atmospheric Research Center, Meteorological State Agency of Spain (AEMET), ES
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L. Paul Steele,

Centre for Australian Weather and Climate Research CSIRO Marine and Atmospheric Research (CMAR), AU
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Dietmar Wagenbach,

Institut für Umweltphysik, University of Heidelberg, DE
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Rolf Weller,

Alfred Wegener Institute for Polar and Marine Research, DE
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Douglas E. Worthy

Environment Canada, Climate Research Division, CA
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Abstract

Global high-precision atmospheric Δ14CO2 records covering the last two decades are presented, and evaluated in terms of changing (radio)carbon sources and sinks, using the coarse-grid carbon cycle model GRACE. Dedicated simulations of global trends and interhemispheric differences with respect to atmospheric CO2 as well as δ13CO2 and Δ14CO2, are shown to be in good agreement with the available observations (1940–2008). While until the 1990s the decreasing trend of Δ14CO2 was governed by equilibration of the atmospheric bomb 14C perturbation with the oceans and terrestrial biosphere, the largest perturbation today are emissions of 14C-free fossil fuel CO2. This source presently depletes global atmospheric Δ14CO2 by 12–14‰ yr−1, which is partially compensated by 14CO2 release from the biosphere, industrial 14C emissions and natural 14C production. Fossil fuel emissions also drive the changing north–south gradient, showing lower Δ14C in the northern hemisphere only since 2002. The fossil fuel-induced north–south (and also troposphere–stratosphere) Δ14CO2 gradient today also drives the tropospheric Δ14CO2 seasonality through variations of air mass exchange between these atmospheric compartments. Neither the observed temporal trend nor the Δ14CO2 north–south gradient may constrain global fossil fuel CO2 emissions to better than 25%, due to large uncertainties in other components of the (radio)carbon cycle.

How to Cite: Levin, I., Naegler, T., Kromer, B., Diehl, M., Francey, R.J., Gomez-Pelaez, A.J., Steele, L.P., Wagenbach, D., Weller, R. and Worthy, D.E., 2010. Observations and modelling of the global distribution and long-term trend of atmospheric 14CO2. Tellus B: Chemical and Physical Meteorology, 62(1), pp.26–46. DOI: http://doi.org/10.1111/j.1600-0889.2009.00446.x
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  Published on 01 Jan 2010
 Accepted on 9 Oct 2009            Submitted on 21 May 2009

References

  1. Andres , R.I. , Marland , G. and Bischof , S . 1996. Global and latitudinal estimates of 13C from fossil fuel consumption and cement manu-facture, ORNL/CDIAC, Oak Ridge Natl. Lab. Report db1013, Oak Ridge, Tenn. USA.  

  2. Allison , C.E. , Francey , R.J. and Krummel , P.B . 2009. 3“C in CO2 from sites in the CSIRO Atmospheric Research GASLAB air sampling network, (2009 version). In: Trends: A Compendium of Data on Global Change, Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, TN, USA.  

  3. Battle , M. , Bender , ML. , Tans , P.P. , White , J.W.C. , Ellis , J.T. and co-authors. 2000. Global carbon sinks and their variability inferred from atmospheric 02 and 313C. Science 287, 2467 – 2470.  

  4. Bousquet , P. , Peylin , P. , Ciais , R , Le Quere , C. , Friedlingstein , P. and co-authors. 2000. Regional changes in carbon dioxide fluxes of land and oceans since 1980. Science 290, 1342 – 1346.  

  5. Braziunas , T.F. , Fung , I.Y. and Stuiver , M . 1995 . The preindustrial at-mospheric 14CO2 latitudinal gradient as related to exchanges among atmospheric, oceanic, and terrestrial reservoirs . Global Biogeochem. Cycles 9 ( 4 ), 565 – 584 .  

  6. Broecker W.S. and Peng , T.-H . 1994 . Stratospheric contribution to the global bomb radiocarbon inventory: model versus observations . Global Biogeochem. Cycles 8 , 377 – 384 .  

  7. Broecker W.S. , Peng , T.-H. , Ostlund , G. and Stuiver , M . 1985 . The dis-tribution of bomb radiocarbon in the ocean . J. Geophys. Res . 90 ( C4 ), 6953 – 6970 .  

  8. Caldeira , K. , Rau , G.H. and Duffy , P.B . 1998 . Predicted net efflux of radiocarbon from the ocean and increase in atmospheric radiocarbon content . Geophys. Res. Lett . 25 ( 20 ), 3811 – 3814 .  

