@latimer
re; logarithmic decline in CO2 LWIR absorption
Quite right. It’s not a just a straight log curve either. The effect increases linearly for about the first 100ppm partial pressure then goes into logarythmic decrease in effectiveness.
I equate it cherry picking. Real cherry picking. If you have a cherry orchard and a number or workers to pick cherries so long as the pickers are not crowding each other you’ll get a linear increase in number of cherries picked each time you add a worker. At some point the workers start competing with each other and then productivity per worker starts to decline. So imagine LWIR photons in the CO2 absorption bands as cherries and CO2 molecules as pickers. Up to about 100ppm there’s a linear increase in absorption per PPM of CO2 added. At 280ppm the linear range is long gone and each PPM has less absorption potential than the PPM which came before it.
The really interesting bit for me is that when you plot the rate of increase of anthropogenic CO2 emission since 1750 against the decrease in CO2 infrared absorption capacity you find them equal. This means anthropogenic warming due to CO2 has been linear since the industrial revolution got started. Climate boffins increasingly point to the past 50 years as the beginning of significant anthropogenic emission and this is simply not true. It’s been going on with equal efficacy since 1750 not 1950.