The unusually warm temperatures were do to El Nino. Seriously, how much of a difference could global warming make in one year?
I would think one would have to keep in mind how active the sun is? More intensity, nence warmer water ... or volcanic activity on the sea floor causes it... ??
Good questions, too bad I'm a amateur "rocket scientist" and not an astroclimatologist. But I don't believe we could do it all by our lonesome or actually have as much influence as some say in a year. :-}