  9. Ciais , R , Tans , RP. , Trolier , M. , White , J.W.C. and Francey , R.I . 1995 . A large Northern Hemisphere terrestrial CO2 sink indi-cated by the 13C/12C ratio of atmospheric CO2 . Science 269 , 1098 – 1102 .  

  10. Cox , P.M. , Betts , R.A. , Jones , CD. , Spall , S.A. and Totterdell , I.J . 2000 . Acceleration of global warming due to carbon-cycle feedbacks in a coupled climate model . Nature 408 , 184 – 187 .  

  11. Cramer , W , Kicklighter , D.W. , Bondeau , A. , Moore , B. , DI , Churkina , G. and co-authors. 1999. Comparing global models of terrestrial net primary productivity (NPP): overview and key results. Global Change Biol. 5(suppl. 1), 1 – 15.  

  12. Czeplak , G. and Junge , C . 1974 . Studies of interhemispheric exchange in the troposphere by a diffusion model. Adv. Geophys. 18 , 57 – 72. Damon, P.E. and Sternberg, R.E. 1989. Global production and decay of radiocarbon. Radiocarbon 31 , 697 – 703 .  

  13. Degens , E.T . 1969. Biogeochemistry of stable carbon isotopes. In: Or-ganic Geochemistry: Methods and Results, (eds G. Eglington and KT. Murphy). Springer, Berlin, Germany, 304 – 439.  

  14. Denman , K.L. , Brasseur , G. , Chidthaisong , A. , Ciais , P. , Cox , P.M. and co-authors. 2007. Couplings Between Changes in the Climate System and Biogeochemistry. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (eds S. Solomon, D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and H.L. Miller). Cambridge University Press , Cambridge , United Kingdom and New York, NY, USA.  

  15. Diirr , H. and Miinnich , K.O . 1986. Annual variations of the 14C content of soil CO2. Radiocarbon 28(2A), 338 – 345.  

  16. Duffy , P.B. , Eliason , D.E. , Bourgeois , A.J. and Covey , C.C . 1995. Simu-lation of bomb radiocarbon in two global general circulation models. J. Geophys. Res . 100 (C11), 22545 – 22563.  

  17. Enting , LG . 1982 . Nuclear Weapons Data for Use in Carbon Cycle Mod-eling , Commonwe. Sci. and Ind. Res. Organ ., Melbourne , Australia , 1–18, pp .  

  18. Francey , R.J. , Tans , RP. , Allison , CE. , Enting , LG. , White , J.W.C. and co-authors. 1995. Changes in oceanic and terrestrial carbon uptake since 1982. Nature 373, 326 – 330.  

  19. Francey , R.J. , Allison , CE. , Etheridge , D.M. , Trudinger , CM. , Enting , LG. and co-authors. 1999.1000-year high precision record of 313C in atmospheric CO2. Tellus 51B, 170 – 190.  

  20. Friedli , H. , Loetscher , H. , Oeschger , H. , Siegenthaler , U. and Stauffer , B. 1986. Ice core record of the 13C/12C ratio of atmospheric carbon dioxide in the past two centuries. Nature 324, 237 – 238.  

  21. Friedlingstein , P. , Dufresne , J.L. , Cox , P.M. and Rayner , P. 2003. How positive is the feedback between the climate change and the carbon cycle? Tellus 55B, 692 – 700.  

  22. Gaudinski , J.B. , Trumbore , SE. , Davidson , E.A. and Zheng , S.H . 2000 . Soil carbon cycling in a temperate forest: radiocarbon-based estimates of residence times, sequestration rates and partitioning of fluxes . Bio-geochemistry 51 ( 1 ), 33 – 69 .  

  23. GlobalView- 002, Cooperative Atmospheric Data Integration Project - Carbon Dioxide, Tech. rep., NOAA ESRL, Boulder, CO, USA, 2008, available via anonymous FTP: www.cmdl.noaa.gov , path: ccg/CO2/GLOBALVIEW.  

  24. Goudriaan , J . 1992 . Biosphere structure, carbon sequestration poten-tial and the atmospheric 14C carbon record . J. Exp. BoL 43 , 1111 – 1119 .  

