Paleoclimate-conditioning reveals a North Africa land–atmosphere tipping point

Significance Understanding of climate “tipping points” is extremely limited. Their representation within Earth System models (ESMs) is completely unconstrained because of a lack of any actual occurrences of these events in recent times. As an example, most ESMs fail to simulate the rapid desertification of the Sahara during the Holocene. Here, we overcome this by tuning uncertain aspects of one ESM using the climate of 6,000 y ago. This approach reveals a hitherto-absent tipping point within this ESM that produces excellent agreement between the modeled and observed timing of abrupt change in North Africa. This demonstrates how paleoclimate information can be used to radically improve the representation of abrupt changes in the ESMs that are employed for future projections.