And a reply just for Donutz.
Global warming due to increased atmospheric CO2 has never been proven in a scientific sense. Basically because the planet is such a complex thing with so many variables, it is damn near impossible to "prove". And we're not talking about mankind being the sole cause of all this, we're talking about mankind contributing just enough to be the tipping point. There is always going to be "wiggle room" for the deniers. Hell, we don't even know for certain what killed the dinosaurs or what caused or ended the last ice age. We don't even know where the "tipping point" is. Climate change advocates are never going to win the argument over climate change deniers. And it is tedious and a waste of time and energy to continue arguing.
That said, I definitely fall on the "if it walks like a duck and quacks like a duck" side of the debate.
In my mind, the best way to "win" the argument is to prove to climate change deniers that it is too expensive to continue down the "fossil fuel as energy" economic path. Case in point, the Alberta Oil Sands are only viable because of the current world price of oil, just like Gold Rush Alaska exists because of the price of gold.