The problem I see is that the opponents to the concept of global warming look at a number like 1 to 1.5 degree warming and say "so what?" What they fail to comprehend is the fragility of many environments and that small a tempersture rise is significant. As one ecosystem fails, so do others in a domino effect.

Decomposition of massive amounts of organic material in the Arctic Circle floods the atmosphere with carbon dioxide. This too begins a cascading event with even more warming due to the atmospheric greenhouse effect. This in turn accelerates the global waming cascade.

We are going to find out very soon if we don't change our dependence on fossil fuel. I think it will be devastating to humans way of life, maybe even an extinction event.