YES!!!! Cars are evil!!!!! Don't you know? The Ice Age ended - know why? Cave men and their goddam SUVs that's why. The Mesopotamians drove cars, that's what caused the Holocene Maximum. The Roman chariots had internal combustion engines. And the Vikings, their ships actually ran on diesel.
Had to be, otherwise how could warming have happened?
OK all humor aside - it COULD be us this time, and the FACT that it has happened MANY times in the past, including within human history, with zero human involvement, does not necessarily mean that it's not us this time.
But it DOES mean that you can't just INFER that it's us because of the very rough overlap between the industrial revolution and the present warming / warmth (hottest year on record was 1998, it's been 9 years, I think we're entitled to question whether it's even still warmING).
And that inference, and our inability to prove that it's something else, is all the "proof" there is.
Since the Industrial Revolution began we humans have added CO2 to the atmosphere. The total increase, human and non-human combined, is 1 / 11,000ths of the atmosphere.