Hot off the press :
Have they gotten to the point where the only thing left to do is make things up?
If all CO2 were removed from the atmosphere, the greenhouse effect (downwelling longwave radiation) in the tropics would be reduced by only 1.3%, from 397.08 watts per metre² to 392.23 watts per metre².
That is correct – in the tropics, H20 is responsible for essentially all of the greenhouse effect. As you move to drier locations, CO2 becomes relatively more important. Most of the earth has reasonably high humidity, so the new claims are beyond ridiculous.
Look at the absorption spectra below. Water vapour covers a much broader spectrum than CO2, it overlaps with CO2 and is much more abundant than CO2. Of course it dominates the greenhouse effect.