Validation Of A Climate Model Is Mandatory: The Invaluable work of Dr. Vincent Gray

WUWT
No computer model has ever been validated. An early draft of Climate Change 95 had a Chapter titled “Climate Models – Validation” as a response to my comment that no model has ever been validated. They changed the title to “Climate Model – Evaluation” and changed the word “validation” in the text to “evaluation” no less than describing what might need to be done in order to validate a model.
Without a successful validation procedure, no model should be considered to be capable of providing a plausible prediction of future behaviour of the climate."

Fudging To Assure Reliability Masquerading As Validation
Attempts at validation during the 120 years of the instrumental period also proved problematic for the same reasons as for the historical record. A major challenge was the cooling period from 1940 to 1980 because it coincided with the greatest increase in human production of CO2. This contradicted the most basic assumption of the AGW hypothesis that a CO2 increase caused a temperature increase. Freeman Dyson described the practice, generally described as “tweaking”, and discussed in several WUWT articles. It is the practice of covering up and making up evidence designed to maintain the lies that are the computer models.
They sought an explanation in keeping with their philosophy that any anomaly, or now a disruption, is, by default, due to humans. They tweaked the model with human sourced sulfate, a particulate that blocks sunlight and produces cooling. They applied it until the model output matched the temperature curve. The problem was after 1980 warming began again, but sulfate levels continued. Everything they do suffers from the T. H. Huxley truth; “The great tragedy of science, the slaying of a beautiful hypothesis by an ugly fact.”
As Gray explained,
Instead of validation, and the traditional use of mathematical statistics, the models are “evaluated” purely from the opinion of those who have devised them. Such opinions are partisan and biased. They are also nothing more than guesses."