  25. Gibson , J.K. , Milberg , P. , Uppala , S. , Hernandez , A. , Nomura , A. and co-authors. 1997. CMWF Re-Analysis, Project Report Series: 1. ERA description , European Center for Mid-Range Weather Forecast, Reading , UK.  

  26. Graven , H.D. , Stephens , B.B. , Guilderson , T.P. , Campos , T.L. , Schimel , D.S. and co-authors. 2009. Vertical profiles of biospheric and fossil fuel-derived CO2 and fossil fuel CO2 CO ratios from airborne measurements of 414C, CO2 and CO above Colorado, USA. Tellus 61B , https://doi.org/10.1111/j.1600-0889.2009.00421.x.  

  27. Gurney , KR. , Law , R.M. , Denning , AS. , Rayner , P.J. , Baker , D. and co-authors. 2002. Toward robust regional estimates of CO2 sources and sinks using atmospheric transport models. Nature 415 , 626 – 630.  

  28. Hesshaimer , V. , Heimann , M. and Levin , I . 1994 . Radiocarbon evidence for a smaller oceanic carbon dioxide sink than previously believed . Nature 670 , 201 – 203 .  

  29. Houghton , R.A . 2003 . Revised estimates of the annual net flux of carbon to the atmosphere from changes in land use and land management 1850-2000 . Tellus 55B , 378 – 390 .  

  30. Hua , Q. and Barbetti , M . 2004 . Review of tropospheric bomb 14C data for carbon cycle modelling and age calibration purposes . Radiocarbon 46 , 1 – 26 .  

  31. Jacob , D.J. , Prather , M.J. , Wofsy , S.C. and McElroy , KB. 1987. At-mospheric distribution of 85Kr simulated with a general circulation model. J. Geophys. Res . 92 , 6614 – 6626.  

  32. Jain , AK. , Kheshgi , H.S. and Wuebbles , D.J . 1996 . A globally aggre-gated reconstruction of cycles of carbon and its isotopes . Tellus 48B , 583 – 600 .  

  33. Johnston , H.S . 1989 . Evaluation of excess carbon-14 and strontium-90 data for suitability to test two-dimensional stratospheric models . J. Geophys. Res . 94 , 18485 – 18493 .  

  34. Joos , F. and Bruno , M . 1998 . Long-term variability of the terrestrial and oceanic carbon sinks and the budgets of the carbon isotopes 13C and 14C . Global Biogeochem. Cycles 12 ( 2 ), 277 – 295 .  

  35. Kalnay , E. , Kanamitsu , M. , Kistler , R. , Collins , W. , Deaven , D. and co-authors. 1996. The NCEP/NCAR 40-year reanalysis project. Bull. Am. Meteorol. Soc. 77, 437 – 471.  

  36. Keeling , CD. , Whorf , T.P. , Wahlen , M. and Van Der Plicht , J . 1995 . Interannual extremes in the rate of rise of atmospheric carbon dioxide since 1980 . Nature 375 , 666 – 670 .  

  37. Keeling , CD. , Bollenbacher , A.F. and Whorf , T.P . 2005. Monthly at-mospheric 13C/12C isotopic ratios for 10 SIO stations. In: Trends: A Compendium of Data on Global Change. Carbon Dioxide Informa-tion Analysis Center, Oak Ridge National Laboratory, Oak Ridge, Tenn., USA.  

  38. Keeling , R.F. , Piper , S.C. , Bollenbacher , A.F. and Walker , J S . 2008. Atmospheric CO2 records from sites in the SIO air sampling net-work. In: Trends: A Compendium of Data on Global Change. Carbon Dioxide Information Analysis Center, Oak Ridge Na-tional Laboratory, U.S. Department of Energy, Oak Ridge, Tenn., USA.  

  39. Key , R.M. , Kozyr , A. , Sabine , CL. , Lee , K. , Wanninkhof , R. and co-authors. 2004. A global ocean carbon climatology: results from Global Data Analysis Project (GLODAP). Global Biogeochem. Cycles 18(4), GB4031, https://doi.org/10.1029/2004GB002247 .  

  40. Kjellstriim , E. , Feichter , J. and Hoffmann , G . 2000 . Transport of SF6 and '4CO2in the atmospheric general circulation model ECHAM . Tellus 52B , 1 – 18 .  

  41. Krakauer , N.Y. , Randerson , J.T. , Primeau , F.W. , Gruber , N. and Mene-menlis , D . 2006 . Carbon isotope evidence for the latitudinal distribu-tion and wind speed dependence of the air-sea gas transfer velocity . Tellus 58B , 390 – 417 .  

