GCM’s are already at the point where competent can run them as evidenced by our weather forecasts several days in advance which are based on GCM model output because this is what GCM’s are designed to do. GCM’s take an initial set of conditions for millions of cells and project the interacion between cells based on sound physical theory to predict movement of weather patterns which become our forcasts.
The predictions of global warming from CO2 are based on inputting initial conditions which already attribute prescribed forcing to CO2 increases which the models incorporate into the calculations and produce output with a range of values centred on the input CO2 forcing.
For a doubling of CO2 the models input forcing of 5.35ln(2)= 3.71W/m^2 and output a range of forcing which averages around 3.71W/m^2.
All that the models do is create the statistical range for the forcing but in no way make change the mean value from what was originally input as the CO2 forcing parameter. Essentially all the models do is consume a lot of electricity in the process of giving the illusion that they are defining thye effect from increased CO2.
The output from the models is converted from flux in W/m^2 to temperature in degrees C by means of an arbitrary “climate sensitivity factor” typically in the range of 0.75°C for each W/m^2.
3.71W/m^2 x 0.75°C/W/m^2 = 2.78°C
In his 1981 Paper:
Climate Impact of Increasing Atmospheric Carbon Dioxide
J. Hansen, D. Johnson, A. Lacis, S. Lebedeff P. Lee, D. Rind, G. Russell
Hansen states: The most sophisticated models suggest a mean warming of 2° to 3.5°C for doubling of the CO2 concentration from 300 to 600 ppm
SCIENCE, VOL. 213, 28 AUGUST 1981
The average between 2°C and 3.5°C is 2.75°C which is awful darn close to 2.78°C.
The real proof of mischief is the model # 4 in this 1981 paper which protrays the output for a doubling of CO2 at exactly the same 2.78°C value calculated by the combination of CO2 forcing parameter and climate sensitivity factor identified in 2001 by the IPCC attributed to Mehre 1997 which is 16 years after the 1981 paper by Hansen!!
You are very accurate when you state: “Science does settle. At which point, it becomes technology, and no longer the domain of a scientist.” but in this case it is unfounded conjecture and not technology that is not in the domain of a scientist; nor should it ever be!