It's impossible to find evidence to prove that global warming isn't caused by humans because it's patently obvious it IS caused by human technologies--from carbon monoxide generated by automobiles and the cattle we farm to provide meat in massive quantities, to chlorinated fluorocarbons used in refrigerants and spray cans, to any God's quantities of other human-created and human-abused technologies/modalities you can name!
It's caused by humans because just stop and think, this wasn't happening pre-industrial ages alot believe its caused by carbon dioxide when it's caused by the spray deodorant companies, there is alot of evidence against them
Earth has gone through ice ages and tropical ages before. The last extreme we had was an ice age. Guess where we're going now? I'm not saying we're not contributing to things, and I certainly think we need to stop treating the air and the sea like trash cans. But the climate is bound to change, and we had better learn to live with it. Like we have a choice!