Breathing Planet Earth: Analysis of Keeling’s Data on CO 2 and O 2 with Respiratory Quotient (RQ), Part I: Global Respiratory Quotient (RQ Glob ) of Earth

In biology, respiratory quotient ( RQ ) is defined as the ratio of CO 2 moles produced per mole of oxygen consumed. Recently, Annamalai et al. applied the RQ concept to engineering literature to show that CO 2 emission in Giga Tons per Exa J of energy = 0.1 ∗ RQ . Hence, the RQ is a measure of CO 2 released per unit of energy released during combustion. Power plants on earth use a mix of fossil fuels (FF), and the RQ of the mix is estimated as 0.75. Keeling’s data on CO 2 and O 2 concentrations in the atmosphere (abbreviated as atm., 1991–2018) are used to determine the average RQ Glob of earth as 0.47, indicating that 0.47 “net” moles of CO 2 are added to which means that there is a net loss of 5.6 kg C(s) from earth per mole of O 2 depleted in the absence of sequestration, or the mass loss rate of earth is estimated at 4.3 GT per year. Based on recent literature on the earth’s tilt and the amount of water pumped, it is speculated that there could be an additional tilt of 2.7 cm over the next 17 years. While RQ of FF, or biomass, is a property, RQ Glob is not. It is shown that the lower the RQ Glob , the higher the acidity of oceans, the lesser the CO 2 addition to atm, and the lower the earth’s mass loss. Keeling’s saw-tooth pattern of O 2 is predicted from known CO 2 data and RQ Glob . In Part II, the RQ concept is expanded to define energy-based RQ Glob,En , and adopt the CO 2 and O 2 balance equations, which are then used in developing the explicit relations for CO 2 distribution amongst atm., land, and ocean, and the RQ -based results are validated with results from more detailed literature models for the period 1991–2018.