Here is another good summary of the issue http://www.freerepublic.com/focus/f-news/1732479/posts
...Now imagine that all the variables about global climate are known with less than 100 percent certainty. Let's be wildly and unrealistically optimistic and say that climate scientists know each variable to 99 percent certainty! (No such thing, of course). And let's optimistically suppose there are only one-hundred x's, y's, and z's --- all the variables that can change the climate: like the amount of cloud cover over Antarctica, the changing ocean currents in the South Pacific, Mount Helena venting, sun spots, Chinese factories burning more coal every year, evaporation of ocean water (the biggest "greenhouse" gas), the wobbles of earth orbit around the sun, and yes, the multifarious fartings of billions of living creatures on the face of the earth, minus, of course, all the trillions of plants and algae that gobble up all the CO2, nitrogen-containing molecules, and sulfur-smelling exhalations spewed out by all of us animals. Got that? It all goes into our best math model.So in the best case, the smartest climatologist in the world will know 100 variables, each one to an accuracy of 99 percent. Want to know what the probability of our spiffiest math model would be, if that perfect world existed? Have you ever multiplied (99/100) by itself 100 times? According to the Google calculator, it equals a little more than 36.6 percent.
The Bottom line: our best imaginable model has a total probability of one out of three. How many billions of dollars in Kyoto money are we going to spend on that chance?
Or should we just blow it at the dog races?
So all ye of global warming faith, rejoice in the ambiguity that real life presents to all of us. Neither planetary catastrophe nor paradise on earth are sure bets. Sorry about that. (Consider growing up, instead.)
That's why human-caused global warming is an hypothesis, not a fact. Anybody who says otherwise isn't doing science, but trying to sell you a bill of goods.
Probably.