  42. Kromer B. and Miinnich , K.O . 1992. CO2 gas proportional counting in Radiocarbon dating-review and perspective. In: Radiocarbon After Four Decades (eds R. E. Taylor, A. Long and R. S. Kra). Springer-Verlag, New York, 184 – 197.  

  43. Land , C. , Feichter , J. and Sausen , R . 2002 . Impact of vertical resolution on the transport of passive tracers in the ECHAM4 model . Tellus 54B , 344 – 360 .  

  44. Lassey , K.R. , Enting , I. and Trudinger , C.M . 1996 . The earth's radiocar-bon budget: a consistent model of the global carbon and radiocarbon cycles . Tellus 48B , 487 – 501 .  

  45. Le Quere , C. , Aumont , O. , Bopp , L. , Bousquet , P. , Ciais , P. and co-authors. 2003. Two decades of ocean CO2 sink and variability. Tellus 55B, 649 – 656.  

  46. Levin , I. , Miinnich , K.O. and Weiss , W . 1980 . The effect of anthro-pogenic CO2 and 14C sources on the distribution of 14CO2 in the atmosphere . Radiocarbon 22 , 379 – 391 .  

  47. Levin , I. , Kromer , B. , Schoch-Fischer , H. , Bruns , M. , Miinnich , M. and co-authors. 1985.25 Years of tropospheric MC observations in Central Europe. Radiocarbon 27, 1 – 19.  

  48. Levin , I. , Kromer , B. , Wagenbach , D. and Miinnich , K.O . 1987 . Carbon isotope measurements of atmospheric CO2 at a coastal station in Antarctica . Tellus 39B , 89 – 95 .  

  49. Levin , I. , Bösinger , R. , Bonani , G. , Francey , R.J. , Kromer , B. and co-authors. 1992. Radiocarbon in atmospheric carbon dioxide and methane: global distribution and trends. In: Radiocarbon After Four Decades: An Interdisciplinary Perspective (eds R. E. Taylor , A. Long and R.S. Kra ). Springer-Verlag , New York , 503 – 517.  

  50. Levin , I. and Hesshaimer , V . 1996 . Refining of atmospheric transport model entries by the globally observed passive tracer distributions of 85krypton and sulfur hexafluoride (SF6) . J. Geophys. Res . 101 , 16745 – 16755 .  

  51. Levin , I. and Hesshaimer , V . 2000 . Radiocarbon—a unique tracer of global carbon cycle dynamics . Radiocarbon 42 , 69 – 80 .  

  52. Levin , I. and Kromer , B . 1997 . Twenty years of atmospheric 14CO2 observations at Schauinsland station, Germany . Radiocarbon 39 , 205 – 218 .  

  53. Levin , I. , Kromer , B. , Schmidt , M. and Sartorius , H . 2003 . A novel approach for independent budgeting of fossil fuel CO2 over Eu-rope by 14CO2 observations . Geophys. Res. Lett . 30 ( 23 ), 2194 https://doi.org/10.1029/2003GL018477 .  

  54. Levin , I. and Kromer , B . 2004 . The tropospheric 14CO2 level in mid-latitudes of the Northern Hemisphere (1959-2003) . Radiocarbon 46 ( 3 ), 1261 – 1272 .  

  55. Levin , I. and Karstens , U . 2007 . Inferring high-resolution fossil CO2 records at continental sites from combined 14CO2 and CO observa-tions . Tellus 59B ( 2 ), 245 – 250 .  

  56. Levin , I. and Rödenbeck , C . 2008 . Can the envisaged reductions of fossil fuel CO2 emissions be detected by atmospheric observations? Naturwissenschaften 95 , 206 – 208 .  

  57. Levin , I. , Hammer , S. , Kromer , B. and Meinhardt , E 2008 . Radiocarbon observations in atmospheric CO2: determining fossil fuel CO2 over Europe using Jungfraujoch observations as background . Sci. Total. Environ ., 391 , 211 – 216 .  

  58. Levitus , S. , Boyer , T. , Conkright , M. , O'Brien , T. , Antonov , J. and co-authors. 1998. World Ocean Database 1998. National Oceanic and Atmospheric Administration, Silver Spring, MD, USA.  

