The distortion of science for ideological purposes has a long history, and the results are generally ugly.
Real-world measures suggest moderate to strong negative feedback, currently unnamed and un-quantified, mitigates the Earth's thermal response to additional radiative forcing from both human activity and natural variation. Justification for amplification factors >2.5 for unmitigated positive feedback mechanisms is not evident in empirical measures. It is not clear whether any amplification factor should be applied or even what sign any such factor should be. Nor is there evidence to support such large λ values in GCMs. Division of real-world measures continue to exhibit the same surface thermal response derived by Idso for contemporary local, regional and global climate, for ancient climate under a younger, weaker sun and for Earth's celestial neighbors, Mars and Venus.
In the absence of support for amplification factors and in view of their erroneously large λ values it is apparent that the wiggle fitting so far achieved with climate model output is accidental or that these models contain equally large opposing errors in other portions of their calculations such that a comedy of errors produce seemingly plausible results in the short-term. In either case no confidence is inspired.
On balance of available evidence then the current model-estimated range of warming from a doubling of atmospheric carbon dioxide should probably be reduced from 1.4 - 5.8 °C to about 0.4 °C to suit observations or ≈ 0.8 °C to accommodate theoretical warming -- and that's including ΔF of 3.7 Wm-2 from a doubling of pre-Industrial Revolution atmospheric carbon dioxide levels, a figure we suspect is also inflated.
The bottom line is that climate models are programmed to overstate potential warming response to enhanced greenhouse forcing by a huge margin. The median estimate 3.0 °C warming cited by the IPCC for a doubling of atmospheric carbon dioxide is physically implausible.Source
Note: Every GCM assumes as a start that doubling CO2 results in a rise in atmospheric temperature.
It might be expressed thus:
Future T = F(CF) - Feedback where F(CF) is the climate forcing and Feedback an innumerable number of factors which decrease the effect of F(CF).
F(CF) has never been determined experimentally - it is at best a GUESS!
This is not science, this is pure junkscience.