What will happen as a result of increasing concentrations of the IR-active gases CO2, CH4, N2O in the atmosphere, in respect to sensible heat gain on land, in the oceans, and in the lower atmosphere itself? That was the question to be investigated, and it remains open.
One way to state the “warming” hypothesis is that the Earth system’s longwave emitter to space will experience a de-rating as an end result, requiring a higher temperature at the land + ocean interface with the atmosphere to maintain the longwave emitter output to space.
On the other hand, the valid null hypothesis is that there will be no significant de-rating as an end result; i.e. the emitter output to space is insensitive to the incremental change in the clear-sky IR absorbing power of the atmosphere.
I hold that the “forcing” + “feedback” framing of the investigation pre-supposes the de-rating and then treats the implied direct “warming” influence as a driver of amplification through “feedbacks.” Semantics? Maybe, but using the word “forcing” presumes capability.
This is why I keep posting comments that the entire climate modeling exercise is circular. If you use pre-stabilized, parameter-tuned general circulation models and apply radiative “forcings” computed from incremental CO2, CH4, N2O – you have hard-coded the de-rating of the emitter, and the “warming” result is baked in. This is the outcome, despite the inherent inability of any of the models to directly compute cloud formation and dissipation, which is already known to be the main controller of the longwave emitter output to space.
This is why I also encourage skeptics of climate alarm to stop conceding the “forcing” + “feedback” semantic framing of the investigation. This does not dispute the concept of IR-active gases or that a static radiative effect at the surface can be computed. It simply recognizes that the hypothesized end result cannot be assumed at the outset.
Has the null hypothesis been falsified? No. Not even close.
Thank you for listening.