Can't resist adding a point, since I just said something similar here:
http://www.iceinspace.com.au/forum/s...ad.php?t=84528
(Hope that works, it's the faster than light thread.)
Briefly, my point is that science is an
integrated body of knowledge, so that all the different things known in science support each other and can't be viewed in isolation. Claim one thing is wrong, and you are generally forced to accept a whole bunch of other things must be wrong too. This narrows down what can 'reasonably' be questioned - not because 'scientists say so', but because there are things we really
know on the basis that so much stuff works as a result.
In climate science, we
know that burning CO2 is warming the globe because the science that tells us this is the same basic science that makes aeroplanes stay up (fluid dynamics), runs refrigerators (thermodynamics), produces materials (chemistry) and makes TV and radio work (electrodynamics).
Of course, the climate is wildly complicated,which is why (a) there are specific behaviours which are not understood, even though the basics are and (b) scientists continue to research it.
If you're going to say the basic proposition of global warming is wrong, you need to explain why you think the planes stay up and the fridges still run, event though the science behind them is wrong.
I've never heard a 'sceptic' (the inverted commas are important) even try to explain this.