Abrupt Climate Change

TLDR

Large, abrupt, widespread climate changes have repeatedly occurred when the Earth system crosses thresholds, and human forcing may increase their probability, with unpredictable projections and potentially serious economic and ecological impacts. Policy‑makers should expand research, improve monitoring, and take actions to enhance the adaptability and resilience of ecosystems and economies in the face of abrupt climate change.

Abstract

Large, abrupt, and widespread climate changes with major impacts have occurred repeatedly in the past, when the Earth system was forced across thresholds. Although abrupt climate changes can occur for many reasons, it is conceivable that human forcing of climate change is increasing the probability of large, abrupt events. Were such an event to recur, the economic and ecological impacts could be large and potentially serious. Unpredictability exhibited near climate thresholds in simple models shows that some uncertainty will always be associated with projections. In light of these uncertainties, policy-makers should consider expanding research into abrupt climate change, improving monitoring systems, and taking actions designed to enhance the adaptability and resilience of ecosystems and economies.