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Keeling, RF, Piper SC, Heimann M.  1996.  Global and hemispheric CO2 sinks deduced from changes in atmospheric O2 concentration. Nature. 381:218-221.   10.1038/381218a0   AbstractWebsite

THE global budget for sources and sinks of anthropogenic CO2 has been found to be out of balance unless the oceanic sink is supplemented by an additional 'missing sink', plausibly associated with land biota(1,25). A similar budgeting problem has been found for the Northern Hemisphere alone(2,3), suggesting that northern land biota may be the sought-after sink, although this interpretation is not unique(2-5); to distinguish oceanic and land carbon uptake, the budgets rely variously, and controversially, on ocean models(2,6,7), (CO2)-C-13/(CO2)-C-12 data(2,4,5), sparse oceanic observations of p(CO2) (ref. 3) or C-13/C-12 ratios of dissolved inorganic carbon, (4,5,8) or single-latitude trends in atmospheric O-2 as detected from changes in O-2/N-2 ratio.(9,10). Here we present an extensive O-2/N-2 data set which shows simultaneous trends in O-2/N-2 in both northern and southern hemispheres and allows the O-2/N-2 gradient between the two hemispheres to be quantified. The data are consistent with a budget in which, for the 1991-94 period, the global oceans and the northern land biota each removed the equivalent of approximately 30% of fossil-fuel CO2 emissions, while the tropical land biota as a whole were not a strong source or sink.

Keeling, RF.  2009.  Triage in the greenhouse. Nature Geoscience. 2:820-822.   10.1038/ngeo701   AbstractWebsite

The path towards mitigating global warming is going to be tortuous. capturing carbon dioxide and pumping it directly into the deep ocean to avoid atmospheric build-up is an option that has been dismissed prematurely.

Keeling, RF.  2002.  On the freshwater forcing of the thermohaline circulation in the limit of low diapycnal mixing. Journal of Geophysical Research-Oceans. 107   10.1029/2000jc000685   AbstractWebsite

[1] A conjecture is offered on the stability characteristics of the thermohaline circulation in the limit of very low diapycnal mixing. In this limit the action of the winds on the Antarctic Circumpolar Current (ACC) can sustain a deep overturning pattern known as the "reconfigured conveyor,'' consisting of upwelling around Antarctica and sinking in the North Atlantic, as shown by the work of Toggweiler and others. It is conjectured that in this limit, northern sinking should be stabilized in an "on'' state because of the penetration of freshwater into the ocean interior via isopycnal layers that outcrop to the surface within and south of the ACC. This conjecture is supported by qualitative arguments and by a hydraulic model for the reconfigured conveyor. The hydraulic model takes into account the freshwater budgets of the Atlantic basin, Antarctic surface waters, and the remaining oceans. It also takes into account, in simple terms, wind-driven Antarctic upwelling, eddy transports and mixing within the ACC, changes in pycnocline depth, the role of temperature forcing, and advective feedbacks on salinity. The hydraulic model suggests that multiple "on/off'' states of the reconfigured conveyor are possible but only if the deep waters that form in the Northern Hemisphere are fresher than the intermediate waters that form in the vicinity of the ACC in the Southern Hemisphere, a condition that is not satisfied in the modern ocean.