Breathing Planet Earth: Analysis of Keeling’s Data on CO 2 and O 2 with Respiratory Quotient (RQ), Part II: Energy-Based Global RQ and CO 2 Budget

For breathing humans, the respiratory quotient (RQ = CO 2 moles released/O 2 mols consumed) ranges from 0.7 to 1.0. In Part I, the literature on the RQ was reviewed and Keeling’s data on atmospheric CO 2 and O 2 concentrations (1991–2018) were used in the estimation of the global RQ as 0.47. A new interpretation of RQ Glob is provided in Part II by treating the planet as a “Hypothetical Biological system (HBS)”. The CO 2 and O 2 balance equations are adopted for estimating (i) energy-based RQ Glob(En) and (ii) the CO 2 distribution in GT/year and % of CO 2 captured by the atmosphere, land, and ocean. The key findings are as follows: (i) The RQ Glob(En) is estimated as 0.35 and is relatively constant from 1991 to 2020. The use of RQ Glob(En) enables the estimation of CO 2 added to the atmosphere from the knowledge of annual fossil fuel (FF) energy data; (ii) The RQ method for the CO 2 budget is validated by comparing the annual CO 2 distribution results with results from more detailed models; (iii) Explicit relations are presented for CO 2 sink in the atmosphere, land, and ocean biomasses, and storage in ocean water from the knowledge of curve fit constants of Keeling’s curves and the RQ of FF and biomasses; (iv) The rate of global average temperature rise (0.27 °C/decade) is predicted using RQ Glob,(En) and the annual energy release rate and compared with the literature data; and (v) Earth’s mass loss in GT and O 2 in the atmosphere are predicted by extrapolating the curve fit to the year 3700. The effect of RQ Glob and RQ FF on the econometry and policy issues is briefly discussed.