Which statement describes Scheffer and colleagues' argument about ecosystems?

Which statement describes Scheffer and colleagues' argument about ecosystems?

• A. Ecosystems change gradually in a linear fashion.
• B. Ecosystems can undergo sudden, irreversible shifts due to small pressures; tipping points.
• C. Ecosystems are perfectly predictable.
• D. Catastrophic shifts are impossible in natural systems.

Answer: (A)

Ecosystems can sit in a stable state until a small amount of pressure pushes them past a tipping point, at which moment the system undergoes a rapid, often irreversible shift to a different regime. This happens because feedbacks within the ecosystem create alternate stable states, so once the threshold is crossed the old state loses resilience and the new state becomes self-reinforcing. The result is non-linear behavior: a little stress can trigger a big change rather than a smooth, gradual response. This idea also means ecosystems aren’t perfectly predictable; sudden transitions can occur even when changes seem modest, and returning to the original state can be difficult or impossible because the conditions that stabilized the former state are no longer present. For example, a lake might flip quickly from clear to turbid with small increases in nutrients, or a coral reef might shift to an algae-dominated system after prolonged stress.

Ecosystems can sit in a stable state until a small amount of pressure pushes them past a tipping point, at which moment the system undergoes a rapid, often irreversible shift to a different regime. This happens because feedbacks within the ecosystem create alternate stable states, so once the threshold is crossed the old state loses resilience and the new state becomes self-reinforcing. The result is non-linear behavior: a little stress can trigger a big change rather than a smooth, gradual response. This idea also means ecosystems aren’t perfectly predictable; sudden transitions can occur even when changes seem modest, and returning to the original state can be difficult or impossible because the conditions that stabilized the former state are no longer present. For example, a lake might flip quickly from clear to turbid with small increases in nutrients, or a coral reef might shift to an algae-dominated system after prolonged stress.