Frankly: I don't know. I don't know if it's 100% caused by humans, 0% caused by humans, or somewhere (could be anywhere, IMO) in between. *** I DO know that scientists are agreed that humans are the cause, but then scientists are ALSO agreed that the Earth has been much, much warmer during many periods of the past, and scientists are NOT agreed as to how that happened before - that is: how that happened WITHOUT humans. *** If they don't know what caused it before (but they KNOW for a FACT that it wasn't humans before), and they don't KNOW (they do NOT know for sure) what is causing it now, then why are they so convinced that it is humans causing it now? *** That's an honest question. I keep seeing studies that show that human activity MIGHT be A cause - typically studies related to CO2 levels. I've yet to see a study (and note: I'm no well-read expert on this subject or anything) that indicates humans MUST be a significant cause, or that humans MUST be the SOLE cause, or that humans MUST be the PRIMARY cause. *** As far as ***I*** know, the global warming -- WHICH IS DEFINITELY OCCURRING -- MIGHT be just another natural occurrence that has happened umpteen times in the past. *** As far as ***I*** know, the global warming MIGHT be entirely and solely the consequence of human activities *** as far as ***I*** know, the global warming MIGHT be PRIMARILY caused by either one of those things. ***I*** certainly don't know which.

Our planet has been slowly warming since the Ice Age. It was actually much warmer during the age of the dinosaurs. No SUV's running around.