Originally Posted by DaveN007
What percentage of current climate change is caused by man?
That is EXACTLY the right question and the focus of furious research. I do not believe anybody can give a meaningful answer, yet. What can be clearly demonstrated is correlative evidence of a relationship between the expansion of the human population, increase in atmospheric greenhouse gases and increase in global temperatures. What cannot be demonstrated is a causal-deductive link among those factors. That's why it is called, "research" and not, "explained."
Most folks who actually review the data or work with the data believe that the correlative evidence is too compelling to reject out-of-hand. Also, some of the model outcomes are so awful that given the correlative evidence, it would be unconscionable NOT to determine the degree to which the global warming phenomenon is due to some aspect of Man's presence that can be ameliorated through changes under Man's control.
Finally, as Kirk mentioned earlier (I believe it was Kirk, may have been Prof), if the theory of human-induced global warming is wrong, but we act as though it is correct, what is the worst possible outcome? Conversely, if the theory of human-induced global warming is correct and we do NOTHING, what is the worst possible outcome? Those are the two boundary conditions within which are a large, probably infinitely large, set of responses. Are they not worthy of investigation?