That would be news to the IPCC, which stated in 2007:
From an interview with EurActiv:
EurActiv: Our stories often receive comments from climatesceptics, who say that such statements are just based on unreliable computer models and climate science is not robust enough to compensate for the economic cost of decarbonisation…
Hansen: In fact, we base our understanding more on observations of how the Earth has responded in the past to changes in the boundary conditions, including the atmospheric composition. I’m using models less and less – although they are very helpful in confirming our understanding – but it is not correct to say that these assessments are based on models.