To appreciate the validity (or not) of climate models, the layperson should have an appreciation of some of the fundamental science underpinning them. It may be easier to link the science with individuals. This chapter in Volume One covers only some of the detail and Volume Two goes into depth.
His radiative transfer equation describes how radiation from a warm surface passes up through the atmosphere where some is absorbed (Greenhouse effect) and the balance leaves the top of the atmosphere for the cold of space. Schwarzschild's equation is proved to accurately describe what happens and is not questioned. However, its numerical application in the real world is difficult.
These late 19th / earlyy 20th century scientists describe how, given the temperature of the surface, the intensity and frequency range of emitted radiation. This is another firmly proven law. It is easier to apply to the real world than Schwarzschild's equation.
Is the author's term for a technique applicable to the Greenhouse Effect calculation. It is not associated with a famous name. Its application is based on spectroscopic data and requires assumptions to be made for real-world applications. It is not fundamentally proven and has not been scientifically verified. However, the calculation technique is seldom critisized.
These models start at the finishing line. They are constucted on the assertion that 'Anthropogenic emissions cause Global Warming'. By forcing Schwarzschild's equation to mate with Spectral Analysis an equation linking surface temperature to atmospheric levels of carbon dioxide results. This forms the fundamental drive for Global Warming used in all Anointed models. It has never been validated experimentally and direct observation is impossible. Curiously, despite this equation's dubious origins, it is accepted without question by all Anointed modellers and some Dissenter modellers.
This equation is called the 'Direct effect'. Using it to calculated whaat will happen when carbon dioxide doubles (probably in the 2050s) results in quite modest predictions (generally less than 0.8°C).
To predict 'Climate Armageddon' another mechanism is required. This called 'Sensitivity'. The IPCC assert 'doubling' will be between 2.5°C and 4.0°C. This is considerably larger than the 0.8°C 'Direct' effect.
The mechanism for 'Sensitivity' is 'feedbacks'. Although 'consensus' science says this massive multiplier is operating, no coherent mechanism has been offered for proper scientific testing.
Chapter 7 (pp 268-284) covers the various philosphical approached to modelling
Chapter 8 (pp 284-296) discusses the various outcomes