Partitioning of the global fossil CO<sub>2</sub> sink using a 19-year trend in atmospheric O<sub>2</sub>

Langenfelds, RL, Francey RJ, Steele LP, Battle M, Keeling RF, Budd WF.  1999.  Partitioning of the global fossil CO2 sink using a 19-year trend in atmospheric O2. Geophysical Research Letters. 26:1897-1900.

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air, carbon-dioxide, cycle, oceanic uptake, ratio


O-2/N-2 is measured in the Cape Grim Air Archive (CGAA), a suite of tanks filled with background air at Cape Grim, Tasmania (40.7 degrees S, 144.8 degrees E) between April 1978 and January 1997. Derived trends are compared with published O-2/N-2 records and assessed against limits on interannual variability of net terrestrial exchanges imposed by trends of delta(13)C in CO2. Two old samples from 1978 and 1987 and eight from 1996/97 survive critical selection criteria and give a mean 19-year trend in delta(O-2/N-2) of -16.7 +/- 0.5 per meg y(-1), implying net storage of +2.3 +/- 0.7 GtC (10(15) g carbon) yr(-1) of fossil fuel CO2 in the oceans and +0.2 +/- 0.9 GtC yr(-1) in the terrestrial biosphere. The uptake terms are consistent for both O-2/N-2 and delta(13)C tracers if the mean C-13 isotopic disequilibrium flux, combining terrestrial and oceanic contributions, is 93 +/- 15 GtC parts per thousand yr(-1).