There is no proof it is going to happen. No way to prove it for sure.
Global warming is happening, the debate is over how much humans are impacting it. Personally, I don't think we are making that big of an impact. The Earth naturally goes through warmer and colder cycles (think - Ice Ages) and this is just part of a warmer cycle. No doubt we are impacting it some, but I don't believe it's significant enough.