What if the climate models have been the instrument of an utterly circular exercise?
That is what is implied by the successful emulation of the model outputs, in terms of the global average surface temperature projections, by simplified computation from the so-called “forcings.”
It is trivially true that any increase or decrease in the amount of solar energy that is absorbed instead of reflected will result in sensible heat gain or loss down here. But is NOT in evidence at the outset that the static longwave radiative effect of incremental CO2, CH4, N2O, etc. is capable of de-rating the dynamically variable emitter to space, therefore requiring a higher temperature at the surface to restore the previous output. The hypothesized de-rating, if any, is what you are supposedly investigating.
This is why it is wrong to concede that the incremental “greenhouse gases” represent a climate “forcing.” Once you include it in the specified forcing scenarios, the models will respond accordingly because they are coded and tuned for stability with no forcing, and for response to the forcing. You will get a rising surface temperature projection, and your hindcasting will have roughly followed the “forcing” history. Circular.
It is to the great credit of both Willis Eschenbach and Patrick Frank to have so successfully demonstrated the simplified emulation.
Willis here: https://wattsupwiththat.com/2013/06/03/climate-sensitivity-deconstructed/
And Pat Frank here:
https://www.frontiersin.org/journals/earth-science/articles/10.3389/feart.2019.00223/full
What to do? Expose the circular exercise. Stop conceding the core claim that emissions of CO2, CH4, N2O, etc. are capable of any perturbing climate “forcing” at all. No one knows that.
Thank you for listening.