  59. Libby , W.F . 1961 . Radiocarbon dating (Noble Lecture) . Science 133 , 621 – 629 .  

  60. Lingenfelter , RE . 1963 . Production of carbon 14 by cosmic-ray neu-trons . Rev. Geophys . 1 , 35 – 55 .  

  61. Maier-Reimer , E. and Hasselmann , K . 1987 . Transport and storage of CO2 in the ocean—an inorganic ocean-circulation carbon cycle model . Clim. Dyn . 2 , 63 – 90 .  

  62. Manning , MR. , Lowe , D.C. , Melhuish , W.H. , Sparks , R.J. , Wallace , G. and co-authors. 1990. The use of radiocarbon measurements in atmospheric studies. Radiocarbon 32(1), 37— 58.  

  63. Manning , A.C. and Keeling , R.F . 2006 . Global oceanic and land biotic carbon sinks from the Scripps atmospheric oxygen flask sampling network . Tellus 58B ( 2 ), 95 – 116 .  

  64. Manning , KR. and Melhuish , W.H . 1994 . Atmospheric 14C record from Wellington . In: Trends: A Compendium of Data on Global Change , Carbon Dioxide Information Analysis Center, Oak Ridge, TN, USA .  

  65. Marland , G. , Boden , TA. and Andres , R.J. 2007. Global , Regional, and National Fossil Fuel CO2 Emissions. In: Trends: A Compendium of Data on Global Change. Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tenn., USA.  

  66. McCormac , F.G. , Reimer , P.J. , Hogg , A.G. , Higham , T.F.G. , Baillie , M. and co-authors. 2002. Calibration of the radiocarbon time scale for the southern hemisphere: AD 1850-950. Radiocarbon 44 ( 3 ), 641 – 651.  

  67. Meijer , H.A.J. , Van Der Plicht , J. , Gislefoss , J.S. and Nydal , R. 1995. Comparing long-term atmospheric 14C and 3H records near Gronin-gen, The Netherlands with Fruholmen, Norway and Izafia, Canary Islands 14C stations. Radiocarbon 37 ( 1 ), 39 – 50.  

  68. Meijer , H.A.J. , Pertuisot , M.H. and Van Der Plicht , J . 2006 . High-accuracy 14C measurements for atmospheric CO2 samples by AMS . Radiocarbon 48 ( 3 ), 355 – 372 .  

  69. Morimoto , S. , Nalcazawa , T. , Higuchi , K. and Aoki , S . 2000 . Latitu-dinal distribution of atmospheric CO2 sources and sinks inferred by 313C measurements from 1985 to 1991 . J. Geophys. Res . 105 ( D19 ), 24315 – 24326 .  

  70. Muller , S.A. , Joos , F. , Plattner , G.-K. , Edwards , N.R. and Stocker , T.F . 2008, Modelled natural and excess radiocarbon—sensitivities to the gas exchange formulation and ocean transport strength. Global Bio-geochem. CycL 22, GB3011, https://doi.org/10.1029/2007GB003065 .  

  71. Naegler , T. , Ciais , P. , Rodgers , K. and Levin, 1. 2006. Excess radiocarbon constraints on air-sea gas exchange and the uptake of CO2 by the oceans. Geophys. Res. Lett. 33, L11802, https://doi.org/10.1029/2005GL025408 .  

  72. Naegler , T. and Levin , I . 2006 . Closing the global radio-carbon budget 1945-2005 . J. Geophys. Res . 111 , D12311 , https://doi.org/10.1029/2005JD006758 .  

  73. Naegler , T . 2009 . Reconciliation of excess 14C-based global CO2 pis-ton velocity estimates . Tellus 61B , 372 – 384 , https://doi.org/10.1111/j.1600-0889.2008.00408.x .  

  74. Naegler , T. and Levin , I . 2009a . Observation-based global biospheric excess radiocarbon inventory 1963-2005 . J. Geophys. Res . 114 , D17302 , https://doi.org/10.1029/2008JDO11100 .  

  75. Naegler , T. and Levin , I . 2009b . Biosphere-atmosphere gross carbon exchange flux and the 313CO2 and A14CO2 disequilibria constrained by the biospheric excess radiocarbon inventory . J. Geophys. Res . 114 , D17303 , https://doi.org/10.1029/2008JDO11116 .  

  76. Nakazawa , T. , Ishizawa , M. , Higuchi , K. and Trivett , N.B.A . 1997 . Two curve fitting methods applied to CO2 flask data . Environmetrics 8 , 197 – 218 .  

