Nobelist Mario Molina sums up why deniers of climate science are so misled in their assumptions (via NY Times Dot Earth):
"They convey the idea that the science in question behaves like a house of cards: if you remove just one of them, the whole structure falls apart. However, this is certainly not the way the science of complex systems has evolved. A much better analogy is a jigsaw puzzle: many pieces are missing, and some might even be in the wrong place, but there is little doubt that the overall image is clear, namely that climate change is a serious threat that needs to be urgently addressed. It is also clear that modest amounts of warming will have both positive and negative impacts, but above about 4 or 5 degrees Fahrenheit most impacts turn negative for many ecological systems, and for most nations."