Does CO2 or H2O dominate Earth’s temperature? Chuck Wiese, Meteorologist Communication to retired NASA scientist, Donald Bogard July 23, 2019 It is well understood that in the vicinity of 15 microns of infrared (IR) wavelength that CO2 is dominant over H2O. But the actual IR absorption from water vapor in the vicinity of the 15 micron wavelength is more significant than you would like to portray because of the actual water vapor abundance or concentration compared to CO2. Water vapor has an average atmospheric abundance of 23,000 ppmv while CO2 is currently at 410 ppmv. Without the relative concentrations, you are not seeing the actual spectral absorption in these graphs. So in your first set of graphs, water vapors absorption is significant near 15 microns, enough such that it competes with CO2 over roughly 37% of CO2's absorption lines there. With respect to your second graph sets, there is not enough CO2 in the earth's atmosphere to activate the overtone wavelengths beyond the spike near 17 microns and higher, and the spikes at the shorter wavelengths near the atmospheric window and even shorter towards the near IR spectrum, such as 4 microns, have virtually no absorption because of either lack of abundance or not enough IR emission at those wavelengths from the earth's surface based upon the earth's spectral emissive temperature or both. Like I said, you get "more bang for the buck" over the very narrow range of IR wavelength near 15 microns that CO2 absorbs at compared to water vapor, but nowhere else in the earth's atmospheric IR spectrum. On the other hand, water vapor has massive vibrational and rotational absorption wavelengths that are very significant because of abundance and IR wavelength range over CO2 based upon the earth's black body emission curve. Water vapor totally dominates the IR domain of wavelength over the earth's IR emission and because of this fact, totally controls the atmospheric greenhouse effect. Further, the very thermodynamic properties of water prohibit it from becoming an amplifying agent of CO2 IR radiation in optical depth. The feedbacks must be negative on optical depth and because of this fact, CO2 cannot drive earth temperature or control climate in the presence of the earth's hydrological cycle.
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