"97% of scientists" don't know.
"97% of climate scientists" don't know.
97% of scientists can't do statistics, so don't know what the other 4% are doing.
A coupla hundred IPCC leading, contributing, and review authors don't know.
1,200 IPCC cited authors don't know.
2,500 IPCC reviewers don't know.
Rajendra K. Pachauri doesn't know, though he might know the time of the next train to Mumbai from Delhi - for his staff of course, he travels by limo or jet.
Barack Hussein Obama II doesn't know. (ya mean there's more than one?)
Al (green thru an' thru) Gore doesn't know, he's too busy selling out to the enemy.
Topnotch bloggers don't know.
The remainder of the world's population,
So why all the fuss, when nobody knows precisely what weather they'll see tomorrow? Because the Great and the Good, and the climate modellers, and Gavin Schmidt, and Kevin Trenberth, think they've got it pretty well pinned down, which is a word they rarely use of course. Michael ("two-graphs", to use his Sioux name) Mann thinks he knows, because he's sawn a few logs in his time, don'tcha know? Bill "Cry me a river" Mckibben thinks he knows because he saw the digits 350 in the flames of a burning bush, or something. Joe Romm thinks he knows, 'cos he's posted so many posts there must be a grain of truth in there somewhere. Obama doesn't know, and he really doesn't care, as long as he can tee-up on the 1st as usual next Tuesday.
Those who think they know are guessing. They're guessing because they're trying to out-guess natural processes which contribute to a chaotic climate system. "Contribute to"? - indeed, not all the processes which are known are known with any degree of certainty, and there must be many unknown contributing processes of equally unknown effect.
It's a bit like trying to build a television set from scratch. You stick the screen at the front, and the power supply at the back. You have a large box of components, but without a circuit board or manual you don't know which order the components have to be connected, nor in which order, nor the values of the components needed, nor which connections must be looped back to make the whole kit-and-caboodle work. You have a go anyway, using hints from the worlds greatest electronic experts. You twiddle the knobs, using your left hand 'cos your right's bandaged after multiple electric shocks. The screen flickers - a picture! The digits "42" appear - "42 what?" you yell. The answer is of course contained (or is it?) in "The Hitchhiker's guide to the Galaxy - a trilogy in four parts", which is the source of my blog "handle" - MostlyHarmless. If you haven't read it, do so - it's a great antidote to life, the universe, and everything.
Modelling bits of the climate system to understand those bits better is science. The models can be refined to give something close to the "right" answer. Trying to connect the partial models together to make a climate model is a waste of time, as now the problem of the interactions and feedbacks between the "bits" rears its head, that's insurmountable, and it's not science. It's not science because the models need to have artificial constraints built in at various levels and in various places, to stop them "running away" and producing chaotic and nonsensical results. The artificial constraints (bounds) are just limits - mustn't go higher than X, mustn't go lower than Y. The modellers know that the limits are necessary, but they don't know what negative feedbacks they represent, and so the models don't recreate the entire climate system. The best might seem to get close, but they've still got those fixed constraints. The climate has no fixed constraints.
Now you know even less than you thought you knew before you read through this post, take away my final message - it's not what you know that counts, it's what you know you don't know.