1. But the rest of his point is that the variables that determine climate are so vast that no model can possibly reproduce it accurately, and he's right.
2. At best we have rough guesses with significant margins of error.
3. We do know the earth is almost certainly going to get warmer as we keep adding GHG, we just don't know how warm.
1. No he is wrong. To a layman like him, or likely you, this would make sense but here's an analogy: you have to predict how long it will take you to drive to the take-out place and bring dinner back for your family. What variables do you need to know to predict how long it will take ?
I would submit something like: traffic levels for your route at similar hours, and maybe emergency notices... the point being that you can pretty much predict how long it will take given two variables. With temperature it is two basic things: sunlight levels and CO2 concentration in the atmosphere.
2. You are at this point just repeating what you have heard armchair skeptics say. Let me ask you (without looking) what the IPCC prediction for temperature change is... the fact is that they have been pretty accurate.
3. I'm glad you said that... very true.