And here we have a textbook example of someone who doesn't understand the scientific method. NOTHING is 100% provable.
Very few people really understand this: A theory is only valid if both
1) It could be some how dis-proven and
2) No one has disproven it yet.
One other thing: You don't have to believe the Earth has heated. Even if I were to think that is has not happened yet. I would still think it a very bad idea to add an in-balance of carbon dioxide to the atmosphere.
Same argument for using sunblock. You say "I am not sunburned." Well maybe, maybe not. The redness is not that bad and it could be natural but either way we know that in the near future you WILL be sunburned if you stay in the sun without sunblock. It's stupid t say "I don't need sunblock because I am not now sunburned." So right now a lot of people are saying "we see warming" but it could be natural, hard to tell. We can argue about the data from the last 100 years but who cares it's the next 100 years we are worried about, and we all know there WILL be warming later if you don't do something.