The evidence for climate change isn't just in weather records for the past hundred years or so, but in understanding the physics. The Earth "normally" has a temp about 30 deg C above that you would calculate from the Planck Theory of heat radiation. That is due to Greenhouse effect of CO2 and other gases with optical absorption bands around 10-15 microns. During the industrial age we have nearly doubled the CO2 levels in the atmosphere and the amount is about half that released by fossil fuel burning. (the rest was mostly absorbed int he oceans making them more acidic.) Isotopic analysis shows that the added CO2 came from fossil fuel. I recommend an excellent article in the Jan. 2011 "Physics Today."

If a kid is batting baseballs at a house, d owe have to wait till he has broken a window to predict that eventually he will?