When I was young and working on the Apollo program we would often joke about computer anaysis being GIGO; that is, garbage in, garbage out. For the UN IPCC's Global Circulation Models GIGO appears have a different meaning, as in this bit fronm the blog Powerline:

The computer models that predict global warming are ridiculously primitive. They still can't recreate the past accurately, let alone predict the future. As Howard Hayden, professor of physics at the University of Connecticut, says, they take "garbage in" and spit "gospel out."