"I am talking about "man made global warming" to be clear."
In regards to the human race's contribution to global warming I think we should err on the side of caution. I believe that we, as humans, have contributed somewhat to global warnig (scientific modeling indicates that our activity does contribute but so does the production of methane gas from animals - imagine how much dinosaurs contributed.) I'll grant you that how much we contribute (in terms of overall percentages) is up to debate. Yet, if models prove that some of our activities as humans does contribute (an I believe that models are somewhat accurate) then, I think it would be wise to curb and/or limit our activities that contribute to global warming in ways that are possible.
Also, arguing that global warming has been going on since the beginning of time and is part of nature's cycle and thereby implying we should do nothing (which is what some on the right suggest) is like saying we should do nothing to prevent an asteroid from hitting the earth even if it is within the realm of our technology to do so since asteroids have struck the earth in the past.