And they know it's "man-made" because?
Because Al Gore said so thats how we know. It is heresy to question Al Gore or Obama or any other liberals who spout the global warming theology.
We have consensus.........................
And they know that it's warming in spite of evidence to the contrary because ... Once upon a time, I was in the middle of Pleistocene research. It didn't pay well and research grants were few and far between. Then along came the environmental movement and the requirements for environmental impact studies that lead the way to the real pot of gold: climate research. Woo hoo, life is good and everyone has jumped on the bandwagon with half assed studies, nonsense findings, and reports written from Wikipedia research. There is so much money being thrown around that everyone can cash in. The only ones excluded from the cash cow are those who suggest that this is nothing but a political phenomenon.
How do they know it wasn’t man made last time?