Well, the problem here is that we're talking about a possible run away greenhouse effect that will condemn most of humanity to death. The point being is that

Well, the problem here is that we're talking about a possible run away greenhouse effect that will condemn most of humanity to death. The point being is that you must act now in order to stop it and that this is the rational approach even if you do not have conclusive evidence. Your gamble is an unacceptable risk, or so the principle would say. I spent a couple years living in mainland China with pollution so bad that you literally could barely see across the street. On many clear sky days you could look directly at the sun with no issue. I flew over the country to different cities dozens of times and always the entire country was covered in a thick smog for thousands of kilometres. We really have no idea here in North America of the scale of things going on. And China is going to massively increase their emissions in the coming decades.