and there is no conclusive proof that cigarette smoking causes lung disease. No, really, there has never been an observation of a cell mutating after exposure to a puff of smoke. The evidence is only statistical. And yet... reasonable people can accept that the odds are that smoking is unhealthy, in spite of the lack of "hard" scientific proof. Proof of the kind that Climate Change Deniers seem to be demanding. Arctic ice that is 60% thinner than it was when our first nuclear sub crossed under it in the 60s, Old photos of curling (that obscure shuffle board type sport) on fjords that haven't frozen over in decades, the no longer needed fleet of ice breakers on our Great Lakes, fauna found further and further north every year, tree rings, ice cores, historical records...all prove...nothing...but still, reasonable people can conclude that there is a link between our draining of the carbon sinks, and greenhouse warming. It's really not a stretch is it?