Fred Guterl in Scientific American:
The true gloomsters are scientists who look at climate through the lens of “dynamical systems,” a mathematics that describes things that tend to change suddenly and are difficult to predict. It is the mathematics of the tipping point—the moment at which a “system” that has been changing slowly and predictably will suddenly “flip.” The colloquial example is the straw that breaks that camel's back. Or you can also think of it as a ship that is stable until it tips too far in one direction and then capsizes. In this view, Earth's climate is, or could soon be, ready to capsize, causing sudden, perhaps catastrophic, changes. And once it capsizes, it could be next to impossible to right it again.
The idea that climate behaves like a dynamical system addresses some of the key shortcomings of the conventional view of climate change—the view that looks at the planet as a whole, in terms of averages. A dynamical systems approach, by contrast, consider climate as a sum of many different parts, each with its own properties, all of them interdependent in ways that are hard to predict.