What evidence is there to make us think global warming exists?

Answer 1

Well, there's the hole in the atmosphere over Antarctica which is causing warmer winds from the Pacific to blow over the Arctic Circle. That's causing the ice and snow to melt even more than usual. Recently, scientists have said this is now bad enough that polar bears in the Arctic are suffering. The winds from the Arctic are generally mild, but with the extra winds across it, they are speeding up, causing the increase in storms across the Atlantic. I'd say that's quite a bit of evidence.