Increasing CO2 has little to no heating effect

The Shrill at work.
Another debunking of one of UNSkeptical UNScience -SS's- so-called "Myths." This time debunking their #30

"Increasing CO2 has little to no effect"The strong CO2 effect has been observed by many different measurements.

Why the Shrill via people like UNSkeptical UNScience (SS) imagine that human's emissions of carbon dioxide have anything to do with the climate is an exercise in hubristic nonsense, which seems to be the Shrill and the Green's greatest talent.

NZCSC write in

Why is it that mostly chemists seem to understand the behaviour of carbon dioxide whilst even professors of physics appear incapable of grasping the basics of thermodynamics?
In every 85,800 molecules of air, 33 are CO2. Of those humans produce just one. That the UN IPCC claim that one (1) molecule of CO2 in 85,800 molecules of air causes catastrophic warming while the remaining 32 molecules of Nature's identical CO2 do not is insanity.

Temporarily suspending science by assuming the UN radiative back-warning 'theory' of global warming is valid. Purely for purposes of illustration one can calculate an indicative impact of human production of CO2 on rising temperature.

 Use relevant assumptions widely acknowledged world-wide:
  • CO2's theoretical maximum share of the greenhouse gas theory's effect is 3% (water vapour is 95%)
  • Total human production of CO2 is 3% of Earth's annual production (UN IPCC figure), and
  • Using temperature increase of 0.8°C since 1860 - close to start of industrialisation and the end of Little Ice Age. 
Then human affect be: 0.8 × 0.03 × 0.03 = 0.0007ºC

These indicative calculations exaggerate the UN IPCC's theorised impacts of human CO2 because
they ignore the logarithmically decreasing impact of raising CO2

First 20 ppm causes warming of 15.3 watts per square metre; 
            next 20 ppm causes warming of  2.9 W/m2;
            next 20 ppm causes warming of  1.7 W/m2.

Anthony Cox continues

Increasing CO2 has little to no effect. Correct.

It’s the logarithmic decline in extra CO2. This means more CO2 has LESS effect on temperature. It’s a diminishing return. This has been known for a long time.

Even the IPCC concedes this noting that for CO2, RF increases logarithmically with mixing ratio.

But alarmists still maintain temperature could go up basically forever (items 7, 34, 91, 110); this is another prime example of alarmists ignoring their own ‘evidence’.

Professor William Happer has a straightforward explanation of where the IPCC goes wrong in respect of the log effect.