Models, especially computer models only work when you can include all possible variables.

With climate thats an impossibility, we don't know the temperatures or precipitation that will occur in the coming weeks, months or years. We don't know cloud cover, or what volcanic eruptions, forest fires or earthquakes will occur and all of these things plus many more affect future climate.

Computer models do one thing, they provide a result based upon the variables (data) provided in the programming. Alter the data and you get a different result. Climate model results are never factual, since the variables used are best guesses of future events.