I asked Dr. Keeling for his opinion on this possibility. He said, "I agree qualitatively with your arguments. Some time ago I also calculated the sea- level rise that would be caused by the water generated as a bi-product of fossil-fuel burning. I got quite a small number. I can make a similar calculation here:
O2 lost into forming water: 35.2 - 26.3 = 8.9 Pmol.
Amount of H2O formed: 8.9x2 = 17.8 Pmol
Volume occupied by water formed:
(17.8x10(15) mol)(18g/mol)/(1000000g/m3) = 3.2x10(11) m3.
Resulting sea-level rise (taking ocean area of 3.6x10(14)m2):
3.2x10(11)/3.6x10(14) = 9x10(-4) m
So the effect is only ~1 millimeter since the industrial revolution. This is small compared to the other factors that have contributed to sea level rise over this period."
In conclusion, it seems that the depletion of atmospheric oxygen will continue until such time as we stop burning hydrocarbons faster than the environment can absorb the byproducts of the reaction and replenish the oxygen. The only solution to this problem is to determine beyond the shadow of a doubt just how much carbon dioxide that our atmosphere and environment in general can absorb and process back into oxygen and then limit our burning of carbon containing fuels so that we stay within that “safe zone” and using non carbon based energy sources to make up for what we can no longer produce via fossil fuels.
The problem with this solution is that, in order to keep our economy cooking along, we need to produce and consume ever increasing amounts of energy and so we can’t stop using fossil fuels, including coal, without a lot of economic pain because there currently are no alternatives in place to pick up the slack. The sequestration of carbon dioxide by pumping it under the ground would only dispose of the carbon dioxide with unknown consequences, but would do nothing to stop the depletion of oxygen from the atmosphere. Dr. Keeling agreed that carbon sequestration would do nothing to stop oxygen depletion but reassured me that "... the O2 loss is too small to be much of a concern."