CO2 alarmism is based on an unphysical version of Stefan-Boltzmann's Law and associated Schwarzschild equations for radiative heat transfer stating a two-way radiative heat transfer from-warm-to-cold and from-cold-to-warm with net transfer as the difference between the two-way transfers.
This is expressed as "back radiation" from a colder atmosphere to warmer Earth surface in Kiehl-Trenberth's Global energy budget (above) and in Pierrehumbert's Infrafred radiation and planetary temperature based on Schwarzschild's equations, presented as the physical basis of CO2 alarmism.
In extended writing I have exposed the unphysical nature of radiative heat transfer from-cold-to-warm as violation of the 2nd law of thermodynamics, see e.g.
- Mathematical Physics of Blackbody Radiation
- Unphysical Schwarzschild vs Physical Model for Radiative Transfer
So, when you meet the argument that Pierrehumbert is an authority on infrared radiation and planetary temperature, you can say that this is not convincing because Pierrehumbert is using incorrect physics (which also comes out by the fact that he forgets gravitation as the true origin of the very high temperature on the surface of Venus and not radiation).
If now CO2 alarmism is based on incorrect physics or non-physics, then it may be fair to describe it as "hoax".
Think of it: Suppose that "scientific consensus" through MSM is bombarding you with a message that the Earth has to be evacuated because there is imminent fear that the "sky is going to fall down" because Newton's law of gravitation says that "everything is pulled down". Would you then say that "since it is said so it must be so" or would you say that this is a non-physical misinterpretation of Newton's law? Think of it!
The edX course Making Sense of Climate Science Denial is a typical example of the CO2 alarmism based on the incorrect physics of "back radiation", which is forcefully trumpeted by the educational system, as illustrated in the following key picture of the course: