Global warming

It's exreme winter as it's very warm these days. I was arguing with my friends that sth like this happens every 50-100 years. But they insist that it's result of the global warming. They say, that it can be extremely cold one winter and then next winter in the same place it would be extremely warm. Hmm, I don't know. I still think that it's not possible. At least I hope so. Anyway, I really enjoy warm winter!