Global circulation models - AKA climate models claim to be legitimate because they say they can hindcast previous atmospheric temperatures. i.e. They claim their model projections reproduce past climate. For example: The global cooling period from the early 1940s to mid-1970s. This was done by adding a special factors (aerosols) for this period which they claim is no longer important today. Some people this is just fabricated data to give the GCMs a gloss of legitimacy. Just about all GCMs run too hot. They mis-forecast future temperatures too hot.
This is another 'reblog' of a comment.
Ladies and Germs,
Have you looked at the model-hindcasting/fabricated-aerosol issue, as described below?
The climate models do not honestly hindcast the global cooling period from ~1940 to ~1975, because their authors fabricated false aerosol data to force hindcasting.
Therefore, the models cannot forecast anything, because they cannot hindcast. except through fraudulent inputs.
The climate models cited by the IPCC typically use values of climate sensitivity to atmospheric CO2 (ECS) values that are significantly greater than 1C, which must assume strong positive feedbacks for which there is NO evidence. If anything, feedbacks are negative and ECS is less than 1C. This is one key reason why the climate models cited by the IPCC greatly over-predict global warming.
I reject as false the climate modellers’ claims that manmade aerosols caused the global cooling that occurred from ~1940 to ~1975. This aerosol data was apparently fabricated to force the climate models to hindcast the global cooling that occurred from ~1940 to ~1975, and is used to allow a greatly inflated model input value for ECS.
Some history on this fabricated aerosol data follows:
More from Douglas Hoyt in 2006: