6.2.13 (HL)—Critical thresholds and tipping points

A tipping point is a threshold where reinforcing feedback can push a system into a substantially different, persistent state.

Name the pressure, threshold evidence, positive feedback and possible new equilibrium. Examples include Antarctic ice-sheet melting, slowing Atlantic thermohaline circulation, and an Amazon Rainforest–Cerrado transition; timing and reversibility remain uncertain.

For Antarctic ice, warming can increase melt and reduce reflective ice area, reinforcing energy absorption; the threshold concerns persistent state change rather than one dramatic day.

A credible claim identifies nonlinear response, reinforcing mechanism, possible persistence and uncertainty—not only a severe impact.

‘Tipping point’ does not mean sudden, exact or certainly irreversible in every case.