For balance, there is a good level of scientific discussion of the pros and cons of global warming at:
http://www.global-warming-debate.com/
Many scientists active in the field post at this site. You will see that the consensus amongst serious climate scientists is that this is real. That a few high profile scientists disagree does not change that consensus.
That climate changes naturally is undeniable - we all know about Ice Ages. That the climate has been warmer than at present is also undeniable (indeed in the Cretaceous it was probably much warmer). However, the climate appears to be changing more rapidly now than the historic record shows, and these changes are pretty much those that are predicted by the Global Climate Models (which are rather more sophisticated than some here would have you believe).
Dr D.