Basically, the question is whether climate is stable, like a ball in a bowl, or metastable, like a ball on a flat spot on a hill, which, with a sufficient nudge will careen down the hill accelerating.

The Intergovernmental Panel on Climate Change is now warning that once that ball is pushed too hard, it will start accelerating on its own.

I tend to agree, particularly when one considers things like hydrates on the ocean floor, and the massive amount of organic material that would start to decompose and emit gasses in the tundra areas of the world.