Environmental Tipping Points

Tipping points-where a small perturbation triggers a large response-can occur in many complex environmental systems. They produce abrupt and sometimes irreversible change, are inherently difficult to predict, and thus pose considerable challenges to the occupants and managers of those systems. However, tipping points can also represent opportunities. Here, different mathematical types of tipping points and different environmental processes that can give rise to them are distinguished. Then, I chart the crucial role that tipping points played in creating the modern Earth system. Looking ahead, potential large-scale tipping points are briefly reviewed before highlighting systems that could harbor tipping points across mechanisms and scales. The prospects for anticipating tipping points, avoiding dangerous ones, and encouraging others are outlined. Finally, a series of virtuous tipping points are identified, which can help transform the relationships between human societies and the environmental systems we depend upon.