CONCEPT
The Threshold Effect
Diamond's term for the point at which cumulative depletion produces qualitative shift in system behavior — when the system's operation moves from normal-despite-ongoing-depletion to sudden and often irreversible failure.
The threshold effect is a specific phase of resource depletion that Diamond identified across his archive of collapsed civilizations. Before the threshold, a system can absorb ongoing depletion while appearing to function normally — the forest continues to provide timber, the grasslands continue to support cattle, the fisheries continue to yield catches. After the threshold, the system's behavior changes rapidly and often irreversibly. The shift from functioning to failure is not gradual; it is sudden, because the system has been operating on a diminishing margin that collapses when the margin reaches zero. The threshold cannot be identified in advance; it is a property of the system's dynamics rather than a fixed quantity, and it becomes visible only in retrospect.
In The You On AI Field Guide
Diamond documented the phenomenon across ecological systems with particular clarity. Soil fertility declines gradually with overgrazing, but at some threshold the topsoil loses cohesion and erodes catastrophically, producing a sudden loss of agricultural capacity that gradual replanting