Physicist William Happer is an authority on Atomic, Molecular, and Optical Physics (AMO) including spectroscopy (the which study of interactions between matter and electromagnetic radiation as it varies with wavelength (frequency). This is closely related to the greenhouse effect. Leftists criticize Happer by claiming he is not really a climate scientist. Leftists character attack anyone who does not agree with them. They wanted to call Happer a science denier, I suppose, but he is known as a brilliant scientist, so that would not work
Happer says the hysteria over climate is an example of a human failing described in the “Extraordinary Popular Delusion and the Madness of Crowds” by Charles MacKay (1841). There's also nothing new about people wanting to save the planet, whether it needed saving or not.
Happer discusses the work of Karl Schwarzschild and Max Plank. Plank devised a smooth curve showing intensity of outgoing radiation as a function of wavelength. The curve, called black body radiation, shifts for different temperatures and as used by Happer provides the theoretical value for the earth’s outgoing radiation (which is how our planet cools irself. The curve is at a surface temperature of 288.7 K (15.6 C., or 60F.) and assumes there were no greenhouse gases to interfere with outgoing radiation.
Schwarzschild devised the method of calculating the actual absorption of outgoing radiation by different greenhouse gases. Happer shows it as a jagged curve below the Plank curve, covering the same frequencies. The Schwarzschild curve used by Happer is based on the current level of greenhouse gases. The greenhouse effect suppresses the outgoing radiation to space and is demonstrated by the difference between the two curves.
Observations from satellites confirm the calculations.Happer shows the interference for zero CO2, 400 parts per million (ppm) of CO2 and 800 ppm of CO2. Removing CO2 will significantly increase cooling (the loss of heat). Doubling CO2 to 800 ppm will have little effect in slowing cooling (usually called "warming the earth") because the increase in interference with outgoing radiation is small. The physicists define such a condition for CO2 as saturated.
Happer says the amplification (tripling) of CO2 caused warming by increased water vapor in the air [a positive feedback asserted in the 1979 Charney Report) as the the dangerous effect of global warming] is nonsense. This water vapor amplification is the basis for claiming global warming is dangerous in the UN Intergovernmental Panel on Climate Change (IPCC) reports. No positive feedback has ever been measured.
Happer also demonstrates that adding methane to the atmosphere will NOT cause dangerous warming are nonsense.