  77. Nydal , R. and Liivseth , K . 1983 . Tracing bomb 14C in the atmosphere 1962-1980 . J. Geophys. Res . 88 , 3621 – 3642 .  

  78. Nydal , R. and Lövseth , K . 1996. Carbon-14 measurements in at-mospheric CO2 from northern and southern hemisphere sites, 1962-1993. ORNL/CDIAC-93, NIP-057, Oak Ridge National Lab-oratory, Oak Ridge, TN, USA.  

  79. Oeschger , H. , Siegenthaler , U. , Schotterer , U. and Gugelmann , A . 1975 . A box diffusion model to study the carbon dioxide exchange in nature . Tellus 27 ( 2 ), 168 – 192 .  

  80. Piper , S.C. , Keeling , C.D. and Stewart , E.F . 2001 . Exchange of atmo-spheric CO2 and 13002 with the terrestrial biosphere and the oceans from 1978 to 2001 . II. A three-dimensional tracer inversion model to deduce regional fluxes. SIO Reference Series. Scripps Institution of Oceanography, La Jolla, CA , USA .  

  81. Prentice , IC. , Farquhar , G.D. , Fasham , M.J.R. , Goulden , M.L. , Heimann , M. and co-authors. 2001. The carbon cycle and atmospheric CO2, In: Climate Change: The scientific basis, the contribution of WGI of the IPCC to the IPCC Third Assessment Report (TAR) (eds J. T. Houghton, Y. Ding, D. J. Griggs, M. Noguer, P. J. van der Linden and co-editors). Cambridge University Press , Cambridge , UK.  

  82. Quay , P. , Sonnerup , R. , Westby , T. , Stutsman , J. and McNichol , A . 2003 . Changes in the 13C/12C of dissolved inorganic carbon in the ocean as a tracer of anthropogenic CO2 uptake . Global Biogeochem. Cycles 17 ( 1 ), 1004 , https://doi.org/10.1029/2001GB001817 .  

  83. Randerson , J.T. , Enting , I.G. , Schuur , E.A.G. , Caldeira , K. and Fung , I.Y . 2002 . Seasonal and latitudinal variability of troposphere 414CO2: post bomb contributions from fossil fuels, oceans, the stratosphere, and the terrestrial biosphere . Global Biogeochem. Cycles 16 ( 4 ), 1112 , https://doi.org/10.1029/2002GB001876 .  

  84. Rayner , P.J. , Enting , LG. , Francey , R.J. and Langenfelds , R . 1999 . Re-constructing the recent carbon cycle from atmospheric CO2, 313C and 02/N2 observations . Tellus 51B , 213 – 232 .  

  85. Rayner , P.J. , Law , R.M. , Allison , C.E. , Francey , R.J. , Trudinger , C.M. and co-authors. 2008. The interannual variability of the global car-bon cycle (1992-2005) inferred by inversion of atmospheric CO2 and 13CO2 measurements. Global Biogeochem. Cycles 22, GB3008, https://doi.org/10.1029/GBC2007GB003068 .  

  86. Reimer , P.J. , Baillie , M.G.L. , Bard , E. , Bayliss , A. , Beck , J.W. and co-authors. 2004. INTCAL04 terrestrial radiocarbon age calibration, 0-26 cal kyr BP. Radiocarbon 46(3), 1029 – 1058.  

  87. Rödenbeck , C. , Houweling , S. , Gloor , M. and Heimann , M . 2003 . Time-dependent atmospheric CO2 inversions based on interannually vary-ing tracer transport . Tellus 55B , 488 – 497 .  

  88. Rodgers , K.B. , Cane , M.A. and Schrag , D.P . 1997 . Seasonal variability of sea surface 414C in the equatorial Pacific in an ocean circulation model . J. Geophys. Res . 102 ( C8 ), 18627 – 18638 .  

  89. Rozanski , K. , Levin , I. , Stock , J. , Guevara Falcon , R.E. and Rubio , E 1995. Atmospheric 14CO2 variations in the equatorial region. Radio-carbon 37, 509 – 515.  

  90. Sabine , C.L. , Feely , R.A. , Gruber , N. , Key , R.M. , Lee , K. and co-authors. 2004. The oceanic sink for anthropogenic CO2. Science 305, 367 – 371.  

