conservative in its estimates? its conservative because the natural forcings are left out. the issue is what is the magnitude of the human forcings compared to the magnitude of the natural forcings. comparitively speaking, the natural forcings are much more significant the the human forcings. THATS WHY THEY LEFT THEM OUT!!!!!! i love how this issue has evolved from global warming to climate change and now the foundation for this arguement, which is humans do it, is getting flossed over. no one doubts the average temps are increasing. the problem is there are hacks that push this "humans warm planets" theory. as far as i'm concerned, if you want to engage in this debate, you need a sophmore level thermodynamics course. if you don't have the BASIC knowledge spare us all, please.