I'm not a global warming naysayer, but are humans solely to blame for this? How much of it would have happened anyway? (I'm thinking of the sun's 11-year cycle and the recent larger-than-normal volcano activity)
Um, maybe other people have already tried to answer those questions?
The answer is that the majority(*) of warming is due to human activity.
(As for the solar cycle - it's pretty obvious that an 11 year cycle can't make a 30 odd year trend).
(What "recent" larger than normal volcano activity? Also large volcanic events tend to reduce global temperatures.)
(* scientists tend not to say "all", there might be a little bit of warming coming from somewhere else).