Here is how Ray L explains it:
Excellent post as usual. The seeming glee that denialists sieze upon any result that could be interpreted as calling model results into question has always amused me. The empirical data are sufficient to establish that warming is occurring. The fact that nobody can construct even a semblance of a scientific model that explains these data without anthropogenic CO2 being the driver establishes convincingly the cause. And the paleoclimate is sufficient to establish that the consequences of rapid, significant warming can be severe indeed. The models are the only tools we have that could LIMIT how much we should be concerned. Right now it is the models that are suggesting scenarios by which we could limit the consequences of climate change without significantly harming our global economy. If the models are wrong, the upside risk of climate change cannot be limited, and arguments for draconiam measures are strengthened rather than weakened. That is why I keep telling responsible skeptics that the models are the best friends they have.