Source: Robert A. Rohde (Dragons flight at English Wikipedia) – This figure was created by Robert A. Rohde from published data and is part of the Global Warming Art project. http://www.atmo.arizona.edu/stud…
This figure requires a bit of explaining. The top spectrum shows the wavelengths at which the atmosphere transmits light and heat as well as the “black body” idealized curves for no absorption. It is a little misleading because the data is not based on actual solar and earth data. It is based on two experimental heat sources, one centered at 5525 K (5252o C or 9485o F), the approximate temperature of solar radiation, and one centered in the range of 210 to 310 K (-63o C to 36.8o C or -82oF to 98o F), the approximate temperature range of re-radiated heat from the earth. In reality solar radiation power, (Watts/m2/micron), shown in red, is six million times as strong as the power of re-radiated heat from the earth, shown in blue.
The other spectra are absorption spectra. The top one shows the relative percent absorption by total atmospheric gases at various wavelengths, (note that this spectrum is practically the inverse of the transmission spectrum above it), and the spectra below that show the absorption wavelength ranges of individual atmospheric gases, but not the relative strength of that absorption in reality. As experimental, not real atmospheric, data they can only tell us the wavelength ranges of the absorption, not their relative strengths.
Note that CO2 absorbs in the 15 micron range, which is within both the range of re-radiated heat and the strong absorption by water vapor, of which the CO2 peak forms a mere shoulder. This is used to claim forcing of water vapor by CO2, without regard to the real near-saturation level of CO2 absorption. Lesser CO2 peaks in the 2.7 and 4.3 micron ranges also only contribute in a minor way, the first is completely covered by a water vapor absorption peak and the second forms a shoulder in another water vapor peak. These minor peaks occur in a region where both solar radiation and re-radiation are minimized. Methane and nitrous oxide are also shown to be minor players, having narrow absorption ranges and low concentrations. Note too that ozone blocks most of the ultraviolet light from the sun.
The CO2 hypothesis is based on bad science; first that of John Tyndall, 1862, and then of Gilbert Plass, 1955.
- In 1872 John Tyndall measured the heat absorption of various atmospheric gases over the entire wavelength range of his heat source. He found that water vapor and CO2 absorbed more strongly than other atmospheric gases such as oxygen and nitrogen. Oxygen and nitrogen, major components of the atmosphere, had little or no absorption of heat in the range tested. It is important to note that his experiments did not separate the heat into specific wavelengths.
Quote: “…if, as the above experiments indicated, the chief influence be exercised by the aqueous vapour, every variation of this constituent must produce a change of climate. Similar remarks would apply to the carbonic acid [CO2] diffused through the air… they constitute true causes, the extent alone of the operation remaining doubtful.”
— Contributions to Molecular Physics in the Domain of Radiant Heat, John Tyndall, 1872, Cambridge University Press
2. In 1955 Gilbert Plass claimed that a doubling of CO2 would result in a 3.6 degree temperature increase.
Quotes: “ … average surface temperature of the earth increases 3.6o C if the CO2 concentration in the atmosphere is doubled …”
“The extra CO2, released into the atmosphere by industrial processes and other human activities may have caused the temperature rise during the present century. In contrast with other theories of climate, the CO2 theory predicts that this warming trend will continue, at least for several centuries.”
— The Carbon Dioxide Theory of Climatic Change by Gilbert Plass, 1956, Johns Hopkins University
This was followed by mathematical climate models, originally in climate alarmism testimony before Congress, 1988, by James Hansen at NASAs Goddard Institute for Space Studies that was based on calculations that worked for Venusian atmospheric gases, Sulfuric Acid clouds and a thick, heavy CO2 atmosphere. The models exclude clouds as a factor and claim a forcing of water vapor heat retention. The premise only works if evaporated vapor remains as low level vapor rather that forming clouds.