[Bob434]

how is it known that 20ppm causes warming, or causes a ‘huge effect’? If 400ppm that we have today only amountsw to 0.04%, then how on earth can 20ppm, and even more insignificant amount, be the cause of warming? or is that just a guess?

and yep and increase from 280 to 400ppm sounds scary, just like the alarmists wish it to, but it still only amounts to 0.04% of the TACO2 levels (total atmospheric CO2)- this maount simply is nowhere near enough to create a blanket thick enough around the globe to trap heat- it’s simply impossible for that small amount to accomplish that

Think of it like the following- 0.04% would be very small splotches here and there across the globe- I’m guessing at these figures, but for the sake of visualization, I’ll just say it would bel ike having a splotch of CO2 about a mile wide over Australia, one over japan, one over china, the us perhaps, maybe one over bhudapest, - but the point is, you have these small insignificant pockets of CO2 scattered far apart from each other , and relatively few of them at that, and the rest of the atmosphere is completely free of CO2- infact 99.96% of the atmosphere is free from CO2- in other words, almost 100% of our atmosphere has no CO2 in it

Either that OR, the CO2 formed a blanket- a microscopically thin blanket around the entire globe, a ‘blanket’ so thin that it is simply ridiculous to even suggest that it can trap heat and then reflect it back to earth- CO2 isn’;t even a very efficient heat trapper to begin with- let alone the fact that even IF CO2 blankets the earth, it’s so thin that it can’t possibly be causing rising temperatures

[palmer]

The reason is pretty simple, the number of molecules of air in a cubic meter of air is something like 10^25. That means 20 ppm of CO2 gives you 10^20 molecules of CO2. It doesn't take a very big thickness of air (100 meters?) to absorb every every outgoing IR photon with the right wavelength. Of course those same molecules emit those same wavelengths and send them off into space (and 1/2 back to earth). The key is that the transfer of energy from CO2 to the bulk atmosphere (mainly N2 and O2) is much faster than the release of energy via the photon release. Therefore the rest of the atmosphere warms.

Either that OR, the CO2 formed a blanket- a microscopically thin blanket around the entire globe, a ‘blanket’ so thin that it is simply ridiculous to even suggest...

Very thin blanket indeed, but with 10^20 molecules of CO2 per cubic meter, it is thick enough to absorb many outgoing IR photons. I suppose you could think of taking all those CO2 molecules and replacing them with a single very thin sheet of mylar somewhere well above the surface. One difference however would be that the mylar would also reflect (scatter) IR photons, not just absorb and release them like CO2.