Land cover, especially in the tropics, will continue to change—probably at increasing rates. This change will have multiple implications for human societies. There will be surprises, “black swans,” that will derail our best laid plans (51, 52). One unintended consequence is that the opening up of the forest frontier by agricultural expansion is bringing people into closer contact with the wild animal hosts of diseases that can spread through human populations (51). New zoonotic diseases are emerging with greater frequency—a major threat to humanity but one that defies prediction. New plant diseases and invasive animals and plants will also challenge future food production. These are just examples of a diversity of shocks that will inevitably introduce volatility into the continuing dynamic at the agriculture–environment nexus