So far we have been tracking the worst case scenario models. If feedback loops like the release of the methane stored in the arctic permafrost begin to run away from us, it could get pretty bad. We haven't seen most of the warming yet - most of it has been going into the oceans, but now they are reaching their capacity.

The earth's climate is a complex system that is incredibly tricky to predict. But the more we know about it, the worse things seem to be. :(

http://www.yaleclimateconnections.org/2014/06/new-video-repo...

http://www.yaleclimateconnections.org/2013/02/video-on-froze...