The only defined mechanism by which CO2 can affect climate change is by affecting outgoing radiation between the wavelengths of 13 and 18 microns.
- Incoming visible radiation has a wavelength between 0.4 and 0.7 microns, and is consistent with a black body of temperature of around 5,200 degree C (the Sun). CO2 is transparent to these wavelengths.
- The earth emits IR mostly between 6.5 and 12.5 microns, with a peak near 9.5 microns. 9.5 microns is consistent with a black body of temperature 18 degrees Celsius. CO2 is mostly transparent to those wavelengths.
- CO2’s absorbs between 13 and 18 microns, with a peak near 15 microns. Those wavelengths are consistent with a black body of temperature -80 degrees Celsius.
- H2O is by far the most significant GHG, and absorbs across the IR Spectrum.
- CO2 absorbs a small fraction of the IR Spectrum having 3 narrow peaks at 2.7, 4.3 and 15 microns, all of which largely miss the peak outgoing IR radiance of the earth at 9.5 microns.
- H2O largely absorbs the same IR spectrum as CO2, and is at much higher concentrations in the atmosphere. H2O IR absorption makes CO2 contribution to warming inconsequential.