  91. Siegenthaler , U. , Heimann , M. and Oeschger , H . 1980 . 14C varia-tions caused by changes in the global carbon cycle . Radiocarbon 22 , 177 – 191 .  

  92. Siegenthaler , U. and Joos , F . 1992 . Use of a simple model for studying oceanic tracer distributions and the global carbon cycle . Tellus 44B , 186 – 207 .  

  93. Stuiver , M. and Polach , H . 1977 . Discussion: reporting of 14C data . Radiocarbon 19 , 355 – 363 .  

  94. Stuiver , M. and Quay , P. 1981. Atmospheric 14C changes resulting from fossil fuel CO2 release and cosmic ray flux variability. Earth Planet. Sci. Lett. 53, 349 – 362.  

  95. Stuiver , M. and Reimer , P . 1993 . Extended 14C data base and revised CALB3 3.0 14C Age calibration program. Radiocarbon 35 , 215 – 230. Stuiver, M. and Braziunas, T.F. 1998. Anthropogenic and Solar Compo-nents of Hemispheric 14C. Geophys. Res. Lett. 25(3), 329-332. Suess, H.E. 1955. Radiocarbon concentration in modern wood. Science 122 , 415 .  

  96. Sweeney , C. , Gloor , M. , Jacobson , A.R. , Key , R.M. , McKinley , G. and co-authors. 2007. Constraining air-sea gas exchange for CO2 with recent bomb 14C measurements. Global Biogeochem. Cycles 21, GB2015, https://doi.org/10.1029/2006GB002784 .  

  97. Telegadas , K . 1971 . The seasonal atmospheric distribution and invento-ries of excess carbon-14 from March 1955 to July 1969. HASL report 243 , Health and Safety Lab ., U.S. At. Energy Comm ., New York .  

  98. Toggweiler , J.R. , Dixon , K. and Bryan , K . 1989 . Simulations of ra-diocarbon in a coarse-resolution world ocean model 1: steady state prebomb distributions . J. Geophys. Res . 94 , 8217 – 8242 .  

  99. Turnbull , J. , Miller , J.B. , Lehman , S.J. , Tans , RR , Sparks , R.J. and Southon , J . 2006 . Comparison of 14CO2, CO, and SF6 as tracers for recently added fossil fuel CO2 in the atmosphere and implica-tions for biological CO2 exchange . Geophys. Res. Lett . 33 , L01817 , https://doi.org/10.1029/2005GL024213 .  

  100. Turnbull , J. , Rayner , P. , Miller , J.B. , Naegler , T. , Ciais , P. and Cozic , A . 2009. On the use of MCO2 as a tracer for fossil fuel CO2: quantifying uncertainties using an atmospheric transport model. J. Geophys. Res . https://doi.org/10.1029/2009JD011982 .  

  101. Trumbore , S.E . 1993 . Comparison of carbon dynamics in tropical and temperate soils using radiocarbon measurements . Global Bio-geochem. Cycles 7 ( 2 ), 275 – 290 .  

  102. Trumbore , S.E . 2000 . Age of soil organic matter and soil respiration: ra-diocarbon constraints on belowground C dynamics . EcoL AppL 10 ( 2 ), 399 – 411 .  

  103. Trumbore , S.E . 2009 . Radiocarbon and soil carbon dynamics . Annu. Rev. Earth Planet. Sci . 37 , 47 – 66 .  

  104. UNSCEAR . 2000. Sources and effects of ionizing radiation, UNSCEAR 2000 Report to the General Assembly, United Nations Scientific Com-mittee on the Effects of Atomic Radiation, Vienna, Austria.  

  105. Vogel , J.C. , Fuls , A. , Visser , E. and Becker , B . 1993 . Pretoria calibra-tion curve for short-lived samples, 1930-3350 BC . Radiocarbon 35 , 73 – 85 .  

  106. Vogel , J.C. , Fuls , A. and Visser , E . 2002 . Accurate dating with radiocar-bon from the atom bomb tests . S. Afric. J. Sci . 98 , 437 – 438 .  

  107. Wanninkhof , R . 1992 . Relationship between wind speed and gas-exchange over the ocean . J. Geophys. Res . 97 ( C5 ), 7373 – 7382 .  

  108. Yang , X. , North , R. and Romney , C . 2000. CMR nuclear explosion database (revision 3), CMR Tech. Rep. 00/16, Cent. for Monitor. Res., U. S. Army Space and Missile Defense Command, Arlington, VA.  

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