Ars Technica: Yesterday, the National Research Council (a branch of the US' National Academies of Science) released a report in which it called for the creation of an early warning system that would let us know when we're approaching tipping points in the climate.
While talk of climate tipping points is fairly common, most of it focuses on the climate itself changing to a new state. The new report is quite different, in that it's focused on things that can enter new states even when the climate is only changing...